October 2003: A 59-year-old woman with sudden onset of diplopia

A 59-year-old woman experienced sudden onset of horizontal binocular diplopia and right-sided facial paresthesias. The patient was in her usual state of good health until one week before, when she began complaining of severe occipital headaches. The patient had a past medical history that was significant for hypertension, non-insulin dependent diabetes meilitus, coronary artery disease, hyporhyroidism and dental implants placed 4 weeks before the onset of symptoms. On physical examination the patient was afebrile, awake and oriented. Cranial nerve examination revealed equal and reactive pupils, the visual fields were full to confrontation bilaterally. Extraocular movements were full both horizontally and vertically. However, she experienced horizontal diplopia with distant vision. Sensation was intact to light touch, pinprick and temperature over the face; however, the corneal reflex was absent on the right side. The face was asymmetric with marked settling of the right nasolabial fold. The tongue was midline, and the uvula and palate elevated symmetrically Motor examination revealed normal and equal fine motor movements bilaterally. Strength was normal throughout. Sensory examination revealed mild loss of pinprick sensation in her lower extremities, and was otherwise intact to light touch and temperature. There was normal finger-to-nose coordination bilaterally and no evidence of ataxia. Reflexes were normal and symmetrical throughout. The remainder of the physical exam was unremarkable. MRI of the brain revealed a 1.3 x 1.3 x 1.5-cm ring-enhancing lesion with central hypointensity, predominantly located in the left cerebral peduncle (Figures 1, 2), extending inferiorly to the pons at the level of the brachium pontis. There was a significantly increased T2 signal, which extended superiorly to the level of the posterior limb of the left internal capsule, medially throughout the entire pons, and inferiorly to the left pontomedullary junction. The patient under),vent a CT guided stereotactic biopsy.