Botulinum Toxin A Injection into the Subscapularis Muscle to Treat Intractable Hemiplegic Shoulder Pain

OBJECTIVE To evaluate the beneficial effect of botulinum toxin A (Botox) injection into the subscapularis muscle on intractable hemiplegic shoulder pain. METHODS Six stroke patients with intractable hemiplegic shoulder pain were included. Botulinum toxin A was injected into the subscapularis muscle. Intractable hemiplegic shoulder pain was evaluated using an 11-point numerical rating scale. Pain-free range of motion was assessed for shoulder abduction and external rotation. The spasticity of the shoulder internal rotator was measured using the modified Ashworth scale. Assessments were carried out at baseline and at 1, 2, 4, and, if possible, 8 weeks. RESULTS Intractable hemiplegic shoulder pain was improved (p=0.004) after botulinum toxin injection into the subscapularis muscle. Restricted shoulder abduction (p=0.003), external rotation (p=0.005), and spasticity of the shoulder internal rotator (p=0.005) were also improved. Improved hemiplegic shoulder pain was correlated with improved shoulder abduction (r=-1.0, p<0.001), external rotation (r=-1.0, p<0.001), and spasticity of the internal rotator (r=1.0, p<0.001). CONCLUSION Botulinum toxin A injection into the subscapularis muscle appears to be valuable in the management of intractable hemiplegic shoulder pain.