To report a case of reversible trigeminal neuritis due to petrous segment giant  ICA aneurysm

Trigeminal neuralgia is well characterized as short -lasting electric shock or stabbing pain in the distribution of trigeminal nerve. Trigeminal neuralgia can be typical or atypical based on the persistence of symptoms. It is classified as classical, secondary and idiopathic depending on the underlying etiology. Of the various etiologies that have been delineated for classical and secondary types, neurovascular compression of the trigeminal nerve root at the level of superior cerebellar artery is the most common. Other causes are tumors at cerebellopontine angle, demyelinating disorder and rarely trigeminal artery aneurysm. ICA aneurysms have not been reported as a cause of trigeminal neuralgia.

A 58-year-old right handed Caucasian female with controlled hypertension who initially presented with pain and numbness on the right side of her face and right ear. The symptoms were intermittent at first however evolved to become persistent without significant improvement despite treatment with carbamazepine. Additionally, she developed frequent episodes of right head “banging” and scalp tingling while brushing her hair. She was then referred to an otolaryngologist and underwent neuroimaging. MRI brain with contrast which revealed a partially thrombosed aneurysm about 2.7 X3.1 cm in the petrous segment of the internal carotid artery on the right side extending into the right temporal lobe and causing mass effect on the right Meckel's cave. She underwent aneurysm embolization using a telescoping Pipeline flow diverters. Her symptoms improved immediately and completely disappeared the following weeks. A follow up angiogram after a year showed no evidence of aneurysm.

Vertebro-basilar aneurysms have been reported as a cause of Trigeminal neuralgia. Giant ICA aneurysm at the level of petrous segment is thus far an unreported cause of a compressive trigeminal neuropathy which can be completely reversed with embolization.