RESUMO
Spinal cord stimulation (SCS) affects peripheral, coronary and cerebral blood flow (CBF) in humans. In 1986 Meglio et al. [Appl Neurophysiol 1986;49:139-146] advocated a functional reversible sympathectomy as one of the mechanisms of SCS in man. An experimental animal model was developed to study SCS effects on CBF and to investigate the possible mechanisms. Twenty-one white New Zealand rabbits were anesthetized with Fluothane; spontaneous ventilation was permitted. A steady hemodynamic and metabolic state was maintained. A small cervical laminectomy was performed and an electrode (Medtronic Sigma 3483) was placed in the epidural space over the posterior spinal cord. Both common carotid arteries were exposed and external carotid arteries were ligated. In 3 animals, the cervical symapthetic trunk (CST) was exposed and wrapped with bipolar hook-stimulating electrodes. SCS was performed for 20 min with electrical square waves of 210 microseconds duration, 80 cycles/s, at 2/3 motor threshold intensity. CST stimulation was delivered for 1 min with the following parameters: 10 V, 10 cycles/s, 0.5 ms duration. CBF velocities of both internal carotid arteries were measured by using a CW Doppler (in all the animals) and electromagnetic flowmeter (in 2 animals), at rest, during sympathetic trunk stimulation, during SCS, during simultaneous SCS and CST stimulation. During SCS, an increase of CBF was detected in 11 rabbits (52.4%); a decrease was observed in two cases (9.5%). No change was detected in the remaining 8 animals (38%). CST stimulation induced a decrease of CBF in all animals. Electromagnetic flowmetry confirmed velocitometric findings in the 2 cases studied.(ABSTRACT TRUNCATED AT 250 WORDS)