A case of ocular neuromyotonia with tonic pupil

A 48-year old woman with hypertension experienced painful oculomotor nerve palsy. After surgery for a giant aneurysm of the internal carotid artery in the cavernous sinus, phasic constrictions of the pupil developed. Two year s later, this phenomenon disappeared and was replaced by intermittent invol untary cyclic spasms elevating the ptosed lid. These cyclic lid movements w ere not elicited with any eye movement or by increased accommodation. The p upil now manifested the pharmacologic features of a tonic pupil. The explan ation for this unique case of ocular neuromyotonia is based on a misdirecti on phenomenon, possibly caused by ephaptic transmission.