Transient internuclear ophthalmoplegia in post anteromesial temporal lobectomy

Internuclear ophthalmoplegia (INO) due to lesion in medial longitudinal fasiculus was described due to head injury, multiple sclerosis, pontine infarct and drug intoxication. INO due to head injury was reversible and may be due to ischemia of perforators of vertebrobasilar circulation. Post operative INO is a possibility in brainstem surgery but as a complication of classical epilepsy surgery is not available in the English literature searched.

We present a classical case of left mesial temporal sclerosis for which left anteromesial temporal lobectomy was done. Surgical procedure was uneventful. No hematoma noted at surgical site. Patient had post operative left INO with MRI showing signal changes in midbrain with no features of infarct. Considering the possibility of demyelination Visual evoked potentials was done which was not suggestive of it. Patient had spontaneous improvement in 1 week after a short course of steroids. The probable explanation for transient internuclear ophthalmoplegia may be due to vasospasm of perforators supplying pons and caudal mesenecephlon which is a possibility if pia is breached during posterior dissection of hippocampus or injury to any small vessel which was not noticeable during the surgery.

We should be aware of such complication for better counselling and prognostication.