Fourth nerve palsy: historical review and study of 215 inpatients.

A review of inpatient trochlear nerve pareses diagnosed over 23 years revealed head trauma as the principal cause, with surgical injury, inflammation, and brain tumors seen occasionally. Ischemic (microvascular) neuropathies were rare. About one-half of the patients (52%) had no other neuro-ophthalmologic signs, but only 5% were truly isolated, without other neurologic or ophthalmologic signs or symptoms. Fourth nerve palsies are underdiagnosed on hospital services, where stuporous patients encounter unsuspecting physicians.