Pediatric Annals

Rehabilitation of Infants and Children with Neuromuscular Disorders

Gloria D Eng, MD; Helga Binder, MD

Abstract

Rehabilitation of children with neuromuscular diseases has markedly changed in the past two decades because of three developments: (1) increased sophistication in diagnosis due to the recognition of genetic markers and the discovery of crucial enzymes and muscle proteins; (2) better understanding of the natural course of the various diseases, including respiratory and nutritional aspects; and (3) advances in rehabilitation engineering.

A physician faced with a weak child must arrive at an accurate diagnosis to project the patient's future needs and to design a reasonable rehabilitation program. The first task involves eliciting a detailed medical history of the patient's gestation and delivery and of medical problems in the parents' extended families. Important features in the gestational history, for instance, are oligohydramnios or polyhydramnios, decrease in fetal movement, problems during labor and delivery, and finally a history of previous spontaneous abortions or stillbirths.

In the neonatal period, respiratory and feeding problems due to weakness are common. It is important to elicit the exact time weakness was first noted, whether the onset was sudden or imperceptible and gradual, and whether the weakness was associated with dehydration and acidosis, as in certain lipid myopathies. The history of muscle cramps with or following exercise is helpful in diagnosing specific disorders of glycogen metabolism. Regarding the family history, death, especially sudden infant death or death from respiratory problems (such as pneumonia in another sibling), and family members with physical disabilities, limps, and the need for walking aids (special shoes or braces) or wheelchairs give important clues for the diagnosis. Most neuromuscular disorders are hereditary.

The next step is a careful general physical, musculoskeletal, and neurological examination. In the general physical examination, auscultation of the heart and palpation of the liver are particularly important in storage diseases, and abnormal heart rate and rhythm are sometimes found in muscular and myotonic dystrophy. Increased respiratory rate and diaphragmatic breathing are important clues in infants with neuromuscular diseases. Evidence of scoliosis, dislocatable hips, and extremity contractures or deformities are noted during the musculoskeletal examination, which also includes assessment of muscle bulk and consistency, such as the doughy texture of dystrophic muscles. Weak infants often present with a pectus excavatum.

The neurological examination, in addition to testing strength of peripheral muscles and reflexes, must focus on evidence of facial or extraocular muscle weakness, ptosis, and voice volume and articulation problems. The "myopathic facies," for instance, is well known to most pediatricians. Muscle strength testing is accomplished by observing gait and the way the child rises from the floor and climbs stairs (in the child old enough to accomplish these tasks). In the infant, "slipping through the hands," head lag, pulling up from supine, and inability to extend the trunk or head in horizontal suspension are sure signs of substantial weakness. Formal manual muscle testing is possible from age 5 onward. 1-3

DIAGNOSIS

Serum muscle enzyme levels can be helpful in delineating neuromuscular disorders. Creatine kinase is elevated in all dystrophic processes, except in very advanced cases. Transient elevations occur in a newborn or following excessive exercise and therefore repeat determinations are frequently indicated.4 Mild elevation of serum creatine Phosphokinase occurs in many myopathies. Persistently low levels of serum lactate and pyruvate following ischemic exercise is diagnostic of McArdle's disease or other glycolytic cycle disorder. Serum biochemistry is helpful in metabolic and some lipid myopathies.

Electrodiagnosis is extremely useful in diagnosing neuromuscular disorders. Slowed nerve conduction is typically found in hereditary sensory motor neuropathies. The electromyogram helps to delineate acute membrane instability as seen in polymyositis and certain metabolic dysfunctions, as well as changes typical for a myopathic or neurogenic disorder.…

Rehabilitation of children with neuromuscular diseases has markedly changed in the past two decades because of three developments: (1) increased sophistication in diagnosis due to the recognition of genetic markers and the discovery of crucial enzymes and muscle proteins; (2) better understanding of the natural course of the various diseases, including respiratory and nutritional aspects; and (3) advances in rehabilitation engineering.

A physician faced with a weak child must arrive at an accurate diagnosis to project the patient's future needs and to design a reasonable rehabilitation program. The first task involves eliciting a detailed medical history of the patient's gestation and delivery and of medical problems in the parents' extended families. Important features in the gestational history, for instance, are oligohydramnios or polyhydramnios, decrease in fetal movement, problems during labor and delivery, and finally a history of previous spontaneous abortions or stillbirths.

In the neonatal period, respiratory and feeding problems due to weakness are common. It is important to elicit the exact time weakness was first noted, whether the onset was sudden or imperceptible and gradual, and whether the weakness was associated with dehydration and acidosis, as in certain lipid myopathies. The history of muscle cramps with or following exercise is helpful in diagnosing specific disorders of glycogen metabolism. Regarding the family history, death, especially sudden infant death or death from respiratory problems (such as pneumonia in another sibling), and family members with physical disabilities, limps, and the need for walking aids (special shoes or braces) or wheelchairs give important clues for the diagnosis. Most neuromuscular disorders are hereditary.

The next step is a careful general physical, musculoskeletal, and neurological examination. In the general physical examination, auscultation of the heart and palpation of the liver are particularly important in storage diseases, and abnormal heart rate and rhythm are sometimes found in muscular and myotonic dystrophy. Increased respiratory rate and diaphragmatic breathing are important clues in infants with neuromuscular diseases. Evidence of scoliosis, dislocatable hips, and extremity contractures or deformities are noted during the musculoskeletal examination, which also includes assessment of muscle bulk and consistency, such as the doughy texture of dystrophic muscles. Weak infants often present with a pectus excavatum.

The neurological examination, in addition to testing strength of peripheral muscles and reflexes, must focus on evidence of facial or extraocular muscle weakness, ptosis, and voice volume and articulation problems. The "myopathic facies," for instance, is well known to most pediatricians. Muscle strength testing is accomplished by observing gait and the way the child rises from the floor and climbs stairs (in the child old enough to accomplish these tasks). In the infant, "slipping through the hands," head lag, pulling up from supine, and inability to extend the trunk or head in horizontal suspension are sure signs of substantial weakness. Formal manual muscle testing is possible from age 5 onward. 1-3

DIAGNOSIS

Serum muscle enzyme levels can be helpful in delineating neuromuscular disorders. Creatine kinase is elevated in all dystrophic processes, except in very advanced cases. Transient elevations occur in a newborn or following excessive exercise and therefore repeat determinations are frequently indicated.4 Mild elevation of serum creatine Phosphokinase occurs in many myopathies. Persistently low levels of serum lactate and pyruvate following ischemic exercise is diagnostic of McArdle's disease or other glycolytic cycle disorder. Serum biochemistry is helpful in metabolic and some lipid myopathies.

Electrodiagnosis is extremely useful in diagnosing neuromuscular disorders. Slowed nerve conduction is typically found in hereditary sensory motor neuropathies. The electromyogram helps to delineate acute membrane instability as seen in polymyositis and certain metabolic dysfunctions, as well as changes typical for a myopathic or neurogenic disorder. Neuromuscular transmission testing is often diagnostic in myasthenia gravis, infantile botulism, aminoglycoside blockade of the neuromuscular junction, and tick paralysis.5,6

In most neuromuscular diseases, a muscle biopsy with histochemical analysis of the specimen as well as electron microscopy must be performed to confirm the diagnosis, particularly of fatal diseases.7,8

Consultation with colleagues (such as neurologists, physiatrists, cardiologists, gastroenterologists, pulmonologists, and specialists in metabolic diseases) may be necessary to assist in establishing a diagnosis and, depending on the nature of the disease, may have to continue throughout the child's life. The pediatrician furthermore will need the help of therapists, social workers, counselors, psychologists, teachers, parents, and the child (if old enough to understand) in the total rehabilitation process.

PRINCIPLES OF REHABILITATION

The principles of rehabilitation should include:

* Fostering optimal physical, mental, and emotional development of the child, however disabled;

* Maintaining or improving function whenever possible; and

* Preventing secondary complications, such as contractures of the limbs, skin breakdown, and malalignment of the spine.

Anticipatory and supportive planning is necessary as each phase of the disease process evolves.9

The Floppy Infant

When confronted with a floppy infant, the most common peripheral neuromuscular disorder to be considered in the differential diagnosis is spinal muscular atrophy type I (Werdnig-Hoffmann disease). Congenital myotonic dystrophy is the second most common entity. Congenital muscular dystrophy and a myriad of other disorders, such as structural and metabolic myopathies, are histologically distinct entities but are rare. Neuropathies and neuromuscular junction problems also have to be considered in the differential diagnosis. Not all are fatal illnesses. Some children survive the neonatal period and grow into childhood, many reaching adulthood.

Perinatal problems include feeding and difficulties with respiration, including apnea. The expertise of a neonatologist may be required. As these infants emerge from the neonatal period, the problem of exhaustion from feeding and an almost imperceptible development of chronic starvation may compound their muscle weakness. Regular weight should be recorded and special feeding techniques instituted. The use of a large bore nipple with gentle head and jaw support, pursing the cheeks together to sustain the effort of the buccinators, as well as small frequent feeds may be necessary. Nasogastric tube feedings by gravity or pump, as well as gastrostomy in the older infant are sometimes required. The problem of constipation in these babies can be dealt with by adding corn syrup and bulk producing foods to their formulas. The use of stool softeners may be necessary. Some infants, especially those with spinal muscular atrophy type I, breathe primarily with their diaphragms and a distended abdomen may inhibit adequate excursion of these muscles.

The handling and positioning of the floppy infant requires finesse and adaptation of seating systems. The most common preventible deformities in these babies include torticollis, scoliosis, tightness of hip abductors, and flexion contractures of hips, knees, and elbows. The physical therapist should instruct the parents on how to move their baby as well as how to do passive range of motion exercises to the spine and lower extremities on a regular basis to prevent contractures. Well fabricated, lightweight plastic splints can hold the hands or feet in good position. The selection of appropriate lightweight toys for the baby to play with in side lying postures, or dangled close to the hands when in a semireclined position, will provide stimulation and pleasure. As the infant grows, attempts to facilitate some head and trunk control by exercising the child against gravity should be made, otherwise passive movement should be provided. In the babies with limited life expectancy, the need for postural drainage, suction of mucus, and use of ventilator support must be individualized. Parents need and should receive nursing and psychological support in the care of a dying child, in the hospital or at home. 10

The Toddler

The most common disorder affecting the ambulant child is Duchenne muscular dystrophy. It is an Xlinked disorder with a high mutation rate. The gene locus has recently been isolated on XP 21.11,12 A protein, dystrophin, is low or absent in the muscles of affected boys.15 The quantity and quality of dystrophin distinguishes Duchenne from Becker's dystrophy, which is of great prognostic implication. The management of a boy with Duchenne muscular dystrophy is outlined in the Table and emphasizes the need for logical sequencing of therapeutic input. Spinal muscular atrophy, the intermediate or type II variety, is almost as common as Duchenne muscular dystrophy and manifests itself in several subtypes, depending on the attainment of sitting or walking ability. Because the lifestyle of these children is sedentary, they tend to become obese. Careful dietary and psychological counseling is necessary to prevent the otherwise inevitable associated loss of function and respiratory compromise. Children with spinal muscular atrophy, especially the more seriously involved functional types, develop rapid scoliosis and chest cage deformities. Ongoing physical therapy is necessary to maintain optimal spinal alignment and range of motion of the lower extremities to prevent pelvic asymmetry and contractures in the knees and ankles. These children tend to dislocate hips readily, secondary to gluteus medius weakness. Once this occurs they frequently stop walking.

Other neuromuscular disorders that can be identified in children include fascioscapulohumeral muscular dystrophy, limb girdle dystrophy, myotonic dystrophy, hereditary motor sensory neuropathies (Charcot-Marie-Tooth atrophy), and the more unusual scapuloperoneal atrophies and myopathies. Cardiac arrhythmias can occur in the child with myotonic dystrophy and some of the other myopathies, sometimes requiring implantation of a pacemaker. Each disorder requires some modification of the rehabilitation plan, but the general principles still apply.

ADAPTIVE DEVICES

In the very weak child, spinal orthoses may be necessary to provide trunk support for sitting. However, they may not be well tolerated in some children because of encroachment on the intercostal and auxiliary respiratory muscles, including the diaphragm. A reduction in vital capacity can occur.14 For the child who tolerates a jacket, one formed in orthoplast or polypropylene with pelite liner and velcro closures with a cut out anterior window can be applied.

For good seated alignment, custom molded seating devices made from various plastic, foam rubber, and urethane foam are effective. 1^ The child with enough strength in the arms may be fitted with a manual ultralightweight wheelchair or a tricycle with adapted hand cranks to access the environment. For the child who is unable to sit without support but who is intelligent and has the mental age of at least 3 years, a motorized wheelchair with custom made insert can aftord stability and mobility.

The child who has head control with or without the ability to sit can also use standing devices such as the Toronto tir the Rochester parapodium to allow for vertical posture, improved respiration, and normal joint alignment as well as socialization.16

For the child who is able to stand and walk short distances, the fitting of lightweight braces to control ankles, knees, and hips may facilitate walking. The ischial weight-bearing plastic knee ankle/foot orthoses with locked knees have been used in the child with Duchenne muscular dystrophy and spinal muscular atrophy.17»18 The reciprocating orthosis has been successfully used in the child who has enough strength in the arms to manage crutches or a walker.19

Many other seating devices, which do not look like wheelchairs, can be fitted to a child who has good head and trunk stability. These resemble small golf carts and are easily maneuvered. However, most children cannot remain in these types of motorized devices for a very long period. Adaptation of a van with power lift and special controls can allow a wheelchair bound adolescent the opportunity to drive. Custom designed environmental control systems, incorporating computers and various switch systems, have permitted increasing independence for the older child.

ORTHOPEDIC CARE

Orthopedic problems arise in the management of an older child with neuromuscular disease. Some are relatively simple feet and ankle problems, particularly tight Achilles tendons, which prevent stable ambulation. Tensor fasciae latae contractures may result in increasing falls in the child with Duchenne muscular dystrophy. Release of tight tendons followed by instant application of ischial weight-bearing braces has been recommended by some. Hip dislocations are a constant concern in the child with a neuromuscular disorder. Orthopedic intervention is sometimes necessary, not so much to preserve ambulation but to permit comfortable sitting and delay the inevitable scoliosis. Technological advances in spinal stabilization surgery have permitted earlier and more aggressive management of paralytic scoliosis. This has slowed the progressive respiratory compromise and has allowed improved functional endurance.21,22

Table

TABLEDuchenne Muscular Dystrophy

TABLE

Duchenne Muscular Dystrophy

RESPIRATORY CARE

Vaccination against influenza from age 6 months and Hemophilus influenzae and pneumococcus from age 2 years is recommended tor all patients with neuromuscular disease. In the case of frequent upper respiratory infections, a regimen of preventative antibiotics is instituted. Chest physical therapy, postural drainage, and facilitative cough are taught to the parents to be applied in the event of a pulmonary infection. Suction with a soft bulb syringe or portable suction apparatus to remove secretions may be necessary. The use of intermittent positive pressure breathing devices with bronchodilators is helpful, especially in the child with persistent atelectasis. Oxygen by mask or in a hood may be needed during acute respiratory distress. With increasing respiratory failure, the use of positive or negative pressure breathing devices must be discussed with the patient and family long before the need arises.23-28 Prolongation of life on a ventilator is possible even in the child with Duchenne muscular dystrophy.

EDUCATIONAL AND PSYCHOLOGICAL SUPPORT

Most children with neuromuscular disorders can attend school. Certain children have learning disabilities and even mental retardation (one third of boys with Duchenne and some myotonic dystrophic children as well as some with congenital muscular dystrophy are retarded). An individualized education plan must be designed to meet the particular needs of the child. Communicating with the school and the teachers to allay their fears and anxieties will go a long way to facilitate acceptance of the disabled child into the system. Special physical and occupational therapy should be designed for each child. Attendant help may be necessary for safe transfers and toileting. Wheelchair accessibility of schools must be evaluated. Recreational activities, including swimming, bicycling, horseback riding, and wheelchair sports as well as special summer camp programs are recommended for these children. Exercises should never fatigue but may build up endurance if low weights and high repetitions are used.

As in any chronic debilitating disorder, the child with a neuromuscular disease and the family require lifelong help - from the moment the diagnosis is made until death and even years after.12,17 The shock and grief are never assuaged. With the interminable exigencies of daily living, the acuteness of grief may subside for a while, only to emerge in moments of crisis. It is particularly important that the physician/ manager provides counsel in anticipation of each change in the child's status, especially in preparation of functional deterioration, including the need for wheelchair selection, nutritional support, surgical intervention, and decisions regarding ventilator support. The patient and family should never be confronted with sudden decisions, especially regarding artificial ventilation, with or without tracheostomy. They should be permitted ample time to discuss the pros and cons of various options with professionals, other patients, and family members. Some families derive great comfort from patient and parental support groups, sponsored for instance by the Muscular Dystrophy Association.

A further aspect of care the physician should remember is the particular problem that may arise when a child with neuromuscular disorders undergoes anesthesia. Cardiac arrhythmias, respiratory compromise, and the possible development of malignant hyperthermia can occur. The child who has central core diseases, myotonic dystrophy and even Duchenne muscular dystrophy is at particular risk. Competent anesthesiology services must he availahle for all surgical procedures.

SUMMARY

The care of children with neuromuscular disorders is one of total commitment and requires resourcefulness. Technological advances have made the task somewhat easier. Attitudinal changes in accepting a child with neuromuscular disease into the mainstream of today's society have allowed for increased independence and improved quality of life.

REFERENCES

1. Brooke NH: A cCinician's View of Neuromuscular Diseases, ed. 2. Baltimore, Williams and Williams, 1986.

2. Dubowitz V: Muscle Disorders in Childhood. Vol. XIV: Major Problems in Clinical Pediatrics Philadelphia, WB Saunders Co. 1978.

3. Emery AEH: Duchenne muscuclar dystrophy, in Oxford Monographs mi Medical Genetics No. 15 New York, Oxtord University Press, 1987.

4. Emery AEH: Duchenne muscular dystrophy, in Oxford Monographs on Medical Genetics No 15 New York, Oxford University Press, 1987, p 44.

5. Emery AEH: Duchenne muscular dystrophy, in Oxford Monograph on Medical Genetics No. 15. New York, Oxford University Press, 1987, pp 47-53.

6. Kimura J: Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice, Parts 6 & 7. FA Davis. Philadelphia, 1983.

7. Emery AEH. Duchene muscular dystrophy, in Oxford Monographs on Medical Genetics No. 15. New York, Oxford University Press, 1987. pp 53-69.

8. Dubowitz V: Muscle biopsy-A practical approach, ed 2. London. Bailliere-Tindall, 1985.

9. Fowler WM Jr. Rehabilitation management ot muscular dystrophy and related disorders: II. Comprehensive care. Arch Phys Med Rehabil 1982; 61:122-528.

10. Eng GD, Binder H. Koch B: Spinal muscular atrophy: Experience in diagnosis and rehabilitation ol 6 patients Arch Phys; Med Rehabil 1984; 65:549-563.

11. Monaco AP, New RL, Colletti-Seener C, et al: Isolation ot candidate cDNAs lot portion« ol the Duchenne muscular dystrophy nene Nature 1986; 121.646-650.

12. Davies KE, Forrest S. Smith T. et al: Molecular analysis of human muscular dystrophy. Muscle Nerve 1987; 10:191-199.

13. Hoffman EP, Fischback KH, Brown RH, et al: Characterisation ot dystrophies in muscle biopsy specimens from panents with Duchenne or Becker muscular dystrophy. N Engl J Med 1988; 118(21):1363-1368.

14. Noble-Jamieson CM, Heckmatt JC, Dubowitz V, et al: Effects of posture and spinal bracing on respiratory function in neuromuscular disease. Arch Dis Child 1986: 61:178-181.

15. Silverman M. Commercial options lot positioning the client with muscular dystrophy. Clin Prsoth Orth 1986; 10:159-170.

16. Kinnen E, Gram M. Jackman KV, et al: Rochester Parapodium, 1984. Clin Prosth Orthot 1984; 8(4):24-25.

17. Granata C, Cornelio F, Bonfiglioli S, et al: Promotion of ambulation of patients with spinal muscular atrophy by early bring of knee-ankle-toot orthoses. Dev Med Child Neurol 1987; 29:221-224.

18. Siegel IM. Maintenance ot ambulation in Duchenne muscular dystrophy. clin Pediatr 1980: 19:181-588.

19. LSU Reciprocating Gait Orthosis. Chattanooga. Tenn, Durr-Fillauer. Inc,

20. Siegel IM, Miller JE, Ray RD: Subcutaneous lower limb tenotomy in the treatment ol pseudohypertrophic muscular dystrophy. J Bone Joint Surg 1968; 50:1437-1443.

21. Luque ER; Segmental spinal instrumentation lor correction of scoliosis. Clin Orthop 1982; 165:192-198.

22. Aprin H, Bowen JR, MacEwen GD, et al: Spine fusion in patients with spinal muscular atrophy. J Bone Joint Sug; 1982; 64A:1179-1187.

23. O'Leary J, King R, Leblanc M. et al: Cuirass ventilation in childhood neuromuscular diseases. J Pediatr 1979; 94(5):419-421.

24. Smith PEM. Calverley PMA. Edwards RMT, et al: Practical problems in the respiratory care of patients with muscular dystrophy. N Engl J Med 1987; 316(19):1197-1205.

25. Splaingard ML, Frates RM, Harrison GM, et al. Home positive pressure ventilation Twenty years' experience. Chest 1985; 84(4):176-18.

26. Splaingard ML. Frates RC. Jefferson LS, et al: Negative pressure ventilation: Report of 20 years of experience in patients with neuromuscular disease. Arch Phys Med Rehabil 1985; 66(4):239-242.

27. Schock NC, Colbert AP: Ventilators and Muscualr Dystrophy St. Louis Gazette International Networking Institute, 1987.

28. Bach JR. O'Brien |. Krotenberg R. et al; Management of end staue respiratory failure in Duchenne muscular dystrophy. Muscle Nene 1987; 10:177-182.

TABLE

Duchenne Muscular Dystrophy

10.3928/0090-4481-19881201-06

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