title: Normalization of soleus H-reflex recruitment curves in controls and a population of spastic patients.
abstract: We examined soleus H-reflex recruitment in 30 controls and 33 patients with spinal cord lesions and spastic spinal paresis. H-reflex gain and threshold were determined from recruitment curves after normalization of stimulus intensity as a multiple of the current for a threshold M-response. Reflex gain was expressed as the mean slope of the H-reflex recruitment curve up to the half-maximal response size. Up to this point the curve follows an almost linear trajectory and will mainly reflect Ia afferent stimulation. This slope had a large variability but was clearly correlated with the H/M ratio. The mean gain was equal in controls and patients. The relation between H- and M-thresholds was expressed as a ratio which had a lower mean value in the patients. Though both H- and M-thresholds may be influenced by peripheral factors, this lower ratio suggests an increase in spinal motoneuron excitability in patients.
authors.affiliation: Graduate School of Neurosciences Amsterdam, Division of Clinical Neurophysiology (D2), The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: Hilgevoord
authors.forename: J H
authors.initials: JH
authors.lastname: Koelman
authors.forename: L J
authors.initials: LJ
authors.lastname: Bour
authors.forename: B W
authors.initials: BW
authors.lastname: Ongerboer de Visser
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004576:Electromyography; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009128:Muscle Spasticity / Q000503:physiopathology*; D011999:Recruitment, Neurophysiological / Q000502:physiology*