Trochlear nerve palsy
Few cases of isolated trochlear nerve palsy with midbrain hemorrhage or due to midbrain vascular malformation are reported in the literature 1). 2) 3) 4) 5).
A 40-year-old normotensive man suddenly developed diplopia, tinnitus and a burning sensation on the left side of his body while driving a motorcycle. He did not complain of headache, nausea or vomiting. Neurologic examination revealed left trochlear nerve palsy and impaired pinprick, temperature and joint position sensation of the left limbs. There was no ptosis or motor deficit. He had a mild bleeding diathesis due to alcoholic liver cirrhosis. Computerized tomography and magnetic resonance image of the brain disclosed hemorrhages in the right midbrain tectum and the left temporal lobe. After nine months of observation, there was nearly complete recovery of symptoms, except for mild residual diplopia. From a literature review, only nine case of midbrain tectal hemorrhage involving the inferior colliculus have been reported. These patients had a unique clinical presentation. Diplopia due to trochlear nerve palsy, either unilateral or bilateral, was present in all of the cases. Tinnitus and sensory disturbance contralateral to the lesion side were very common. Only three patients had risk factors for hemorrhage, including bleeding diathesis, hypertension and vascular anomalies. In the majority of patients, no underlying causes were detected. The outcome was favorable with conservative treatment 6).