Flexor reflex for assessment of common interneurone activity in spasticity

The purpose of this investigation was to evaluate the alterations of flexor reflex parameters in spasticity and the possibilities to take advantage of them as a method for assessment of common interneurone activity. Clinical and electromyographical examinations were performed on 120 patients with spastic hemiparesis after stroke. The flexor reflex was obtained after supramaximal electrostimulation of the tibial nerve behind the ankle. The stimulus consisted of 50 msec train of 1 msec duration pulses given at 100 Hz. The reflex activity was recorded from the tibialis anterior muscle. As all patients were with hemiparesis the healthy side was used as a control. The patients were subdivided into four groups, each treated with different myorelaxants (Baclofen, Sirdalud, Myolastan and electroacupuncture). After about 25 days treatment the clinical and electromyographic examinations were repeated. The flexor reflex was recorded with two clearly distinguishable responses on the healthy, as well as on the spastic side. On the spastic side a reflex with prolonged latencies and durations, as well as with decreased amplitudes and thresholds of both reflex responses was found. On the spastic side the first reflex response had higher threshold than the second one, while on the healthy side it was vice versa. Moderate correlations were found between most of the reflex parameters. No correlations were found between the reflex parameters and the degree of spasticity. Only after Baclofen treatment all reflex parameters tended to normalized. After treatment with Myolastan, Sirdalud and electroacupuncture only the second response's duration shortened. In conclusion the flexor reflex is a sensitive method for assessment of altered common interneurone activity in spasticity.(ABSTRACT TRUNCATED AT 250 WORDS)