摘要:

&NA;The reaction of periventricular tissue to shunt tubing chronically implanted in the fourth ventricle of the rat was investigated by correlative scanning and transmission electron microscopy. Sterile silicone tubing with four 0.4 mm diameter holes was inserted into the fourth ventricle of adult Sprague‐Dawley rats through an incision in the atlantooccipital membrane and the animals were killed at postoperative intervals of 5 and 8 weeks. Reactive changes that could be correlated with the extent of contact with the implant occurred in the periventricular tissue. The ependyma lining the ventricle underwent a progressive loss of cilia and microvilli, became attenuated and, in circumscribed areas, was lost entirely. A significant subependymal gliosis accompanied these changes. In regions denuded of ependyma, neurons and glia were exposed directly to the cerebrospinal fluid. Eruptions of periventricular tissue corresponding precisely to the location of holes in the implanted tubing were observed on both the vermal surface of the cerebellum and the floor of the ventricle. Evaginations from the surface of the inferior vermis and the floor of the ventricle were most prevalent at 5 and greatest at 8 weeks postimplantation, respectively. Gliosis combined with mechanical factors are believed to be responsible for development of these periventricular tissue evaginations, which may be a factor in the pathogenesis of cerebrospinal fluid shunt obstruction in treated human hydrocephalus. (Neurosurgery19:337‐345, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Hemolysis of periarterial clots after subarachnoid hemorrhage may liberate large quantities of K+ into the vicinity of cerebral blood vessels and possibly change their sensitivity to endogenous vasoactive agents. The current study examined the influence of subarachnoid hemorrhage on the sensitivity of rabbit basilar arterial segments to K+ and Ca++. An analysis of K+ and Ca++ dose‐response curves demonstrated that incubated arterial segments isolated from animals with subarachnoid hemorrhage were substantially more sensitive to these cations than were corresponding controls. We speculate that chronically elevated K+ levels in areas of periarterial clot lysis or brain ischemia might initiate vascular smooth muscle depolarization and vasospasm. Our data provide additional rationale for the use of calcium channel blockers in preventing or treating vasospasm in cases of subarachnoid hemorrhage. (Neurosurgery19:346‐349, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Three methods of inducing hypotension were studied for their effects on the cardiovascular system and intrapulmonary shunting. Thirty patients were anesthetized with isoflurane in 70% N2O to a total of 1.25 to 1.3 MAC. Patients were divided into three groups of 10 each on the basis of the drug used to induce hypotension; sodium nitroprusside (SNP), nitroglycerin (NTG), or deep isoflurane anesthesia (ISF). Cardiac index was significantly decreased by NTG and ISF at a mean arterial blood pressure of 40 mm Hg compared to SNP (P< 0.05). Systemic vascular resistance was decreased in all groups. Mixed venous oxygen content was significantly decreased from control in the NTG and ISF groups. There was no difference between the groups in arterial and mixed venous O2content. Intrapulmonary shunting decreased with induction and, in the NTG and SNP groups, increased slightly but not significantly with induction of hypotension. Our data do not show a clear superiority of any agent over the other to induce hypotension, although SNP and perhaps ISF appear to be better than NTG to induce hypotension. (Neurosurgery19:350‐355, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Cardiac monitors determine heart rate by counting the number of beats in a given time interval. The normal heart, however, does not beat at a constant rate. Instead, there is a continuous change in heart rate on a beat‐by‐beat basis. This is termed the instantaneous heart rate and it represents the projected rate per minute that the heart would beat if only one R‐R interval (the time between sequential R waves) was repeated throughout a 60‐second period. Calculation of the instantaneous heart rate for each heart beat (R‐R interval) produces a pattern that demonstrates the variability in heart rate. This instantaneous heart rate pattern was prospectively studied in 102 patients admitted to a neurosurgical intensive care unit. Short‐term (STV) and long‐term (LTV) heart rate variability were compared to the Glasgow coma scale as a method for patient assessment. LTV seems to be the most useful heart rate parameter in the clinical setting, and both STV and LTV performed better in the serial evaluation of patients. Two postulations found in the heart rate literature were not borne out in this study. First, we did not find a strong correlation between elevated intracranial pressure and decreases in heart rate or variability, as previously reported by Lowensohn et al. Second, the morphological classification of heart rate patterns described by Evans in his study of head‐injured patients did not carry the same prognostic value when applied to this broad spectrum of patients with a variety of acute neurological disorders. Heart rate and its variability is a simple parameter to monitor. In comparison to multimodality evoked potential testing, heart rate monitoring is quicker, less cumbersome, and requires less technical skill. It can provide useful clinical information, especially for frequent serial examination of brain stem‐injured patients. Periodicity in the heart rate pattern was noted in 33% of the patients studied. This technique may provide valuable information about postulated brain stem oscillatory centers governing heart rate, and it should be useful in the future investigation of neurocardiac interrelationships. (Neurosurgery19:356‐362, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Regional brain tissue catecholamine concentrations were measured in 5 control rats and in 10 rats 72 hours after experimental subarachnoid hemorrhage (SAH). Catecholamine levels were determined in the cerebral hemispheres, brain stem, and cerebellum of each animal using a radioenzymatic assay. Three days after SAH, the tissue concentration of norepinephrine (NE) in the cerebral hemispheres was 64% greater than that in control rats (P< 0.001). NE levels did not change significantly in either the brain stem or the cerebellum. Most if not all of the NE in the brain tissue rostral to the brain stem is derived from neurons that originate in the locus coeruleus (LC). These data may therefore indicate that the LC is activated after SAH. The possible pathophysiological consequences of activation of the LC in relation to delayed cerebral ishcemia after SAH will be discussed. (Neurosurgery19:363‐366, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Forty‐five acute head trauma patients were randomized into a neurotrauma nutritional study to compare the efficacy of two forms of standard nutritional supplementation; namely total parenteral nutrition (TPN) versus enteral nutrition (NG). Forty patients were male, 5 were female, with a median age of 28 years. The mean admitting Glasgow coma scale score was 5.8. Patients were given high calorie and nitrogen feedings for the 14 days of the study period in an attempt to achieve positive calorie and nitrogen balance. TPN patients had significantly higher mean daily nitrogen intakes (P< 0.01) and mean daily nitrogen losses (P< 0.001) than the NG fed patients; however, no significant differences were discovered with respect to maintenance of serum albumin levels, weight loss, the incidence of infection, nitrogen balance, and final outcome. The exaggerated nitrogen excretion experienced by patients fed large nitrogen loads illustrates a problem in achieving nitrogen equilibrium in acute head injured patients. (Neurosurgery19:367‐373, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;The authors report their experiences using the anterior approach and osteosynthesis for recent fractures of the pedicles of the axis in eight patients. They describe the transcervical transclival approach and osteosynthesis and discuss the advantages of and indications for this approach. (Neurosurgery19:374‐377, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;To assess the efficacy of operative stabilization techniques, a retrospective study of Harrington distraction rod (HDR) and modified Weiss spring instrumentation was performed in 90 patients. An operation was performed for one or both of two indications: persistent spine instability or the presence of a neurological deficit in patients with incomplete neurological injuries and myelographic evidence of spinal cord or cauda equina compression. The lateral extracavitary operative approach to the spine for decompression and anterior interbody fusion was performed with an accompanying HDR (47 patients) or modified Weiss spring placement (43 patients). Eight HDRs failed, resulting in gross instability (17 per cent) that either resulted in further neurological injury (1 patient), further surgery (2 patients), or increased morbidity secondary to prolonged bed rest (5 patients). One Weiss spring failed, requiring further surgery (2.3 per cent). Nonsurgical complications were similar in both groups and appeared to be unrelated to the type of instrumentation utilized. The modified Weiss spring instrumentation technique, which offers a dynamic compression fixation of the spine, was clearly superior to the HDR technique, which offers a rigid distraction fixation. The biomechanics of distraction versus compression and rigid versus nonrigid spine stabilization are discussed. (Neurosurgery19:378‐385, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Initial experience using the Gildenberg technique for computed tomography‐guided stereotactic biopsies is reviewed. Of 50 patients, adequate tissue was obtained in 49. In one patient, the stereotactic frame was unable to reach the selected biopsy site. In 32 of 49 patients, the diagnosis was obtained with one biopsy; in the remainder, two to five samples were required. In 4 cases, a subsequent craniotomy was performed; these provided similar histopathological tissue and in no case was the diagnosis altered. The lesions were categorized by CT as ring‐enhancing lesions (REL), enhancing lesions with surrounding low density (ELLD), and low density lesions with and without peripheral areas of enhancement. Of the REL, 21 of 23 were primary tumors. Of the ELLD, 5 of 13 were primary tumors; the remainder had a wide spectrum of disease. Of the low density lesions without enhancement, 6 were primary tumors and 1 was an inflammatory process. Three patients had low density lesions with peripheral areas of enhancement and proved to have malignant primary tumors. The remaining patients had multiple lesions with both primary and metastatic disease. Twelve RELs were biopsied in multiple sites. An accurate diagnosis was best obtained by performing the first biopsy in the enhancing rim with additional biopsies as needed in the low density center. Homogeneous lesions could be biospied with target selection based upon a primary regard for safety rather than imaging characteristics. Three patients had transiently increased hemiparesis and one had a transient decrease in level of consciousness after biopsy. There were no patients with long‐term morbidity in this series. From our experience, we believe this technique offers a safe, accurate, and relatively inexpensive alternative for performing‐CT‐guided intracranial biopsies. (Neurosurgery19:386‐391, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Thrombosed arteriovenous malformations initially diagnosed as low‐grade gliomas in a child and her maternal uncle are presented. In both patients, there was progression of the disease as evidenced by the formation of new lesions at distant sites in the brain. (Neurosurgery19:401‐404, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID