Pediatric Annals

CLASSIFICATION AND CLINICAL FEATURES OF EPILEPTIC SEIZURES

Samuel Livingston, MD; Lydia L Pauli, MD; Irving Pruce; Anna Maria Zobniw, R EEG T

Abstract

In this article we will discuss how the epileptic disorders have been classified into three main Types, how epileptic seizures have been classified into various types - grand mal, petit mal, etc. - according to their signs and symptoms, and the clinical features of the various types of seizures the pediatrician is likely to encounter in his practice.

HOW THE EPILEPSIES ARE CLASSIFIED

The epilepsies have been broadly classified into three types - idiopathic, secondary or organic, and symptomatic epilepsy.

Idiopathic epilepsy is the designation given convulsions or seizures in patients in whom no cerebral lesion can be demonstrated. This form is also known as cryptogenic, essential, genetic, primary, pure, and true epilepsy.

Secondary epilepsy (organic epilepsy) is the name given to a seizure condition that develops after nonprogressive, "nonspecific" permanent cerebral changes or damage have occurred. Examples of secondary epilepsy are the recurrent seizures that develop in many patients who have sustained brain injuries in association with birth or cerebral infections.

Symptomatic epilepsy is the name given seizures that appear as one of the clinical manifestations of a specific disorder affecting the brain. Among such disorders are SturgeWeber syndrome, tuberous sclerosis, and cerebral degenerative diseases.

It can be seen that this classification, while traditional, is not entirely correct. In differentiating idiopathic from secondary epilepsy, it makes the presence or absence of brain damage the distinctive difference. One might assume from this that seizures in patients with secondary epilepsy are caused solely by brain damage. Such is hardly the case; if brain damage were the only cause of an epileptic seizure in secondary epilepsy, the seizure would be continuous, since the lesion would be constantly present.

Obviously there must be other factors that operate, since we know that seizures in braindamaged people do not occur constantly but only on certain occasions. Another difficulty with the classification can be seen in the case of two children who have received what appear to be identical insults to the brain during birth. One child develops epilepsy, the other does not, yet both have received irreversible cerebral injury.

So one must remember that brain injury is not the exclusive cause of convulsions. The high incidence of recurrent seizures in patients with cerebral lesions points to the probability that damage to brain tissue, nevertheless, does play a great part in the causation of epileptic seizures.

On the other hand, the terms "idiopathic" and "cryptogenic" suggest that no cerebral damage is associated with such seizures. This assumption also is not justified. It is reasonable to assume that some type of anatomic, metabolic, or physiologic cerebral defect must be present in all patients with epilepsy; therefore, all that can be stated candidly is that the presence of cerebral lesions in patients with "idiopathic" epilepsy cannot be demonstrated with the available diagnostic techniques.

The unknown factor or factors responsible for seizures in patients with "secondary" epilepsy are, in all probability, essentially the same as those for "idiopathic" epilepsy. It may be that localized cerebral damage renders other areas of the brain, particularly the tissue immediately adjacent to the affected area, more susceptible to the unknown factor responsible for seizures. This may explain the elevated incidence of seizures in patients with organic lesions. Obviously, inert tissue, such as a cerebral scar, could not itself be the site of a cerebral discharge that causes a seizure.

HOW SEIZURES ARE CLASSIFIED

As John Hughlings Jackson stated more than 70 years ago, convulsions or seizures are due to the sudden, violent, and disorderly activity of cerebral neurons. Jackson employed the term "discharge" for such phenomena. In the intervening years, physiologic studies not…

In this article we will discuss how the epileptic disorders have been classified into three main Types, how epileptic seizures have been classified into various types - grand mal, petit mal, etc. - according to their signs and symptoms, and the clinical features of the various types of seizures the pediatrician is likely to encounter in his practice.

HOW THE EPILEPSIES ARE CLASSIFIED

The epilepsies have been broadly classified into three types - idiopathic, secondary or organic, and symptomatic epilepsy.

Idiopathic epilepsy is the designation given convulsions or seizures in patients in whom no cerebral lesion can be demonstrated. This form is also known as cryptogenic, essential, genetic, primary, pure, and true epilepsy.

Secondary epilepsy (organic epilepsy) is the name given to a seizure condition that develops after nonprogressive, "nonspecific" permanent cerebral changes or damage have occurred. Examples of secondary epilepsy are the recurrent seizures that develop in many patients who have sustained brain injuries in association with birth or cerebral infections.

Symptomatic epilepsy is the name given seizures that appear as one of the clinical manifestations of a specific disorder affecting the brain. Among such disorders are SturgeWeber syndrome, tuberous sclerosis, and cerebral degenerative diseases.

It can be seen that this classification, while traditional, is not entirely correct. In differentiating idiopathic from secondary epilepsy, it makes the presence or absence of brain damage the distinctive difference. One might assume from this that seizures in patients with secondary epilepsy are caused solely by brain damage. Such is hardly the case; if brain damage were the only cause of an epileptic seizure in secondary epilepsy, the seizure would be continuous, since the lesion would be constantly present.

Obviously there must be other factors that operate, since we know that seizures in braindamaged people do not occur constantly but only on certain occasions. Another difficulty with the classification can be seen in the case of two children who have received what appear to be identical insults to the brain during birth. One child develops epilepsy, the other does not, yet both have received irreversible cerebral injury.

So one must remember that brain injury is not the exclusive cause of convulsions. The high incidence of recurrent seizures in patients with cerebral lesions points to the probability that damage to brain tissue, nevertheless, does play a great part in the causation of epileptic seizures.

On the other hand, the terms "idiopathic" and "cryptogenic" suggest that no cerebral damage is associated with such seizures. This assumption also is not justified. It is reasonable to assume that some type of anatomic, metabolic, or physiologic cerebral defect must be present in all patients with epilepsy; therefore, all that can be stated candidly is that the presence of cerebral lesions in patients with "idiopathic" epilepsy cannot be demonstrated with the available diagnostic techniques.

The unknown factor or factors responsible for seizures in patients with "secondary" epilepsy are, in all probability, essentially the same as those for "idiopathic" epilepsy. It may be that localized cerebral damage renders other areas of the brain, particularly the tissue immediately adjacent to the affected area, more susceptible to the unknown factor responsible for seizures. This may explain the elevated incidence of seizures in patients with organic lesions. Obviously, inert tissue, such as a cerebral scar, could not itself be the site of a cerebral discharge that causes a seizure.

HOW SEIZURES ARE CLASSIFIED

As John Hughlings Jackson stated more than 70 years ago, convulsions or seizures are due to the sudden, violent, and disorderly activity of cerebral neurons. Jackson employed the term "discharge" for such phenomena. In the intervening years, physiologic studies not possible in Jackson's time, including electric stimulation and electroencephalographic investigation, have amply confirmed his theory.

The clinical manifestation of the epileptic attack may take many forms, depending on the site of origin and the intensity and the spread of the abnormal discharge. Seizures are classified by most physicians into specific types by the use of one or more of these three factors: clinical manifestations of the attack, the EEG findings, and the presumptive anatomic site (or origin) of the neuronal discharge.

Some physicians, however, still adhere to the classification method in use many years ago, before electroencephalography was available. Then the duration of the seizure was the distinguishing mark; seizures of momentary duration - particularly those unassociated with clonic movements - were designated as petit mal in type. Those of longer duration were designated grand-mal convulsions. Used in this manner, the terms petit mal and grand mal lack specific meaning, since they refer not to the type of seizure but, rather, to its duration. Historically, these terms go back more than 150 years, having been introduced by Esquirol1 in 1815.

Epileptic seizures of brief duration occur in patients other than those with petit-mal epilepsy. Brief seizures are also encountered in patients with myoclonic epilepsy, in some patients with psychomotor (temporal-lobe) epilepsy, and also in some with autonomic epilepsy.

The classification of epileptic seizures varies from author to author and from one medical discipline to another, so that the reader is often confronted with a myriad of interchangeable, complex, and confusing descriptive terms. Such inconsistency in nomenclature and nosology is undoubtedly responsible for some of the confounding and contradictory reports relative to the treatment and, more important, to the prognosis of epilepsy. Therefore, in order to lessen the likelihood of confusion, we direct attention to some of the different terms that are currently employed to designate the same type of epileptic seizure. For example, some physicians utilize the term "absence" to categorize the clinical spell associated with the classic three-per-second spike and wave-electric discharge, whereas we designate this seizure petit mal. The term "partial seizure with complex symptomatology" is employed by some authors to classify the seizure pattern that we designate as pyschomotor or temporal-lobe. To aggravate an already perplexing situation, psychomotor attacks have recently been classified as "absence" seizures.2

Some physicians categorize all forms of epilepsy as "focal epilepsy" when the electroencephalogram displays a focal abnormality, regardless of the clinical manifestations of the attack. Many authors classify psychomotor epilepsy as "focal epilepsy" because most patients with this type of epileptic -disorder present electroencephalographic aberrations, usually spikes, limited to the anterior temporal area of the brain. Other physicians designate clinical generalized major-motor (grand-mal) epilepsy as "focal epilepsy" when the electroencephalogram exhibits unilateral electric discharges.

The term "Jacksonian" is used very loosely in the medical literature, and many patients who experience focal major-motor seizures of the clonic type are classified as having "Jacksonian" seizures. A typical Jacksonian seizure is one that commences with clonic movements of one part of the body (the hand, for example) that rapidly spread to involve that entire side of the body. The clonic movements then spread in a similar fashion on the other side of the body and finally terminate in a generalized convulsion of the grand-mal type. During the interval when the convulsive motions are spreading over the body, the patient usually maintains consciousness. When the seizure becomes generalized, however, the patient loses consciousness, just as with other types of generalized major-motor seizures. It has been our experience that true Jacksonian seizures are rarely encountered in children.

Gastaut3 has recommended that epileptic seizures be classified into four groups: (1) partial seizures or seizures beginning locally with elementary or complex symptoms - includes Jacksonian and psychomotor seizures; (2) generalized seizures (bilaterally symmetric or without local onset) - includes grand-mal, petit-mal, and myoclonic seizures; (3) unilateral or predominantly unilateral seizures; and (4) unclassified seizures - includes all seizures that cannot be classified because of inadequate or incomplete data. This categorization forms the basis for the almost interminable list of seizure types and patterns that comprise the International Classification of Epileptic Seizures.

The difficulties associated with the formulation of a useful classification of epileptic seizures have been aptly described by Marsden.4 A number of nosologic presentations with modifications have been proposed by the International League Against Epilepsy3,5 as an endeavor to secure worldwide uniformity in the terminology of seizure patterns. These international classifications have been accepted by some neurologists and academicians but have not been adopted by most clinicians.

The prime purpose of any classification is to serve as a guide to treatment and prognosis. Experience has demonstrated that the International Classification is by and large inappropriate6 and unnecessarily elaborate7 for clinical practice. And so in this article we are using the simple and familiar designations that are clinically meaningful. This classification is a purely pragmatic one, based on direct clinical observations and electroencephalographic studies of some 32,000 epileptic patients, predominantly children, who have been evaluated in our clinic during the past 43 years.

MAJOR-MOTOR (GRAND-MAL) EPILEPSY

Major-motor seizures are the most frequent of the epileptic attacks encountered in children. Approximately 80 per cent of epileptic children exhibit this type of seizure either in combination with other types of seizures (mixed epilepsy) or as the only manifestation of their epileptic disorder.

Clinical characteristics of major-motor epilepsy vary considerably from one patient to another. The most common expression of this type of epilepsy is the classic tonic-clonic seizure, the clinical features of which are certainly well known to all physicians. In addition to the tonic-clonic attack, there are three other generalized major-motor seizures that are encountered in children with epilepsy:

Tonic: During this seizure, the musculature remains in a tonic or boardlike state throughout the attack.

Clonic: This type begins with rapid jerking movements of the muscles that continue throughout the acute stages of the seizure.

Atonic: The patient suddenly crumples and falls to the floor unconscious. Musculature remains flaccid until the seizure ends. No apparent clonic or tonic stage is associated with this seizure type. Some authors use the words drop seizure, akinetic seizure, or inhibitory to describe this type of grand-mal attack.

The clinical manifestations of a majormotor seizure may be entirely generalized or completely focal or may begin in a focal fashion and then become generalized. The salient feature of a generalized grand-mal seizure is loss of consciousness, whereas no apparent impairment of consciousness is generally associated with a focal major-motor seizure.

Focal major-motor seizures are most frequently of the clonic type, but they may also be of the tonic, tonic-clonic, or atonic form. Atonic focal major-motor seizures are not commonly observed in children.

Electroencephalograms of patients with major-motor seizures may show a variety of electric aberrations when taken between seizures. Abnormally slow waves, extraordinarily fast waves, independent spikes, and atypical spike-wave forms are seen (Figure 1). But the pediatrician must remember that the incidence of normal EEGs is very high in patients with unequivocal clinical evidence of grandmal epilepsy, especially if they are young children.

During the seizure, however, the EEG is dramatic. Figures 2A to 2F show parts of the electroencephalogram of a five-year-old boy during a generalized major-motor tonic seizure.

Status epilepticus is a term that lacks a universally accepted definition; the interpretation varies from physician to physician and from clinic to clinic. Many physicians use the designation to refer to a series of recurrent major seizures. Others include all types of prolonged seizure activity in this classification. Obviously, such nosologic inconsistency has led to pronounced differences of opinion regarding the etiologic, therapeutic, and prognostic aspects of this type of epileptic disturbance. Thus the following definitions are in order:

Figure 1. An Interseizure EEG of a child with generalized major-motor (grand-mal) epilepsy. This record was obtained during light sleep ot seven-year-old child, artificially induced by chloral hydrate. Note trie short burst of spike-wave forms. The tracing revealed normal findings during the other three phases (awake, voluntary hyperventilation, and intermittent photic stimulation) of the electroencephalographic study.

Figure 1. An Interseizure EEG of a child with generalized major-motor (grand-mal) epilepsy. This record was obtained during light sleep ot seven-year-old child, artificially induced by chloral hydrate. Note trie short burst of spike-wave forms. The tracing revealed normal findings during the other three phases (awake, voluntary hyperventilation, and intermittent photic stimulation) of the electroencephalographic study.

Major-motor (grand-mal) status refers to a state in which the patient has recurrent major-motor seizures without regaining consciousness between seizures. This disorder may continue for three or four days, or even longer.

Serial major-motor (grand-mal) seizures refer to a state in which the patient has recurrent major-motor seizures but regains consciousness between seizures. Serial majormotor seizures are frequently encountered when the patient withdraws abruptly from anticonvulsant medication. The condition may also continue for three or four days or longer.

Prolonged major-motor (grand-mal) epileptic seizures are convulsions in which the active stages (generally the clonic aspects) are of long duration. The active phases of prolonged seizures are almost always followed by a postconvulsive state lasting much longer than in patients with major seizures of average duration.

Although prolonged grand-mal convulsions are usually generalized, focal prolonged seizures are occasionally observed. This latter type of prolonged seizure is referred to in the older medical literature as epilepsia partialis continua.

The criterion in distinguishing between a prolonged major seizure, which may last three to four hours or even longer, and majormotor status epilepticus is that in the former condition the patient does not have a recurence of the tonic or clonic aspects after the termination of the seizure.

Figure 2. EEG of boy taken during generalized major-motor (grand mal) seizure. This five-year-old had a major-motor tonic seizure while the examination was being performed. The seizure began at the point marked by the arrow on 2-A and lasted for approximately one minute (2-B, C1 D, and E), terminating at the point marked with the double arrow on 2-E. The postconvulsive phase lasted about 10 minutes. It consisted of marked drowsiness and was characterized by high-voltage slow-wave activity, ending with the return of normal electrical activity (2-F).

Figure 2. EEG of boy taken during generalized major-motor (grand mal) seizure. This five-year-old had a major-motor tonic seizure while the examination was being performed. The seizure began at the point marked by the arrow on 2-A and lasted for approximately one minute (2-B, C1 D, and E), terminating at the point marked with the double arrow on 2-E. The postconvulsive phase lasted about 10 minutes. It consisted of marked drowsiness and was characterized by high-voltage slow-wave activity, ending with the return of normal electrical activity (2-F).

Figure 2. EEG of boy taken during generalized major-motor (grand mal) seizure. This five-year-old had a major-motor tonic seizure while the examination was being performed. The seizure began at the point marked by the arrow on 2-A and lasted for approximately one minute (2-B, C1 D, and E), terminating at the point marked with the double arrow on 2-E. The postconvulsive phase lasted about 10 minutes. It consisted of marked drowsiness and was characterized by high-voltage slow-wave activity, ending with the return of normal electrical activity (2-F).

Figure 2. EEG of boy taken during generalized major-motor (grand mal) seizure. This five-year-old had a major-motor tonic seizure while the examination was being performed. The seizure began at the point marked by the arrow on 2-A and lasted for approximately one minute (2-B, C1 D, and E), terminating at the point marked with the double arrow on 2-E. The postconvulsive phase lasted about 10 minutes. It consisted of marked drowsiness and was characterized by high-voltage slow-wave activity, ending with the return of normal electrical activity (2-F).

PETIT MAL

In 1906, Friedmann8 described a condition clinically similar to petit-mal spells. He considered the disturbance to be a form of narcolepsy and classified the episodes as "short narcoleptic attacks." Adie's9 description of pyknolepsy, in 1924, is similar in many ways to the entity we classify as petit-mal epilepsy. He defined pyknolepsy as "a disease with an explosive onset between the ages of four and twelve years, of frequent, short, very slight, monotonous minor epileptiform seizures of uniform severity, which recur almost daily for weeks, months or years, are uninfluenced by antiepileptic remedies, do not impede normal mental and physical development and ultimately cease spontaneously never to return." Attention is redirected to the fact that some authors classify the spells of petit-mal epilepsy as "absences."

The age at onset is one of the distinctive characteristics of this disorder. It almost always makes its initial appearance during childhood, with the seizure pattern most commonly beginning when the child is between four and eight years of age; petit mal rarely starts before the age of three or after the age of 15.10 More than 90 per cent of our patients experienced their initial petit-mal attack before the age of 13, and none of the patients had his initial spell after the age of 15.

Our experience indicates that petit-mal epilepsy seldom continues into adulthood. Of our controlled patients, 97 per cent were 20 years of age or younger at the time of cessation of the petit-mal spells, and only 12 per cent of our patients who were still having seizures at the time of this writing were over 20 years of age.

Incidence of petit-mal epilepsy is much lower than many people think. In our experience it must be considered relatively uncommon; of our total clinic population of 32,206, only 708 (2.2 per cent) satisfied our criteria for a diagnosis of petit-mal epilepsy. (This group of 32,206 included patients of all ages, among whom were some 4,000 adults who did not have an initial seizure of any type until after they were 21 years of age.)

Our experience that petit-mal has a relatively low incidence is in accordance with the views of Currier et al.11 that "petit mal is rare, existing in 2 to 3 per cent of a large series of adults and children with seizures and in 6 to 12 per cent of [a series consisting entirely of] children with seizures."

Clinical characteristics. Petit-mal spells are paroxysmal episodes of altered consciousness, usually lasting five to 30 seconds. The clinical manifestations vary somewhat, and because of this we have classified petit-mal seizures into these three types:

Simple petit-mal spells consist essentially of a sudden, vacant stare into space with or without an upward drifting of the eyes. This is the most frequently encountered type of petit-mal spell.

Petit-mal spells with clonic movements consist of the staring episode of simple petitmal spells with concomitant minor clonic movements of the eyelids, head, or upper extremities. These fine clonic motions recur at a frequency of three per second.

Petit-mal spells with automatisms consist of the staring episode of simple petit-mal spells with associated automatisms, usually repetitious smacking of the lips, chewing and swallowing movements, humming, and mumbling. It is important to note that similar automatisms are also observed in many patients with psychomotor (temporal-lobe) epilepsy.

A characteristic feature of a petit-mal spell is the absence of prodromal and postictal phenomena; the attack begins suddenly and terminates abruptly, and the patient is almost always able to continue the interrupted activity. Patients occasionally sway a little during a seizure but rarely fall, and in some instances, particularly in those with prolonged spells, there may be urinary incontinence.

Figure 3. Sample of EEG of 10-year-old child with petit-mal epilepsy shows classic electric discharge (three-persecond spike-wave forms), which lasted approximately 30 seconds. Patient had concomitant clinical petit-mal seizure.

Figure 3. Sample of EEG of 10-year-old child with petit-mal epilepsy shows classic electric discharge (three-persecond spike-wave forms), which lasted approximately 30 seconds. Patient had concomitant clinical petit-mal seizure.

We re-emphasize that petit-mal spells, whether or not associated with clonic movements or automatisms or both, are of brief duration, seldom lasting longer than 30 seconds.

The attacks recur daily, and some patients have as many as 50 to 100 a day. Although these spells may occur at any time of the day, many patients experience an increased incidence of seizures during the first few hours after awakening.

Figure 4. EEG of a 12-year-old child with psychomotor temporaMobe) epilepsy. This record was obtained during light sleep artificially induced by chloral hydrate. It shows spikes localized to the right anterior temporal area. The spikes were also observed during the awake state but were more numerous during sleep.

Figure 4. EEG of a 12-year-old child with psychomotor temporaMobe) epilepsy. This record was obtained during light sleep artificially induced by chloral hydrate. It shows spikes localized to the right anterior temporal area. The spikes were also observed during the awake state but were more numerous during sleep.

Clinical petit-mal episodes can be precipitated in essentially all patients by voluntary hyperventilation. In sensitive patients, the spells usually appear after a short period of hyperventilation (one to two minutes), while in others it may be necessary to continue hyperventilation for four or five minutes in order to evoke a seizure.

It has been our experience that certain psychomotor attacks are frequently misdiagnosed as petit-mal attacks - i.e., those that consist of interruption of activity immediately followed by a period of staring. It is imperative that such a mistake not be made, because the prognoses and treatments of the two conditions are quite different. The staring associated with a petit-mal episode is almost always of shorter duration than that encountered in a psychomotor seizure. In many of our patients with psychomotor attacks, the staring feature persists for five minutes or longer.

Figure 5. EEG of an 18-year-old man with major-motor (grand-mal) epilepsy shows a bilaterally synchronous burst of three-per-second spike-wave forms, most pronounced in the frontal leads, lasting approximately two seconds. This patient started having clinical petit-mal spells accompanied by bilaterally synchronous runs of three-per-second spike-wave discharges lasting about 15 seconds at eight years of age. The clinical petit-mal attacks were controlled by ethosuximide at nine years of age, but he developed grand-mal seizures at the age of 13 that have persisted to the time this EEG was recorded. The patient has been free of clinical petit-mal spells for the past nine years.

Figure 5. EEG of an 18-year-old man with major-motor (grand-mal) epilepsy shows a bilaterally synchronous burst of three-per-second spike-wave forms, most pronounced in the frontal leads, lasting approximately two seconds. This patient started having clinical petit-mal spells accompanied by bilaterally synchronous runs of three-per-second spike-wave discharges lasting about 15 seconds at eight years of age. The clinical petit-mal attacks were controlled by ethosuximide at nine years of age, but he developed grand-mal seizures at the age of 13 that have persisted to the time this EEG was recorded. The patient has been free of clinical petit-mal spells for the past nine years.

The most important method of differentiating between the seizures of psychomotor epilepsy and the spells of petit mal epilepsy is, of course, the electroencephalograph, and with an EEG the differentiation is easily made (Figures 3 and 4).

The electroencephalographic abnormality of petit-mal epilepsy is classic and consists of diffuse, bilaterally synchronous spike-andwave forms recurring at frequencies of two and one-half to four per second, but most commonly at three per second (Figure 3). This electric aberration occurs in most patients during the resting state; however, it may be necessary to hyperventilate some persons for prolonged periods to elicit this electroencephalographic seizure discharge. We emphasize that the three-per-second spike-andwave electrographic pattern is pathognomonic of petit-mal epilepsy.

In our patients with petit-mal spells there was a direct relationship between clinical seizure control and the disappearance from the electroencephalogram of the characteristic spike-wave abnormality. It should be noted, however, that some patients who have been rendered free of clinical petit-mal spells exhibit, particularly during hyperventilation, a short burst of a bilaterally synchronous spike-wave discharge, usually lasting one to two seconds. We classify this electrographic aberration as a remnant of the classic petitmal electric discharge (Figure 5).

Development of other types of epileptic seizures often occurs in patients with petit-mal epilepsy, particularly grand mal (Figure 6). Investigations conducted in our clinic10 have demonstrated that the incidence of development of grand-mal seizures subsequent to petit-mal epilepsy can be considerably reduced if the patient is managed with combined therapy - i.e., given a combination of a major-motor anticonvulsant and a specific anti- petit-mal medication. Our study group consisted of 100 patients. Fifty-nine were treated with both a major-motor anticonvulsant, such as phénobarbital, and a specific anti- petit-mal drug. Forty-one received only an anti- petit-mal drug, such as ethosuximide (Zarontin) or trimethadione (Tridione.) Twenty-one (36 per cent) of the 59 patients who received combined therapy developed grand-mal seizures, whereas 33 (81 per cent) of the 41 patients treated with a specific anti- petit-mal agent alone subsequently developed grand-mal convulsions (Table 1). The use of combined therapy in the treatment of petit-mal epilepsy will be discussed in detail in an article entitled "Medical Treatment of Epilepsy," which will appear in next month's issue of this journal.

Table

TABLE 1DEVELOPMENT OF GRAND MAL AS RELATED TO COMBINED THERAPY AND AGE AT ONSET OF PETIT MAL

TABLE 1

DEVELOPMENT OF GRAND MAL AS RELATED TO COMBINED THERAPY AND AGE AT ONSET OF PETIT MAL

Figure 6. Histogram showing ages of patients at onset of grand-mal seizures that developed after petit-mal spells.

Figure 6. Histogram showing ages of patients at onset of grand-mal seizures that developed after petit-mal spells.

Figure 6 shows the ages of the patients at the onset of the grand-mal seizures that developed subsequent to the petit-mal spells. Although it will be noted that these seizures developed at various ages, the most common age was 10 through 13 years.

Our findings indicate that the later the onset of petit-mal epilepsy, the more likely it is that the patient will develop other types of seizures. As shown in Table 1, 18 (95 per cent) of 19 patients whose petit-mal disorder began between the ages of 11 and 15 years subsequently developed major-motor seizures, as against 36 (44 per cent) of 81 patients who began having petit-mal spells between two and one-half and 10 years of age. This finding was also reported by Lennox,12 who stated, "... the later it [petit-mal epilepsy] begins, the greater are the chances of its being complicated by other forms of epilepsy."

It has been our experience that majormotor seizures that develop subsequent to petit-mal spells are generally not as severe, do not recur as frequently, and are less difficult to control than those that are unassociated with petit-mal epilepsy.

Petit-mal status refers to a state of recurring petit-mal spells that are almost continuous. During these spells the patient frequently appears disoriented and confused but usually is able to walk about and function to the extent that medication and nourishment can be taken orally. During these attacks, patients frequently display purposeless, stereotyped motor or psychic behavior. These episodes usually last five to 10 minutes, but in some cases they persist for 24 hours or longer. Prolonged attacks of petit-mal status are frequently associated with bizarre behavior simulating a protracted psychomotor seizure or a psychiatric disorder. A positive diagnosis of petit-mal status in such instances can be established electroencephalographically.

In our experience, the electroencephalogram obtained during an episode of petit-mal status usually reveals almost continuous classic petit-mal spike-wave discharges interrupted by periodic brief runs of normal electrical activity (Figure 7).

Brain damage and petit mal usually are not associated unless the patient has petit-mal status. In our earlier writings13,14 we emphasized that petit-mal epilepsy does not commonly occur in patients with organic brain damage, and in a report made in 196510 we found that only six of 117 patients manifested brain damage before the onset of a petit-mal disorder (5.1 per cent). Lennox12 reported a similarly low incidence (4.5 per cent).

Brain damage only rarely occurs after the onset of petit-mal seizures, unless the patient has petit-mal status. Our 1965 investigation of 117 patients with "pure" petit-mal epilepsy10 demonstrated that brain damage in patients with petit mal was rare, regardless of the frequency of the spells or the duration of the petit-mal disorder - with the exception of patients with petit-mal status. At the termination of our 1965 study, 13 of the 117 subjects (11.1 per cent) were classified as braindamaged. Since six of these patients presented evidence of brain injury before the onset of the petit mal disorder, the brain damage in these patients could not be attributed to the petit-mal spells. Seven (6.3 per cent) of the 111 patients who did not manifest evidence of brain damage before the onset of the petit-mal epilepsy subsequently showed intellectual impairment; six of these seven patients had experienced frequent episodes of petit-mal status. Of the 117 patients, 11 suffered with attacks of petit-mal status, and six (54.5 per cent) of these 1 1 manifested evidence of brain damage at the termination of the investigation. Our studies thus definitely indicate that petit-mal status, when recurrent, is a serious disorder and is frequently associated with the development of brain damage.

PSYCHOMOTOR (TEMPORAL-LOBE) EPILEPSY

The ictal phenomena of psychomotor epilepsy vary considerably and consist of numerous, varied bizarre psychic or motor performances or a combination of both associated with a clouding of consciousness and partial or complete amnesia for the event.

Figure 7. Section of EEG of a 17-year-old girl obtained at the time she experienced an attack of petit-mal status that lasted 30 minutes. During this episode, the electrographic activity consisted of bursts of classic three-per-second spike and wave forms lasting from 10 to 15 seconds, interrupted by runs of normal electric activity of one second's duration.

Figure 7. Section of EEG of a 17-year-old girl obtained at the time she experienced an attack of petit-mal status that lasted 30 minutes. During this episode, the electrographic activity consisted of bursts of classic three-per-second spike and wave forms lasting from 10 to 15 seconds, interrupted by runs of normal electric activity of one second's duration.

Some physicians currently designate a psychomotor attack as a "partial seizure with complex symptomatology."

Age at onset. In our experience, psychomotor epilepsy is observed very infrequently in the young child. We have only occasionally encountered children under six years of age who presented electroencephalographic abnormalities limited to the anterior temporal area and classic ictal features, particularly automatisms, characteristic of psychomotor attacks in older children and adults. We concur with Gastaut,15 who considers psychomotor epilepsy to be "a disease of older children, of adolescence and of the first part of adult life."

The incidence of psychomotor epilepsy increases with advancing age. In 1954, we13 reported that 209 (5 per cent) of 4,158 epileptic children experienced psychomotor seizures, either in the "pure form" or in combination with other types of epilepsy. Although we have not calculated the exact incidence of psychomotor epilepsy in our current patient population, which is admittedly largely restricted to difficult and recalcitrant cases, we estimate that 10 to 15 per cent of our older patients and young adults under 21 years of age suffer with this form of epilepsy, either as their only manifestation of the disorder or in association with other types of epilepsy, particularly grand-mal seizures. Niedermeyer16 is not impressed with a high incidence of psychomotor epilepsy in children and states, "Among childhood epilepsies, temporal lobe epilepsy (with psychomotor seizures) probably occupies a segment of 1 to 2 per cent and certainly less than 5 per cent; in adult life, this segment will increase to 5 to 15 per cent."

Clinical manifestations: Because the seizures of psychomotor epilepsy are so diverse and varied, satisfactory classification of the clinical manifestations into distinct or precise categories is not readily achieved. Almost all current classifications of psychomotor epilepsy are subject to serious criticisms, and none appears to be entirely satisfactory. We are reluctantly forced to agree with Lennox,12 who, when confronted with the identical task, stated: "The grouping that follows is tentative. We are not fully satisfied, and doubtless other workers are even less pleased. . . . Nevertheless, an orderly mind demands that some assortment be made."

Study and follow-up of a large number of children with psychomotor epilepsy revealed that four seizure patterns could be identified most frequently: (1) arrest of activity with staring; (2) arrest of activity with staring and followed by simple and/or complex automatisms; (3) arrest of activity with staring, followed by pulling of the head and body to one side with concomitant automatisms; and (4) psychic seizures. Each of these will be discussed in turn.

Arrest of activity with staring. This is the simplest type of psychomotor attack. It is characterized by interruption of activity, followed immediately by a period of staring. Because the staring aspect usually is brief, this episode frequently is confused with a "simple" petit-mal spell. Careful observation, however, reveals that the staring feature of a simple petit-mal spell almost invariably is of shorter duration than that encountered in a psychomotor seizure, as was indicated above in the discussion of petit mal. As noted above, the differentiation of this form of psychomotor epilepsy from the spell of petit-mal epilepsy is easily accomplished with the use of the electroencephalograph (Figures 3 and 4).

Arrest of activity with staring, followed by simple andlor complex automatisms. This type of psychomotor attack consists of a sudden arrest of activity; the child stares and then makes repetitive, automatic movements, such as smacking his lips, mumbling, chewing, drooling, muttering, or humming. If the ictal activity does not terminate at this point, the patient may continue with other actions. He may pick at his clothes or attempt to remove them, search through purses or desk drawers, speak irrelevantly or unintelligibly, pick up and handle objects, walk or wander in a disoriented, confused manner, or exhibit other purposeless, inappropriate, bizarre abnormal behavioral patterns.

These apparently purposeless behavioral aberrations vary in character and nature from one patient to another but are relatively stereotyped in an individual patient and vary little from seizure to seizure. In almost all cases, awareness is obviously impaired, and amnesia for the attack is a relatively constant finding. These episodes are generally brief, lasting one to two minutes or so, but may persist for hours or even longer.

We have observed some patients who performed seemingly purposeful activities that required both physical and mental dexterity during a psychomotor seizure but who had no recollection of the episode, despite the fact that awareness was apparently maintained. Such cases are decidedly more frequent in adults than in children.

In our pediatric patients we have only rarely encountered the so-called epileptic fugues or fuguelike states in which a patient may wander away from home, successfully travel even by a complicated transportation system, and "come to" in a distant location with amnesia for the intervening events. Obviously, when the electroencephalogram lacks specific evidence of temporal-lobe dysfunction, such cases present a major diagnostic problem. We agree with Niedermeyer,16 who believes such automatic episodes are "very suspect of a psychogenic ('hysterical') dissociative state. ..."

In some instances, a patient may present grossly abnormal paroxysmal behavioral disorders, such as acts of violence, extreme antisocial activities, furious outbursts of temper, and rages. Accurate diagnosis in the absence of temporal-lobe electrographic discharges in such cases is usually very difficult, and the dilemma is aptly presented by Lennox:12 "Some of the persons in this area are clearly epileptic; others just as clearly are not. There is no line between the two, but a zone of undetermined breadth with markers made by the surveying authors." Markedly abnormal states of mind and personality equally resist definitive diagnosis.

Arrest of activity with staring, followed by pulling of the head and body to one side, with concomitant automatisms. This form of psychomotor seizure was encountered most frequently in those of our patients who had presented electrographic evidence of temporal-lobe dysfunction. Immediately following the cessation of activity and a brief period of staring, these patients display a "tightening of the muscles," with a pulling of the head and body to one side - usually with extension of the arm nearer the side to which the head and body are turning. The rotary aspect of this attack is accompanied by simple, usually oral, automatisms, such as chewing movements, licking, mumbling, lip smacking, puckering, or sucking. If the attack does not terminate with the pulling of the head and body to one side, the patient may subsequently perform any one or a combination of bizarre motor and/or psychic activities.

These seizures are generally brief, lasting several minutes or so. Return of consciousness is usually abrupt in the very short attack but in most instances is gradual. There is almost always complete amnesia for the episode. Precipitous falls and biting of the tongue rarely occur during the spell, but urinary incontinence is sometimes observed.

Psychic seizures. Under this heading are included numerous subjective symptoms that are exceedingly variable in character. Examples are hallucinations, delusions, illusions, reiterated experiences (déjà vu), seizures of pain and pleasure, compulsive crying and laughing, and changes in perception, thought, self-awareness, mood, and affect, which are thought to be primarily temporal-lobe in origin.

Psychic expressions of psychomotor epilepsy are generally of brief duration, usually lasting less than one or two minutes.

In the absence of specific electroencephalographic evidence of psychomotor epilepsy, the discrimination of psychic aberrations from hysteria, imagination, neurosis, and psychosis is a patently formidable task. Again, Lennox12 seems to have presented the most sagacious appraisal of this situation: "The burden of proof rests on anyone who contends that a given psychic episode, isolated from other evidence of epilepsy, is epileptic." We completely concur with his statement. Certainly psychic seizures represent one of our areas of greatest academic and clinical deficiency, and in most instances such episodes baffle the most skillful and experienced physician with regard to specific diagnosis and management.

Electroencephalographic findings. The classic electrographic abnormality of psychomotor epilepsy consists of spiking, slow-wave activity, or sharp waves localized to the anterior temporal area (Figure 4). Some children with this form of epilepsy present diffuse spikes, generalized spike-wave bursts, local spikes in areas other than the anterior temporal region, and midtemporal spikes. Occasionally, the interseizure electroencephalographic tracing may be normal.

MYOCLONIC EPILEPSY

Myoclonic jerks or twitchings occur in association with some cerebral degenerative diseases, such as subacute sclerosing panencephalitis (Dawson's subacute inclusion-body encephalitis) and progressive familial myoclonus epilepsy (Unverricht's disease).17 These can be observed in some patients with major-motor epilepsy just before the onset of a grand-mal seizure18 and in some with photic epilepsy.19 The discussion here will be limited to the childhood cerebral disorder that we classify as myoclonic epilepsy.

To date some 1,600 children with myoclonic epilepsy have been studied in our clinic. Myoclonic seizures had appeared during the first two years of life in 1,225 of them - most commonly between three and nine months of age. In the remaining 375, seizures had started most frequently between the ages of three and seven years.

Types of myoclonic epilepsy have thus been classified by us into two types, on this basis of age at onset.

1. Myoclonic epilepsy of infancy, occurring before the age of two. In previous writings we have referred to this form of epilepsy as minor-motor epilepsy. Infantile spasms, hypsarrbythmia, and massive myoclonic jerks or seizures are some other terms that have been used for this seizure pattern.

2. Myoclonic epilepsy of older children initially occurring during or after the third year of life. Some other names that have been given to this form are akinetic seizures, headdropping spells, Lennox's syndrome, Lennox-Gastaut syndrome, and petit-mal variant.

In 1969, we20 stated that these two types of myoclonic epilepsy are essentially the same entity presenting at different ages. Subsequent concurrent opinions have been expressed by Jeavons19 and Ohtahara et al.21

The clinical manifestations and mental impairment characteristic of infantile myoclonic epilepsy were first presented in 1841 by West,22 who reported the case of his own child. Sir Charles Clarke, of London, examined Dr. West's son and designated the attack as a "salaam convulsion." Other early writings on myoclonic epilepsy include those of Newnham23 in 1849 and Barnes24 in 1873. Lennox25 included these attacks in his "petit-mal triad," and we13 assigned the term "minor-motor epilepsy" to such seizures. The clinical features of myoclonic epilepsy of older children were described by Lennox in 194525 and I960,12 and pertinent findings were added by Gastaut et al.26 in 1966; consequently, the designation of "Lennox-Gastaut syndrome" was proposed by Niedermeyer.27,28

We do not believe that any form of epilepsy surpasses the myoclonic type in regard to nosologic confusion and inconsistency. In our opinion, this is due in large measure to the indiscriminate use of the terms "akinetic," "astatic," and "atonic," which are employed by many authors on an interchangeable and synonymous basis. A cursory review of the literature relative to myoclonic epilepsy8 of older children reveals a kaleidoscope of classificational designations - akinetic petit mal, astatic epilepsy, atonic epileptic seizures, centrencephalic myoclonic-astatic petit mal, childhood epileptic encephalopathy with diffuse, slow spike waves, childhood epileptic encephalopathy with slow spike waves and myoclonic epilepsy, drop seizures, headbobbing spells, head-dropping spells, Lennox's syndrome, Lennox-Gastaut syndrome, petit-mal variant, petit-mal variant with myoclonic jerks, severe myoclonic epilepsy, static seizures, and true myoclonic epilepsy of childhood. It is no wonder that the reader remains in a perpetual state of perplexity with regard to myoclonic epilepsy.

The solution, we feel, lies in using the terms defined by Lennox12 (see box). Those describing or categorizing the spells of myoclonic epilepsy would be well advised to use them.

Another attempt to organize the nosologic chaos of myoclonic seizures into a simplified, meaningful form was made recently by Jeavons.19 He separated them into six categories, based on a combination of clinical and electrographic features; infantile spasms, myoclonic astatic epilepsy, myoclonic absence, myoclonic epilepsy of childhood, myoclonic epilepsy of adolescence, and photomyoclonic epilepsy. We admire Jeavon's attempt to resolve the difficult classificational problems associated with myoclonic epilepsy but are not convinced that his designations will be of significant value to the clinician.

Figure 8. Typical flexor spasm of Infantile myoclonic epilepsy - recumbent position. (Courtesy of the Spastics Society Medical Education and Information Unit in association with William Heinemann Medical Books, London, from Infantile Spasms, by P. M. Jeavons and B. D. Bower, 1964.)

Figure 8. Typical flexor spasm of Infantile myoclonic epilepsy - recumbent position. (Courtesy of the Spastics Society Medical Education and Information Unit in association with William Heinemann Medical Books, London, from Infantile Spasms, by P. M. Jeavons and B. D. Bower, 1964.)

Clinical manifestaions. The predominant clinical feature of myoclonic epilepsy is a sudden flexor spasm of the body musculature, although extensor spasms are sometimes observed. The clinical manifestations vary, depending upon the posture of the patient.

Table

How to describe myoclonic seizures

How to describe myoclonic seizures

When the patient is recumbent, the myoclonic seizure most commonly consists of a sudden flexion of the head with a simultaneous outward thrust of the upper extremities and flexion of the thighs on the abdomen (Figure 8). It is sometimes preceded by a short cry, giggle, or laugh. The seizure varies somewhat in clinical features in different patients.

This type of myoclonic attack is encountered most often in the young infant, who, obviously, is in the recumbent position most of the time. It is currently usually designated as a massive myoclonic seizure, infantile myoclonic seizure, minor-motor seizure, infantile spasm, or hypsarrhythmia.

We have seen many patients who were considered by their parents as having ordinary abdominal pain and also some children who were diagnosed by their physicians as suffering with infantile colic when they actually had myoclonic epilepsy of infancy. This mistaken impression or diagnosis was entertained because the child initially issued a cry and then suddenly drew his or her thighs up on the abdomen as if in severe pain. In such cases, the diagnosis can be established electroencephalographically (Figure 9) if the physician cannot identify these two disorders on a clinical basis.

Figure T. EEG of a seven-month-old child with infantile myoclonic epilepsy. Onset of myoclonic seizures was at four months of age. Because of patient's age, this EEG could be performed only during sleep induced by secobarbital (Seconal). Note short burst of high-voltage, diffuse, fast spikes (polyspikes) and high-amplitude slow waves associated with high-voltage fast spikes (hypsarrhythmia). These electric aberrations recurred at least once every 10 seconds throughout the entire tracing.

Figure T. EEG of a seven-month-old child with infantile myoclonic epilepsy. Onset of myoclonic seizures was at four months of age. Because of patient's age, this EEG could be performed only during sleep induced by secobarbital (Seconal). Note short burst of high-voltage, diffuse, fast spikes (polyspikes) and high-amplitude slow waves associated with high-voltage fast spikes (hypsarrhythmia). These electric aberrations recurred at least once every 10 seconds throughout the entire tracing.

When the patient is sitting. The myoclonic attack in this position usually consists of a sudden jerk of the head (usually forward), with an associated outward thrust of the arms (Figure 10). This type of seizure will be found in infants with myoclonic epilepsy who are old enough to assume a sitting position. The seizure pattern is frequently described as a "head-bobbing," "head-dropping" or "headnodding" spell.

When the patient is standing. If the flexor spasm is mild when the child is in the upright position, this seizure consists of a sudden nodding of the head forward, with simultaneous extension of the upper extremities. Most frequently, however, the flexor spasm is severe, resulting in a sudden forceful forward or backward jerk of the head and often an associated outward thrust of the arms. These latter attacks frequently cause a violent fall, usually forward, with resultant injury to the face. The patient is usually able to resume his previous posture immediately after the fall. Recurrent injuries to the face, particularly the chin and forehead, are a major problem in children with this form of myoclonic epilepsy, but they can be considerably mitigated or prevented by having the patient wear a protective headgear.18

Figure 10. Typical flexor spasm of Infantile myoclonic epilepsy - sitting position. (Courtesy of the Spastics Society Medical Education and Information Unit in association with William Heinemann Medical Books, London, from Infantile Spasms, by P. M. Jeavons and B. D. Bower, 1964).

Figure 10. Typical flexor spasm of Infantile myoclonic epilepsy - sitting position. (Courtesy of the Spastics Society Medical Education and Information Unit in association with William Heinemann Medical Books, London, from Infantile Spasms, by P. M. Jeavons and B. D. Bower, 1964).

This type of myoclonic attack is, of course, encountered almost exclusively in the older child. Such seizures are also referred to as Lennox's syndrome, Lennox-Gastaut syndrome, and petit-mal variant.

Duration of an individual myoclonic attack is brief, lasting but a few seconds or so. The myoclonic seizures occurring in infants (massive myoclonic and head-dropping types) usually recur very often, and some patients experience as many as 50 to 100 attacks per day. A characteristic feature of these seizures is that they frequendy recur in rapid succession (series) lasting for one to two minutes, during which there is apparently no impairment of consciousness.

Figure 11. EEQ of an eight-year-old child with myoclonic epilepsy of older children. Myoclonic seizures began at three years of age. This record was obtained during sleep artificially induced by chloral hydrate. Note very short bursts of diffuse fast spikes, followed by high-amplitude slow waves and bursts of irregular spikes and high-voltage slow waves lasting about four and one-half seconds (modified hypsarrhythmia). These electric abnormalities were present in all leads and occurred during all phases of EEG examination (awake, voluntary hyperventilation, intermittent photic stimulation); however, they were greatly accentuated during sleep.

Figure 11. EEQ of an eight-year-old child with myoclonic epilepsy of older children. Myoclonic seizures began at three years of age. This record was obtained during sleep artificially induced by chloral hydrate. Note very short bursts of diffuse fast spikes, followed by high-amplitude slow waves and bursts of irregular spikes and high-voltage slow waves lasting about four and one-half seconds (modified hypsarrhythmia). These electric abnormalities were present in all leads and occurred during all phases of EEG examination (awake, voluntary hyperventilation, intermittent photic stimulation); however, they were greatly accentuated during sleep.

All forms of myoclonic epilepsy almost invariably recur on a daily basis; however, the infant experiences many more attacks per day than does the older child. Massive myoclonic seizures often occur just before the onset of natural sleep and immediately after awakening.

Electroencephalographs findings. Abnormalities designated as hypsarrhythmia (Figure 9) are found in the EEGs of patients with infantile myoclonic epilepsy. In older children with myoclonic epilepsy (Lennox-Gastaut syndrome), the EEG abnormalities are classified by us as modified hypsarrhythmia (Figure 11).

Brain damage is a very prominent part of the general clinical picture of myoclonic epilepsy. Clinical evidence of brain damage is usually present before the onset of this disorder, especially in patients whose myoclonic seizures begin during the first year of life. In 1958, we29 reported our findings in a large group of patients, almost all of whom experienced infantile myoclonic seizures. There were sufficient data to estimate the intelligence of 671 of the 698 patients in our series when they were approximately one year of age.

Mental retardation of some degree was apparent in 657 of the 671 children (98 per cent). The extent of the intellectual deficiency varied from mild to severe, but most patients were severely retarded both mentally and physically. Jeavons and Bower30 reported similar findings, in that only three (2.7 per cent) of their 112 patients with infantile spasms were mentally normal when first seen and only 10 (8.9 per cent) were mildly subnormal. We have encountered only rare instances of patients with myoclonic epilepsy of infancy who, after prolonged follow-up, had normal intelligence. The overwhelming majority of our patients with infantile myoclonic seizures exhibited clinical evidence of varying degrees of developmental retardation before the onset of the seizure disorder.

We evaluated the mental status in the majority of our 375 patients with myoclonic epilepsy of older children and found that approximately 85 per cent of them manifested mental retardation (IQ 75 or lower). However, these children were by no means as intellectually impaired as those with myoclonic seizures of infancy. Ohtahara et al.21 reported that 84.5 per cent of their 116 patients with the Lennox syndrome (myoclonic epilepsy of older children) were mentally retarded, and Markand31 found an incidence of 87.8 per cent of mental retardation (IQ 75 or less) in his series of children whose myoclonic attacks commenced at two or more years of age.

A more promising report was given by Harper,32 who found that there was no intellectual impairment in eight of a group of 14 children (57 per cent) whose myoclonic epilepsy had begun after the age of two years. These eight children all attended an ordinary school. Four other children (29 per cent) had a slight but definite intellectual deficit and attended a special school. The remaining two (14 per cent) were severely impaired and attended training or occupational centers. To our knowledge, no other investigator has reported as optimistic results regarding the intellectual capacity of children with myoclonic epilepsy.

In our own experience, the extent of the mental defect in infants with myoclonic at tacks certainly suggests that this type of seizure is associated with severe organic brain damage in nearly every case. Each of our 1,225 patients with infantile myoclonic epilepsy was investigated with the best diagnostic techniques and procedures available at the time he was under our care in order to rule out the possibility that a degenerative disease might be responsible for his symptoms.

The cause of myoclonic epilepsy, as with other forms of epilepsy, still is not known with certainty. However our investigations have disclosed an association with cerebral injury or damage in 64 per cent of the children with infantile myoclonic epilepsy (infantile spasms). The presumptive causes of the brain damage in these children were varied, but the most common causes, in order, were (1) cerebral birth injury, (2) congenital defect in cerebral development, and (3) some variety of encephalopathy or meningitis. A presumptive etiologic factor could not be determined in 36 per cent of our patients.

Similar findings are reported by Jeavons and Bower30 from their study of 112 patients with myoclonic epilepsy of infancy. They were unable to determine a causative factor in 36 of their series (32 per cent). Each of these 36 children had had an uneventful birth at or near full term after a normal pregnancy; development of each had been normal until the onset of seizures, which usually had occurred at about five months of age. We have also observed many children who appeared to be developing normally until the onset of this type of seizure. Cerebral pathology could have been present in the very young child despite apparent normal developmental patterns.18 It is also possible that an unrecognized insult to the brain, such as encephalitis or hemorrhage, could have been the basis for the mental retardation and the seizures.

In 1957, Baird and Borofsky 33 suggested that pertussis immunizations may be a factor in the production of infantile myoclonic seizures in some patients. In eight of their 24 patients with a previously normal developmental history, myoclonic seizures developed within one to five days after diphtheriapertussis immunizations and in another instance, within 15 days. Jeavons and Bower30 also considered pertussis antigen to be the etiologic factor in 16 of their 112 patients with infantile spasms. In each of these 16 cases, the myoclonic attacks commenced within one week after the inoculation. We also have observed patients who received pertussis antigen (generally as a constituent of diphtheria-tetanus-pertussis vaccine) and then developed myoclonic seizures. However, their attacks did not begin right after receiving the DTP vaccine but at some later date. We believe the relationship between pertussis inoculation and the development of myoclonic seizures is in all probability one of coincidence rather than one of cause and effect.

Among older children with myoclonic epilepsy, our data show that a smaller percentage had cerebral injuries associated with birth (i.e., specific brain damage) than was the case in those with infantile myoclonic epilepsy. These older children with myoclonic epilepsy are somewhat slower than their "normal" contemporaries, and some of them experienced various types of meningitis and encephalitis before the onset of their myoclonic attacks. However, we were able to elicit specific etiologic factors in only a few patients whose seizures began after infancy. Thus, the overwhelming majority of myoclonic epilepsies of older children must be classified as idiopathic, while - in our experience - only 36 per cent of the myoclonic epilepsies of infancy were so classified.

Other types of seizures occur in many patients with myoclonic epilepsy, particularly older children. A variety of other types of seizures are found, most commonly majormotor seizures (grand mal) and staring spells. In fact, myoclonic epilepsy is first manifested in some patients by a series of major motor seizures; subsequently the myoclonic seizures appear and, after a period of time, become the predominant and most disturbing pattern.

The staring episodes that simulate the simple staring spells of petit-mal epilepsy are also encountered in some patients with childhood myoclonic epilepsy. Differentiation between the two is not difficult, however, since the staring spells of myoclonic epilepsy cannot be precipitated by voluntary hyperventilation and, in our experience, the electroencephalograms of these patients do not exhibit the classic petit-mal spike-wave complex (Figure 3). In many patients the staring episodes immediately precede the myoclonic jerks, but on occasion they occur independently of the myoclonic seizures.

The prognosis for children with myoclonic epilepsy is exceedingly poor, especially in those with the infantile form of the disorder.

Our study of 1,225 patients with infantile myoclonic epilepsy (infantile spasms) and 375 with myoclonic epilepsy of older children (Lennox-Gastaut syndrome) has definitely established that the earlier the onset of myoclonic seizures, the worse the prognosis - particularly with respect to mental status and motor development.

We have previously reported prognostic data relative to a large group of patients with myoclonic epilepsy. The vast majority of these patients (95 per cent) had experienced myoclonic seizures of infancy. This study has demonstrated that infantile myoclonic attacks are associated with a high mortality.29 Twenty-three of the 622 children (3.7 per cent) who had been followed up for periods ranging from three to 22 years had died by the end of our investigation. In each case death occurred before the sixth year of life. It should also be noted that by the end of our study 142 of these 622 patients - 22.8 per cent - were in institutions. Jeavons and co-workers34 have also reported high mortality among patients with infantile spasms.

The results of our investigations indicate that the incidence of both mortality and institutionalization in patients with myoclonic epilepsy of older children is considerably lower than that of patients with myoclonic epilepsy of infancy.

It is stressed that myoclonic epilepsy is exceedingly refractory to antiepileptic-drug therapy. Attention is directed to the fact that in those relatively rare instances when seizure control is achieved with pharmacotherapy or in patients whose seizures disappeared spontaneously in association with increasing age, mental retardation, when present, remains unaffected.

AUTONOMIC EPILEPSY

Other terms employed to designate this form of epilepsy are thencephalic epilepsy, thalamic and/or hypothalamic epilepsy, abdominal epilepsy, visceral epilepsy, epileptic variant, convulsive equivalent, epileptic equivalent, and nonconvulsive epileptic equivalent syndrome.

If one reviews the medical literature over the past years, it will be noted that almost every symptom thought to be of central origin and not related to a specific cerebral disease has been diagnosed as a manifestation of autonomic epilepsy. Our study of the literature revealed that the following factors were utilized as criteria for this diagnosis in many of the reported cases: recurrence of symptoms, nonspecific intersymptom electrographic abnormalities, and favorable response to antiepileptic-drug therapy. It is true that in the past we assigned a diagnosis of autonomic epilepsy to some patients on the basis of an abnormal intersymptom electroencephalogram or a favorable response to anticonvulsant medication; however, it is our present belief that the occurrence of one or any combination of the three previously cited criteria is not sufficient evidence to warrant a positive diagnosis of epilepsy in any given case.

Gastrointestinal disturbances (particularly abdominal pain), headache, and other symptoms suggestive of autonomic dysfunction occur, as is well known, at the onset (aura) in some patients or during the postictal phase of a frank epileptic seizure - especially a grand-mal convulsion.

When such symptoms occur at these times, they are unquestionably of epileptic origin and constitute an integral part of the complete epileptic discharge. It is obvious, therefore, that when such disturbances recur and are not associated with overt epileptic symptoms, the possibility that they may be manifestations of an epileptic disorder should be considered. This assumption, of course, presupposes that all diagnostic efforts have been made to rule out causes for the symptoms.

A definite diagnosis of epilepsy can be made if an electroencephalographic examination reveals seizure discharges occurring concomitantly with the clinical disturbance in question. Unfortunately, as most pediatricians realize, it is quite rare for one to be in the process of recording an electroencephalogram of an epileptic patient at the time clinical symptoms of such brief duration are occurring.

Headache and gastrointestinal disturbances may occur independently or together as clinical manifestations of autonomic epilepsy. They are the most frequent expressions of this disorder. Although we assigned a diagnosis of ''abdominal epilepsy" to many patients in the past and in fact authored some publications on the subject,13,35 our subsequent experience has convinced us that "true" abdominal epilepsy is extremely rare. Our criteria for designating headache and gastrointestinal disturbances as epileptic manifestations are detailed in the preceding article in this issue, "Diagnosis of Epilepsy."

Recurrent attacks of syncope are among the most common disturbances we are called upon to examine in our center. In most instances, syncopal episodes are without major implications, but if they recur periodically or are prolonged, one may have considerable difficulty in establishing a definite diagnosis. Over the years, hundreds of patients who experienced recurrent attacks of syncope have been referred to us with a diagnosis of epilepsy, based on "minimal," "borderline," or "nonspecific electrical irregularities" or a favorable response to antiepileptic-drug treatment. However, extensive investigation and protracted follow-up study of these patients revealed that the symptoms, in the preponderance of cases, were not epileptic in origin. Diagnostic criteria that we have found useful in the differentiation of syncope from epilepsy are presented in the previous article in this issue.

Some patients, particularly older children and young adults, complain of vertigo or dizziness immediately before the onset of an overt epileptic seizure. These symptoms thus represent the aura of an epileptic attack and, as such, are unequivocally of epileptic origin. Therefore, when either of these disturbances recurs in a person in whom functional or specific organic causes cannot be elicited, the possibility of an epileptic basis should be considered. The presence of seizure discharges in an electroencephalogram recorded during an episode of vertigo or dizziness is definite proof of an epileptic disorder; however, as stated previously, one rarely has the opportunity to obtain an electroencephalogram at such times.

In 1951, Gibbs and Gibbs38 reported the occurrence of 14-and-six-per-second positive spikes in a large group of patients who "suffered with epilepsy or who were suspected of having epilepsy." Many of these patients also presented symptoms referable to the autonomic nervous system, such as headaches, attacks of nausea and vomiting, and abdominal pain. Since that time, this electrographic pattern has been reported in patients who presented a wide variety of disturbances and abnormal performances, among which may be mentioned abdominal pain, fainting spells, headaches, hyperkinesis, larceny, bad-check writing, juvenile delinquency, defective hearing, enuresis, loss of interest in school, behavior disorders of various types, and criminal tendencies.37*39

Some investigators37*39 considered the 14and-six-per-second discharge to be positive electric evidence of an epileptic disorder and stated that it is found most commonly in patients with symptoms suggestive of autonomic dysfunction. On the other hand, Bickford and Klass40 state, "At present no adequate evidence has been obtained to show that this rhythm arises from the hypothalamus or that it signifies a convulsive disorder." Niedermeyer41 states that he does not regard the 14and-six-per-second electric discharge as an epileptic abnormality.

As previously stated, some investigators have reported that the 14-and-six-per-second spike complex occurs most frequently in patients with recurrent attacks suggestive of autonomic dysfunction. Our experience has not substantiated this finding, and at present we are not convinced that the 14-and-six-persecond positive spike discharge is a manifestation of an epileptic disorder.

Management of children with the various forms of epilepsy we have discussed in this issue will be considered next month.

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TABLE 1

DEVELOPMENT OF GRAND MAL AS RELATED TO COMBINED THERAPY AND AGE AT ONSET OF PETIT MAL

How to describe myoclonic seizures

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