Ann Acad Med Singap
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Ann Acad Med Singap · Nov 2007
The role of electrophysiology in the diagnosis and management of cervical spondylotic myelopathy.
Cervical spondylotic myelopathy (CSM) is managed by conservative or surgical measures. While surgery is often performed in cases of longstanding or severe CSM, there is a lack of evidence concerning its efficacy. Transcranial magnetic stimulation (TMS) is a quick, safe, painless and non-invasive technique to study conduction in the descending corticospinal pathways in the spinal cord. The conduction time from the motor cortex to the anterior horn cell [central motor conduction time (CMCT)] is a measure of the integrity of corticospinal pathways. We have previously established the role of TMS in diagnosis and screening of CSM. In this study, we further investigate the use MEPs obtained with TMS in the outcome prediction of severe CSM patients requiring operative intervention. ⋯ In early CSM, lateral corticospinal tracts are first to be affected. It is thus possible that UL CMCT abnormality reflect more severe affectation of the corticospinal tracts placed relatively more medially in the cervical cord. Surgical intervention may have then effectively relieved the clinically significant compression, leading to a better outcome. This was further corroborated by our finding of negative correlation of S1 with UL CMCT, suggesting that patients who were clinically more severe were also electrophysiologically more abnormal, and subsequently benefited more from surgical decompression relative to patients with normal UL CMCT. This the largest series, to our knowledge, showing for the first time that UL CMCT abnormality obtained with TMS is an independent predictor of good surgical outcome in severe CSM.