Endoscopy during neurotomy of the nervus intermedius for nervus intermedius neuralgia: a case report

Nervus intermedius neuralgia (NIN) is a rare craniofacial neuralgia with features of paroxysmal pain in the deep ear. Because of sensory nerves overlap in the ear, the diagnosis of NIN is often difficult and not definitive. Here, we present the case of a 70-year-old woman who had deep-ear pain for more than 4 years and was diagnosed with trigeminal neuralgia and treated with carbamazepine without relief in another hospital. Magnetic resonance tomographic angiography revealed no neurovascular conflict with the trigeminal nerve, whereas the anterior inferior cerebellar artery (AICA) was close to the VII/VIII complex. We performed left-sided suboccipital retrosigmoid craniotomy. Surgical exploration under endoscopy clearly showed that the nervus intermedius was compressed by the AICA from behind. The ear pain was completely relieved immediately after nervus intermedius sectioning. The intraoperative findings and postoperative results confirmed that the compression of the nervus intermedius by the AICA caused the otalgia. A patient's specific pain, combined with preoperative imaging examination, is useful in the diagnosis of NIN. Neuroendoscopy has the advantages of enabling a clear field of view and close observation, thus aiding in the identification and accurate cutting of the nervus intermedius during the operation.