Related Experiment Videos
Transient forearm conduction block in the median nerve.
Bradley V Watson1, Anthony W Parkes, John D Brown
1Department of Clinical Neurological Sciences, London Health Sciences Centre, University Campus, 339 Windermere Road, P.O. Box 5339, London, Ontario N6A 5A5, Canada.
Muscle & Nerve
|March 1, 2002
Summary
Carpal tunnel syndrome (CTS) can present with normal initial tests. A transient conduction block in the forearm, possibly due to ischemia, can cause temporary symptoms.
Area of Science:
- Neurology
- Electrophysiology
Background:
- Carpal tunnel syndrome (CTS) is a common condition affecting the median nerve at the wrist.
- Standard electrophysiological tests are crucial for diagnosing CTS.
Observation:
- Two patients with suspected CTS showed normal initial nerve conduction studies.
- During testing, patients developed sensory symptoms and weakness with forearm supination and elbow extension.
- These symptoms resolved rapidly upon forearm pronation.
Findings:
- Electrophysiology revealed a complete, transient conduction block in the median nerve across the forearm.
- Conduction velocities were normal or only mildly slowed.
- The symptoms and electrophysiological abnormalities resolved within minutes of changing forearm position.
Implications:
- These findings suggest a proximal forearm abnormality causing transient median nerve dysfunction, potentially due to focal ischemia.
- Patients experiencing new symptoms during electrodiagnostic assessments warrant further investigation for proximal nerve issues.
- This highlights the importance of considering positional maneuvers during nerve conduction studies for suspected CTS.