title: H reflex threshold in Parkinson's disease patients for different stimulus duration.
abstract: Electrical stimulus, with duration starting at 0.1 ms and gradually increased to 1.0 ms, was used for eliciting the H reflex in 14 normal subjects and 19 patients with Parkinson's disease (PD). In 71.1% of normal subjects and in 13.2% of PD patients the H reflex to M response threshold ratio (H/M TR) was <1 and the H reflex was obtained before the M response for all duration stimuli. For all stimulus durations a significant difference between the H/M TR in normal subjects and PD patients was found (t test 0.002-0.007). The duration effect was found to be highly significant-H/M TR for short stimulus duration was greater than for long stimulus durations (p<0.001). The optimal stimulus duration for evaluating H reflex behavior in PD patient was 0.2 ms. These very significant differences in behavior of the H reflex in PD patients could be used as another parameter in the assessment of extrapyramidal rigidity in PD patients.
authors.affiliation: Department of Neurology, Assaf Harofe Medical Center Zerifin, Sackler School of Medicine, Tel-Aviv University, Zerifin 70300, Israel.
authors.forename: Mark
authors.initials: M
authors.lastname: Kushnir
authors.forename: Colin
authors.initials: C
authors.lastname: Klein
authors.forename: Lea
authors.initials: L
authors.lastname: Pollak
authors.forename: Jose Martin
authors.initials: JM
authors.lastname: Rabey
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*