Congenital ocular aberrant innervation--new concepts

Abstract

Background: We have the impression that congenital aberrant innervations are more common than previously reported. Many varieties exist and typically involve the sixth nerve. The most common ocular miswirings are Duane's syndrome and Marcus Gunn jaw-winking ptosis. The second most common miswiring involves lateral rectus activation in upgaze causing a "Y" pattern exotropia (pseudo inferior oblique overaction). This commonly is confused with inferior oblique overaction but surgery on the obliques does not cure the condition. Lateral rectus recession and elevation are required.

Methods: We selected demonstrative cases from our practices to illustrate a variety of congenital aberrant innervations. A literature search for previous reported cases of aberrant innervations was performed. This report is an eclectic collection of observations of individual selected cases.

Results: We found aberrant innervations of unusual varieties. These miswirings involve simultaneous firing of the lateral rectus with other muscles, including: the ipsilateral superior rectus, causing "pseudo inferior oblique overaction"; the contralateral lateral rectus, causing synergistic divergence; the ipsilateral superior rectus, in upward saccades only; and the masticatory muscles, causing exotropia with sucking. The third nerve by itself rarely is involved in congenital miswirings, but commonly shows aberrant regeneration after traumatic injuries. We know of no cases of aberrant innervation involving the fourth nerve.

Summary: We present cases describing these congenital aberrant innervations and discuss a unifying hypothesis as to their typical involvement of the sixth nerve.