Paresis of lateral gaze alternating with so-called posterior internuclear ophthalmoplegia. A partial paramedian pontine reticular formation-abducens nucleus syndrome.

A patient with multiple myeloma developed gaze paresis to the left with slowed saccades and gaze-paretic nystagmus, which alternated with abduction palsy in the left eye (with preserved oculocephalic deviation) and dissociated adducting nystagmus in the right eye, suggesting so-called posterior internuclear ophthalmoplegia. At autopsy multiple small infarcts were found with partial destruction of the left paramedian pontine reticula formation (PPRF) extending towards the abducens nucleus, which was involved only in its inferior pole. The medial longitudinal fasciculus and other oculomotor structures were spared.

Encephalopathy, peripheral neuropathy, dysautonomia, myasthenia gravis, malignant thymoma, and antiacetylcholine receptor antibodies in the CSF.

A 54-year-old man suffered from multiple neurologic disturbances (polyneuropathy, encephalopathy, dysautonomia) associated with myasthenia gravis and malignant thymoma. No morphological signs of inflammation were present in the brain and peripheral nerves. Antiacetylcholine receptor antibodies were present in the brain and peripheral nerves.