title: Methods of H-reflex evaluation in the early stages of Parkinson's disease.
abstract: Differentiating the early stages of Parkinson's disease from the normal consequences of aging or from other common neurologic conditions can be diagnostically problematic. The purpose of this study was to compare methodologies for measuring motor neuron excitability of Parkinson's disease patients with a control group. H-reflexes were monitored in 16 patients diagnosed in the early stages of Parkinson's disease (Hoehn & Yahr stages I and II) compared with 30 subjects who were disease free. Methods of measurement included H-reflex latencies, the relative values of maximum H-reflexes to maximum direct motor responses (H-to-M ratio), the relative values of H-reflex amplitudes during vibration compared with control H-reflex amplitudes (Hv-to-Hc ratio), and double-stimulation H-reflex recovery curves using different interstimulus interval parameters. No significant differences were observed for the H-to-M or Hv-to-Hc ratios, or for the H-reflex latencies. The H-reflex recovery curves for the patients with Parkinson's disease demonstrated significantly greater ratio amplitudes than the control group during the double-stimulus responses between the 150-msec and 700-msec interstimulus intervals. Although comparisons of simple H-reflexes and H-reflexes during vibration did not differentiate the patients in the early stages of Parkinson's disease from the control group, the double-stimulation paradigm was a sensitive method for detecting early diagnoses of this disease.
authors.affiliation: Texas Woman's University, 1130 John Freeman Boulevard, Houston, TX 77030, USA.
authors.forename: M
authors.initials: M
authors.lastname: Sabbahi
authors.forename: B
authors.initials: B
authors.lastname: Etnyre
authors.forename: I A
authors.initials: IA
authors.lastname: Al-Jawayed
authors.forename: S
authors.initials: S
authors.lastname: Hasson
authors.forename: J
authors.initials: J
authors.lastname: Jankovic
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D010300:Parkinson Disease / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D012021:Reflex, Abnormal / Q000502:physiology*; D014732:Vibration