Biomedical subjects
Publications and source records attributed to W E Hunt.
A muscle-splitting incision for cervical disc disease is described. It is based upon sound surgical principles. There have been no wound complications in the last 60 patients treated by the authors. Its most stringent demand is that the surgeon be familiar with the anatomical planes to be certain of the level which he wishes to explore.
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The fluorescent tracer Evans blue (EB) was studied after circulation time ranging from 30 seconds to 5 minutes following blood-brain barrier (BBB) injuries in 42 dogs. Selective neuronal stainings (sns), associated with BBB injuries, occurred to a high degree. This phenomenon was examined by modifications in existing fluorescence techniques. The mechanism of SNS was seen to lie in an almost imperceptible transport of EB along astrocytic processes connecting SNS with the adjacent vasculature. This report presents visual evidence under pathological conditions, and supports the concept of astrocytic processes as the normal route of transport between blood vessels and neurons. This requires long exposure photomicrographs since the fluorescing material is subtle within the neuroglial processes.
The authors used indicator fractionation techniques to determine blood flow in normal and bluntly traumatized spinal cords of Macaca rhesus monkeys. Normal flow rates were determined for several levels of spinal cord as well as differential values for white and gray matter from representative areas. Flow rates in traumatized tissue, obtained at several different time intervals up to 4 hours after injury, demonstrated marked differences in regional perfusion of the white matter and gray matter after trauma. Gray matter perfusion was nearly obliterated while white matter blood flow persisted and in fact was higher than uninjured controls. The findings do not support the concept of ischemia as a factor in white matter failure. If toxic pathobiochemical alterations are induced by trauma, it may be possible to reverse these changes by exploiting the preserved white matter blood flow for chemotherapeutic intervention.
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Electrical stimulation of the nervous system has been advocated as a means of alleviating pain in situations in which more conventional methods have been ineffective. A chronically implanted electrode on the dorsal surface of the spinal cord may prove to be a valuable adjunct to the neurosurgeon's armamentarium for pain control in selected individuals. The physiologic basis for this action is unclear but has been related to Melzack and Wall's gate control theory. This preliminary report deals with a series of patients treated with implanted dorsal cord stimulators.
The importance of autacoidal substances in the genesis of cerebral vascular constriction and spasm is an unresolved issue. Comparative vasoactivity of 5-hydroxytryptamine (5HT) and norepinephrine (NE) on the human basilar artery was quantitatively assessed in vitro. 5HT was decidedly more vasoactive in this preparation. Three patterns of vasoactivity were noted with 5HT. Type I was an immediate sustained increase in tension lasting more than 30 minutes. Average increase in tension was 2988 mg (range 120-8600). Type II consisted of a sharp immediate increase in tension to average 1555 mg (range 240-4500) followed by gradual dissipation to base-line levels within 15 minutes. Type III pattern was a lesser immediate increase (372 mg; range 100-850) and more rapid dissipation over ten minutes. NE-induced Type I and Type III activity was present in only six of 20 segments. This study demonstrates that 5HT is vasoactive in human cerebral arteries. Type I sustained contractions may possibly be implicated in spasm. It is hypothesized that such autacoid-induced contraction may contribute to vascular wall ischemia, necrosis, and irreversible constriction as seen in human vasospasm.
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