Classification of Duane's retraction syndrome: two additional electromyogram types

Huber's clinical and electromyographical classifications of Duane's retraction syndrome have been considered to correspond to each other. However, cases that do not correspond to these classifications have been reported recently. Retrospectively, we tried to classify the clinical types and electromyogram types of 17 eyes (15 cases) with Duane's retraction syndrome according to Huber's classification. OBSERVATIONS. Eleven eyes could not be classified into any of Huber's electromyogram types. Among these eyes, two major additional electromyogram patterns were newly classified: a center-peak type, in which the lateral rectus or medial rectus muscle showed maximum activity in the primary position; and a type with continuous lateral rectus muscle discharge. Some minor electromyogram patterns were also recorded. The wide variation in these electromyogram patterns may be due to the diversity of the lesions in Duane's retraction syndrome, which can be the result of muscular, nuclear, internuclear, or supranuclear failure.