Effect of noxious electrical stimulation of the peroneal nerve on stretch reflex activity of the hamstring muscle in rats: possible implications of neuronal mechanisms in the development of tight hamstrings in lumbar disc herniation.
METHODS
The effect of noxious electrical stimulation of the peroneal nerve on the stretch reflex electromyogram activity of the hamstring muscle (semitendinous) was studied.


OBJECTIVE
To verify the following hypothetical mechanisms underlying tight hamstrings in lumbar disc herniation: stretch reflex muscle activity of hamstrings is increased by painful inputs from an injured spinal nerve root and the increased stretch reflex muscle activity is maintained by central sensitization.


BACKGROUND
It is reported that stretch reflex activity of the trunk muscles is induced by noxious stimulation of the sciatic nerve and maintained by central sensitization.


METHODS
In spinalized rats (transected spinal cord), the peroneal nerve was stimulated electrically as a conditioning stimulus. Stretch reflex electromyogram activity of the semitendinous muscle was recorded before and after the conditioning stimulus.


RESULTS
Even after electrical stimulation was terminated, an increased stretch reflex activity of the hamstring muscle was observed.


CONCLUSIONS
It is likely that a central sensitization mechanism at the spinal cord level was involved in the increased reflex activity. Central sensitization may play a part in the neuronal mechanisms of tight hamstrings in lumbar disc herniation.
Hirayama
Jiro
J
Center for Spinal Disorder and Low Back Pain, Department of Orthopedic Surgery, Chiba Rosai Hospital, Chiba, Japan. j-hiraya@bk9.so-net.ne.jp
Yamagata
Masatsune
M
Takahashi
Kazuhisa
K
Moriya
Hideshige
H
D000818:Animals; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000009:adverse effects; D004576:Electromyography; D006614:Hindlimb; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000503:physiopathology*; D008297:Male; D009132:Muscles / Q000293:injuries; D010543:Peroneal Nerve / Q000503:physiopathology*; D011843:Radiculopathy / Q000209:etiology / Q000503:physiopathology*; D016059:Range of Motion, Articular; D051381:Rats; D017207:Rats, Sprague-Dawley; D012026:Reflex, Stretch; D012399:Rotation; D013119:Spinal Cord Injuries; D013180:Sprains and Strains / Q000503:physiopathology*; D013708:Tendon Injuries / Q000150:complications / Q000503:physiopathology