Bilateral inverse globe retraction (Duane's) syndrome.

A case of true inverse Duane's retraction syndrome, bilateral inverse globe retraction syndrome apparently due to abnormal innervation, is the subject of this clinical report.

Prior reports of inverse globe retraction syndrome (globe retraction during attempted abduction) describe restrictive rather than innervational etiologies.1,2,3,4,5 The subject of this report is a case of bilateral inverse globe retraction syndrome apparently due to abnormal innervation. The patient showed globe retraction during attempted abduction that seemed to be due to simultaneous co-contraction of both horizontal rectus muscles.

Case Report

A seven-month-old male with an eye turn since birth had an esotropia (ET) at near of 60 prism-diopters (PD), alternate fixation with a preference for the right eye (R/E), -4 abduction of both eyes (B/E), a cycloplegic refraction of +1.50 diopters (D) B/E and an otherwise unremarkable ophthalmic examination. Uncomplicated 6mm medial rectus muscle recession B/E and 6 mm lateral rectus resection of the left eye (L/E) were performed; intraoperative forced duction test did not reveal significant restriction. One week postoperatively the patient was orthotropic with a narrow palpebral fissure L/E (described as 1 mm narrower than that of R/E).

The patient was next seen at 16 years of age because of exotropia (XT) L/E that reportedly occurred gradually one year after his strabismus surgery. Vision was 20/20 R/E, 20/30 L/E. Fixating R/E, there was a 40PD XT with a variable left hypertropia (LHT) up to 25PD. The variable LHT was related to an upshoot during abduction L/E. Motility was significant for the following: -2 abduction and -1 adduction R/E; -1 adduction and -3 abduction L/E; severe palpebral fissure narrowing and marked globe retraction during attempted abduction in either eye that appeared to be due to horizontal rectus muscle co-contraction [Fig. 1]. There was no significant refractive error. Forced duction test performed in the office under topical anesthesia revealed no resistance to abduction and slight resistance to adduction in either eye. The patient was undecided about further strabismus surgery.

Figure 1

Horizontal eye movements at 16 years of age. (A) In right gaze there is significant right globe retraction. (B) In primary position, the patient fixates with his right eye. The exotropic left eye retracts posteriorly and develops an upshoot. (C) In left gaze both globe retraction and the upshoot increase in the left eye

Discussion

The most common form of globe retraction syndrome is Duane′s retraction syndrome, a form of congenital incomitant strabismus typically characterized by inappropriate lateral rectus muscle co-contraction during attempted adduction with resultant globe retraction.4,5 Inverse globe retraction syndrome is much rarer.1,2,3,4,5 A computerized Medline search revealed only restrictive causes for the phenomenon - trauma,1,2 conjunctival scarring3 and abnormally restrictive medial rectus muscles.4,5 Our report is the first of which we are aware to document inverse globe retraction syndrome apparently due to abnormal innervation, a true inverse Duane′s retraction syndrome. Clinically, our patient appears to have bilateral "miswiring" between the abducens nerve and the ipsilateral medial rectus muscle. Rectus muscle resection is generally contraindicated in Duane′s syndrome because it can exacerbate effects of co-contraction and lead to complicated strabismus, as occurred in this case.