摘要:

&NA;During experimental supratentorial epidural compression of the brain, cerebrospinal fluid (CSF) pressure and pressure‐volume index (PVI) were measured in the supra‐ and infratentorial compartments of the craniospinal axis in anesthetized ventilated cats. A transtentorial gradient of CSF pressure developed when CSF pressure in the lateral ventricle exceeded 20 mm Hg at balloon volumes of 0.4 to 1.2 ml. The shapes of both the pressure vs. volume and the pressure gradient vs. volume curves were exponential. PVI in the supratentorial compartment was lowered more rapidly as brain compression advanced than PVI in the infratentorial compartment. An index was calculated to represent the relative resistance to the flow of CSF across the tentorial hiatus during supratentorial brain compression. This revealed different resistances to the flow of CSF in the cephalic and caudal directions. A hypothesis concerning the hydrodynamic aspects of the development of tentorial herniation is presented. (Neurosurgery19:1‐8, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;We have previously reported that a motor evoked potential (MEP) can be produced by transcranial stimulation of the motor cortex in cats and humans. This signal travels in both dorsolateral and ventral spinal cord. We report here the evaluation of this evoked potential in comparison to the somatosensory evoked potential (SEP) in an acute spinal cord weight drop model. In all animals, the peripheral nerve signal was the component of the MEP most sensitive to injury. Often, it was significantly reduced in amplitude by incidental manipulation of the spinal cord during a careful laminectomy and then returned. It was lost first in animals with weight drop spinal cord injury and was abolished with as little as 50 to 75 g/cm of force. The spinal cord signal of the MEP was consistently more sensitive to injury than the SEP and was abolished at about 100 to 150 g/cm of impact. The cortical SEP was abolished at about 200 to 250 g/cm, and the spinal cord SEP was abolished at similar levels. The SEP returned earlier after injury than the MEP. Anesthestic agents had an effect on the MEP in the spinal cord and substantially changed the peripheral nerve signal, in both wave form shape and optimal stimulation frequency. Marginal cord injury and abnormal metabolic conditions caused the peripheral nerve signal to decrement in amplitude with increasing trial numbers during a run and become unstable. These latter effects need further characterization and are critical guides to investigative and clinical use of this test. This study indicates that the MEP is more sensitive than the SEP in detecting spinal cord injury. (Neurosurgery19:9‐19, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Utilizing a double subarachnoid blood injection model in pigs, we have evaluated the protective effect of the intracisternal injection of the thrombolytic agent, plasmin, in preventing the secondary intracranial arteriopathy seen after artificial subarachnoid hemorrhage in untreated animals. Twelve animals injected with plasmin revealed markedly less intimal proliferation and medial necrosis than were seen in control animals. These observations support the hypothesis that the persistence of clotted blood around the intracranial arteries is the cause of the vasculopathy. (Neurosurgery19:20‐25, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Anterior cerebral artery end‐to‐end, end‐to‐side, and side‐to‐side anastomoses and grafting procedures including bypass and interposition using segments of the posterior cerebral artery harvested from the same specimen were performed. The reconstruction procedures were accomplished experimentally with the A1 and A2 segments of the anterior cerebral artery. the recurrent artery of Heubner (RAH), and the orbitofrontal and frontopolar arteries in end‐to‐end or end‐to‐side anastomosis to the A1 segment. Side‐to‐side anastomoses between both A2 or A3 segments were completed without difficulty. We utilized the anatomical and experimental reconstruction data in the performance of three surgical procedures for aneurysms in this area. An A1 to A2 end‐to‐end anastomosis, an A2 to A2 end‐to‐side anastomosis, and an end‐to‐end anastomosis of the RAH were performed with no technical difficulties or complications. This study shows the feasibility of these microvascular reconstruction procedures in the anterobasal part of the interhemisphere, where cerebral aneurysms frequently develop. (Neurosurgery19:26‐35, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;We examined the effects of graded doses of methylprednisolone sodium succinate (MPSS)—0.05 (low), 0.5 (medium), and 5 mg/kg/hour (high)—on the development of neurogenic pulmonary injury in rabbits. The aerosolized drug was administered intratracheally for 5 hours beginning 10 minutes after a 2‐minute elevation of the cerebrospinal fluid pressure (Pcsf) to 250 mm Hg. Compared to untreated control animals, the percentage of increase in pulmonary capillary permeability, as determined by51Cr‐labeled ethylenediaminetetraacetic acid clearance, was significantly less in the low and high dose MPSS groups. However, high dose MPSS was also associated with a significant decrease in compliance and increase in tissue hemorrhage (quantified by visual inspection). These results indicate biphasic effect of MPSS on alveolar capillary integrity after elevated Pcsf. The low dose minimized the extent of lung hemorrhage, pulmonary capillary leakage, and loss of lung compliance. In contrast, the high dose accelerated tissue hemorrhage and compliance loss. even though pulmonary capillary permeability was maintained near base line rates. (Neurosurgery19:36‐40, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Vasospasm of the vertebrobasilar system was induced in seven dogs by the intracisternal injection of autologous blood. Somatosensory and brain stem auditory evoked potentials were recorded before and after the induction of angiographically confirmed vasospasm. Additionally, somatosensory evoked potentials were monitored during graded hypotension to 40 mm Hg. There was no significant alteration in the evoked potentials by vasospasm or hypotension. Detailed clinical examination and postmortem histopathological studies did not demonstrate any focal neurological deficit or infarction attributable to vasospasm. Previous studies have noted close correlations between decreased cerebral blood flow and evoked potential alterations. Induced hypotension to a mean arterial pressure of 40 mm Hg in the presence of documented vasospasm was not sufficient to cause evoked potential changes, focal neurological deficit, or pathological evidence of infarction in the canine model. (Neurosurgery19:41‐48, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;An intraoperative technique for deep brain biopsy is described. It features the use of an integrated surgical support system for the instruments and a rod that provides external topographical maintenance of the coordinates established ultrasonographically. A cystoscope, when supported mechanically by this system, permits multiple entries of the biopsy forceps to the lesion without further disturbance of the brain, as well as irrigation, coagulation, and visualization, if desired. When used in conjunction with real time intraoperative ultrasonography, the surgeon may view the entire procedure and be certain that the biopsy sample has been obtained from the lesion, major deep blood vessels have been avoided, and the biopsy site is stable after the procedure. The advantages of this technique include simplicity, low cost, accuracy, stability, and availability to every neurosurgeon in every hospital. (Neurosurgery19:49‐58, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Fifteen patients with large pituitary tumors were studied with computed tomography (CT) and magnetic resonance imaging (MRI). CT was performed using General Electric 8800 and 9800 scanners (General Electric Co., Medical Systems Division, Milwaukee, Wisconsin). MRI was performed utilizing a Technicare superconducting scanner (Technicare, Cleveland, Ohio) at 0.5 tesla. Based on the operative findings, the tumors were divided into two groups. Tumors in Group 1 (n = 12) were described by the surgeon as soft or partially necrotic and easily removed by suction and curettage. Tumors in Group 2 (n = 3) were firm and required sharp dissection or the laser for removal. The tumors were divided into four categories based on MRI signal: (a) isointense with surrounding brain on spin echo (SE) 30 and SE 90, (b) increased signal intensity on SE 30 and SE 90, (c) decreased signal intensity on SE 30 and increased signal intensity on SE 90, and (d) isointense signal on SE 30 and increased signal intensity on SE 90. All three of the firm tumors were isointense with brain on MRI appearance. The tumor consistency (firm vs. soft) was not differentiable on CT scan. The transsphenoidal approach is less satisfactory than craniotomy in cases of firm, fibrous pituitary tumors. Based on our preliminary data, if the MRI signal in the tumor is isointense, then the surgeon should be prepared to deal with a fibrous tumor and might elect a transcranial rather than a transsphenoidal approach. (Neurosurgery19:59‐64, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Despite the availability of high resolution computed tomography, severely head‐injured patients often present diagnostic dilemmas. An initially negative computed tomographic scan in the presence of severe multiple trauma does not predict an uncomplicated course. Early repeat scanning should be considered. We present three cases of delayed epidural hemorrhage in multiple trauma patients who initially were hypotensive secondary to hypovolemia. Possible etiologies for the hemorrhage as well as a list of indications for repeat scanning in the posttraumatic period are discussed. (Neurosurgery19:65‐68, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

&NA;Although thrombocytopenia occurs in approximately 10% of medical patients who receive heparin, this complication has not been described in neurosurgical patients. We report the clinical course of two patients who in the immediate postoperative period developed heparin‐associated thrombocytopenia that resulted in significant morbidity. In these two cases, the origin of the heparin was in “flush” solutions used to maintain the patency of indwelling vascular catheters and was infused at a dose of 250 to 500 units/day. The minimal daily dose previously reported to result in thrombocytopenia is 9000 units/day administered in divided doses subcutaneously. The case reports indicate that heparin in “flush” solutions should be considered as a cause for unexpected thrombocytopenia and that platelet counts should be monitored in patients receiving heparin in any amount. (Neurosurgery19:69‐72, 1986)

ISSN:0148-396X    

出版商:OVID    

年代:1986

数据来源: OVID