[A case report of alternating abducens hemiplegia with special reference to the supranuclear pathway to the facial nucleus].

A case of alternating abducens hemiplegia was reported. A 16-year-old girl developed alternating hemiplegia characterized by the left abducens nerve palsy and right hemiparesis. In addition, she had right supranuclear facial nerve palsy. A brain MRI showed left mid to lower pontine lesion and vertebral angiography revealed medullary venous malformation in the left pons. SEP with right posterior tibial nerve stimulation showed a delayed central conduction time, suggesting that the lesion involved left medial lemniscus. We previously reported a 39-year-old man who developed pure alternating abducens hemiplegia. He did not show supranuclear facial nerve palsy or SEP abnormality. These findings support the idea that the supranuclear facial nerve fiber leaves the pyramidal tract at the upper to middle pons and descends in the area of the pontine tegmentum around the medial lemniscus.