Trigeminal neuropathy--new observations.

Five cases of trigeminal neuropathy of the idiopathic variety are reported; one patient had an associated unilateral hypoglossal neuropathy with fasciculations and wasting of the ipsilateral half of the tongue. No demonstrable cause was found with the usual laboratory and neuroradiological examinations. Four of the patients underwent retromastoid craniectomy, and the microsurgical observations of the cerebellopontine angle are noted. The superior cerebellar artery (three cases) or anterior inferior cerebellar artery (one case) was found to be stretching the trigeminal nerve in all four case. Microvascular decompression provided pain relief and sensory recovery or improvement in all patients operated upon. In one case, the hypoglossal nerve was also found to be distorted by an arterial loop of a medullary artery; decompression of the loop resulted in complete recovery of hypoglossal function on the affected side. In cases of persistent idiopathic trigeminal neuropathy with or without intractable pain, retromastoid craniectomy with microvascular decompression of the 5th nerve is a therapeutic alternative. (Neurosurgery, 7: 347-351, 1980).