Neuromyotonia of the abducens nerve after hypophysectomy and radiation.

The clinical signs of the rarely encountered ocular neuromyotonia consist of transient involuntary tonic contraction and delayed relaxation of single or multiple extraocular muscles, resulting in episodic diplopia. With a mean time delay of 3.5 years, this motility disorder frequently follows tumor excision or adjuvant radiation near the skull base. Ocular neuromyotonia may reflect inappropriate discharge from oculomotor neurons with unstable cell membranes because of segmental demyelinization by tumor compression and radiation-induced microangiopathy. In the present paper, the authors present the case of a 53-year-old patient with a history of transsphenoidal hypophysectomy and adjuvant radiotherapy, who underwent strabismus surgery for abducens palsy.