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 years later, this phenomenon disappeared and was replaced by intermittent involuntary cyclic spasms elevating the ptosed lid. These cyclic lid movements were not elicited with any eye movement or by increased accommodation. The pupil now manifested the pharmacologic features of a tonic pupil. The explanation for this unique case of ocular neuromyotonia is based on a misdirection phenomenon, possibly caused by ephaptic transmission.