Duane retraction syndrome comprises a group of motility disturbances in which the common feature is co-contraction of medial and lateral rectus muscles on attempted adduction of the involved eye(s). Abnormal clinical features associated with DRS include horizontal deviation in primary position, abnormal head
position, retraction of the globe on attempted adduction leading to pseudoptosis, up shoot and/or down shoot in attempted adduction, amblyopia, A,V and X patterns and various ocular and systemic anomalies can also occur. The syndrome is bilateral in 10% to 20% of cases.
Electromyographic (EMG) and saccadic velocity studies suggest that abnormal firing of lateral rectus is responsible for the globe retraction and pseudoptosis on attempted adduction. Neuropathologic studies confirmed that in at least some patients with DRS there is co-innervation between lateral rectus and extraocular muscles innervated by the third cranial nerve. In the two patients studied, the abducens (sixth cranial) nucleus was absent or hypoplastic and the lateral rectus innervated by a branch of inferior division of third nerve.
Published on: Feb 20, 2015 Pages: 19-25