Isolated abducent nerve palsy after microvascular decompression for trigeminal neuralgia: case report

Microvascular decompression (MVD) is a safe and effective treatment for trigeminal neuralgia. Isolated postoperative ipsilateral abducent nerve palsy is an extremely rare complication of this procedure and has not been reported before. The author wishes to report this rare complication, discuss its aetio-pathogenesis and the natural course.

A 57-year-old man underwent MVD for right sided medically refractory trigeminal neuralgia based on the MRI finding of ectatic basilar artery compression at its root entry zone. The procedure was uneventful with complete relief of pain. However, he developed isolated ipsilateral sixth nerve palsy following surgery that lasted for six weeks.

Anterior displacement of tortuous and dilated basilar artery to create space between the artery and the nerve during MVD operation probably resulted in inadvertent neuropraxia to the abducent nerve that was located immediately anterior to the artery but was not in the surgical field. Immediate sixth nerve palsy resulted post-operatively. A conservative route was adopted with spontaneous improvement of the extraocular eye movements after six weeks.

Isolated abducent nerve damage is a rare complication of the MVD procedure. Surgical manipulation of the dilated and tortuous vessels located anterior to the trigeminal nerve may cause indirect stretching of the delicate abducent nerve with resultant neuropraxia. This complication is difficult to recognize and prevent intra-operatively as the nerve lies on the far side of the artery. Fortunately, spontaneous recovery of the neural function seems to be the most likely outcome.