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Updated: Jul 15, 2026
Bilateral Assessment of the Corticospinal Pathways of the Ankle Muscles Using Navigated Transcranial Magnetic Stimulation
Published on: February 19, 2019
Altered soleus responses to magnetic stimulation in pure cerebellar ataxia
Tomomi Kurokawa-Kuroda1, Katsuya Ogata, Rie Suga
1Department 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
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.
Significance:
SLR can be a useful neurophysiological parameter for evaluating cerebellofugal function.
