摘要:

&NA;Although previous ultrasonographic studies did monitor ventricular enlargement successfully in experimentally‐induced models of feline hydrocephalus, the resolution of neuroanatomic detail was relatively poor after placement of a ventriculoperitoneal (VP) shunt because the skull had ossified over the coronal sutures. Therefore, the present study employed magnetic resonance imaging to follow the progression of ventriculomegaly more accurately, as well as to evaluate the compensatory effects of VP shunting. Hydrocephalus was induced in kittens between 7 and 10 days old by injection of kaolin into the cisterna magna. Age‐matched controls received similar injections of saline. At 9 to 14 days after the kaolin injection, the hydrocephalic animals received VP shunts. Anesthetized kittens were scanned at various intervals before and after shunt placement and were killed for morphological correlation. The features observed on the magnetic resonance imaging scans were consistent with the gross morphological changes that accompanied ventricular enlargement. The lateral ventricle began to enlarge as early as 1 day after the kaolin injection, and within 3 days, both the occipital and temporal horns, along with the 4th ventricle, showed signs of moderate dilatation. By 5 days, a bilateral communication had been established through the septum pellucidum. Continued expansion of the ventricular system occurred from 6 to 20 days after injection, to the point where the cerebral cortex was reduced to less than 25% of its original thickness. The internal capsule was stretched and edematous, the caudate nucleus was compressed ventrolaterally, and the cerebellar hemispheres were eroded and/or compressed. Animals in which shunts were successfully placed demonstrated a dramatic improvement in behavior, and a reduction of about 50% in the size of the lateral ventricles within 2 days. In some cases, the lateral ventricles became slit‐like within 1 week. When they were killed, about half of the animals that received shunts exhibited mild to moderate ventriculomegaly. These results indicate that magnetic resonance imaging is an excellent method for visualizing the morphological changes associated with this animal model, that these alterations occur soon after the onset of hydrocephalus, and that VP shunting can successfully reduce ventriculomegaly. (Neurosurgery29:329‐340, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;A model of rat arteriovenous fistula (AVF) was created using a proximal common carotid artery to distal external jugular vein anastomosis. Anatomical dissections revealed that the external jugular vein is the primary vessel draining intracranial venous blood. Physiological measurements were made with the AVF open and closed, and during venous outflow occlusion of the contralateral external jugular vein. Opening the AVF increased torcular pressure from 6.5 ± 0.6 to 13.5 ± 1.1 mm Hg and decreased mean arterial pressure from 82.7 ± 1.8 to 62.8 ± 1.8 mm Hg (bothP< .05), decreasing cerebral perfusion pressure from 76.2 ± 1.7 to 49.3 ± 2.2 mm Hg (P< .05). Middle cerebral artery blood flow velocity (MCA BFV) decreased from 6.8 ± 1.1 to 4.2 ± 0.7 cm/s (P< 0.05). In rats with an AVF, occlusion of venous outflow increased torcular pressure to 34.8 ± 3.1 mm Hg (P< 0.05), MCA BFV decreased to 1.8 ± 0.5 cm/s (P< 0.05), and severe ischemic changes were seen on the electroencephalogram. Under this condition, torcular pressure and systemic arterial pressure had a positive linear relationship (P< 0.05), whereas in control rats torcular pressure and arterial pressure had no relationship. Restoration of cerebral perfusion pressure by release of venous outflow occlusion and AVF closure transiently increased MCA BFV to 69% above baseline (P< 0.05). Histological examination 1 week after permanent venous outflow occlusion revealed venous infarction, subarachnoid hemorrhage, and severe brain edema in rats with an AVF but not in control rats without an AVF. This model of cerebrovascular steal with venous hypertension reproduces both hemodynamic and hemorrhagic complications of human AVF and emphasizes the importance of venous outflow obstruction and venous hypertension in the pathophysiology of these lesions. (Neurosurgery29:341‐350, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;A total of 24 patients harboring arteriovenous malformations (AVMs) in either the dominant hemisphere (n = 12) or the nondominant hemisphere (n = 12) were examined neuropsychologically. When compared with 24 matched normal control subjects, the AVM patients demonstrated differential degrees of impairment in verbal or visuospatial processing, depending on whether the lesion involved the dominant or nondominant hemisphere. As predicted, most compelling were the findings of cognitive deficit associated with the hemisphere contralateral to the AVM relative to matched normal control subjects. Evidence of higher cortical dysfunction contralateral to the residing AVM is discussed in the context of cerebrovascular steal. (Neurosurgery29:351‐357, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;Forty‐nine patients with cerebral arteriovenous malformations (AVMs) were treated with preoperative embolization followed by resection using a microsurgical approach. In 27 patients, the AVM was located in an eloquent area; in 32 patients, the volume of the AVM was over 20 cm3. Preoperatively, flow‐directed embolization was performed in 10 patients (28 procedures), selective embolization with threads was performed in 35 patients (46 procedures), and a combination of flow‐directed and selective embolization was performed in 4 patients (12 procedures). The percentage of reduction of the AVM volume averaged 36% after embolization. Five minor complications (transient neurological deficits, in 2 cases associated with ischemic areas on the CT scan) were observed after embolization. The interval between the last embolization and surgery was as follows: within 10 days in 7 patients; between 11 and 20 days in 3 patients; between 21 and 30 days in 10 patients; between 31 and 60 days in 11 patients; and 2 months later in 18 patients. The efficacy of this combined treatment (embolization plus surgery) was evaluated by the incidence of hyperemic complications and the clinical outcome. Hyperemic complications occurred more frequently in patients with an AVM volume greater than 20 cm3. When compared with flow‐directed embolization, selective embolization was linked with decreased bleeding during surgery; postoperatively, the incidence of cerebral edema was also lower. Clinical outcome was better after selective embolization, with no occurrence of major deficits and no mortality. When the percentage of reduction of the AVM volume after embolization was 40% or more, the incidence of intraoperative hyperemic complications was lower; moreover, new permanent deficits were never observed in patients with this volume reduction. A retrospective clinical comparison of two groups of patients with similar AVM volumes (>20 cm3)—those given combined treatment (n = 32) versus those treated by direct surgery alone (n = 27)—showed that intraoperative bleeding appeared to decrease in patients treated by embolization; the incidence of postoperative hyperemic complications was not different in the two groups. New major deficits and deaths were less frequent in patients treated by embolization (P= 0.05 for the incidence of major deficits); postoperative epilepsy was also less common in these patients. In conclusion, combined treatment with selective preoperative embolization and direct surgery may help the neurosurgeon in the treatment of large, high‐flow AVMs, reducing the risks connected with their surgical removal. (Neurosurgery29:358‐368, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;The effect of transient hypothermia on focal cerebral ischemia was evaluated using a rat model of permanent middle cerebral artery (MCA) occlusion. MCA occlusion was performed on 10 rats at a temporalis muscle temperature of 24°C (hypothermic group) and on 10 rats at 36°C (normothermic group). Rats in the hypothermic group were maintained at 24°C for 1 hour after MCA occlusion and then allowed to rewarm to 36°C over the next 2 hours. Animals in both groups were killed 24 hours after MCA occlusion. Cerebral infarcts were visualized by staining of coronal brain sections with 2,3,5‐triphenyltetrazolium chloride. Normothermic rats displayed an average infarct volume of 233.1 ± 13.2 mm3(standard error of the mean), whereas hypothermic rats had an average infarct volume of 166.2 ± 22.8 mm3(P< 0.01). Expressed as a percentage of the volume of the right hemisphere, the normothermic group had an infarct volume of 22.1 ± 1.5% and the hypothermic group an infarct volume of 16.0 ± 2.2% (P< 0.05). These results demonstrate that transient hypothermia to a temporalis muscle temperature of 24°C significantly reduces subsequent infarct size in an experimental model of permanent arterial occlusion. (Neurosurgery29:369‐373, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;Previous reports of computed tomographic scan with contrast myelography in cervical spinal cord injury have shown a rate of disc herniation of less than 5%. We hypothesized that injuries associated with forces adequate to cause bone or ligamentous injury in the region of the disc space could be associated with higher and more significant rates of disc herniation. Thirty‐seven consecutive traumatic midcervical fracture subluxations were reviewed. Fracture subluxation was defined by fracture of the facet joints, pedicles, or vertebral bodies or more than 3.5 mm subluxation from C2‐C3 to C7‐T1. Reduction was achieved in 97% and was not associated with neurological deterioration. On the basis of plain films, tomograms, and plain computed tomographic scans, the injuries were classified as flexion dislocation, flexion compression, compression burst, or extension injuries. Twenty‐five computed tomographic scans with contrast myelograms and one magnetic resonance imaging scan were obtained. All patients with partial neurological deficits were studied. A herniated disc was defined as that which deformed the thecal sac and/or nerve roots. Retrospectively, a neuroradiologist reviewed the studies for the presence of herniated disc. Disc herniation was seen at the level of injury in 9 (35%) patients and not seen in other patients. Forty‐seven percent of the patients with partial deficits had herniated discs. Herniated discwas seen most frequently in flexion dislocation and flexion compression injuries. Three patients (20%) with partial deficits underwent discectomy. Patients with partial spinal cord injury and discectomy, on average, improved more than other patients with partial spinal cord injury. The authors conclude that: 1) herniated discs occur frequently in cervical fracture subluxation and are clinically significant; 2) disc herniation is associated with flexion dislocation and flexion compression injuries; 3) neuroimaging studies should be obtained in all patients with cervical fracture subluxation and neurological deficit to rule out compressive discs. (Neurosurgery29:374‐379, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;This is a prospective study of the treatment of penetrating missile injuries to the brain without intracranial surgery carried out at the American University of Beirut Medical Center between 1981 and 1988. Of 600 patients treated for missile injuries to the head. 32 satisfied the study criteria. There were 27 shrapnel and 5 bullet injuries. The mean patient age was 23 years (range, 3‐51 years). Twenty patients had intracranial indriven bone fragments. Six patients had exposed brain tissue. The mean follow‐up was 3.5 years (range, 1‐7.5 years). The superficial entry wound was debrided and closed without drainage in the Emergency Room within a mean of 3 hours (range, 0.5‐6 hours), and the patient received methicillin for 14 days. All patients survived and had no or improved neurological deficits. No leakage of the cerebrospinal fluid, infection, or seizures occurred in 31 patients. One patient with indriven bone fragments had leakage of the cerebrospinal fluid and developed seizures and a brain abscess 20 days after the injury. The management of penetrating missile injuries to the brain without intracranial surgery in a select patient population is a reasonable option. This treatment becomes important for a surgeon facing large numbers of casualties, or when operative personnel or resources are limited or unavailable. (Neurosurgery29:380‐384, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;Current neurosurgical opinion favors the radical surgical removal of supratentorial gliomas, when feasible, in the belief that this optimizes patient survival. Although bolstered by the results of some early investigators, the efficacy of this approach remains debatable. Therefore, we undertook a review of the English language literature of the past 30 years for a series of surgically treated malignant gliomas. Twenty reports comprising 5691 patients were identified. Only 4 found the extent of the surgical resection related to survival. In 2 of these, it followed age, histological findings, and performance status in importance. The 2 other studies did not rank the prognostic variables at all. On closer inspection, however, there does appear to be a subgroup of young patients with favorable histological findings and good performance status for whom surgery is beneficial. Future reporting of surgical results of patients with gliomas will require stratification by the known prognostic variables of age. histological findings, and performance status to characterize better this subgroup for whom surgery is beneficial. (Neurosurgery29:385‐389, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;A brain tumor is composed not only of tumor cells, but also of normal glial, mesenchymal, endothelial, and microglial cells, as well as lymphocytes and macrophages. Therefore, homogeneous cultures of tumor cells, currently used for chemosensitivity testing, do not accurately model in situ tumors. We have developed an in vitro growth assay for brain tumors that includes normal host cells and is potentially useful for studies of chemotherapy and biological response modifiers. Human glioblastoma xenografts (U251‐MG) were resected from mice, minced, and explanted into agarosecoated culture wells. After 5 to 7 days, microtumors emerged as expanding spheroids, which grew most efficiently in minimum essential medium supplemented with 20% fetal calf serum, 90% of which was replaced on alternate days. The growth rate and bromodeoxyuridine labeling index were similar in the microtumors and the xenografts, and light microscopy revealed highly cellular, pleomorphic tumors with high mitotic activity in both. Immunohistochemical studies also demonstrated the persistence of macrophages in both xenografts and microtumors. Microtumors treated for 2 hours with 75 &mgr;mol/L l,3‐bis‐(2‐chloroethyl)‐1‐nitrosourea showed a growth delay of 1.5 days; no effects were observed after treatment with lower doses. This in vitro system for brain tumor culture may provide a useful technique for the study of new therapies as an alternative to in vivo xenograft studies using immunodeficient animals. (Neurosurgery29:390‐398, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

&NA;Immunohistochemical studies of the expression of protein kinase C isozymes were done in 38 human brain tumors using monoclonal antibodies to three major isozymes: Type I, Type II. and Type III. The brain tumors, with the exception of 3 medulloblastomas and 2 of 6 pituitary adenomas, showed strong immunoreactivity for the Type III isozyme. Astrocytomas, anaplastic astrocytomas, and glioblastomas also showed weak immunostaining for Type II, whereas other tumors lacked this staining. Immunoreactivity for Type I was present, although weak, in some astrocytic gliomas. There was no correlation between the presence of immunoreactivity for protein kinase C isozymes or the intensity of staining for the Type III isozyme and the pathological grade of malignancy. In normal human brain tissue, Type I is localized mainly in neuronal cells, Type II in the neuropil of the cerebral cortex and the molecular and granular layers of the cerebellum. and Type III almost exclusively in astrocytes. The presence of immunoreactivity for the Type III isozyme in varying tumor cells, including those of non‐astrocytic tumors and the presence of the Type II and/or Type I isozymes in astrocytic gliomas demonstrate that the expression of protein kinase C isozymes differs between normal and transformed cells. (Neurosurgery29:399‐404, 1991)

ISSN:0148-396X    

出版商:OVID    

年代:1991

数据来源: OVID