PHYSIOLOGICAL-EFFECTS OF SELECTIVE TIBIAL NEUROTOMY ON LOWER-LIMB SPASTICITY

Objectives-To assess by electrophysiology the effect of tibial selecti ve neurotomy on muscle imbalance of the spastic ankle. Method-The ampl itudes of the H reflexes, M responses (muscle contractions recorded af ter stimulation of the tibial nerve), and Hmax:Mmax ratio were recorde d in 12 patients with chronic lower Limb spasticity, before and one mo nth after tibial selective neurotomy. Recordings were done on medial a nd lateral gastrocnemius and soleus muscles. Clinical evaluation was d one with both global (Held's score) and analytical tests (step measure ments, gait velocity, and ankle angulation during active and passive m ovements). Results-After neurotomy, gait improved in all patients. Hel d's score of spasticity was better in all patients. Active dorsiflexio n of the ankle was unchanged in three patients, but the others improve d by 5 degrees to 12 degrees. Hmax, Mmax, and Hmax:Mmax ratios were lo wer. The Hmax on the gastrocnemius muscle, clinical strength, Mmax of all the muscles, and Hmax:Mmax ratio for the soleus and lateral gastro cnemius muscle were significantly lower after surgery. Conclusion-Ther e was an improvement of clinical and electrophysiological spastic indi ces after selective tibial neurotomy. Neurotomy acted not only on moto r neurons by decreasing strength, but also the reflex enlargement by d ecreasing sensory afferents.