title: Comparison of tibial nerve H-reflex excitability after cervical and lumbar spine manipulation.
abstract: BACKGROUND
  Previous investigations indicate that spinal manipulation leads to short-term attenuation of alpha-motoneuron excitability, when assessed by means of the Hoffmann reflex. Past studies, however, are limited to regional effects, such as lumbar manipulation effects on lumbar alpha-motoneuron activity.
  
  
  OBJECTIVE
  This study compared and contrasted the effects of cervical and lumbar spine manipulation on the excitability of the lumbar alpha-motoneuronal pool in human subjects without low back pain, and compared the effects of cervical (nonregional) and lumbar (regional) spinal manipulation on lumbar alpha-motoneuron pool excitability in healthy subjects. The specific aim of this study was to determine if the inhibitory effects on the lumbar alpha-motoneuron pool associated with spinal manipulation are limited to the specific region in which the manipulative procedure is applied, or if rostral (cervical) manipulation can also influence caudal (lumbar) motoneuron excitability.
  
  
  METHODS
  Thirty-six nonpatient human subjects were used to study the effect of cervical and lumbar spinal manipulation on the amplitude of the tibial nerve Hoffmann reflex, recorded from the gastrocnemius muscle. The Hoffmann reflex (H-reflex) technique allows for an indirect index of motoneuron pool excitability by means of peripheral nerve Ia-afferent fiber stimulation. Reflexes were recorded before and after spinal manipulative procedures.
  
  
  RESULTS
  Lumbar spinal manipulation, as measured by amplitude changes of the tibial nerve H-reflex, attenuated lumbar alpha-motoneuronal activity. Suppression of motoneuronal excitability was significant (P <.05) but transient, with a return to baseline within 60 seconds after manipulation. Cervical spinal manipulation had no significant effect on lumbar motoneuron activity.
  
  
  CONCLUSIONS
  These data indicate that the inhibitory effects of spinal manipulation on motoneuronal excitability are regional, rather than global.
authors.affiliation: Department of Anatomy, New York Chiropractic College, Seneca Falls, NY 13148, USA. ddishman@nycc.edu
authors.forename: J Donald
authors.initials: JD
authors.lastname: Dishman
authors.forename: Brian M
authors.initials: BM
authors.lastname: Cunningham
authors.forename: Jeanmarie
authors.initials: J
authors.lastname: Burke
mesh_terms: D002574:Cervical Vertebrae / Q000294:innervation*; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008159:Lumbar Vertebrae / Q000294:innervation*; D008297:Male; D026882:Manipulation, Chiropractic / Q000379:methods*; D009046:Motor Neurons / Q000502:physiology; D011187:Posture / Q000502:physiology; D012021:Reflex, Abnormal / Q000502:physiology; D013979:Tibial Nerve / Q000502:physiology*