Quantitative measures of spasticity in post-stroke patients.
OBJECTIVE
Quantitative evaluation of muscle tone in post-stroke patients; correlation of biomechanical indices with conventional clinical scales and neurophysiological measures; characterization of passive and neural components of muscle tone.


METHODS
Mechanical stretches of the wrist flexor muscles of 53 post-stroke patients were imposed by means of a torque motor at constant speed. Patients were clinically studied using the Ashworth scale for spasticity and the Medical Research Council score for residual muscle strength. The neurophysiological measures were Hoffmann reflex latency, Hmax/Mmax ratio, stretch reflex threshold speed (SRTS), stretch reflex (SR) latency and area, passive (ISI) and total (TSI) stiffness indices.


RESULTS
Hmax/Mmax ratio, SR area, ISI and TSI values were significantly higher in patients, while SRTS was significantly lower. TSI, SRTS and SR area were highly correlated to the Ashworth score.


CONCLUSIONS
This EMG-biomechanical technique allows an objective evaluation of changes in muscle tone in post-stroke patients, providing easily measurable, quantitative indices of muscle stiffness. The linear distribution of these measures is particularly indicated for monitoring changes induced by treatment. The apparatus seems suitable to characterize neural stiffness, while difficulties were found in isolating the passive components, because of the occurrence of tonic EMG activity in most spastic patients.
Pisano
F
F
Department of Neurology, Unit of Neurophysiology, 'Salvatore Maugeri' Foundation, IRCCS, Rehabilitation Institute 28010 (NO), Veruno, Italy. neufis.veruno@fsm.it
Miscio
G
G
Del Conte
C
C
Pianca
D
D
Candeloro
E
E
Colombo
R
R
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D004576:Electromyography / Q000295:instrumentation / Q000379:methods; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D005260:Female; D006181:H-Reflex / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D009128:Muscle Spasticity / Q000209:etiology / Q000503:physiopathology*; D009129:Muscle Tonus / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation*; D011930:Reaction Time; D020521:Stroke / Q000503:physiopathology*; D019415:Torque; D014955:Wrist Joint / Q000294:innervation