Herald facial numbness.

Three unusual patients who developed subacute facial numbness as the heralding symptom of an expanding tumor that involved the trigeminal nerve fibers are reported. The first patient had clinical and electrophysiological evidence of an isolated mental neuropathy as a result of metastatic lesions with bone destruction from a renal cell carcinoma. The second patient had a sensorimotor trigeminal neuropathy caused by a direct compression of the semilunar ganglion by a cavernous hemangioma of Meckel's cave. The last patient experienced facial numbness as the unusual presenting manifestation of a primary brainstem lymphoma. Patients 1 and 3 died a few weeks after the admission, whereas patient 2 poorly recovered. Despite the availability of new techniques for early diagnosis, this report demonstrates how difficult it can initially be to differentiate a 'benign' trigeminal neuropathy from serious conditions and underscores the poor prognosis of fifth nerve fibers involvement by an expanding mass. Early referral with clinical and electrophysiological evaluation appears to be of crucial importance.