From the Safdarjung Hospital (MG, HSS, VSG, KPSM); and the Dr. R.P. Centre for Ophthalmic Sciences (HSS), AIIMS, New Delhi, India.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Harinder Singh Sethi, MD, House No. 20, West Avenue, IIT Delhi, Haus Khas, New Delhi, 110016, India.
Cases diagnosed as Duane’s retraction syndrome (DRS) were first described in 1905 by Alexander Duane.1 Synergistic divergence is described as a possible variant of DRS type II. It is a congenital syndrome of unilateral paralysis of adduction associated with simultaneous bilateral abduction on attempted gaze into the field of action of the paretic medial rectus muscle. Features of globe retraction on adduction, narrowing of the palpebral fissure on attempted adduction, and widening on abduction may also be present. We describe a case with features of atypical DRS with unilateral congenital adduction palsy with synergistic divergence in association with aberrant trigeminal innervation and facial hypoplasia. Such association is known to be extremely rare and, to our knowledge, this is the first reported case of its kind.
A 6-year-old boy presented to the outpatient services of our center with the primary complaint of a divergent left eye since birth. Associated complaints of occasional wandering movements of the left eye were present. An abnormal head posture was also noted by his parents shortly after birth.
The father reported that the boy had an outward deviation of his left eye since birth. The deviation was variable, increasing temporarily when the child looked toward the right. It had been constant and nonprogressive since then. He also noted the child’s inability to move his left eye inward and an awkward disconjugate movement toward the left when attempting to do so. Some nonspecific wandering movements were noted by the family on certain occasions. An anomalous position of the head (face toward the right) was noted during periods of increased concentration.
The parents had not sought any previous form of medical or ophthalmic help for the condition. No prior history existed of spectacle prescription, occlusion therapy, or surgical correction.
The child was the first and only child born to the parents, and the mother reported a normal pregnancy and a full-term normal vaginal delivery with an uneventful prenatal and postnatal course. There was no history of febrile illness, radiation exposure, or substance abuse during pregnancy. The child developed normal timely socio-motor milestones. There was also no family history of eye disease or ocular motility problems.
On local examination, a moderate compensatory head posture (Fig. 1) (head turn to the right) was noted. Facial hypoplasia of the left side was also present (Fig. 1). Snellen visual acuity was 6/9 in the right eye and 6/24 in the left eye. Visual improvement was noted to 6/6 with a pinhole in the right eye, but the left eye failed to improve.
Figure 1. Clinical Profile of the Patient. (Left) Child Assumes a Position of Right Head Turn when Attempting to Focus at a Target. (right) Presence of Facial Hypoplasia of the Affected Left Side Is Evident in the Picture.
On correcting the head posture, an exotropia of 60 PD was noted at 33 cm and 6 m. Nystagmoid movements were elicited in both eyes, which increased on alternate cover test, suggesting the presence of manifest latent nystagmus. Fast phase was present toward the right side and no null point could be found.
Motility of the right eye was normal in all directions of gaze, whereas the left eye was unable to adduct past the midline. The right eye abducted normally when dextroversion was attempted, whereas the left eye assumed a greater position of abduction and depression. Nine gaze pictures are depicted in Figure 2. On levoversion, the right eye adducted normally and the left eye abducted, as expected. The pupils were normal with no abnormal miosis or mydriasis on ductions or versions. The child also demonstrated abnormal adducting movements of the left eye when chewing and swallowing (Fig. 3). No Marcus Gunn jaw winking phenomenon or upper eyelid ptosis was present to suggest aberrant regeneration of congenital third nerve palsy. There was also no evidence of the narrowing of the palpebral fissure or retraction of the globe on attempted adduction. Convergence was normal in the right eye but the left eye failed to show any adduction on presentation of an accommodative stimulus.
Figure 2. Nine Gaze Photographs of the Patient. Left-Sided Adduction Palsy with Synergistic Divergence Can Be Seen on Observation of the Ocular Motility Pattern.
Figure 3. Trigemino-Oculomotor Synkinesis. (Top Left) Exotropic Position of Rest Can Be Seen in the Left Eye with the Jaw Closed. (Top Right) On Jaw Opening, the Left Eye Is Seen to Adduct and Come to Lie in the Primary Central Position. (Bottom Left) On Movement of the Jaw to the Right, Adducting Movement Is Observed in the Left Eye, Bringing It to Primary Central Position. (Bottom Right) On Left Side Movement of the Jaw, the Left Eye Returns to Its Exotropic Position of Rest.
Remaining anterior segment examination was unremarkable. Both fundi were normal. Fixation was central, non-steady, and not maintained in the left eye. Cycloplegic refraction showed +0.5 diopter sphere in the right eye with an acceptance of 6/6 and +0.75 diopter sphere in the left eye with no acceptance. Results of magnetic resonance imaging with attention to posterior cranial fossa and integrity of extraocular muscles were normal. A diagnosis of atypical Duane’s retraction syndrome with synergistic divergence was made with the presence of anomalous trigemino-oculomotor synkinesis in the left eye.
Occlusion therapy was advocated, covering the right eye for 6 hours per day. Visual rehabilitation to date has been achieved to 6/12 in the left eye with the right eye maintaining 6/6 visual acuity with the newly prescribed glasses. We continue to prescribe the patient occlusion therapy and observe the natural course of the disease until the patient achieves full acuity or an age of 8 to 9 years, when further trial of occlusion therapy may be abandoned. A surgical correction of the exotropia and a trial to mitigate the aberrant innervation may then be planned.
As Duane described, the complete syndrome of Duane consisted of: (1) complete or less often partial absence of outward movement of the affected eye; (2) partial or rarely complete deficiency of movement inward of the affected eye; (3) retraction of the affected eye into the orbit when it is adducted; (4) a sharply oblique movement of the affected eye either up and in or down and in when it is adducted; (5) partial closure of the eyelids (pseudoptosis) of the affected eye when it is adducted; and (6) paresis, or at least marked deficiency of convergence, with the affected eye remaining fixed in the primary position while the sound eye is converging.
The initial possible mechanisms of the features of Duane’s retraction syndrome were theorized as mechanical with attribution to structural anomalies of the lateral rectus muscle and abnormal posterior insertion of the medial rectus muscle.2 With the advent of electromyography (EMG) in the 1950s, innervational theories suggesting co-contraction of the medial and lateral rectus muscles on adduction were postulated.
The case that we report here shows complete deficiency of adduction in the absence of any abduction deficiency with sharp oblique movement of the left eye downward and outward on attempted adduction, suggesting synergistic divergence. These features, in the absence of any abduction deficiency, pseudoptosis, or globe retraction in adduction of the affected eye, point toward an atypical presentation of Duane’s retraction syndrome. The last two features are not always found in Duane’s retraction syndrome, as described in his original1 and subsequent articles,3 but total absence of abduction deficiency is extremely rare.
Synergistic divergence is a congenital syndrome of unilateral paralysis of adduction associated with simultaneous bilateral abduction on attempted gaze into the field of action of the paretic medial rectus muscle. It was first reported by Barany in 1930.4 It is generally unilateral and affects the left eye (78%) and males (71%).5 A compensatory head posture positioning the eye away from the affected medial rectus muscle is often present to maintain binocular single vision. As a possible variant of Duane’s retraction syndrome type II,6 features of globe retraction on adduction, narrowing of the palpebral fissure on attempted adduction, and widening on abduction may also be present.
Wilcox et al.7 proposed that the abducens nerve and nucleus are either hypoplastic or absent in synergistic divergence and the innervation from the oculomotor nerve to the medial rectus muscle is directed mainly to the lateral rectus muscle. Using EMG techniques, they demonstrated simultaneous innervation of the horizontal recti muscles on the involved side. They suggested that this entity may be a variant of Duane’s retraction syndrome.
Hamed et al.8 later suggested that the abducens nerve is not necessarily hypoplastic or absent, based on saccadic velocity and EMG studies, but at the same time did not dispute the anomalous innervation suggested by Wilcox et al.7
A review of cases reported in the literature5,7,8 showed that depression and abduction of the affected eye on attempted gaze toward the affected medial rectus muscle was present in 71% of cases. Subsequent to such evidence, although in the absence of confirmatory evidence, such a downshoot was suggested as an associated characteristic feature of synergistic divergence. Such a downshoot was seen in the case discussed by the authors.
Hamed et al.8 hypothesized an inadvertent infraplacement of the lateral rectus muscle insertion during a previous recession as a possible explanation. In our case, there is no previous history of eye surgery. On the other hand, Cruysberg et al.9 argued an alternate mechanism based on the absence of the lateral rectus muscle discovered on surgical exploration in a case with synergistic divergence. They postulated that abduction in such cases may be maintained by the inferior rectus and inferior oblique muscles, which, along with the medial rectus muscle, are supplied by the inferior branch of the oculomotor nerve. It was said that some of the neurons intended for the medial rectus muscle aberrantly innervated the inferior oblique and inferior rectus muscles and the lateral rectus muscle, responsible for such a position of abduction and depression on attempted levoversion.
Based on EMG data, it has been postulated that synergistic divergence with aberrant trigeminal innervation is a neural miswiring disorder related to Duane’s retraction syndrome. Although various congenital abnormalities have been reported with Duane’s retraction syndrome,10 few have been seen in association with synergistic divergence. These include Marcus Gunn jaw winking phenomenon,8,11 Horner’s syndrome,12 arthrogryposis multiplex congenita,9 congenital fibrosis,13 and abnormal adducting movements on mastication5 (after a thorough search in our computerized database we could find only the above-mentioned case report). To our knowledge, this case is the second of its kind where abnormal adducting movements on mastication are seen in association with synergistic divergence. The case also is unique because synergistic divergence with such a trigemino-oculomotor synkinesis presents in the absence of typical features of Duane’s retraction syndrome, including the absence of abduction deficit and pseudoptosis or globe retraction on attempted adduction. This may suggest an alternative pathophysiology of synergistic divergence, which to date has been reported to be a variant of Duane’s retraction syndrome, based on EMG data.6,9
Consequent to the inability to obtain EMG data from the patient due to technical constraints of third-world countries, we failed to achieve a complete understanding of the pathophysiology of this occurrence.
The presence of an adducting movement on mastication with synergistic divergence suggests additional anomalous innervation between the motor branch of the trigeminal and oculomotor nerves, as reported by Kaban et al.5 Similar adducting movements of an exotropic eye in association with mastication have been previously described by Mohan and Saroha.14 in the absence of synergistic divergence. Some form of teratogenic disturbance during the second month of pregnancy has been postulated as the causal etiology of such trigemino-oculomotor synkinesis.10 Similar miswiring and synkinesis has been observed in association with synergistic divergence by Hamed et al.8 in the form of Marcus Gunn jaw winking phenomenon in which the aberrant link was noted as upward or downward eyelid movements on mastication. Isenberg and Blechman11 suggested the presence of intraneural association fibers between the third and fifth cranial nerves as a plausible theory to explain the trigemino-oculomotor synkinesis. Kaban et al.5 hypothesized an embryological error due to potential teratogenic stimulus in the first trimester of pregnancy based on the completion of development of innervation to extraocular muscles before the eighth week of intrauterine development. Our case had no history of teratogenic exposure during pregnancy, although the authenticity of the history may be questionable.
- Duane A. Congenital deficiency of abduction, associated with impairment of adduction, retraction movements, contraction of the palpebral fissure and oblique movements of the eye: 1905. Arch Ophthalmol. 1996;114:1255–1256.
- DeRespinis PA, Caputo AR, Wagner RS, Guo S. Duane’s retraction syndrome. Surv Ophthalmol. 1993;38:257–288. doi:10.1016/0039-6257(93)90077-K [CrossRef]
- Isenberg S, Urist MJ.Clinical observations in 101 consecutive patients with Duane’s retraction syndrome. Am J Ophthalmol. 1977;84:419–425.
- Barany F. Ein Fall von monokularer Lahmung aller seitlichen Blickbewegungen, bei Intaktheit der vertikalen Blickbewegungen, mit horizontalem Konvergenz: und Divergenznystagmus im Bereich des fur die Willkurbewegungen gelahmten Adbucens. Arch Ohren Nasen Kehlopfheilkd. 1930;26:237–244.
- Kaban TJ, Smith K, Orton RB. Synergistic divergence associated with aberrant trigeminal innervation. Can J Ophthalmol. 1994;29:146–150.
- Wagner RS, Caputo AR, Frohman LP. Congenital unilateral adduction deficit with simultaneous abduction: a variant of Duane’s retraction syndrome. Ophthalmology. 1987;94:1049–1053.
- Wilcox LM Jr, Gittinger JW Jr, Breinin GM. Congenital adduction palsy and synergistic divergence. Am J Ophthalmol. 1981;91:1–7.
- Hamed LM, Dennehy PJ, Lingua RW. Synergistic divergence and jaw-winking phenomenon. J Pediatr Ophthalmol Strabismus. 1990;27:88–90.
- Cruysberg JR, Mtanda AT, Duinkerke-Eerola KU, Huygen PL. Congenital adduction palsy and synergistic divergence: a clinical and electro-oculographic study. Br J Ophthalmol. 1989;73:68–75. doi:10.1136/bjo.73.1.68 [CrossRef]
- Pfaffenbach DD, Cross HE, Kearns TP. Congenital anomalies in Duane’s retraction syndrome. Arch Ophthalmol. 1972;88:635–639.
- Isenberg S, Blechman B. Marcus Gunn jaw winking and Duane’s retraction syndrome. J Pediatr Ophthalmol Strabismus. 1983;20:235–237.
- Jimura T, Taagami Y, Isayama Y, et al. A case of synergistic divergence associated with Horner’s syndrome. Folia Ophthalmol Jpn. 1983;34L477–480.
- Brodsky MC, Pollock SC, Buckley EG. Neural misdirection in congenital ocular fibrosis syndrome: implications and pathogenesis. J Pediatr Ophthalmol Strabismus. 1989;26:159–161.
- Mohan K, Saroha V. Congenital unilateral adduction associated with jaw movement: a rare variant of trigemino-oculomotor synkinesis. J Pediatr Ophthalmol Strabismus. 2004;41:174–176.