Evidence of Increased Motoneuron Excitability in Stroke Patients Without Clinical Spasticity

Abstract

Introduction. The contribution of hyperreflexia to impairment after stroke is debated. Spinal motoneuron excitability in healthy subjects and stroke patients with and without spasticity was compared. Methods. Twenty-four patients with single stroke more than 6 months ago and 18 gender-matched healthy volunteers were included. Spasticity was assessed according to the Modified Ashworth Scale. Mmax amplitude and F wave frequency in the abductor pollicis brevis muscle were measured by electrical stimulation of the median nerve. Results . Mmax values were comparable between the groups. However, patients with (n = 7) and without (n = 17) clinically evident spasticity had a significant increase in F wave frequency when compared with healthy subjects. F wave frequency did not differ between spastic and nonspastic patients. Discussion. Increase in spinal motoneuron excitability after stroke is present in stroke patients with minor or no motor deficiencies and does not necessarily lead to spasticity.