Evoked potentials and contingent negative variation during treatment of multiple sclerosis with spinal cord stimulation.

Abstract

S U M M A R Y Cervical somatosensory evoked potentials, brainstem evoked potentials, visual evoked potentials, and the cerebral contingent negative variation were recorded in patients with definite multiple sclerosis before, during, and after spinal cord stimulation. Improvements were seen in the cervical somatosensory and brainstem evoked potentials but neither the visual evoked potential nor the contingent negative variation changed in association with spinal cord stimulation. The results indicate that spinal cord stimulation acts at spinal and brainstem levels and that the clinical improvements seen in patients are caused by an action at these levels rather than by any cerebral arousal or motivational effect. The evoked potentials were not useful in predicting which patients were likely to respond to stimulation.

Beneficial Augmentation following Dorsal Column Stimulation in Some Neurological Diseases

“…Patients with neurological dis ease undergoing DCS are made fully aware that this is only an aid and certainly not a treatment or a cure for their neurological problems; a simi lar analogy is made to a hearing device for a patient having progressive nerve deafness. As to the neurophysiological mechanisms underlying DCS effective ness, our clinical findings support the theory that DCS increases the amount of background-afferent activity into a partially deafferented or weakened neuronal system [10,11,20]. DCS activates impulses orthodromically and antidromically in the dorsal columns (fig.…”

“…DCS activates impulses orthodromically and antidromically in the dorsal columns (fig. I); orthodromic impulses ascend and subjectively cause the paresthesia of 'tingling', and supposedly augmenting higher brain stem centers [20] resulting in im provements in speech, swallowing, and eye coordination (tables II-V). Antidromic impulses supposedly travel into motoneuronal pools through the branched dorsal roots ( fig.…”

Spinal Cord Stimulation as a Tool f or Physiological Research

“…In studies of possible [2,3,8,13,17] and questionable [16,24] ef fects of SCS in patients with upper m otor neuron dysfunction syn-drome, the recording of H reflex changes [11,14,21] and cervical so matosensory evoked potential changes [ 17] before and after continuous stimulation provide a better way of assessing the extent of any such ef fects. Furthermore, simultaneous electromyographic recording from several flexor and extensor leg muscles, while eliciting phasic and tonic stretch reflexes, vibratory-induced reflex responses, cutaneomuscular reflexes, and volitional control, along with polyelectromyographic re cording of activity during standing and walking, have been shown to be feasible techniques to monitor functional changes induced in pa tients by spinal cord stimulation [8], Finally, it has been demonstrated that upper thoracic SCS electrodes can be used to condition tendon jerk responses of the quadriceps [7].…”

“…Recent advances in spinal cord stim ulation (SCS) for modification of im paired m otor activity have presented an opportunity for the clini cal researcher to observe [1, 4-7, 9, 12, 13, 15, 21-23], to record [13,17,21], and to study changes in abnorm al m otor activity in patients with upper m otor neuron dysfunctions [8]. However, from an experimental design point of view, the situation is rather complicated, due to the fact that the currently used stim ulation param eters require continuous ap plication o f the stimulus.…”

Propriospinal Mechanisms Involved in the Effects of Spinal Cord Stimulation

“…In addition, IIIis et al [9] re ported that H-reflex inhibition by cutaneous afferents, found absent in patients with multiple sclerosis, reappeared on spinal cord stimulation. Lastly, Sedgwick et al [23] have shown a significant influence of spinal cord stimulation on cervical somatosensory-evoked potentials and on brain stem auditory-evoked potentials. Also of importance in our consi derations is the fact that the effects obtained through a short period of spinal cord stimulation may persist for hours after discontinuation of the stimuli.…”