Botulinum toxin in post-stroke patients: stiffness modifications and clinical implications.

To objectively quantify stiffness and clinical changes in the upper limb of poststroke patients following botulinum toxin (BT) injection. Eighteen consecutive chronic post-stroke spastic patients were injected Botulinum toxin A in the forearm flexor spastic muscles. Spasticity was clinically evaluated with the Ashworth scale. Stiffness was measured with indices (passive stiffness index (ISI) and total stiffness index (TSI) obtained by mechanical wrist displacements induced by a torque motor,which could also provide the stretch reflex threshold speed (SRTS) from flexor muscles. Functional status was measured with the Barthel index and a specific hand ability scale, pain with a visual analogue scale (VAS). The ranges of voluntary wrist extension (EROM) and flexion (FROM) and wrist isometric extension and flexion (IE-IF) strength were also calculated. IE and EROM significantly increased, being respectively p < 0.01 and p < 0.05; also SRTS was augmented (p < 0.001),while TSI showed lower values (p < 0.001); the Ashworth score decreased at least one point. Hand function for selected tasks improved in 50% of patients, the Barthel index only in 4 (22 %), forearm pain was completely relieved in 3 patients (17 %). BT can be considered a valid therapeutic tool in all spastic patients, because of immediate advantages: reduction of muscle hypertonia, pain relief, improvement in selected motor performances.