[A case of post-hemiplegic painful dystonia following thalamic infarction with good response to botulinus toxin].

We report a 67-year-old hypertensive right-handed woman who developed severe pain and dystonia in her left upper and lower extremity after a thalamic infarction. She was well until 9 months prior to the present admission to our hospital, when she had an acute onset of left hemiparesis which turned out to have been caused by a thalamic infarct. Her hemiparesis showed nearly complete recovery during the next four months. She noted an onset of severe spontaneous pain and difficulty in using her left hand four months prior to the present admission. Neurologic examination on admission revealed an alert and well oriented Japanese woman. Cranial nerves were intact. Although she did not have weakness, her left hand showed thalamic posture, and upon standing, she showed a dystonic posture in which her left forearm took pronation and flexion at the elbow joint and her left lower extremity took extension in the knee joint and planter flexion in the ankle joint. Her dystonic posture increased during walking and disappeared in the supine position. She complained of severe spontaneous pain and tingling sensation in her left extremities. Position sense was diminished in her left leg. However other sensations were intact. She had slight ataxia on the left side. Deep tendon reflexes were symmetric, but the planter response was extensor on the left side. MRI revealed a small lacunar infarct involving the right posterolateral thalamic region. EMG with surface electrodes revealed non-reciprocal tonic discharges in the left biceps brachii and forearm flexor and extensor muscles. She responded poorly to various medications. Only trihexyphenidyl showed partial alleviation of her pain and dystonic posture. We thought her pain might be caused by dystonic contraction of the skeletal muscles, at least in part. We injected 25 IU of botulinus toxin as a total dose into her biceps brachii, triceps brachii, and wrist flexor muscles. A few days after the injection, her dystonic posture began to show marked improvement; as her dystonia improved, her pain also showed marked improvement. This patient appeared to represent a case of post-hemiplegic dystonia. Her pain was initially thought to be the thalamic pain. However, as her pain disappeared with improvement of her dystonia, her pain is most likely to have been caused by the dystonic muscle contraction. Botulinus toxin treatment appears to be useful for post-hemiplegic painful dystonia.