Thalamic hemorrhage imitating hyperventilation.

A 52-year-old woman developed subjective right hemiparesthesias over a two-day period. Because of a paucity of physical findings, apparent anxiety with tachypnea, and a respiratory alkalosis with hypocapnia, a diagnosis of hyperventilation syndrome was considered. However, because of the unilateral symptoms, a computed tomography scan was performed, demonstrating a left posterior thalamic infarct. Most reports of thalamic infarct indicate altered mental status, vertical gaze palsies, or sensorimotor hemiparesis with sensory involvement predominant. The case of a patient with thalamic hemorrhage who presented with only hemiparesthesia is reported to heighten clinicians' awareness of this diagnosis.