H-reflex Methods and Significance - PowerPoint PPT Presentation

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H-reflex Methods and Significance

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Title: H-reflex Methods and Significance


1
H-reflex Methods and Significance
  • Chetan Phadke, P.T., Ph.D.
  • Post-doctoral Fellow, Mentor Carolynn Patten
  • Neural Control Movement Lab
  • VA, BRRC

2
Monosynaptic reflex pathway
3
H-reflex
  • Paul Hoffmann first described it in 1910
  • Electrical analog of stretch reflex
  • By-passes muscle spindle and Gamma
  • Direct sensory fiber (Ia) electrical stimulation

4
The H-reflex
Muscle Spindle
Ia
a
H-reflex
Muscle
M-wave
Stimulus Artifact
Courtesy University of Louisville (Dept. of
Neurosurgery) and Frazier Rehab.
5
Window into Spinal Cord
  • Enables study of spinal excitability
  • Excitability is regulated by inhibition from
    supraspinal and sensory flow
  • The level of inhibition on the H-reflex
    determines the amplitude
  • Easily evoked in most muscles
  • Soleus widely studied

Palmieri (2004), Zehr (2001)
6
Functional Significance
  • Greater in Sitting than Standing
  • Greater in stance phase than swing
  • Pedaling modulation similar to walking
  • Arm swing and arm cycling alter soleus H-reflex
  • Walking on a narrow beam
  • Gymnasts

Capaday (1987), Trimble (2001), Phadke (2007),
Boorman (1992), Zehr (2001), Llewellyn (1990),
7
Phase dependent Hreflex modulation
8
H-reflex post-SCI
Non-injured
SCI
5V
31.25 ms
9
Functional Correlation
  • Greater amplitude post-SCI and slower ground
    walking speed
  • Single LT and bicycling session Smaller reflexes
    in walking and semi-reclined and increased ground
    walking speed
  • Long-term LT resulted in smaller reflexes in
    walking and faster ground walking speed

Trimble (2001), Phadke (2009), Behrman (2008 -
unpublished)
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