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Heat-sensitive conduction block in ulnar neuropathy at the elbow
S B Rutkove1, M A Geffroy, S H Lichtenstein
1Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, TCC-810, MA, Boston 02215, USA. srutkove@caregroup.harvard.edu
Summary
Elbow heating worsens ulnar neuropathy at the elbow (UNE) by increasing conduction block (CB) and slowing across-elbow conduction velocity (CV). Baseline CV and CB predict the severity of heating effects in UNE patients.
Area of Science:
- Neurology
- Neurophysiology
- Clinical Electrophysiology
Background:
- Ulnar neuropathy at the elbow (UNE) is a common condition.
- Nerve conduction studies (NCS) are used to diagnose UNE.
- Temperature can affect nerve conduction parameters.
Purpose of the Study:
- To investigate the impact of localized elbow heating on nerve conduction in UNE.
- To assess changes in conduction block (CB) and conduction velocity (CV) across the elbow.
Main Methods:
- Fifteen patients with UNE underwent motor NCS at a baseline temperature (32°C) and after localized elbow heating (42°C).
- Key parameters analyzed included amplitude, area, and across-elbow CV.
Main Results:
- Elbow heating significantly increased the relative drop in amplitude and area of motor responses when stimulating above the elbow compared to below.
- Mean across-elbow CV reduction increased significantly with heating.
- Baseline across-elbow CV and CB correlated with the degree of CB increase upon heating.
Conclusions:
- Localized elbow heating exacerbates conduction block and slows conduction velocity in the across-elbow segment in UNE patients.
- Pre-existing across-elbow CV and CB are predictive of the negative impact of heating on nerve conduction.