Pain and remote weakness in limbs injected with botulinum toxin A for writer's cramp.

We describe two cases of a syndrome resembling neuralgic amyotrophy that occurred in limbs injected with botulinum toxin for writer's cramp. In both cases, one of the injections was followed by pain and the next, 7-10 weeks later, by weakness. We believe that unexplained pain in the shoulder region after an injection of botulinum toxin contraindicates a second injection.