A test to determine the site of abnormal neuromuscular refractoriness
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 th...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-01-01
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| Series: | Clinical Neurophysiology Practice |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2467981X21000470 |
| _version_ | 1811197591662100480 |
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| author | Hatice Tankisi Hugh Bostock Peter Grafe |
| author_facet | Hatice Tankisi Hugh Bostock Peter Grafe |
| author_sort | Hatice Tankisi |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-04-12T01:17:32Z |
| format | Article |
| id | doaj.art-530f8694fc9f42d8861ffb91e20aaede |
| institution | Directory Open Access Journal |
| issn | 2467-981X |
| language | English |
| last_indexed | 2024-04-12T01:17:32Z |
| publishDate | 2022-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Clinical Neurophysiology Practice |
| spelling | doaj.art-530f8694fc9f42d8861ffb91e20aaede2022-12-22T03:53:54ZengElsevierClinical Neurophysiology Practice2467-981X2022-01-01716A test to determine the site of abnormal neuromuscular refractorinessHatice Tankisi0Hugh Bostock1Peter Grafe2Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark; Corresponding author at: Department of Clinical Neurophysiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark.Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UKInstitute of Physiology, Ludwig-Maximilians University Munich, GermanyObjective: 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.http://www.sciencedirect.com/science/article/pii/S2467981X21000470Nerve excitabilityRecovery cycleRefractorinessCooling the nerveCooling the muscleRCSM protocol |
| spellingShingle | Hatice Tankisi Hugh Bostock Peter Grafe A test to determine the site of abnormal neuromuscular refractoriness Clinical Neurophysiology Practice Nerve excitability Recovery cycle Refractoriness Cooling the nerve Cooling the muscle RCSM protocol |
| title | A test to determine the site of abnormal neuromuscular refractoriness |
| title_full | A test to determine the site of abnormal neuromuscular refractoriness |
| title_fullStr | A test to determine the site of abnormal neuromuscular refractoriness |
| title_full_unstemmed | A test to determine the site of abnormal neuromuscular refractoriness |
| title_short | A test to determine the site of abnormal neuromuscular refractoriness |
| title_sort | test to determine the site of abnormal neuromuscular refractoriness |
| topic | Nerve excitability Recovery cycle Refractoriness Cooling the nerve Cooling the muscle RCSM protocol |
| url | http://www.sciencedirect.com/science/article/pii/S2467981X21000470 |
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