Neurosurgery
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This study investigated the spinal evoked response to focal electrical stimulation of the sensorimotor cortex in 32 rats. The results demonstrate a long-latency response (beginning at 8 milliseconds) elicited by electrical stimulation, which is distinct from the short-latency motor evoked potential previously reported. The conduction velocity of this later response is similar to that reported for the pyramidal tract in the rat. ⋯ Experimental lesions of the pyramidal tract or ablating the sensorimotor cortex eliminated the spinal cord evoked response. The results demonstrate that focal stimulation of the sensorimotor cortex results in a spinal cord evoked response that represents activity within the pyramidal system. The utility of this response in the rat model for assessing experimental cord injury is discussed.
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Review Case Reports
Surgical treatment of a rare congenital anomaly of the vertebral artery: case report and review of the literature.
A case of an abnormal loop of the vertebral artery compressing both the cervicomedullary junction and the accessory nerve is reported. The embryological development of the vertebrobasilar system may explain this anatomical anomaly. ⋯ The present patient was cured by microvascular decompression. The pathogenetic and surgical implications are discussed in light of the literature.
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Potential prognostic anatomic and hemodynamic factors were evaluated in 248 patients with cerebral arteriovenous malformations (AVMs), all treated by direct microsurgical removal. The size of each AVM was calculated by its volume, obtained by the multiplication of the three AVM diameters by 0.52. A surgical classification of AVM location (in 11 groups) is proposed. ⋯ As for other anatomic factors: a) the presence of deep feeders significantly increased the incidence of hyperemic complications, as well as the morbidity and mortality rate; b) the presence of deep drainage significantly increased permanent morbidity only; c) the extension of the venous system was significantly related to the development of hyperemic complications, and to morbidity and mortality. Transcranial Doppler examination showed that mean flow velocities greater than 120 cm/s in the main feeder were associated with a significantly higher rate of postoperative hematomas and transient deficits. A classification of cerebral AVMs that takes into account AVM volume and location, the type of feeders, the extent of the drainage system, and the main feeder flow velocity is suggested.
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Spinal cord stimulation has been reported to relieve ischemic pain and to enhance peripheral circulation. To elucidate the still unknown mechanisms behind these effects, changes in the peripheral blood flow in the skin of the hind paw after stimulation applied to the dorsal column was studied in the normal rat. A substantial flow increase, monitored by laser Doppler technique, was observed in response to stimulation with an intensity comparable to that used clinically in man, recruiting only low-threshold neuronal elements. ⋯ Stimulation failed to produce an increase in blood flow in addition to that produced by guanethidine and hexamethonium, but high-intensity dorsal column or dorsal root stimulation still was effective. The results indicate that spinal mechanisms are essential and that antidromic activation of primary afferent fibers is unlikely to account for the peripheral vasodilatation induced by low-intensity spinal cord stimulation. Our observations suggest a transitory inhibition of sympathetic vasoconstriction as the principal underlying mechanism.
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Biography Historical Article
Kenneth McKenzie, Harvey Cushing, and the early neurosurgical treatment of spasmodic torticollis.
In 1923, Dr. Kenneth McKenzie trained at the Peter Bent Brigham Hospital under Dr. Harvey Cushing. ⋯ The record includes postoperative drawings of the intraoperative field by Dr. Cushing, a sketch by Dr. McKenzie illustrating the postoperative sensory examination, and pre- and postoperative photographs of the patient.