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David Yashon, William Stone, Alfred Magness, William E. Hunt and William Hamelberg

✓ The effect of halothane-induced profound systemic arterial hypotension on brain ischemia was evaluated by comparison with hypotension caused by oligemia and trimethaphan as well as nonhypotensive controls. Mean cerebral tissue lactate concentrations after halothane-induced hypotension at 5, 30, and 60 minutes were 4.34, 5.92, and 7.48 mM/kg. There was no significant difference between halothane and control animals during the experimental period. At 30 and 60 minutes, both oligemic and trimethaphan groups were higher than the control and halothane series. Definite protection from cerebral ischemia is provided by halothane during induced hypotension. Exact mechanisms of protection conveyed by halothane are unclear, but are probably not related to relative increased blood flow since cerebral vasodilation is maximal in these low blood-pressure ranges irrespective of etiology.

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William E. Hunt, W. Kemp Clark, Arthur B. Eisenbrey Jr., Louis Finney, William E. Hunt, Bryon C. Pevehouse, Walter W. Whisler and Richard L. Rovit

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Calvin B. Early, Richard C. Dewey, Heinz P. Pieper and William E. Hunt

✓ Pressure-flow data are presented for the brain vascular bed in the rhesus monkey. These data are obtained at fixed levels of vasomotor tone. Resultant flow curves are called the “dynamic pressure-flow relationships” (DPFR). In the experimental model, arterial pressures are oscillated with a sinusoidal pump at frequencies exceeding the vasomotor response lag time. The resultant DPFR curves are discussed. A model is presented to show that changes in vasomotor tone cause a vertical shift of the DPFR. Changes in vascular bed resistance cause a change in the slope of the DPFR (▵P/▵F).

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Pediatric neck injuries

A clinical study

Stephen A. Hill, Carole A. Miller, Edward J. Kosnik and William E. Hunt

✓ This review of pediatric neck injuries includes patients admitted to Children's Hospital of Columbus, Ohio, during the period 1969 to 1979. The 122 patients with neck injuries constituted 1.4% of the total neurosurgical admissions during this time. Forty-eight patients had cervical strains; 74 had involvement of the spinal column; and 27 had neurological deficits. The injuries reached their peak incidence during the summer months, with motor-vehicle accidents accounting for 31%, diving injuries and falls from a height 20% each, football injuries 8%, other sports 11%, and miscellaneous 10%.

There is a clear division of patients into a group aged 8 years or less with exclusively upper cervical injuries, and an older group with pancervical injuries. In the younger children, the injuries involved soft tissue (subluxation was seen more frequently than fracture), and tended to occur through subchondral growth plates, with a more reliable union than similar bone injuries. In the older children, the pattern and etiology of injury are the same as in adults. The entire cervical axis is at risk, and there is a tendency to fracture bone rather than cartilaginous structures.

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William E. Hunt, J. N. Meagher, A. Friemanis and C. W. Rossel

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David Yashon, W. Michael Vise, Richard C. Dewey and William E. Hunt

✓ The temperature of the spinal cord parenchyma during local hypothermia was recorded in 18 dogs with and without a 300 to 500 gm-cm spinal cord injury. Other variables included opening the dura, location of the inflow stream, and the use of alcohol bath cooling. In nontraumatized cord, the temperature varied between 5.4° and 23.5°C depending on the location of the inflow stream; the variable range of 10–15 minutes of perfusion to reach these levels was unexpected. Temperatures of the injured cord fell to those of the reservoir (1.0° to 3.8°C) within 2½ minutes. The fact that the temperature of nontraumatized areas two segments cephalad to the injury was also reduced showed the capacity of the cord for thermal conduction. Opening the dura or use of an alcohol bath had little effect on cord temperature. Lack of heat transport due to ischemia is postulated as the primary cause of the rapid reduction of temperature in the injured cord to that of the surrounding environment.

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Carole Miller, Thomas V. Lloyd, John C. Johnson and William E. Hunt

✓ The authors present an unusual case of eosinophilic granuloma arising in the region of the foramen rotundum.

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Stephen A. Hill, James M. Falko, Charles B. Wilson and William E. Hunt

✓ Hyperthyroidism due to thyrotrophin (TSH)-secreting pituitary tumors is rare. Four cases are described, with the features that allow preoperative diagnosis. In all the patients, thyroid hormone production was consistently elevated despite antithyroid therapy, and TSH levels were inappropriately elevated. All patients were treated with both surgery and irradiation. Each patient had recurrent tumor with suprasellar, intrasphenoidal, or intraorbital spread. The combination of a recurrent, aggressive tumor complicated by thyrotoxicosis makes this a complex and difficult surgical problem.

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Joseph H. Goodman, W. George Bingham Jr. and William E. Hunt

✓ Endothelial changes leading to edema formation are examined in the primate spinal cord (Macaca mulatta) following a lesion created by a 20-gm weight falling 15 cm onto the exposed dura. Intravascular perfusion of a paraformaldehyde-glutaraldehyde solution followed by carbon black provides adequate fixation of vascular structures and glial elements. Myelin is poorly preserved. Ultrastructural alterations of the blood-brain barrier consist of loss of integrity of the endothelial tight junctions. Edema caused by vascular disruption and parenchymatous extravasation of intravascular contents is observed along with glial swelling. Interglial gap junctions persist in areas of marked cellular separation and do not impede the migration of edema fluid.

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Intramural neural elements in components of the carotid bifurcation

A histological basis for differential function

Sheldon B. Meyerson, James L. Hall and William E. Hunt

✓ The histology of the specialized region of the carotid bifurcation in man was studied with Orcein stain for elastic tissue, Masson's trichrome for muscle and connective tissue, and Bodian's silver method for neural elements. Four distinct regions exist: the common carotid, which appears to be solely a conduit; the carotid sinus, which is thin and very elastic with its baroreceptors in the medial wall; the external carotid, which is highly muscular and presumably active; and the internal carotid, also highly muscular and presumably active. The transition between zones is abrupt. Prominent clusters of up to 30 or 40 multipolar nerve cells, 15 to 25 µ in diameter, were found in the subintimal region of the internal carotid artery, some in the common, and a few in the external carotid. Occasional rounder cells of similar size with only one process were seen, possibly of sensory type. No cell bodies were seen in the adventitia of any vessel. No relation to the perivascular plexus was established. It is speculated that the neurons may be related to the reported local differential response to environment by the internal and external carotid systems.