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H reflex threshold in Parkinson's disease patients for different stimulus duration
Mark Kushnir1, Colin Klein, Lea Pollak
1Department of Neurology, Assaf Harofe Medical Center Zerifin, Sackler School of Medicine, Tel-Aviv University, Zerifin 70300, Israel.
Parkinsonism & Related Disorders
|December 11, 2002
Summary
The H reflex, a muscle response to electrical nerve stimulation, differs significantly between healthy individuals and Parkinson's disease (PD) patients. This difference, particularly at shorter stimulus durations, can aid in assessing PD-related rigidity.
Area of Science:
- Neuroscience
- Clinical Electrophysiology
Background:
- The H reflex is a well-established electrophysiological measure.
- Assessing Parkinson's disease (PD) often involves evaluating extrapyramidal rigidity.
Purpose of the Study:
- To investigate the H reflex characteristics in normal subjects and PD patients.
- To determine if H reflex alterations can serve as a biomarker for PD rigidity.
Main Methods:
- Electrical stimulation with varying durations (0.1 ms to 1.0 ms) was applied to elicit the H reflex.
- The H reflex to M response threshold ratio (H/M TR) was calculated for 14 normal subjects and 19 PD patients.
- Statistical analysis (t-test) was used to compare H/M TR between groups and assess duration effects.
Main Results:
- A significantly lower H/M TR was observed in PD patients (13.2%) compared to normal subjects (71.1%).
- A significant difference in H/M TR was found across all stimulus durations between the two groups (p < 0.007).
- Shorter stimulus durations (optimal at 0.2 ms) yielded greater H/M TR differences, indicating higher sensitivity for PD assessment.
Conclusions:
- The H reflex exhibits distinct electrophysiological behavior in PD patients compared to healthy individuals.
- The H reflex, particularly its H/M TR at optimal stimulus durations, shows potential as a novel parameter for assessing extrapyramidal rigidity in Parkinson's disease.