Magnetic resonance imaging in Duane's retraction syndrome.

PURPOSE The aim of this study was to visualize the subarachnoid portion of the nervus abducens by magnetic resonance imaging and to analyze whether aplasia of the nervus abducens is an etiologic factor in Duane's retraction syndrome. METHODS We performed thin-sectioned magnetic resonance imaging across the brainstem level in 8 cases (11 eyes) that were clinically diagnosed as Duane's retraction syndrome. The same test was applied to 8 healthy control subjects to verify the accuracy of this technique. RESULTS The nervus abducens on the affected side could not be observed in 6 (54.5%) of 11 eyes (8 cases) that were clinically diagnosed as having Duane's retraction syndrome. The nervus abducens was observed in 15 (94%) of 16 eyes that were screened as the control group. CONCLUSIONS The results showed that aplasia of the nervus abducens, although an important etiologic factor, is not the only factor responsible for the diagnosis of Duane's retraction syndrome.