Duane retraction syndrome: MRI features in two cases.

PURPOSE Neuroimaging findings in Duane's retraction syndrome (DRS), through magnetic resonance imaging (MRI), suggest that aplasia of the abducens nerve (VI) can be responsible for several forms of DRS. METHODS Brain MRI was performed in two children of 2.5 and 7 years of age with left sided DRS type II and right sided DRS type I, respectively. 3D T2 weighted images through the brainstem were acquired in order to visualize the cranial nerves especially the abducens (VI) and oculomotor (III) nerves. RESULTS The abducens nerve on the affected side could not be observed in these two different types of DRS with normal morphology of the third nerves. CONCLUSION Absence of the VI nerve has been described recently in DRS types I and III only, while DRS type II is usually associated with normal VI nerve on MRI. However our results show that aplasia of the VI nerve can also be seen in DRS type II resulting in new insight of the pathogenesis of this clinical entity.