Microvascular Decompression for the Treatment of Intermediate Nerve Neuralgia: Case Series of 8 Patients

Introduction: Intermediate nerve neuralgia is a rare condition defined by mild constant pain at the depth of the external auditory canal, punctuated by brief episodes of severe pain, which can be triggered by stimulation of the posterior wall of the external ear canal. The etiology of INN is likely analogous to that of trigeminal neuralgia, which is commonly believed to result from a neurovascular conflict of the TN at the root entry zone. Although diverse treatment strategies have been attempted, microvascular decompression of the VII/VIII cranial nerve complex has rarely been described and is a promising treatment strategy.

Methods: This study concerns a retrospective review of patients who received microvascular decompression of the VII/VIII cranial nerve complex for intermediate nerve neuralgia. Prior to surgery, all other causes of ear pain had been excluded by thorough otorhinolaryngological, neurological and radiographic investigation. We analyzed baseline patient characteristics, presenting symptoms, radiographic findings, intraoperative findings and immediate, short-term and long term surgical outcomes with regard to pain, complications and recurrences.

Results: Eight patients were included in this study. All patients had severe pain deep inside the ear and some had radiating pain on the ipsilateral side of the face. A neurovascular conflict was found on MRI in all cases and it was the only radiographic abnormality. Seven out of eight (88%) of patients were pain-free immediately post-surgery and remained so in the follow-up period (mean 2 years). Complications included diminished hearing (3 cases), sigmoid sinus thrombosis (1 case), CSF leakage (1 case) and dysesthesia of the face (1 case).

Conclusions: Microvascular decompression of the VII/VIII cranial nerve complex for intermediate nerve neuralgia leads to a high remission rate. The risk of surgical complications needs to be further evaluated.