DOES SPASTICITY CONTRIBUTE TO WALKING DYSFUNCTION AFTER STROKE

Objectives-Clinically, it is assumed that spasticity of the calf muscl es interferes with walking after stroke. The aim was to examine this a ssumption by evaluating the contribution of spasticity in the gastrocn emius muscle to walking dysfunction in an ambulant stroke population s everal months after stroke. Methods-Fourteen stroke patients who were able to walk independently and 15 neurologically normal control subjec ts were recruited. Both resting and action stretch reflexes of the gas trocnemius muscle were investigated under conditions that simulated wa lking. Resting tonic stretch reflexes were measured to assess spastici ty whereas action tonic stretch reflexes were measured to assess the p ossible contribution of spasticity to gait dysfunction. Results-Two th irds of the stroke patients exhibited resting tonic stretch reflexes w hich indicate spasticity, whereas none of the control subjects did. Ho wever, the stroke patients exhibited action tonic stretch reflexes tha t were of similar magnitude to the control subjects, suggesting that t heir reflex activity during walking was not different from that of con trol subjects. Furthermore, there was no evidence that the action stre tch reflex in the stroke patients contributed a higher resistance to s tretch than the control subjects. Conclusions-Whereas most of the stro ke patients exhibited spasticity when measured both clinically and phy siologically, they did not exhibit an increase in resistance to dorsif lexion due to exaggerated action tonic stretch reflexes. It is conclud ed that it is unlikely that spasticity causes problems in walking afte r stroke in ambulant patients. Therefore, it seems inappropriate to ro utinely reduce or inhibit the reflex response to improve functional mo vement in stroke rehabilitation. Factors other than spasticity should be considered when analysing walking after stroke, so that appropriate treatment is provided to patients.