Biomedical subjects
Publications and source records attributed to J T Hoff.
The University of Michigan Medical School was founded in 1847, 30 years after the university itself. The first hospital in Ann Arbor was a 20-bed unit converted from a private house, that admitted only charity patients. The second University Hospital was built in 1925. The Section of Neurosurgery was founded by Dr. Max Peet, who was followed by Drs. Kahn and Schneider as section heads.
When the cervical spine is affected by disease that is predominantly anterior, we prefer to take an anterior operative approach. Whether or not fusion is indicated depends largely upon the case. In general, we do not fuse the spine unless it is unstable. Widening of the spinal canal and the neural foramina can be done effectively by the anterior route, with or without anterior fusion. When the spine is unstable from disease affecting the vertebral bodies, we routinely fuse with bone graft or provide mechanical stability with a vertebral body prosthesis if life expectancy is short.
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This paper presents a simple method of maintaining good donor organ oxygenation during a prolonged test of apnea used to determine brain death prior to cadaver transplantation. Apneic diffusion oxygenation can maintain arterial pO2 above 200 torr for periods exceeding 15 minutes, thereby allowing a more definitive determination of brain death without concomitant tissue hypoxia and possible damage to donor organs.
Hemorrhagic pulmonary edema was produced consistently in 19 of 20 anesthetized, paralyzed, ventilated cats when intracranial pressure (ICP) was raised for 30 minutes by intraventricular infusion of mock CSF to 150 mm Hg in 14, or 200 mm Hg in six. However, under identical conditions, except that ICP was raised to only 100 mm Hg, three of seven animals did not develop hemorrhagic edema of the lungs and the remaining four had spotty hemorrhage. Thirteen control animals with normal ICP had normal lungs. Gravimetric lung water analysis by Pearce's method confirmed gross and microscopic appearance of hemorrhagic pulmonary edema. Extravascular lung water (p less than 0.05) and lung blood (p less than 0.05) were significantly greater than control values when ICP was raised to or exceeded 150 mm Hg. Despite hemorrhagic edema, pulmonary gas exchange (O2, CO2) remained unaffected. This animal model allows quantitative measurement of neurogenically-mediated hemorrhagic edema of the lungs before gas exchange is impaired. The model may facilitate clarification of the pathogenesis of neurogenic pulmonary edema and, consequently, refine evaluation of therapy.
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No deaths have occurred among 20 consecutive patients with intraparenchyma brain abscesses treated at the University of California, San Francisco, since computerized tomographic (CT) brain scanning became a routine diagnostic procedure (study period: July, 1974, to June, 1977). These patients have been compared to 18 consecutive cases treated without benefit of CT analysis (January, 1970, to June, 1974) in order to determine the factors responsible for the recently improved prognosis. The mortality rate was 44% for all cases and 36% for all operated patients treated before the availability of CT. Similar morbidity (about 33%) was seen in survivors from both series. No significant differences in the two groups were noted with respect to patient population and antibiotic or corticosteroid therapy. Among the factors that may have contributed to the improved results for patients diagnosed with CT are: less frequent occurrence of multiple abscesses, fewer patients with poor preoperative clinical status, and a greater incidence of total abscess removal. In addition, CT scanning provided more accurate diagnosis and localization of abscesses and aided in the rapid detection of postoperative complications that probably accounted for six out of eight deaths in the earlier series. Serial CT studies provide a means to optimize the timing for surgical intervention and plan appropriate medical therapy. It is noteworthy that two patients have been followed by serial CT scans to non-surgical cures.
In 100 patients intracranial exploration was done soon after severe head injury when signs of transtentorial herniation were present. A third of patients had extracerebral hematomas shown on initial burr hole examination. An additional 18 percent had parenchymal clots of clinical significance disclosed only by angiography after burr hole exploration or at autopsy. Half the patients in whom exploration was done did not have intracranial hematomas of sufficient size to warrant an operative approach. Detailed neurological examinations soon after injury and the availability of more rapid diagnostic tools may improve the accuracy of early diagnosis and allow more specific prognostication in patients with severe head injury.
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It has been proposed that the responses of the cerebral circulation to hypoxia, hypercapnia and hypotension may be partially mediated by an autonomic reflex with receptors in the carotid body or sinus serving as sensors and the efferent limbs being the 7th cranial nerves. Transection of the 7th cranial nerve has been reported to impair the cerebral circulatory response to isolated chemoreceptor stimulation by hypoxia and hypercapnia. To test this hypothesis we measured cerebral blood flow (CBF) by an intra-arterial 133Xe technique in 10 baboons during periods of induced hypoxia and hypercapnia, both before and after transection of the 7th cranial nerve, We found that the responses of CBF were unaltered by either unilateral or bilateral section of the nerve. Our results showing the preservation of normal CBF responses, following transection, suggest that neurogenic control of the cerebral circulation by an autonomic reflex involving the 7th nerve is unlikely.
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Unlike the penetrating injuries to the brain caused by missiles, injuries by stabbing are largely restricted to the wound tract. Early recognition, debridement and judicious antibiotic therapy can limit or prevent complications in the management of stab wounds. Among the common sequelae of stab wounds of the brain are pneumocephalus, meningitis, intracerebral hemorrhage and direct blood vessel or nerve injury.
Thirty-seven patients with severe head injury underwent radionuclide cisternography to detect early and late effects of trauma on cerebrospinal fluid (CSF) circulation. Thirty-one patients had subdural hematomas or hygromas and six had cerebral contusions without extracerebral masses. Cisternographic results were abnormal in 23 patients with subdural masses and normal in five who had only cerebral contusions. Of eight patients undergoing serial studies, one had persistent partial obstruction, five had partial resolution of abnormalities, and the two with progressive obstruction had their conditions improved by shunting. Angiography suggested transtentorial herniation in 11 patients with cisternal block, six of whom had clinical signs of herniation on the same side.
Review of cerebral arteriograms of all our patients [19] with epidural hematoma over a 2 year period revealed evidence of localized extrinsic compression of the cerebral cortex in all cases. This finding, although not as specific as those previously described for epidural hematoma, was strongly suggestive. A 2 year prospective study was then initiated employing internal, rather than common carotid arteriography, because opacification of the external carotid artery is not necessary for evaluation of cortical compression. In this study, which consisted of 21 patients, epidural hematoma was correctly diagnosed in all, relying primarily on signs of localized extrinisic cerebral cortical compression. No epidural hematoma was misinterpreted as being a subdural hematoma or an intracerebral injury, and all epidural hematomas that were present were diagnosed correctly. We conclude that internal carotid arteriography is a sensitive method for diagnosing epidural hematoma. The signs of extrinsic cortical compression should be emphasized in the interpretation of arteriograms of patients with head injuries whether the internal or the common carotid artery is injected.
A 26-year-old man who had become comatose after having inhaled carbon monoxide developed retinal venous engorgement and peripillary hemorrhages. Retinal changes closely resembled those that accompany hypoxemia.
In most patients with head or neck trauma, a single angiogram is sufficient to guide therapy. For those who improve slowly or not at all, however, this is not an adequate basis for diagnosis. Angiography should be repeated after an interval of time to exclude development of a surgically correctable lesion, such as pseudoaneurysm or intracerebral or extracerebral fluid collection.