Ipsilateral silent period: a marker of callosal conduction abnormality in early relapsing-remitting multiple sclerosis?

Abstract

OBJECTIVE:

The corpus callosum (CC) is commonly affected in multiple sclerosis (MS). The ipsilateral silent period (iSP) is a putative electrophysiological marker of callosal demyelination. The purpose of this study was to re-assess, under recently established optimised protocol conditions [Jung P., Ziemann U. Differences of the ipsilateral silent period in small hand muscles. Muscle Nerve in press.], its diagnostic sensitivity in MS, about which conflicting results were reported in previous studies.

METHODS:

ISP measurements (onset, duration, and depth) were obtained in the abductor pollicis brevis (APB) muscle of either hand in 49 patients with early relapsing-remitting MS (RRMS) (mean EDSS, 1.3). Standard central motor conduction times to the APB (CMCT(APB)) and tibial anterior muscles (CMCT(TA)), and magnetic resonance images (MRI) were also obtained.

RESULTS:

ISP measurements showed a similar diagnostic sensitivity (28.6%) as CMCT(APB) (24.5%), while diagnostic sensitivities of CMCT(TA) (69.4%) and MRI of the CC (78.6%) were much higher. Prolongation of iSP duration was the most sensitive single iSP measure. ISP prolongation occurred more frequently when CMCT(APB) to the same hand was also prolonged (40.0% vs. 8.4%, p<0.0001). The correlation between iSP duration and CMCT(APB) was significant (Pearson's r=0.24, p<0.02), suggesting that iSP duration can be contaminated by demyelination of the contralateral corticospinal tract. ISP duration did not correlate with MRI abnormalities of the CC.

CONCLUSIONS:

ISP measures are neither a sensitive nor a specific marker of callosal conduction abnormality in early RRMS.

• Authors: Patrick Jung, Astrid Beyerle, Marek Humpich, Tobias Neumann-Haefelin, Heinrich Lanfermann, Ulf Ziemann
• Journal: Journal of the neurological sciences (J Neurol Sci) Vol. 250 Issue 1-2 Pg. 133-9 (Dec 01 2006) ISSN: 0022-510X [Print] Netherlands
• PMID: 17011585 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adult
• Corpus Callosum (pathology, physiopathology)
• Disease Progression
• Early Diagnosis
• Electrodiagnosis (methods)
• Female
• Hand (innervation, physiopathology)
• Humans
• Magnetic Resonance Imaging
• Male
• Middle Aged
• Motor Cortex (physiopathology)
• Multiple Sclerosis, Relapsing-Remitting (diagnosis, physiopathology)
• Muscle, Skeletal (innervation, physiopathology)
• Nerve Fibers, Myelinated (pathology)
• Neural Conduction (physiology)
• Pyramidal Tracts (physiopathology)
• Reaction Time (physiology)
• Transcranial Magnetic Stimulation (methods)