摘要:

OBJECTIVE:To define the factors of importance for the obliteration of cerebral arteriovenous malformations (AVMs), thus making a prediction of the probability for obliteration possible.METHODS:In 945 AVMs of a series of 1319 patients treated with the gamma knife during 1970 to 1990, the relationship between patient, AVMs, and treatment parameters on the one hand and the obliteration of the nidus on the other was analyzed.RESULTS:The obliteration rate increased both with increased minimum (lowest periphery) and average dose and decreased with increased AVM volume. The minimum dose to the AVMs was the decisive dose factor for the treatment result. The higher the minimum dose, the higher the chance for total obliteration. The curve illustrating this relation increased logarithmically to a value of 87%. A higher average dose shortened the latency to AVM obliteration. For the obliterated cases, the larger the malformation, the lower the minimum dose used. This prompted us to relate the obliteration rate to the product minimum dose (AVM volume)1/3(K index). The obliteration rate increased linearly with the K index up to a value of approximately 27, and for higher K values, the obliteration rate had a constant value of approximately 80%. For the group of 273 cases treated with a minimum dose of at least 25 Gy, the obliteration rate at the study end point (defined as 2-yr latency) was 80% (95% confidence interval = 75-85%). If obliterations that occurred beyond the end point are included, the obliteration rate increased to 85% (81-89%).CONCLUSION:The probability of obliteration of AVMs after gamma knife surgery is related to the lowest dose to the AVMs and the AVM volume, and it can be predicted using the K index.

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

OBJECTIVE:To characterize late neuropathological findings of pediatric closed head injury (CHI), to assess depth of brain lesion in relation to acute severity, and to assess long-term outcome to test the Ommaya-Gennarelli model.METHODS:Magnetic resonance imaging (MRI) at least 3 months postinjury in a prospective sample (n 5 169) and at least 3 years CHI in a retrospective sample (n 5 82) was studied. Lesion volume was measured by planimetry. Acute CHI severity was measured by the Glasgow Coma Scale. Patients were classified according to the depth of the deepest parenchymal lesion into no lesion, cortical, subcortical, and deep central gray/brain stem groups. The outcomes were assessed by the Glasgow Outcome Scale and the Vineland Adaptive Behavior Scale, which were performed at the time of the MRI in the retrospective sample and up to 3 years postinjury in the prospective sample.RESULTS:Focal brain lesions were present in 55.4% of the total sample. Depth of brain lesion was directly related to severity of acute impairment of consciousness and inversely related to outcome, as measured by both the Glasgow Outcome Scale and the Vineland Adaptive Behavior Scale. A restrocaudal gradient of hemispheric lesion frequency was observed, whereas the posterior lesions of the corpus callosum were particularly common. Total lesion volume could not explain the depth of lesion effect.CONCLUSION:Our findings extend support for the Ommaya-Gennarelli model to pediatric CHI, indicating that depth of brain lesion is related to functional outcome. The relative frequency of focal brain lesions revealed by late MRI is higher than that of previous findings using acute computed tomography. Future investigations could explore whether depth of lesion observed using late MRI is sensitive to neuroprotective interventions.

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

OBJECTIVE:The cerebral hemodynamic and metabolic effects of aneurysmal subarachnoid hemorrhage are complex. To investigate the impact of surgical retraction, we analyzed positron emission tomography (PET) studies that measured the regional cerebral metabolic rate for oxygen, regional oxygen extraction fraction, and regional cerebral blood flow in four patients before and after right frontotemporal craniotomies for clipping of ruptured anterior circulation aneurysms.METHODS:Preoperative studies were conducted 1 day before surgery and postoperative studies 6 to 17 days after surgery. No patient had hydrocephalus or intracerebral hematoma. At the time of the second PET study, none of the patients had signs of clinical vasospasm. Regional measurements were obtained from the right ventrolateral frontal and anterior temporal regions corresponding to the area of retraction and compared to the same regions in the opposite hemisphere. To establish a quantitative means to differentiate between hemodynamic and metabolic changes related to arterial vasospasm and those caused by brain retraction, we studied a second group of preoperative patients, who had undergone PET during angiographic and clinical vasospasm.RESULTS:There was a 45% reduction in regional cerebral metabolic rate for oxygen(1.87 ± 0.22 to 1.04 ± 0.28 ml 100 g-1min-1) and 32% reduction in regional oxygen extraction fraction (0.41 ± 0.04 to 0.28 ± 0.03) in the region of retraction but no change in the opposite hemisphere (pairedttest;P= 0.042 and 0.003, respectively). There was no change in regional cerebral blood flow in any region. Brain retraction produced a focal area of tissue injury at the site of retractor blade placement, as compared to more diffuse vascular territory changes produced by vasospasm.CONCLUSION:This reduction in the cerebral metabolic rate of oxygen and the oxygen extraction fraction indicates a primary reduction in metabolism and uncoupling of flow and metabolism (luxury perfusion). Similar findings of luxury perfusion have been reported after ischemic stroke and traumatic brain injury. Further studies will be necessary to fully understand the clinical and pathophysiological significance of these observations.

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

OBJECTIVE:In recent years, dural arteriovenous fistulas (DAVFs) have been primarily thought to be acquired lesions, formed after sinus thrombosis. The pathogenesis of DAVF, however, is still controversial. We have studied histopathological aspects of DAVFs in resected specimens obtained from nine patients, to obtain clues to the pathogenesis of DAVFs.METHODS:Histological comparison was made among nine DAVF cases and five control cases without venous sinus disease. In addition, the relationship between the clinical course and histological aspects was investigated.RESULTS:The essential abnormality found was a connection between the dural arteries and the dural veins within the venous sinus wall, through small vessels averaging approximately 30 µm in diameter. By using several staining methods, we confirmed that the vessels were part of the venous system; we named these dilated venules "crack-like vessels."CONCLUSION:The development of abnormal communications between dural arteries and dural veins (crack-like vessels) is regarded as the essential part of the pathogenesis of DAVFs, and sinus thrombus is not thought to be an essential lesion of DAVFs. It might be postulated that sinus hypertension caused by stenocclusive disease of the venous sinuses triggers the development of fistulous connections between arteries and veins in the dural wall, which may result in increasingly dilated venules and the formation of DAVFs.

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

OBJECTIVE:The present study investigated the significance of the presence or absence of auditory brain stem response (ABR) Waves I, III, and V as functional representatives of the cochlea, the nucleus cochlearis, and the colliculus inferior, respectively, and attempted to identify the microsurgical maneuvers that were especially likely to cause isolated or combined component losses and subsequent hearing losses.METHODS:Based on the previously described ABR classification system, 201 patients with preserved Waves I, III, and V or Waves I and V were investigated for the peak latencies and amplitudes of the waves at 15 defined microsurgical stages. Analysis was performed with respect to the presence or absence of ABR components during specific microsurgical actions and the related danger of deafness.RESULTS:Temporary or permanent losses of Waves V, I, and III occurred with 21, 27, and 29% of surgical actions, respectively, leading to deafness in 65 to 78% of the patients. Wave III disappearance was identified as the earliest and most sensitive sign. Wave V loss was usually preceded by disappearances of Waves I and III. During the most dangerous actions (drilling, pulling downward, medially, or laterally, and direct nerve manipulation), special attention was paid to deterioration of Wave III and then Wave I; if impairment was seen, intermittent breaks or changes in the type or site of microsurgical action were used to enable wave recovery. Acute, simultaneous, and permanent loss of all waves occurred in 27.5% of postoperatively deaf patients, whereas stepwise wave deterioration and losses occurred in 72.5%.CONCLUSION:Useful (in-time) recognition of significant waveform changes is possible and enables a change of microsurgical maneuvers to favor ABR recovery.

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

OBJECTIVE:Tumor-induced bony and soft tissue findings might reflect, in part, the biological characteristics of vestibular schwannomas and could predict clinical findings. In addition, the role of the individual anatomic conditions of the posterior fossa is of interest to the surgeon.METHODS:Of 1000 vestibular schwannomas treated surgically at the neurosurgical department at Nordstadt Hospital, 202 cases, which were consecutively investigated at the same computed tomography (CT) unit and using the same technique (high-resolution CT at bone windows before and after surgery, contrast-enhanced high-resolution CT before surgery, and native high-resolution CT after surgery), were evaluated for special radiological features. Evaluation included, in 103 cases, anatomic parameters of the petrous bone and posterior fossa cavity and, in 202 cases, tumor-induced changes of bony structures, tumor relations with bony structures and with neural structures, and postoperative findings of bony structures and of neural tissues. These radiological parameters and the related clinical pre- and postoperative findings were transferred to a database for statistical evaluation of their positive or negative correlations, i.e., for their reliability in diagnosis and their importance in predicting postsurgical outcome.RESULTS:As important parameters, the following could be identified. The length of the posterior auditory canal wall and the interear difference of the maximum porus width both correlate with the degree of preoperative hearing deterioration (P< 0.05). The extent of the widening of the internal auditory canal is of predictive importance for the chances of postoperative hearing preservation or hearing loss (P< 0.01). The extent of tumor growth anterior and caudal to the internal auditory canal in large tumors is of significant importance for prediction of postoperative hearing function (P< 0.05). The tumor extension in all directions and the extent of cystic tumor components correlate with the pre- and postoperative function of the facial and cochlear nerves. The positions of the labyrinthine structures and their geographical relations to the fundus and the sigmoid sinus and, thereby, to the suboccipital route, enable reliable calculations of the danger of labyrinthine destruction and help improve the planning of the surgical strategy.DISCUSSION AND CONCLUSIONS:In addition to the importance for surgical planning, preoperative bone window CT and contrast-enhanced images offer the opportunity to identify traits of tumor biology, such as bony destruction of the internal auditory canal, tumor shape and cyst formation, and aspects with predictive importance for postoperative outcome. The average size for hearing preservation in tumors was 14.5 × 16.5 × 11.8 mm (coronal × sagittal× axial). The recent finding(8)of a higher presentation age in female patients has an apparently anatomic basis, which is a relatively larger internal auditory meatus.

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

OBJECTIVE:Subdural hematomas and hygromas are infrequently encountered complications of arachnoid cysts of the middle cranial fossa and are particularly rare with cysts of other regions. Reports in the literature focus on casuistic observations. Therapeutic recommendations often include fenestration or extirpation of the cyst wall, in addition to evacuation of the space-occupying lesion. This study evaluates the results of and rationale for a more conservative approach, usually without cyst removal.METHODS:Sixteen cases of complicated arachnoid cysts, from a total of 658 patients with subdural hematomas or hygromas, were analyzed retrospectively together with 75 other cases reported in the literature. Additionally, 94 magnetic resonance imaging scans from 89 patients with untreated arachnoid cysts, from a total of 11,487 examinations, were reviewed for signs of hemorrhagic complications.RESULTS:Arachnoid cysts of the middle cranial fossa were found in 2.43% of patients with chronic subdural hematomas or hygromas. This indicated a fivefold greater prevalence of arachnoid cysts, compared with our magnetic resonance imaging-examined patient group. Only two patients with untreated cysts showed signs of hemorrhage in magnetic resonance imaging scans. An excellent or good therapeutic result was achieved with evacuation of the subdural fluid by drainage or craniotomy in 13 cases and with conservative treatment in two cases. Only one patient underwent additional fenestration of the cyst wall. No additional symptoms from the arachnoid cysts occurred in a follow-up period of up to 14 years after therapy.CONCLUSIONS:We do not generally consider it necessary to perform cyst diversion or fenestration at the time of drainage of a hematoma or hygroma in previously asymptomatic arachnoid cysts.

ISSN:0148-396X    

出版商:OVID    

年代:1997

数据来源: OVID