Assessing segmental excitability after acute rostral lesions. I. The F response.

F responses were elicited from both hands of patients shortly after they sustained unilateral cerebrovascular lesions. In 17 of 29 patients, significant abnormalities were found; F responses occurred with decreased persistence and/or amplitude on the clinically involved side, a change which was seen only in patients studied within 4 weeks of the ictus. The most prominent changes (in comparison with the clinically uninvolved side) occurred with extensive lesions. The abnormalities of F response correlated clinically with severity of the weakness, decrease in tone, and decrease in deep tendon reflexes. These changes in F response are consistent with a decreased "central excitatory state" at the spinal segmental level during the early phase after a supratentorial stroke.