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Biomedical subjects

R F Spetzler

Publications and source records attributed to R F Spetzler.

At least 217 records · Page 12Linked to original sources
PubMed1988

Middle cerebral artery aneurysm due to Nocardia asteroides: case report of aneurysm excision and extracranial-intracranial bypass.

Nocardia asteroides is an uncommon human pathogen typically encountered in immunocompromised patients. Primary central nervous system (CNS) nocardiosis is rare and usually manifests as cerebritis or abscesses. The case of a young woman who presented with CNS Nocardia abscesses complicated by an infective middle cerebral artery aneurysm is reported. Treatment, which included abscess aspiration, aneurysm excision, and end-to-end extracranial to intracranial bypass and prolonged antibiotic therapy, resulted in an excellent outcome. This case and the management of CNS nocardiosis are reviewed.

Adult↗
PubMed1987

Magnetic resonance imaging and trigeminal schwannoma.

A case of trigeminal schwannoma, extending from the posterior fossa into Meckel's cave, is reported. The information provided by computed tomography, angiography, and magnetic resonance imaging allowed a correct preoperative diagnosis to be obtained. Due to the excellent sensitivity, the absence of bone artifacts, and the ease of imaging in any plane, magnetic resonance imaging best defined the "dumbbell" nature of the tumor, the atrophy of the masticatory muscles, and the infiltration of the third division of the trigeminal nerve.

Adult↗
PubMed1987

A comparison of the cerebral protective effects of isoflurane and barbiturates during temporary focal ischemia in primates.

Isoflurane has protective properties during experimental global brain ischemia or hypoxia. However, this has not been evaluated in the more common case of focal ischemia, e.g., as caused by middle cerebral artery occlusion (MCAO). The authors therefore compared the effects of isoflurane, thiopental, and N2O/fentanyl anesthesia on neurologic and neuropathologic outcome in baboons subjected to 6 h of transorbital left MCAO. Prior to MCAO, animals were assigned to one of three groups: Group 1 (n = 7) received isoflurane (in O2/air) in concentrations sufficient to maintain deep burst suppression on the EEG (2.0% +/- 0.5% inspired, mean +/- SD); group 2 (n = 6) received thiopental (O2/air) in doses adequate to maintain similar EEG suppression (3.6 +/- 0.7 g total); and group 3 (n = 6) received 60% N2O/40% O2 and fentanyl (25 micrograms/kg load, 3 micrograms X kg-1 X h-1 infusion). Efforts were made to keep mean arterial pressure (MABP) between approximately 80 and 100 mmHg, using nitroprusside/hydralazine or phenylephrine/metaraminol, with PaCO2 at approximately 30 mmHg. The selected anesthetic was established 45 min before MCAO, was maintained until 1 h after clip removal, and in decreasing concentrations for 5 h. Neurologic status was scored for 7 days and formalin-fixed brains were later sectioned for determination of infarction volume. Six of seven group 1 (isoflurane) animals were hemiplegic, and 7/7 had verified infarctions. By contrast, 4 of 6 group 2 (thiopental) animals were normal, with 2/6 having infarctions. Outcome in group 3 (N2O/fentanyl) was intermediate between groups 1 and 2 (3/6 hemiplegic, 4/6 with infarctions). Differences in the infarction rates between groups 1 and 2 was significant (P less than 0.05), while a similar comparison of neurologic outcome scores achieved a P value of 0.055. Infarctions in group 1 were more hemorrhagic in character than in group 3 (groups 1 and 2 could not be meaningfully compared). These results must be considered in light of differences in MABP during the occlusion period; MABP in group 1 was approximately 80 mm Hg in spite of vasopressor use, while that in group 2 was approximately 100 mmHg (in spite of vasodilators). Nevertheless, they fail to demonstrate any protective value of isoflurane anesthesia, at least when compared with thiopental.

Anesthesia, Inhalation↗
PubMed1987

Incidental lesions noted on magnetic resonance imaging of the brain: prevalence and clinical significance in various age groups.

With the advent of magnetic resonance imaging (MRI) of the brain, a large number of incidental lesions (ILs) are being identified. The prevalence and clinical significance of these ILs are not known. The MRI and clinical records of 86 consecutive patients who underwent technically satisfactory brain imaging at a large urban referral center were reviewed. Patients with definite or probably demyelinating disease were excluded. Incidental lesions were defined as parenchymal areas of increased signal intensity on T2-weighted imaging, which could not be directly explained by the patient's current clinical diagnosis, neurological status, or computed tomographic (CT) scan. The ILs were noted and graded according to size, multiplicity, and location and were correlated with age, clinical presentation, CT scan findings, and risk factors for cerebrovascular disease. One or more IL were identified in 22% of patients under 40 years of age, in 57% of patients 41 to 60 years of age, and in 90% of patients over 60 years of age. Large patches of confluent ILs were not encountered in any patient less than 40 years of age; they were present in 10% of patients 41 to 60 years of age, and in 30% of patients over 60 years of age. The incidence of severity of ILs correlated significantly with age (P less than 0.0005) and with risk factors for cerebrovascular disease (P less than 0.02). Patients with most severe ILs also had areas of vague periventricular leukomalacia on the CT scan. The clinical significance of incidental MRI lesions in various age groups is discussed in detail.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Multiple intracranial aneurysms due to Coccidioides immitis infection. Case report.

True mycotic (fungal) aneurysms are distinctly uncommon. The case of a young woman with multiple intracranial aneurysms of Coccidioides immitis origin is presented. Coccidioides immitis organisms are not uncommon central nervous system pathogens and usually cause basilar meningitis and hydrocephalus. There are no previous reports of a coccidioidal mycotic aneurysm. The management of intracranial coccidioidomycosis and fungal aneurysms is reviewed.

Adult↗
PubMed1987

Vertebrobasilar insufficiency. Part 1: Microsurgical treatment of extracranial vertebrobasilar disease.

Extracranial vertebrobasilar artery thrombo-occlusive disease may cause repetitive transient ischemic episodes and, less frequently, brain-stem or cerebellar infarction. This report describes 40 patients who experienced repetitive vertebrobasilar ischemic symptoms despite maximal medical therapy. The natural history, pathogenesis, and treatment options for each causative lesion are reviewed. The operative approaches to symptomatic disease of the proximal vertebral arteries, arterial compression by cervical osteophytes, traumatic lesions of the vertebral arteries, and thrombo-occlusive pathology of the distal extracranial vertebral arteries are outlined. Specific anesthetic and surgical techniques that have proved successful while achieving zero operative mortality and low perioperative morbidity rates are reported.

Adolescent↗
PubMed1987

Vertebrobasilar insufficiency. Part 2. Microsurgical treatment of intracranial vertebrobasilar disease.

Posterior circulation transient ischemic attacks have an associated risk of subsequent infarction of approximately 5% per year. Intracranial vertebrobasilar thrombo-occlusive lesions appear particularly likely to result in repetitive ischemic symptoms and in infarction due to hemodynamic insufficiency. The authors present their experience with 45 patients with symptomatic intracranial vertebrobasilar vascular disease despite maximal medical therapy. The specific operative approaches for intracranial vertebral artery endarterectomy and extracranial to intracranial posterior circulation revascularization procedures are outlined.

Adult↗
PubMed1987

Surgical management of large AVM's by staged embolization and operative excision.

A series of 20 patients with giant arteriovenous malformations (AVM's) managed with staged embolization and surgical resection is presented. Complete excision was accomplished in 18 of these patients. There were no deaths and only three complications, of which one was disabling. Further evidence for the presence of low perfusion surrounding the AVM, emphasizing the risk of normal perfusion pressure breakthrough, is provided by cortical perfusion pressure, cortical cerebral blood flow (CBF), and stable xenon computerized tomography CBF measurements. The staged approach to giant AVM management is a proposed method to render AVM's that were previously considered inoperable or marginally operable into totally excisable lesions, while maintaining an acceptable level of morbidity and mortality.

Adolescent↗
PubMed1987

The effect of nimodipine on intracranial pressure. Volume-pressure studies in a primate model.

Nimodipine was administered by intravenous infusion to six male baboons before, during, and after 6 hours of middle cerebral artery occlusion. Intracranial pressure (ICP) and systemic blood pressure were monitored continuously. An epidural balloon was inflated at regular intervals at three levels of arterial CO2 tension (25, 35, and 50 mm Hg) before and after the administration of nimodipine, and volume-pressure curves were generated. In every case, curves generated after intravenous nimodipine infusion were lower and shifted more to the right than the same set of curves generated before nimodipine administration, regardless of the baseline ICP. The reduction in ICP following nimodipine infusion was not due to a reduction in mean arterial blood pressure and was statistically significant at all three levels of pCO2 (p less than 0.01). These results suggest that, in the presence of elevated ICP due to cerebral infarction, there is no increased risk of exacerbating intracranial hypertension with the addition of nimodipine.

Animals↗
PubMed1987

The MRI appearance of cavernous malformations (angiomas).

The angiographic, computerized tomography (CT), and magnetic resonance imaging (MRI) findings were compared in 10 patients with a total of 16 pathologically verified cavernous angiomas. Only three lesions had abnormal vasculature in the form of venous pooling or a capillary blush. The CT scans were positive in seven patients and detected 14 lesions, while high-field strength (1.5 Tesla) MRI was positive in each case and demonstrated 27 distinct lesions. On T2-weighted MRI, the combination of a reticulated core of mixed signal intensity (SI) with a surrounding rim of decreased SI strongly suggests the diagnosis of a cavernous malformation. Smaller lesions appear as areas of decreased SI (black dots). The sensitivity of MRI is based on magnetic susceptibility and possibly diffusion effects related to field heterogeneity that is more conspicuous on high-field imaging and caused by the presence of excessive iron (hemosiderin).

Adolescent↗
PubMed1986

The transoral surgical approach to craniovertebral pathology.

The transoral approach is a surgical technique that can be used effectively in the treatment of anterior craniovertebral junction (CVJ) pathology. In this review, we outline the signs, symptoms, and diagnostic studies that identify the pathology and help to determine subsequent therapy. The transoral approach, preoperative and postoperative management problems, and potential complications of the procedure are reviewed. The nursing care of a patient with CVJ pathology is discussed.

Atlanto-Axial Joint↗
PubMed1986

Chronic cerebral vasospasm: effect of volume and timing of hemorrhage in a canine model.

The effect of altering the volume and timing of hemorrhage on the severity of spasm was studied in a canine model. All animals received three cisterna magna injections of fresh unheparinized autologous arterial blood. Selective left vertebral arteriograms were obtained during the week before and exactly 7 days after the initial subarachnoid injection. Increasing volumes of hemorrhage (from 9 to 15 ml of blood) delivered over 24 hours produced increasingly more severe arterial spasm, with reductions in basilar artery diameter of 37% +/- 14 (SD) and 58% +/- 15, respectively. Delay of the final injection of blood to 96 hours in the 15-ml hemorrhage group resulted in even more intense spasm, with an average 71% +/- 12 reduction in basilar artery diameter. Serial angiographic evaluation demonstrated the resolution of spasm in this group over approximately 3 weeks. Finally, small, late rebleeding episodes resulted in the rapid onset of intense spasm. Our results support the clinical impression of previous studies that the severity of spasm is related to the volume of hemorrhage and, in addition, suggest that the time course of hemorrhage may play a significant role in determining the overall severity of chronic cerebral vasospasm.

Animals↗
PubMed1986

Giant congenital cellular blue nevus of the scalp of a newborn with an underlying skull defect and invasion of the dura mater.

A case of a giant congenital cellular blue nevus of the scalp of a newborn with focal areas of malignant melanoma is presented. The nevus was associated with focal invasion of the underlying soft tissues, calvarium, epidural space, and dura mater. The later appearance of pigmented nevi in the submandibular region, sternocleidomastoid muscle, and testicular hydrocele raises the question of future metastases despite the nonmalignant microscopic appearance. Therapy consisted of total excision with cranioplasty and rotation and split skin grafts after temporary closure with silicone mesh.

Dura Mater↗
PubMed1986

Chronic cerebral vasospasm: effect of calcium antagonists.

The efficacy of the calcium antagonists nifedipine and nimodipine was evaluated in a multiinjection canine model of severe chronic cerebral vasospasm. Each of 21 adult mongrel dogs (15 to 20 kg) was assigned to one of four experimental groups. All animals received a total of 15 ml of fresh, unheparinized arterial blood via three cisterna magna injections. Selective left vertebral arteriography was performed 1 week before and exactly 7 days after the simulated subarachnoid hemorrhage. Treatment with calcium antagonists was initiated at 24 hours and continued for 7 consecutive days. Comparisons were based on the percentage of reduction in basilar artery diameter. On a milligram/kilogram basis, we used the manufacturer's maximal recommended daily dosages of nifedipine, whereas the dosages of nimodipine used were 3 to 7 times greater than that reported to be therapeutically effective in reducing the incidence of severe deficits from vasospasm in patients with aneurysmal subarachnoid hemorrhage. In this laboratory trial, systemic treatment with calcium antagonists did not prevent or significantly reduce chronic arterial narrowing. In the control group, spasm reduced basilar artery diameter an average of 71% +/- 11 (SD). In the group treated with nifedipine, 10 mg orally every 6 hours, vessel diameter was reduced an average of 58% +/- 13%. In those animals treated with nimodipine, 20 or 40 mg orally every 4 hours, the basilar artery diameter was decreased an average of 59% +/- 8 and 56% +/- 7, respectively. A preliminary trial using direct intracisternal administration of these agents demonstrated increased vessel diameter within 20 minutes in four of six animals, supporting other reports that this route of administration may prove more efficacious in the treatment of chronic cerebral vasospasm.

Animals↗
PubMed1986

Management of asymptomatic carotid atherosclerosis.

The detection, evaluation, and treatment of patients with asymptomatic carotid artery disease are controversial issues. In this review, these issues are addressed and the appropriate application of medical and surgical therapies is discussed. There seem to be two subgroups of asymptomatic patients with angiographically defined lesions (marked stenosis or large, deep, and compound ulcers) who have a significant risk of subsequent cerebral infarction. These patients should be considered for carotid endarterectomy at a surgical center with an established low incidence of perioperative complications.

Angiography↗
PubMed1986

Extracranial-intracranial bypass surgery: a critical analysis in light of the International Cooperative Study.

The ability of extracranial-intracranial bypass surgery to alter favorably the natural history of ischemic cerebrovascular disease remains in question. A recently completed prospective randomized multicenter cooperative trial failed to confirm the hypothesis that the procedure prevents further cerebral ischemia in patients with atherosclerotic internal carotid artery or middle cerebral artery disease. We analyze findings of the study in detail, including possible effects on the natural history of the disease beyond the immediate perioperative period. Potential sources of bias that may have unpredictably affected the study are discussed. These include observational bias (patient and therapist not blinded), "randomization-to-treatment" bias (high morbidity after randomization but before operation), and "prerandomization" or allocation bias (patients in the study representing a selected sample of the population with cerebrovascular disease). The extensive analysis of secondary subgroups with small numbers of patients is discussed in light of the statistical methods used. Two particular classes of patients not addressed in the study who might benefit from the procedure are defined. They are patients failing the best available medical therapy and patients with clearly documented hemodynamic compromise. Possible indications for bypass surgery are suggested for the various lesions in light of the trial and of recent reports on the natural history and pathophysiology of ischemic cerebrovascular disease. Selected cases illustrating these indications are presented.

Adult↗