Effects of cervical spinal cord stimulation on cerebral blood flow in the rat.
OBJECTIVE
Spinal cord stimulation (SCS) is frequently used for the treatment of chronic pain. Although the mechanisms by which SCS alleviates pain are unclear, they are believed to involve changes within the dorsal horn of the spinal cord. Spinal cord stimulation has also been found to cause significant vasodilation in the peripheral vasculature. The mechanisms underlying this effect are thought to involve sympathetic blockade. A rostral vasodilatory effect has also been described, but changes in cerebral blood flow (CBF) have been poorly delineated. Using laser Doppler flowmetry (LDF), the authors examined the effects of cervical SCS on CBF in rats.


METHODS
Cervical SCS was found to result in a significant increase in cortical LDF values (83 +/- 11% [mean +/- standard error of the mean]). The increase in cortical LDF values was not accompanied by a significant increase in systemic blood pressure. Stimulation of the upper cervical spinal cord was more effective in inducing LDF changes than was that of the lower cervical cord. Changes in SDS-induced LDF values were significantly attenuated after spinal cord transection at the cervicomedullary junction and by the administration of the sympathetic blocker hexamethonium.


CONCLUSIONS
These results indicate that cervical SCS may induce cerebral vasodilation and that this effect may involve indirect effects on vasomotor centers in the brainstem as well as an alteration in sympathetic tone.
Sagher
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Section of Neurosurgery, University of Michigan Health System, Ann Arbor 48109, USA. osagher@umich.edu
Huang
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DL
D000704:Analysis of Variance; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001933:Brain Stem / Q000187:drug effects / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy; D005730:Ganglionic Blockers / Q000494:pharmacology; D018738:Hexamethonium / Q000494:pharmacology; D017078:Laser-Doppler Flowmetry; D008297:Male; D010100:Oxygen / Q000097:blood; D020671:Posterior Horn Cells / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology* / Q000601:surgery; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014666:Vasomotor System / Q000187:drug effects / Q000502:physiology
D005730:Ganglionic Blockers; D002245:Carbon Dioxide; D018738:Hexamethonium; D010100:Oxygen