Motor and sensory evoked potentials in syringomyelia

Seventy nine patients were admitted for syringomyelia. Fifty-nine had a mal formative syringomyelia, 15 a post-traumatic syrinx and 5 a syringomyelia r elated to a meningitis. For all the patients, the diagnosis of syringomyeli a was performed by MRI with measures of syrinx extension and transverse dia meter. Posterior tibial somato sensory evoked potentials (PT SEP), median ( M SEP), trigeminal (V3 SEP), brain stem auditory evoked potentials (BEAP), cortical and cervical motor evoked potentials (MEP) were correlated with cl inical and radiological findings. SEP abnormalities were not correlated with the duration of symptoms. PT SEP proved to be more sensitive than M SEP, MEP abnormalities were very freque nt (72 % of the cases), even without clinical motor deficit. Trigeminal SEP were more sensitive than BAEP which were not related to the presence of as sociated cranio vertebral abnormalities No significant relationship between clinical and radiological results was o bserved There was a positive relationship between electrophysiological and radiological results. Nethertheless, a good correlation was observed betwee n lateral clinical, MRI and electrophysiological results. Abnormal trigemin al SEP were detected in 46.6 % of the patients with high cervical syringomy elia. In all cases, trigeminal SEP and MEP should be done in association with M a nd PT SEP as both of them detect subclinical evidence of spinal cord dysfun ction in syringomyelia.