Altered cerebral inhibition of respiratory and cardiac responses to hypercapnia in acute stroke.

Ventilatory and heart-rate responses to hypercapnia were evaluated by a CO2 rebreathing technique in 56 patients with acute ischemic stroke and 14 normal controls. Both ventilatory and heart-rate responses were increased in patients with hemispheral lesions, but not in patients with brainstem lesions. In patients with hemispheral infarct, there was a decrease in CO2 sensitivity 1 to 3 weeks later. Acute hemisphere lesions may result in a transient decrease of cerebral inhibition of brainstem-mediated autonomic responses to a chemical stimulus.