Preemptive spinal cord stimulation reduces ischemia in an animal model of vasospasm

Spinal cord stimulation (SCS) has been increasingly used in the treatment of ischemia caused by obliterative diseases in the extremities and in the cardiac circulation. The most promising effects have been obtained when physicians suspect that a major vasospastic component underlies the ischemic symptoms (e.g., as in Raynaud's disease). Despite the clinical success of this treatment method, little is known about the mechanisms underlying the pain relief it produces and its anti-ischemic effects. Most earlier experimental studies have used normal animals or animals with cerebral vasospasm induced by injection of autologal blood into the cerebrospinal fluid space. In the present study, we applied SCS in a rat model via implanted electrodes to study the effect of preemptive stimulation on the ischemia caused by vasospasm in a neurovascular flap in the groin; the vasospasm was induced by mechanical pressure applied to the feeding artery. In rats treated with SCS, delivered with parameters similar to those used clinically, the percentage of flaps recovering normal microcirculation after the spasm was significantly higher than in the untreated control group (100 and 28%, respectively; P < 0.05), and the maximal blood flow after the ischemic episode was significantly higher in the SCS group than in the control group (127 and 51 arbitrary units, respectively; P < 0.05). The percentage of animals regaining the premanipulation circulation after the provocation of a second spasm was also greater in the SCS-treated group than in the control animals (50 and 14%, respectively; P < 0.05). Pilot studies showed that this protective effect was specific to SCS given before spasm induction, an observation corroborated by clinical experiences.(ABSTRACT TRUNCATED AT 250 WORDS)