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Methodological considerations contributing to variability of the quadriceps H-reflex
O Kameyama1, K C Hayes, D Wolfe
1Department of Orthopaedic Surgery, Kansai Medical University, Osaka, Japan.
American Journal of Physical Medicine & Rehabilitation
|December 1, 1989
Summary
This study investigated factors affecting the quadriceps H-reflex amplitude. Turning the head to the right significantly increased reflex amplitude, while remote muscle contractions also enhanced it, offering insights into electrodiagnostic variability.
Area of Science:
- Neuroscience
- Clinical Electrophysiology
Background:
- The quadriceps H-reflex is valuable for assessing neuromuscular function but suffers from elicitation difficulties and amplitude variability.
- Understanding factors influencing H-reflex amplitude is crucial for improving its clinical diagnostic utility.
Purpose of the Study:
- To determine the impact of methodological variables, specifically head position and remote muscle contractions, on quadriceps H-reflex amplitude.
- To identify controllable sources of variability in this electrodiagnostic test.
Main Methods:
- 13 healthy adults participated, with H-reflexes evoked in vastus medialis, vastus lateralis, and rectus femoris via femoral nerve stimulation.
- Stimuli were delivered percutaneously using square waves (1-ms duration) at 50% maximal amplitude.
- Variations included head positions (right, left, up, down), Jendrassik's maneuver, eye closure, and remote muscle contractions.
Main Results:
- Head position significantly influenced H-reflex amplitude, with a notable increase when the head turned right.
- Mild increases or no change were observed with other head positions (left, up, down).
- Remote muscle contractions enhanced reflex amplitude, while eye closure showed a tendency to decrease it.
Conclusions:
- Postural influences, particularly head position, represent a significant and controllable source of variability in quadriceps H-reflex amplitude.
- These findings contribute to a better understanding of quadriceps H-reflex characteristics and its application in L3-L4 root electrodiagnostic testing.