Tankisi, H;
Bostock, H;
Grafe, P;
(2022)
A test to determine the site of abnormal neuromuscular refractoriness.
Clinical Neurophysiology Practice
, 7
(2022)
pp. 1-6.
10.1016/j.cnp.2021.11.001.
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Abstract
Objective: The relative refractory period (RRP) of motor axons is an important parameter in nerve excitability tests of the recovery cycle (RC). Abnormalities may have a site in the axonal membrane, the neuromuscular junction, or in a dysfunction of the muscle. We aimed in this study to determine the site of abnormality, using a modified protocol of the conventional RC test, whereby an additional supramaximal stimulus is added at the same interstimulus interval as in RC recordings (RCSM). Methods: Twenty-four healthy subjects aged 37.8 ± 2.4 years (mean ± SE) were examined with median nerve excitability testing using RC and RCSM protocols at normal temperature (34.1 ± 0.2 °C). The recordings were repeated in 12 subjects after selective cooling of the thenar muscle (25.2 ± 0.7 °C) and in 12 subjects after cooling the nerve trunk at the wrist (24.9 ± 0.3 °C). Results: After cooling the nerve, RRP measured with RC and RCSM were prolonged similarly (medians by 1.8 ms, and 2.1 ms respectively). In contrast, cooling the muscle prolonged RRP measured with RC (by 1.3 ms), but did not significantly prolong RRP measured with RCSM. RRPs measured by RC and RCSM were significantly different when cooling was at the muscle (P = 5.10-4), but not when cooling was at the nerve (P = 0.57). Conclusions: A difference between RC and RCSM indicates abnormal excitability distal to the axonal membrane under the stimulating electrode. Significance: Combining RCSM with the conventional RC protocol should help to localize the site of abnormal neuromuscular refractoriness.
| Type: | Article |
|---|---|
| Title: | A test to determine the site of abnormal neuromuscular refractoriness |
| Location: | Netherlands |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.cnp.2021.11.001 |
| Publisher version: | https://doi.org/10.1016/j.cnp.2021.11.001 |
| Language: | English |
| Additional information: | This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). |
| Keywords: | Cooling the muscle, Cooling the nerve, Nerve excitability, RCSM protocol, Recovery cycle, Refractoriness |
| UCL classification: | UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10144491 |
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