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Updated: Jun 7, 2026
06:40
Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies
Published on: January 11, 2019
Frequency-dependent conduction block in ulnar neuropathy localized to the elbow
Bradley V Watson1, Timothy J Doherty
1School of Kinesiology, The University of Western Ontario, London, Ontario, Canada. brad.watson@rogers.com
Summary
Frequency-dependent conduction block (FDB) was not observed in acute ulnar neuropathy. However, FDB did appear in the recovery phase, suggesting demyelinating lesions respond differently to high-frequency stimulation.
Area of Science:
- Neuroscience
- Clinical Electrophysiology
Background:
- Acute ulnar neuropathy at the elbow can cause conduction block and slowing.
- Frequency-dependent conduction block (FDB) is a phenomenon observed in some neuropathies, like carpal tunnel syndrome (CTS).
Purpose of the Study:
- To investigate if FDB occurs in acute ulnar neuropathies localized to the elbow.
- To compare FDB response in ulnar neuropathy to that seen in CTS.
Main Methods:
- High-frequency nerve stimulation (30Hz, 20 stimuli) was applied to the ulnar motor nerve above and below the elbow.
- Studies were conducted on 15 controls and 10 patients with acute ulnar neuropathy (2-16 weeks duration) showing moderate to severe conduction block and slowing.
Main Results:
- FDB was not detected in any of the 10 patients during the acute phase of ulnar neuropathy.
- In follow-up studies of three patients, FDB was observed during the recovery period in two cases, similar to CTS patterns.
Conclusions:
- The unblocked ulnar motor fibers in acute ulnar neuropathy with conduction block do not exhibit FDB at 30Hz stimulation.
- These findings suggest that demyelinating lesions, such as conduction block in ulnar neuropathy, respond differently to high-frequency stimulation compared to other neuropathic conditions like CTS.
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