The Effect of Muscle Selection for Botulinum Toxin A Injection on the Treatment Outcome in Poststroke Elbow Flexor Spasticity

Botulinum neurotoxin A (BoNT A) has been reported to be effective in the treatment of elbow flexor spasticity. In the treatment of poststroke elbow flexor spasticity with BoNT A, three main muscles injected individually or in combination are musculus biceps brachii, musculus brachialis and musculus brachioradialis. Although BoNT is an efficacious treatment option, there is a debate in the selection of target muscle(s) for BoNT A injection in the treatment of poststroke elbow flexor spasticity. Superficiality of the biceps brachii muscle makes it an easy target for botulinum toxin injection. In dynamic electromyography studies, it has been reported that brachioradialis muscle is the most common contributor one to elbow flexion spasticity, followed by biceps brachii muscle. In the diagnostic selective nerve blocks, the brachialis muscle has been reported to be foreground. In a recent study using the modified Delphi Method Design, the expert committee was only fully agree on the application of BoNT A into the brachioradialis muscle.

The decision of muscle selection for BoNT A injection is mostly made according to the physical examination findings in real life practice. One of the guiding findings in this decision is the position of the spastic arm. The typical pattern of spastic elbow and forearm in patients with stroke is characterized by flexion at the elbow, and pronation in the forearm. As far as the investigators know, there has not been carried out any study investigating the effect of muscle selection for BoNT application on the treatment outcome (severity of spasticity) in chronic stroke patients with elbow flexor and forearm pronator spasticity.

The aim of this study is to investigate whether treatment response (change in severity of spasticity) differs according to BoNT A injected muscle in chronic stroke patients with elbow flexor and forearm pronator spasticity.