APPLICATION OF NUCLEUS PULPOSUS TO THE NERVE ROOM SIMULTANEOUSLY REDUCES BLOOD FLOW IN THE DORSAL ROOT GANGLION AND CORRESPONDING HINDPAW IN THE RAT.  Shoji Yabuki, MD, DMSc, Tamaki Igarashi, MD, and Shinichi Kikuchi, MD, DMSc.  Spine, Volume 25, Number 12,  June 15, 2000.

ABSTRACT

In this study, 16 rats had nucleus pulposis (NP) applied to the L5 nerve root in order to clarify the effects on the dorsal root ganglion (DRG) and hindpaws.  For the control group, the same volume of muscle tissue was applied.  Blood flow to the DRG, and hindpaws was measured with a 2 channel laser Doppler flowmeter.

The results are as follows:

1.        Only the NP-treated nerve roots showed blood flow reduction and edema formation in the DRG

2.        NP also affected the blood flow to the corresponding hindpaw.

The authors consider the following hypothesis:  NP causes increased endoneurial fluid pressure and decreased blood flow to the DRG.  This may cause sympathetic activity and ectopic firing in the DRG.  The sympathetic activity may cause even further decreased blood flow in the DRG, and cause a vasocontriction via a somatosympathetic reflex, inducing decreased blood flow in the hindpaw.  This could explain the decreased temperature that can sometimes be seen or reported in HNP cases.  This activity could also explain the etiology of radicular pain

COMMENT

  While this study may not directly affect treatment, it helps the clinician better understand the pathogenesis of HNP patients, and may give the clinician more information to explain to the patient exactly what may be happening, and why the pain may be occurring.