Bennett M. Stein

Transcallosal approach to the anterior ventricular system.

Using an anterior transcallosal approach, we operated upon 25 patients with lateral and 3rd ventricular lesions. The facility of this route is discussed, and the operative technique is presented.

Supratentorial Ependymomas in Adult Patients

OBJECTIVEnEpendymomas arise from different areas in the neuraxis and have variable outcomes that depend on tumor location and patient age at the time of presentation. The predictive value of histology for these tumors is unresolved. We report a series of adult patients with supratentorial ependymomas to characterize the roles of surgery, histology, ploidy, and proliferation index in tumor control.nnnMETHODSnFourteen of the 23 supratentorial ependymomas were in the region of the third ventricle and the remainder were located in the hemispheres. Resections were gross total in 12 patients, subtotal in 8, and biopsy in 3. A single pathologist reviewed all slides and quantitated the deoxyribonucleic acid. The mean follow-up duration was 95 months (+/-75 mo).nnnRESULTSnAll of the malignant ependymomas were hemispheric (n = 4). Mortality occurred only in patients with third ventricular tumors; two patients died as a result of surgical complications and three as a result of tumor progression. Kaplan-Meier estimates of 5- and 10-year survival rates were 100% for hemispheric and 72.5% for third ventricular tumors (62.5% including the two perioperative deaths). The median time to recurrence was 53 months, with a 10-year progression-free survival rate of 27%. Univariate analysis revealed that recurrence was associated with malignant histology, including mitoses, cellularity, and aneuploidy. For nonmalignant ependymomas, recurrence was associated with subtotal resection and metastases. S-phase fraction did not correlate with recurrence. Only malignant histology correlated with recurrence on multivariate analysis.nnnCONCLUSIONnAlthough the numbers are too small to draw any definite conclusions, treatment of ependymomas that arise in the supratentorial compartment in adult patients results in excellent outcomes despite frequent recurrences. Association with the third ventricle and metastases seem to have a negative impact on survival, whereas malignant histology, subtotal resection, and metastases may be predictors of recurrence.

The effect of arteriovenous malformation resection on cerebrovascular reactivity to carbon dioxide.

To investigate the cerebral hemodynamic changes associated with obliteration of arteriovenous malformations (AVMs), we studied 26 patients undergoing total microsurgical AVM resection during isoflurane and N2/O2 anesthesia. Detectors were placed 5 to 6 cm from the margin of the lesion and in a homologous contralateral position. Cerebral blood flow (CBF) was measured using the intravenous xenon-133 technique before and after AVM resection, during both hypocapnia and normocapnia at each stage. Intraoperative changes in CBF were related to a risk score system based on the patients history and preoperative angiograms. Seven otherwise healthy patients undergoing spinal surgery were studied to control for anesthetic effects. Patient demographic and clinical data for the AVM group conformed to the expected strata of a large AVM population. The CBF increased after excision (22 +/- 1 ml/100 g/min before excision to 30 +/- 2 ml/100 g/min after excision; mean +/- SE, n = 25, P less than 0.002) without a hemispheric difference. CO2 reactivity increased slightly after excision (4.2 +/- 0.3% change/mm Hg before excision to 4.7 +/- 0.3% change/mm Hg after excision; n = 14, P less than 0.02). The baseline CBF and CO2 reactivity were not different from the control group. There was a weak correlation between the risk score and the percentage of change in the ipsilateral CBF, with a trend for the patients with the lowest risk to have the lowest CBF changes after resection. There was no relationship between CO2 reactivity and risk grade. None of the patients awoke from anesthesia with unexpected neurological deficits. The highest CBF increases were associated with postoperative brain swelling in one patient and fatal intracerebral hemorrhage in another. Both patients had normal CO2 reactivity before excision. One patient suffered postoperative intracerebral hemorrhage, attributable to technical problems, and had no increase in CBF. We conclude that, with an acute increase in the arteriovenous pressure gradient (and cerebral perfusion pressure) that results from shunt obliteration, there is an immediate global effect of AVM resection to increase CBF. Cerebrovascular reactivity to CO2 remains intact both before and after excision.

Ablations of the mammillary nuclei in monkeys: Effects on postoperative memory

A new procedure was developed for ablating the mammillary nuclei in nonhuman primates via direct visual exposure. Using this technique, monkeys receiving lesions of the mammillary nuclei were compared to control animals after surgery to assess the retention of preoperatively acquired visuospatial discriminations and subsequent postoperative ability to attain a demanding spatial memory task. Although the lesions proved to be accurate and complete, no changes in gross behavior or deficits in preoperatively acquired visual and spatial behaviors were noted. The monkeys with mammillary body lesions were, however, impaired in their ability to acquire postoperatively the demanding spatial memory task. These findings are consistent with previous investigations suggesting that the mammillary bodies are involved in the acquisition of spatial discriminations and skills.

Meningiomas of the Pineal Region and Third Ventricle

The clinical presentation, radiological findings, and surgical management of two cases of meningioma arising from the velum interpositum without dural attachment are described. The true nature of these tumors was not suspected despite extensive preoperative diagnostic evaluation. A total removal was effected in both cases with the use of the operating microscope and a posterior fossa approach to the pineal region. A review of similar cases from the English literature is presented.

An examination of the effects of mammillary-body lesions on reversal learning sets in monkeys

Monkeys with mammillary-body lesions were compared with operated and unoperated control monkeys on the acquisition of a series of place and object reversal discriminations. The animals with mammillary-body lesions were found not to differ from the control animals on either the initial acquisition of a place response or the visual discrimination of two junk objects. On subsequent reversals, however, monkeys with mammillary-body lesions were severely impaired on the spatial task, but showed no impairment in reversal learning in the object task. These results are consistent with our previous findings of an impairment in spatial alternation learning following mammillary-body lesions in monkeys and supports the hypothesis that the role of the mammillary nuclei in cognition may be limited to the spatial domain.

Combined supratentorial and infratentorial exposure for low-lying basilar aneurysms.

Details of an operative approach for low-lying basilar aneurysms utilizing a combined supratentorial and infratentorial exposure with tentorial section are presented. This approach permitted the successful clipping of aneurysms of the caudal basilar artery in both of the cases presented. The advanta

Report of Joint Committee for Stroke Facilities-- IX. Strokes in Children (Part 1)

The study group assigned the task of reviewing what is known about strokes in children has performed an outstanding service in bringing to the attention of readers of Guidelines for Stroke Care an important but little-publicized subject. They have given an analysis in depth, covering epidemiology, neuropathology, diagnosis and medical treatment, neurosurgical management, neuroradiology, rehabilitation, and psychological and educational problems. Strokes occur in children much less frequently than in the adult population. Nevertheless their significance should not be underestimated or underemphasized, for they have unusual features because their impact affects the developing nervous system. The Strokes in Children section of the Report of the Joint Committee for Stroke Facilities is being published in two parts of which this is the first; the second part will appear in the November-December issue of this Journal.

A study of the reactivity of feeding vessels to arteriovenous malformations: correlation with clinical outcome

Isolated segments from the feeding arteries to arteriovenous malformations (AVMs) from 24 patients were studied in vitro. In a perfusion chamber, isometric contraction of these arterial rings to various vasoactive substances was recorded and correlated with the following: spontaneous activity, spasm as seen in the operating room; radiographic evidence of ectasia preoperatively and postoperatively; and postoperative course. Of the 24 patients studied, four patients had nonreactive AVM nutrient vessels upon in vitro testing. In addition, these vessel segments displayed no spontaneous activity although all of the other vessels tested developed spontaneous activity while in the perfusion chamber. The patients with unreactive vessels had an increased incidence of postoperative edema and hemorrhage in the surrounding brain, consistent with the symptoms of normal perfusion pressure breakthrough. Thus, our study utilizes an in vitro technique to evaluate a specific segment of the AVM complex, the feeding vessel, which permitted us to assess abnormalities of reactivity in these vessel segments. This method may be useful for future evaluations of the pathophysiology of AVMs.

Removal of an arteriovenous malformation from the basal ganglion.

A case is reported in which an arteriovenous malformation was removed from a portion of the basal ganglion and region of the lenticulostriate arteries. The patient made an excellent recovery. The importance of stereoangiography and the operating microscope are emphasised.