Intracortical inhibition of the motor cortex is normal in chorea
- Ritsuko Hanajima,
- Yoshikazu Ugawa,
- Yasuo Terao,
- Toshiaki Furubayashi,
- Katsuyuki Machii,
- Yasushi Shiio,
- Hiroyuki Enomoto,
- Haruo Uesugi,
- Hitoshi Mochizuki,
- Ichiro Kanazawa
- Department of Neurology, Division of Neuroscience, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
- Dr Yoshikazu Ugawa, Department of Neurology, Division of Neuroscience, Graduate School of Medicine, University of Tokyo, 7–3–1, Hongo, Bunkyo-ku, Tokyo, 113–8655, Japan. Telephone: 0081 3 3815 5411 ext 3783; fax 0081 3 5800 6548.
- Received 12 June 1998
- Revised 11 November 1998
- Accepted 22 December 1998
Abstract
Intracortical inhibition of the motor cortex was investigated using a paired pulse magnetic stimulation method in 14 patients with chorea caused by various aetiologies (six patients with Huntington’s disease, one with chorea acanthocytosis, a patient with systemic lupus erythematosus with a vascular lesion in the caudate, three with senile chorea and three with chorea of unknown aetiology). The time course and amount of inhibition was the same in the patients as in normal subjects, suggesting that the inhibitory mechanisms of the motor cortex studied with this method are intact in chorea. This is in striking contrast with the abnormal inhibition seen in patients with Parkinson’s disease or focal hand dystonia, or those with a lesion in the putamen or globus pallidus. It is concluded that the pathophysiological mechanisms responsible for chorea are different from those producing other involuntary movements.
