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Biomedical subjects

R F Spetzler

Publications and source records attributed to R F Spetzler.

300 records · Page 17Linked to original sources
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Pediatric intracranial aneurysms: simple and complex cases.

Between 1984 and 1990, 20 aneurysms in 16 patients (9 males and 7 females), 18 years or younger (mean age, 8 years; range, 7 months to 18 years), were treated at our institution. Seven patients had a solitary saccular aneurysm located at an arterial bifurcation which manifested as a subarachnoid hemorrhage. Six of these patients were treated with clip obliteration. Postoperative results were excellent or good in 5 and fair in 1. Nine patients had complex or multiple aneurysms of variable origins (3 giant, 2 infectious, 2 traumatic and 2 associated with an arteriovenous malformation) and presentation. Surgical treatment of these children required the use of hypothermic arrest, trapping, bypass and anastomotic procedures. Outcome was excellent or good in 7 and fair in 2. An analysis of these patients with regard to pathogenesis and management is presented.

Adolescent↗
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Acute NMR changes during MCA occlusion: a preliminary study in primates.

Advancements in computer science and magnet design have resulted in the recent development of high resolution NMR imaging systems. Using our primate model we evaluated the ability of NMR scanning to detect early changes following middle cerebral artery (MCA) occlusion. Serial NMR scans documented progressive changes secondary to edema and swelling beginning ninety minutes after MCA occlusion. NMR was also able to readily demonstrate the area of cerebral infarct 10 days after a six hour episode of MCA occlusion. Soft tissue contrast and image resolution were superb. Correlation with pathologic sections was excellent.

Animals↗
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Middle cerebral artery perfusion pressure in cerebrovascular occlusive disease.

We measured the MCAP (middle cerebral artery pressure)/MSBP (mean systemic blood pressure) ratio in 76 patients who underwent an EIAB (extracranial-intracranial arterial bypass). Patients were divided into groups on the basis of angiographic findings. We found a definite correlation between increasing angiographic cerebral vascular occlusive disease and lower MCAP/MSBP ratios. Six of 32 patients with a preoperative neurologic deficit demonstrated mild but definite postoperative neurologic improvement. The mean MCAP/MSBP ratio in these six patients was significantly lower than that for the remainder of this group (p less than .05). Finally, postoperative filling of the middle cerebral artery territory through the graft was found to correlate in an inverse linear relationship with MCAP/MSBP. Evidence is presented that hypoperfusion produced by occlusion of major cranial vessels plays an important role in temporary and permanent neurological deficits seen in patients with cerebrovascular disease.

Adult↗
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Naloxone therapy during focal cerebral ischemia evaluation in a primate model.

Conflicting reports have appeared in the literature regarding the effect of the opiate antagonist naloxone on ischemic neurologic deficits. We report the results of a study using naloxone in our model of focal cerebral ischemia in the awake primate. A total of 14 adult baboons were subjected to six-hour occlusion of the left middle cerebral artery (MCA). Seven animals served as controls and seven received treatment with naloxone (5 mg/kg) beginning 30 min after MCA occlusion and continuing until two hours after reperfusion. All animals developed profound hemiparesis and homonymous hemianopsia within seconds of inflating the MCA occluder. Acutely, therapy with naloxone partially reversed ischemic neurologic deficits in five of the seven treatment animals. Within minutes of receiving the loading dose of naloxone, responding animals were more alert and demonstrated improvements in motor function. Naloxone did not affect mortality: Three animals in the treatment group and two in the naloxone group died secondary to malignant intracranial pressure within 48 hours of the ischemic episode. In animals surviving the ischemic insult however, treatment with naloxone significantly improved neurologic outcome at 10 days (p less than 0.05). Neuropathologic examinations in these animals revealed amelioration of ischemic tissue damage, with three of the five suffering only small focal areas of infarction. (All control animals suffered large infarcts of the MCA territory.) Our results verify that naloxone can reverse ischemic deficits, and more importantly may improve the outcome from focal ischemic insults.

Animals↗
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Cortical blood flow during extracranial-intracranial bypass surgery.

Cortical blood flow was evaluated at the time of surgery with a thermal diffusion flow probe in 25 extracranial-intracranial bypass operations. The procedures were performed 14 times for carotid occlusion, 6 times for inaccessible carotid stenosis, on 3 occasions for middle cerebral occlusion, once for basilar occlusion and once for middle cerebral stenosis. Fifty-seven different cortical regions were evaluated before and after completion of the anastomosis. During temporary occlusion of the cortical vessel, no significant changes in cortical blood flow were identified. The mean flow pre-bypass was 58 ml/100 g/min and postbypass was 66. This was a significant difference. When initial ischemic areas were evaluated, flows increased from 36 ml/100 g/min to 52 ml/100 g/min. These postbypass flows were statistically different than the flow values in the nonischemic areas of 75 ml/100 g/min. Blood pressure and arterial carbon dioxide tension did not vary significantly. Extracranial-intracranial bypass increases cortical flow in ischemic areas although this does not bring the flow into the normal range.

Cerebral Revascularization↗
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Incidental subcortical lesions identified on magnetic resonance imaging in the elderly. I. Correlation with age and cerebrovascular risk factors.

Patchy subcortical foci of increased signal intensity are frequently identified on magnetic resonance imaging (MRI) in the elderly. The incidence and clinical correlates of these lesions remain unknown. In this report, 240 consecutive MRI scans performed over a 6-month period were reviewed (excluding patients with recent brain trauma or known demyelinating disease). Subcortical incidental lesions (ILs) were identified, which could not be accounted for by the patient's current clinical diagnosis, neurological status, or CT scan. The ILs were graded according to size, multiplicity, and location. The incidence and severity of ILs increased with advancing age (p less than 0.0005). Among patients over 50 years of age, the incidence and severity of ILs were correlated with a previous history of history of ischemic cerebrovascular disease (p less than 0.05) and with hypertension (p less than 0.05). Multivariable regression analysis identified age, prior brain ischemia, and hypertension as the major predictors of ILs in the elderly. Diabetes, coronary artery diseases, and sex did not play a significant role. With the exception of cerebrovascular disease, there was no association between ILs and any particular clinical entity, including dementia. It is concluded that subcortical parenchymal lesions are frequent incidental findings on MRI in the elderly, and may represent an index of chronic cerebrovascular diseases in such patients.

Age Factors↗
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Incidental subcortical lesions identified on magnetic resonance imaging in the elderly. II. Postmortem pathological correlations.

The pathological correlates of subcortical lesions noted on magnetic resonance imaging (MRI) in the elderly are not known. Postmortem in vitro proton MRI was performed on the brains of seven consecutive elderly patients dying of nonneurologic causes. Scans were done in the fresh and fixed states with the specimen immersed in saline and formaldehyde respectively. A 1.5 Tesla superconductive system was used with a multiple spin-echo protocol generating T2 weighted images. Subcortical MRI lesions were localized in three dimensions and identified at brain cutting. In addition, pathological correlations were obtained from an eighth patient who underwent MRI eleven days before death. Histological examinations were performed in a blinded fashion, including control areas from the same brains. Subcortical MRI lesions were found to be associated with arteriosclerosis, dilated perivascular spaces, and vascular ectasia (p less than 0.05). These histological changes were characteristic of "état criblé" which, like subcortical MRI lesions, is associated with age and hypertension. Shrinkage (or atrophy) of the brain parenchyma around ectatic blood vessels would result in an extensive network of tunnels filled with extracellular water. The proton MRI signal from such areas of the brain would be increased. Gliosis and small areas of infarction occasionally coexisted with "état criblé," but these were not present in all areas with MRI lesions and could not be distinguished by MRI signal alone. In conclusion, clinical and pathological correlations lend support to the uniform hypothesis that MRI provides a nonspecific index of brain parenchymal alterations caused by aging and chronic cerebrovascular disease.

Age Factors↗
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Clinical vasospasm after subarachnoid hemorrhage: response to hypervolemic hemodilution and arterial hypertension.

Delayed neurologic deterioration from vasospasm remains the greatest cause of morbidity and mortality following subarachnoid hemorrhage. The authors assess the incidence and clinical course of symptomatic vasospasm following subarachnoid hemorrhage using a uniform management protocol over a 24-month period. One hundred eighteen consecutive patients were admitted to the neurovascular surgery service within 2 weeks of subarachnoid hemorrhage not attributed to trauma, tumor, or vascular malformation (113 patients had aneurysms). Early surgery was performed whenever possible, and hypertensive hypervolemic hemodilution therapy was instituted at the first sign of clinical vasospasm. Forty-two patients (35.6%) developed characteristic signs and symptoms of clinical vasospasm with angiographic verification of spasm in 39 cases. All patients with clinical vasospasm received hypervolemic hemodilution therapy aiming for a hematocrit of 33-38%, a central venous pressure of 10-12 mm Hg (or a pulmonary wedge pressure of 15-18 mm Hg), and a systolic arterial pressure of 160-200 mm Hg (120-150 mm Hg for unclipped aneurysms) for the duration of clinical vasospasm. Over the course of treatment, 60% of patients with clinical vasospasm had sustained improvement by at least 1 neurologic grade, 24% maintained a stable neurologic status, and 16% continued to worsen. At the end of hypervolemic hemodilution therapy, 47.6% had become neurologically normal, 33.3% had a minor neurologic deficit, and 19% had a major neurologic deficit or were dead. There were 3 instances of cardiopulmonary deterioration (7%), all of which were in patients without Swan-Ganz catheters, and all resolved with appropriate diuresis. One patient rebled and died while on hypervolemic hemodilution therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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Synovial cysts of the lumbosacral spine: diagnosis by MR imaging.

Intraspinal synovial or ganglion cysts are uncommon lesions associated with degenerative lumbosacral spine disease. CT usually reveals cystic lesions adjacent to a facet joint, and they may show calcification. MR imaging of four surgically confirmed cases of intraspinal synovial cysts revealed subtle signal changes compared with CSF. Short TR/TE images showed the lesions to be slightly hyperintense in three cases and isointense in one case. Long TR/TE sequences revealed a hyperintense appearance in two cases and a hypointense appearance in the others. A peripheral rim of decreased signal on long TR/TE images probably reflects fine calcification or hemorrhage in the margins of the cysts. The multiplanar and contrast characteristics of MR make this technique well suited to the diagnosis of herniated disk, degenerative facet disease, and synovial cyst.

Aged↗
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The use of intraoperative fluoroscopy and spinal cord monitoring for transoral microsurgical odontoid resection.

The transoral approach to the upper cervical spine has not gained wide acceptance. A reliable intraoperative method to determine the necessary extent of dissection and degree of decompression, as well as to evaluate spinal cord function, should improve the safety and applicability of the transoral approach. Four cases of anterior cervical cord compression were successfully treated by odontoid resection employing a microsurgical transoral approach. Intraoperative fluoroscopy monitored the depth of dissection and adequacy of decompression. Somatosensory cortical evoked potentials (SSEP) allowed assessment of spinal cord function that could be correlated with surgical decompression. In addition, follow-up examination revealed that SSEP was an intraoperative prognosticator of subsequent neurologic improvement.

Adolescent↗