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Normal limits of side-to-side H-reflex amplitude variability
W R Jankus1, L R Robinson, J W Little
1Department of Rehabilitation Medicine, University of Washington, Seattle 98195.
Archives of Physical Medicine and Rehabilitation
|January 1, 1994
Summary
The tibial H-reflex amplitude difference can help diagnose S1 radiculopathy when latency is normal. A side-to-side amplitude ratio below 0.4 suggests an abnormal condition.
Area of Science:
- Neurology
- Neurophysiology
Background:
- Unilateral S1 radiculopathy diagnosis can be challenging with normal H-reflex latency.
- The study investigated the utility of H-reflex amplitude differences in diagnosing this condition.
Observation:
- 45 healthy subjects with normal side-to-side H-reflex latency (difference < 1.5 msec) were analyzed.
- Maximal H-reflex amplitudes were recorded, and the ratio of the smaller to larger amplitude was calculated.
- The mean amplitude ratio was 0.74 +/- 0.17.
Findings:
- A side-to-side H-reflex amplitude ratio below 0.4 (mean - 2 SD) was identified as a potential indicator of abnormality.
- This finding suggests amplitude asymmetry is a valuable diagnostic parameter.
Implications:
- This diagnostic criterion may improve the identification of unilateral S1 radiculopathy.
- It offers a complementary approach to latency measurements in neurophysiological assessments.