Altered soleus responses to magnetic stimulation in pure cerebellar ataxia.
OBJECTIVE
Transcranial magnetic stimulation (TMS) over the leg motor area elicits a soleus primary response (SPR) and a soleus late response (SLR). We evaluated the influence of the cerebellofugal pathway on the SPR and SLR in patients with 'pure' cerebellar ataxia.


METHODS
SPRs and SLRs were recorded from 11 healthy subjects and 9 patients with 'pure' cerebellar cortical degeneration; 5 with spinocerebellar ataxia type 6 (SCA6), and 4 with late cortical cerebellar ataxia (LCCA). In addition, three patients with localized cerebellar lesions were tested.


RESULTS
The SPR latency was significantly longer in patients than in controls, but primary responses in the tibialis anterior muscle were normal. The frequency of abnormal SLR was 38.9% in the supine position and 83.3% in the standing position. Two out of three patients with localized cerebellar lesions also showed abnormal SLR.


CONCLUSIONS
Altered SPRs in patients may result from a dysfunction of the primary motor cortex caused by crossed cerebello-cerebral diaschisis. In addition, our results suggest that 'pure' cerebellar degeneration involves the mechanism responsible for evoking SLR which is related to the control of posture.


CONCLUSIONS
SLR can be a useful neurophysiological parameter for evaluating cerebellofugal function.
Kurokawa-Kuroda
Tomomi
T
Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Fukuoka, Japan. kurokawa@neurophy.med.kyushu-u.ac.jp
Ogata
Katsuya
K
Suga
Rie
R
Goto
Yoshinobu
Y
Taniwaki
Takayuki
T
Kira
Jun-Ichi
J
Tobimatsu
Shozo
S
D000368:Aged; D002524:Cerebellar Ataxia / Q000145:classification / Q000473:pathology / Q000503:physiopathology*; D002531:Cerebellum / Q000503:physiopathology*; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D007866:Leg / Q000294:innervation; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000528:radiation effects; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011187:Posture; D011930:Reaction Time / Q000528:radiation effects; D050781:Transcranial Magnetic Stimulation / Q000379:methods*