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Technical artifact simulating "motor axonopathy".
J M Gilchrist1, E Dosremedios, G Johnson
1Department of Neurology, Rhode Island Hospital, Brown University, Providence.
Muscle & Nerve
|April 1, 1992
Summary
Technical artifact in nerve conduction studies can mimic motor axonopathy. A partial electrode transection caused falsely low compound motor amplitudes, resolved by replacing the electrode.
Area of Science:
- Neurology
- Neurophysiology
Background:
- Nerve conduction studies (NCS) are crucial for diagnosing peripheral nerve disorders.
- Motor axonopathy is characterized by reduced compound motor action potentials (CMAPs).
Purpose of the Study:
- To report a case series where technical artifact mimicked motor axonopathy on NCS.
- To highlight the importance of artifact detection in electrodiagnostic testing.
Main Methods:
- Review of 3 patients with unexpected NCS findings.
- Detailed analysis of nerve conduction study parameters including CMAPs and conduction velocities.
- Identification and correction of a technical artifact involving the active electrode.
Main Results:
- Initial NCS revealed low CMAPs with normal conduction velocities and sensory studies, suggesting motor axonopathy.
- Electromyography (EMG) findings were normal.
- A partial transection of the active electrode was identified as the source of artifact.
- Repeat NCS after electrode replacement normalized the CMAPs.
Conclusions:
- Partial electrode transection can create a technical artifact mimicking motor axonopathy.
- Careful artifact evaluation is essential for accurate NCS interpretation.
- Proper equipment maintenance and checks are vital in electrodiagnostic procedures.