A new concept in the electrophysiological evaluation of syringomyelia

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The current neurophysiological assessment of syringomyelia is inadequate. Early-stage syringomyelia is anatomically predisposed to affect decussating spinothalamic fibers that convey pain and sensation primarily. Silent periods have been proven to be a sensitive tool for detecting alterations in this pathway.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Thirty-seven patients with syringomyelia were included in this prospective study. Routine electrophysiological measurements were applied including somatosensory evoked potential (SSEP) and motor evoked potential (MEP) recordings for all extremities. The silent periods were recorded from the pollicis brevis muscle, and electrical stimuli were applied to the ipsilateral digiti II. To establish baseline values, the authors had 28 healthy controls undergo monitoring. Sensitivity and specificity values were statistically evaluated according to the main clinical symptoms (paresis, dissociative syndrome, and pain).</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>All control individuals had normal silent periods in voluntarily activated muscle. In syringomyelia patients, the affected limb showed pathological silent periods with all symptoms (sensitivity 30–50%). Pain was the most specific symptom (90%), despite SSEP and MEP values that were within the normal range.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Silent period testing is a sensitive neurophysiological technique and an invaluable tool for preoperative assessment of syringomyelia. Silent periods are associated with early dysfunction of thin myelinated spinothalamic tract fibers, even when routine electrophysiological measurements still reveal normal values. Conduction abnormalities that selectively abolish the silent periods can distinguish between hydromyelia (a physiologically dilated central canal) and space-occupying syringomyelia.</jats:p></jats:sec>

Evaluation of quality of life parameters in patients who have syringomyelia

“…8 Thus, it is important to identify and diagnose this subgroup of patients with the help of specific MRI sequences, electrophysiological studies and clinical follow-up, as no surgical intervention is necessary. 22,23 In fact, surgical intervention to relieve chronic symptoms may worsen the condition. Thus, expert guidance and an accurate diagnosis of syringomyelia are necessary to prevent iatrogenic deterioration.…”

Clinical course of incidental syringomyelia without predisposing pathologies

“…2 The term ''hydromyelia'' refers to a dilatation of the central canal, and ''syringomyelia'' refers to a fluid-filled cavity outside of the spinal canal, typically with gliotic walls. 12,16 Although Roser et al 17 distinguished between syringomyelia and hydromyelia using electrophysiological methods, in this study, we used the term ''syringomyelia'' to describe broadly both types of fluid-filled cavities within the spinal cord because it is difficult to distinguish between these two abnormalities in practice, and many spinal cord cavities have features of both conditions. 12,16…”

High sensitivity of contact-heat evoked potentials in “snake-eye” appearance myelopathy

“…EMG testing of the cutaneous silent period (CSP) has also been proposed as a sensitive method in the assessment of spinothalamic function in intramedullary lesions (Kofler et al, 2003;Lo et al, 2007;Roser et al, 2008;Stetkarova and Kofler, 2009;Stetkarova et al, 2001). CSP is a brief pause in voluntary EMG activity of a hand muscle (usually abductor pollicis brevis) following painful (electrical) stimulation of the segments C6 (thumb), C7 (middle finger) or C8 (little finger).…”