No abstract

Exposure of the dorsal ganglion to pulsed RF currents activates pain-processing neurons in the dorsal horn. This effect is not mediated by tissue heating.

TL provides sustained, long-term benefit in patients with medically refractory TLE. Seizure-free status at 2 years from the time of surgery is predictive of long-term remission.

No abstract

✓ Arm pain due to avulsion of the cervical dorsal roots of the brachial plexus may become intractable, ameliorated little, if at all, by contemporary medical or surgical treatment. Severe and sudden trauma to the neck, shoulder, or arm is the usual cause of avulsion of the cervical rootlets. The injury may result in complete sensorimotor paralysis of the involved extremity, or a partial deficit if only a few rootlets are involved. Previous therapies have included stellate block, sympathectomy, high cervical cordotomy, rhizotomy, transcutaneous stimulation, dorsal column stimulation, mesencephalic tractotomy, cingulotomy, and the use of narcotics. The extent of the pathological change in the spinal cord following root avulsion is not completely known; at the time of operation, abnormalities frequently noted included ipsilateral atrophy of the dorsal aspect of the cord, dense arachnoid scarring, microcyst formation, and loss of both dorsal and ventral roots. The cervical myelogram is abnormal, although not necessarily pathognomonic of the extent of injury. The surgical technique of coagulation of the dorsal root entry zone is discussed, and the results and morbidity in 21 patients are reviewed. Thirteen patients (67%) continue to have good pain relief, with follow-up periods ranging from 6 months to 3½ years. Three patients with extremity pain from other causes are included in the series. Clinical observations suggest the possibility that pain resulting from brachial plexus avulsion originates from pathophysiological changes in the injured dorsal horn of the spinal cord. This report is a discussion of a new technique aimed at destruction of the dorsal root entry zone for relief of chronic extremity pain.

✓ Thirty patients with chronic intractable pain have had dorsal column implants and a trial of subsequent electrical self-stimulation to relieve the pain. Burning pain originating from damage to the CNS was most often relieved, while chronic bone, joint, and disc pain responded less well. Patients with severe psychiatric factors should be excluded, but preoperative selection is still difficult because of the lack of objective clinical tests. The long-term effect of the implant on the tissues of the dorsal column is still unknown and requires further evaluation. Although relief of pain has been reported for as long as 3 years, much longer follow-ups are necessary to evaluate the efficiency of this system in patients with chronic pain. Direct stimulation of the spinal cord raises a number of interesting questions in regard to perception and sensory phenomena in man but, as yet, there are no answers as to how dorsal column stimulation effects its relief of pain.

ITUATED deep within the paramedian region of the cerebellum lies a constellation of nuclei that relay cerebellar influences throughout the central nervous system. The dentate, which is the largest of these nuclei in man, was first described in 1685 by VieussenY 9 It relays chiefly the efferent outflow from the lateral hemispheric area of the cerebellum, exerting its influence on the tone and movement of the ipsilateral limbs. 1,~,~4,25 Experimental dentate lesions result in hypotonia, dysmetria, and, in some cases, tremor. 1,~,24 Recently, neurosurgeons have attempted to ablate the dentate in persons with extreme hypertonia and involuntary movements. We have developed stereotaxic coordinates for the cerebellar nuclei in order to explore the paramedian cerebellar regions by electrical stimulation with a view of assessing the therapeutic possibilities of cerebellar nuclear lesions. 26 This report concerns the effects of electrical stimulation and high frequency lesions in the regions of paramedian cerebellar structures.

Unilateral dorsal rhizotomies were done at the cervicothoracic and lumbosacral spinal cord levels in rats. In preliminary experiments dermatome maps were determined for the roots to be sectioned. The behavior of 37 rats was observed for many months after the rhizotomies. The rats with the dorsal roots sectioned in the cervicothoracic spinal cord exhibited the following behavior: at the border of the skin adjacent to the zone of deafferentation, the rat scratched vigorously and progressively denuded the skin; self-mutilation of varying degrees occurred in the deafferented limb. In some animals scratching occurred in the contralateral skin dermatome opposite to the partially deafferented zone. The rats with the dorsal roots sectioned at the lumbosacral level exhibited hypersensitivity to cutaneous stimulation but there was no scratching or self-mutilation. These results are discussed in the light of previous similar research.