Epidural electrical stimulation of posterior structures of the human lumbosacral cord: 3. Control of spasticity

Abstract

Objectives: The purpose of this study was to evaluate the eect of spinal cord stimulation (SCS) on severe spasticity of the lower limbs in patients with traumatic spinal cord injury (SCI) under close scrutiny of the site and parameters of stimulation. Materials and methods: Eight SCI patients (four women, four men) were included in the study. Levels of spasticity before and during stimulation were compared according to a clinical rating scale and by surface electrode polyelectromyography (pEMG) during passive¯exion and extension of the knee, supplemented by a pendulum test with the stimulating device switched either on or o over an appropriate period. Results: Both the clinical and the experimental parameters clearly demonstrated that SCS, when correctly handled, is a highly eective approach to controlling spasticity in spinal cord injury subjects. The success of this type of treatment hinges on four factors: (1) the epidural electrode must be located over the upper lumbar cord segment (L1, L2, L3); (2) the train frequency of stimulation must be in the range of 50 ± 100 Hz, the amplitude within 2 ± 7 V and the stimulus width of 210 ms; (3) the stimulus parameters must be optimized by clinically assessing the eect of arbitrary combinations of the four contacts of the quadripolar electrode; and (4) amplitudes of stimulation must be adjusted to dierent body positions. Conclusions: Severe muscle hypertonia aecting the lower extremities of patients with chronic spinal cord injuries can be eectively suppressed via stimulation of the upper lumbar cord segment. Spinal Cord (2000) 38, 524 ± 531

Epidural electrical stimulation of posterior structures of the human lumbosacral cord: 2. quantitative analysis by computer modeling

“…The level of the electrode with respect to the spinal cord is of high importance for several clinical applications, especially in order to reduce spasms 3 and to activate the spinal cord locomotion pattern generator. 1 Usually the electrode position is de®ned relative to vertebral segments but in living humans the location of the corresponding spinal cord segments cannot be identi®ed by currently available image techniques.…”

Stepping-like movements in humans with complete spinal cord injury induced by epidural stimulation of the lumbar cord: electromyographic study of compound muscle action potentials

“…11 These data were used to evaluate the refractory periods of responses to pairs of stimuli delivered at intervals of 200-10 ms, based on the first two stimuli of the applied trains.…”

“…When epidural spinal cord stimulation (SCS) became a clinical method to control severe spasticity in chronic spinal cord injured individuals, [8][9][10][11] it provided a neurophysiological technique to deliver tonic input to the human spinal cord deprived of supraspinal influence, and to examine locomotor capabilities of the lumbar cord. 12,13 In a clinical program of restorative neurology, we evaluated the optimal site and parameters of SCS for control of spasticity and thereby applied stimulation strengths from 1 to 10 V at frequencies from 2.2 to 100 Hz and tested different contact combinations of an epidurally placed electrode array.…”

“…12,13 In a clinical program of restorative neurology, we evaluated the optimal site and parameters of SCS for control of spasticity and thereby applied stimulation strengths from 1 to 10 V at frequencies from 2.2 to 100 Hz and tested different contact combinations of an epidurally placed electrode array. 11 In the course of the evaluation procedure, we discovered that the electrical stimulation of the posterior structures of the lumbar spinal cord could initiate and maintain rhythmic stepping-like flexion/extension movements of the subject's paralyzed limbs. To illustrate our findings in this initial study, we chose recorded electromyographic (EMG) activity of agonist-antagonist muscles of thigh and leg that lasted for 30 s without changes in the rhythmical patterns.…”

The Recovery Curve of Soleus and Gastrocnemius H-Reflex After Applying Tripolar Electrical Stimulation on the Anesthetized Skin of Vertebral Column: An Emphasis on the Early and Secondary Facilitation Phases

“…Nowadays this method is used to control chronic pain [3][4][5], create changes in muscle tone and control spasticity [6,7], and restore functional capacity in patients with spinal cord injury [8][9][10]. However, in many cases, the main goal is the stimulation of the spinal cord posterior column [11][12][13].…”