Neurophysiological effects of dorsal column stimulation in man and monkey

Abstract

✓ In 18 patients with cancer and intractable pain, capacitatively coupled pulses of 0.25 msec duration were delivered transcutaneously at 100 Hz to sets of five in-line electrodes implanted subdurally over the dorsal columns. Averaged somatosensory-evoked potentials were recorded from scalp electrodes before, during, and after application of current. All but one patient experienced relief of pain during stimulation, persisting for as long as several hours afterward. Eleven patients developed hyperactive deep reflexes, pathological reflexes, and decreased perception of joint rotation, pain, and touch below the level of current application. Somatosensory-evoked potential amplitudes were markedly reduced. All neurological findings returned to control values within 1 hour after each of repeated applications of current. Histological examination of spinal cord sections from four cancer patients showed no changes secondary to long-term current application. Similar currents were applied to the spinal cord of 15 monkeys with chronically implanted bipolar recording or stimulating electrodes over the lower, middle, and upper thoracic cord, in nucleus ventralis posterior lateralis (VPL), and over the sensory motor cortex (SMC). With application of current, the responses in VPL and SMC to peripheral stimulation were abolished. Evoked potential responses were abolished between bipolar stimulating electrodes and bipolar recording electrodes separated by the five in-line electrodes used to supply the 100 Hz current. However, when both stimulating and recording electrodes were either above or below the five in-line electrode set, evoked responses were unaffected. The findings indicate that applied currents blocked neuronal transmission by producing local changes in the cord. The prolonged alteration of cerebral evoked potentials and relief of pain, however, could also be related to involvement of supraspinal neurons.

Firing Pattern of Cells in Human Thalamus during Dorsal Column Stimulation

“…Thus, somatosensory-evoked potentials re corded from the scalp of patients have been found to be reduced in ampli tude during and, in some cases, even following cessation of DCS. Larson et al [6], N yquist and G reenhoot [9], as well as Bantu et al [2] ob tained a reduction in evoked potential amplitude in the cortex, in thalam ic nuclei and in the spinal cord in association with DCS. Lastly, at the cel lular level, D ong and Wagman [4] have reported a reduction in firing of cells in the thalamic posterior group of nuclei.…”

“…The pain re lief produced by DCS, however, could be due to mechanisms other than interactions in the dorsal horn. Thus, it has been shown in Rhesus mon keys that pathways in the ventral as well as in the dorsal quadrants of the cord are activated by DCS [2], and there is evidence in humans [5,6] as well as in animals [3,9] that DCS affects neuronal responsiveness in su-praspinal areas. The present communication extends these concepts by reporting the effect of DCS on single neuronal activity of the thalamus in one patient who underwent stereotaxic thalamotomy following previous implantation of a dorsal column stimulator.…”

“…Electrical stimulation of the dorsal columns of the spinal cord (DCS) has become a widely used technique for the relief of intractable pain [6,8,[10][11][12], This therapeutic method was based originally on the 'gate con trol' theory of Melzack and Wall [7], according to which the segmental collaterals of the posterior columns inhibit, in the dorsal horn, that type of neuronal activity which gives rise to the sensation of pain. The pain re lief produced by DCS, however, could be due to mechanisms other than interactions in the dorsal horn.…”

Effectiveness of spinal cord stimulation for painful camptocormia with Pisa syndrome in Parkinson’s disease: a case report

“…Blockage of pain at the spinal dorsal horn and the spinothalamic tract occurs by retrograde impulse conduction, which activates inhibitory neurons, increases GABA release, and reduces excitatory glutamic acid level. Other mechanisms have also been reported: activation of the descending pain suppression pathway and direct stimulation of the thalamus by SCS ascending impulses, leading to pain relief and improvement of failed sensory modulation action in the basal ganglia [4,[13][14][15][16][17][18][19].…”

Spinal cord stimulation for chronic pain management: mini-review

“…The mechanism of the analgesic action of spinal cord stimulation (SCS) was based initially on the gate control theory of pain proposed by Melzack and Wall [3]. On the other hand, it has been suggested that the SCS has multiple analgesic actions by acting on any abnormal activity in the A-β neurons that receive pain, restoring the normal gamma amino butyric acid levels in the dorsal horn, and releasing adenosine in the central nervous system [4,5]. In the spinal cord, pain modulating neurotransmitters, such as substance-P, and sero tonin, are released by SCS [6].…”