Clinicopathologic study of paraneoplastic brainstem encephalitis and ophthalmoparesis.

We report three patients who exhibited ophthalmoparesis as an early manifestation of progressive paraneoplastic brainstem encephalitis. In two patients, anti-Hu antibodies were detected, whereas in a third, found at postmortem to have thyroid cancer, no antibodies were identified. Postmortem examination of two patients disclosed extensive gliosis, perivascular inflammation, and cell loss in the midbrain and pontine tegmentum. In one of these patients, there was selective neuronal loss within the third, fourth, and sixth nerve nuclei. We conclude that supranuclear or nuclear ophthalmoparesis may be the initial manifestation of paraneoplastic brainstem encephalitis. Our pathologic data suggest that the ophthalmoparesis may result from selective neuronal death within the brainstem tegmentum and ocular motor nuclei.