THE USEFULNESS OF CENTRAL MOTOR CONDUCTION STUDIES IN THE LOCALIZATION OF CORD INVOLVEMENT IN CERVICAL SPONDYLYTIC MYELOPATHY

Cervical spondylytic myelopathy (CSM) is common. Magnetic resonance im aging (MRI), although sensitive, often reveals extensive and sometimes clinically irrelevant findings. The purpose of this study was to inve stigate the usefulness of central motor conduction studies in localizi ng the rostral level of cord involvement in 6 patients with CSM. Centr al motor conduction was assessed using high-voltage stimulation for th e spinal roots and magnetoelectrical stimulation for the motor cortex, recording from ''marker muscles'' innervated by successively higher c ervical cord segments. Abnormal central motor conduction affected all subjects at C8-T1, 5 subjects at C7, but none at the C5-C6 levels. The MRI showed abnormalities at multiple levels as high as C4. Our result s suggest that central motor conduction studies are helpful in localiz ing the clinically relevant levels of spinal cord compression in CSM a nd correlate well with motor abnormalities on clinical examination. (C ) 1998 John Wiley & Sons, Inc.