SPINAL SOMATOSENSORY-EVOKED POTENTIALS IN PATIENTS WITH TETHERED CORDSYNDROME

We studied the electrophysiological changes occurring in six patients with tethered cord syndrome. Evidence of spinal malformations was prov ided by magnetic resonance imaging. The functional assessment of the s pinal cord was performed by analysing both spinal and cortical somatos ensory evoked potentials. The evoked electrospinogram was recorded fro m the thoracic and lumbosacral spinous processes. The N22 lumbosacral potential was selectively affected, being rostrocaudally displaced and reduced in amplitude or even absent in patients with neurological sig ns indicating a segmental lower cord lesion. Inter-peak somatosensory evoked potentials latency was normal in all cases, suggesting that asc ending axonal potentials in the dorsal column fibres may be synchroniz ed. Segmental potentials of the lumbosacral response, originating from the post-synaptic activity of dorsal horn interneurons, are selective ly affected in this syndrome resulting from the rostrocaudal displacem ent of the spinal cord due to tethering. Our findings in the clinical field are consistent with previous experimental evidence indicating a different sensitivity of the gray vs. white matter to progressive stre tching.