Study of sensation and muscle twitch responses to spinal cord stimulation

Dimitrijevič, Milan R.; Faganel, J.; Sharkey, Paul C.; Sherwood, Arthur M.

doi:10.3109/09638288009163961

Cited by 30 publications

(23 citation statements)

References 1 publication

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“…7,38,39 Ventral root (motor) ®bres are not activated in SCS. 38 Model calculations predict that the stimulus amplitude to excite a ventral root ®bre exceeds the value of a DR ®bre of the same calibre 14 times (WA Wesselink, J Holsheimer, unpublished results).…”

Section: Conclusion From Scs Modellingmentioning

confidence: 99%

Computer modelling of spinal cord stimulation and its contribution to therapeutic efficacy

1998

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An overview of computer models developed since the late seventies, which enable the simulation of the primary e ects of spinal cord stimulation (SCS) on nerve ®bres, is presented. These models consist of a 3-dimensional volume conductor model, representing anatomical structures and their electrical conductivities, and cable models representing the electrical behaviour of nerve ®bres. The characteristics of these models and their relation to anatomy and physiology, as well as the calculation of stimulation-induced electrical ®elds and their e ect on nerve ®bre models, are reviewed. It is shown that most characteristics of SCS as predicted by computer modelling correspond well with empirical data. Accordingly, a theoretical framework describing the relations between relevant parameters in SCS is presented. Finally, it is shown how theory and computer modeling are applied to improve the e cacy of SCS by the optimization of its technique, primarily by the design of new epidural electrodes.

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Section: Conclusion From Scs Modellingmentioning

confidence: 99%

Computer modelling of spinal cord stimulation and its contribution to therapeutic efficacy

1998

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“…Using fre quencies above 30 Hz, patients reported a feeling of vibration or 'buzz ing' in the segment adjacent to the epidurally placed cathode. The report ed sensation was variable between patients but quite constant for an indi vidual as long as the cathode did not move [5]. Through neurophysiolo- gical assessment of electrode position, we frequently found that although the electrodes were thought to be in an ideal position, as determined through fluoroscopy, they were not so well placed functionally.…”

Section: Physiological Observationsmentioning

confidence: 99%

Remarks on Spinal Cord Stimulation and the Placebo Effect

Sharkey¹,

Dimitrijevic²,

Campos³

et al. 1981

Stereotact Funct Neurosurg

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Spinal cord stimulation, which has been shown to be beneficial in multiple sclerosis as well as in sustained spinal cord injury, works through modification of specific motor mechanisms. This modification occurs through regional recruitment of spinal cord activity in posterior aspects of the spinal cord. Substantial involvement of the placebo effect can be ruled out by noting the persistence of beneficial effects observed in spinal cord injury patients and by the fact that the effects are related only to depolarization of posterior structures of the spinal cord, rather than to perception of a ''tingling'' sensation caused by spinal cord stimulation. Such a sensation can also occur when electrodes are over anterior or lateral structures of the spinal cord, when the stimulation is not effective in alleviating motor symptoms.

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“…The position of the electrode was veri®ed by¯uoroscopy (AP and lateral X-rays) and muscle twitch distribution patterns. 21 Muscle twitches during intraoperative testing were elicited using a train of 5 Hz at a pulse width of 210 ms, intensifying the amplitude in 0.5-V increments from 0 to 10 at two dierent polarities (37/0+ versus 07/3+). The de®nitive location of the electrode was determined based on muscle twitch responses by the quadriceps and adductor muscles elicited at an amplitude of 1 ± 4.5 V and a pulse width of 210 ms. For a detailed description of this procedure, the reader is referred to the ®rst paper of this series.…”

Section: Site Of Stimulationmentioning

confidence: 99%

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

Pinter¹,

2000

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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

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Study of sensation and muscle twitch responses to spinal cord stimulation

Cited by 30 publications

References 1 publication

Computer modelling of spinal cord stimulation and its contribution to therapeutic efficacy

Computer modelling of spinal cord stimulation and its contribution to therapeutic efficacy

Remarks on Spinal Cord Stimulation and the Placebo Effect

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

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