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Douglas Kondziolka, Mark Bernstein, Lothar Resch, Charles H. Tator, J. F. Ross Fleming, R. G. Vanderlinden and Hart Schutz

✓ A retrospective clinical and pathological review of 905 consecutive brain tumor cases (excluding pituitary adenoma and recurrent tumor) was conducted to identify cases in which intratumoral hemorrhage was confirmed grossly and/or pathologically. There were 132 cases so identified, for an overall tumor hemorrhage rate of 14.6%; of these, 5.4% were classified as macroscopic and 9.2% as microscopic. The presence of hemorrhage was correlated with the neurological presentation. The highest hemorrhage rate (70.0%) was found in patients with prior neurological history who experienced apoplectic deterioration (acute-on-chronic presentation). Only 57.1% of patients with acute deterioration in the absence of prior neurological symptoms had hemorrhages. The highest hemorrhage rate for primary brain tumors was 29.2% for mixed oligodendroglioma/astrocytoma, while the highest hemorrhage rate for any tumor type was 50% for metastatic melanoma. The clinical relevance of tumor hemorrhage is discussed.

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Douglas Kondziolka, Mark Bernstein, S. M. Spiegel and Karel ter Brugge

✓ The authors describe three cases of clinical cerebral ischemia associated with angiographic evidence of cerebral arterial luminal narrowing presenting 7, 14, and 52 weeks after subarachnoid hemorrhage (SAH) and aneurysm clipping. Delayed vasospasm, in its usual time setting 1 or 2 weeks after hemorrhage, did not occur symptomatically in these patients. No evidence for aneurysm clip migration or rebleed was present. All patients responded favorably to volume expansion and elevation of blood pressure. This unusual occurrence of a very delayed vasospasm may further the understanding of the vasospastic process. The symptomatic onset of arterial luminal narrowing months after SAH may suggest that a proliferative vasculopathy more accurately explains the observed vessel narrowing, rather than conventional active constriction of vascular smooth muscle.

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Douglas Kondziolka and Juan M. Bilbao

✓ Monoclonal and polyclonal antisera were used against 12 cases of neuroepithelial (colloid) cysts to determine the specific antigenic profile of the cyst epithelium. Intermediate filament markers (cytokeratin, vimentin, neurofilament, and glial fibrillary acidic protein) and epithelial markers (epithelial membrane antigen and monoclonal antibody lu-5) demonstrated that colloid cyst epithelium has a unique antigenic profile in contrast to that of choroid plexus or glial tissue. Theories raised to explain the etiology of colloid cysts have included derivation from the embryonic paraphysis, detachments of developing neuroepithelium from the tela choroidea, and remnants of respiratory epithelium; a more recent theory suggests that these cysts are products of developing choroid plexus or ependyma. The present study shows that colloid cyst epithelium is distinct from that of choroid plexus or ependyma and therefore does not represent a product of their formation, nor does it represent a form of immature glia. This finding supports the conclusion that colloid cysts in any ventricular location represent a developmental anomaly of primitive neuroectoderm in the embryo, which remains unique from other products of neuroectodermal derivation.

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Douglas Kondziolka, L. Dade Lunsford, Robert J. Coffey and John C. Flickinger

✓ Stereotactic radiosurgery has an expanding role in the management of selected intracranial tumors. In an initial 30-month experience using the 201-source cobalt-60 gamma knife at the University of Pittsburgh, 50 patients with meningiomas were treated. The most frequent site of origin was the skull base. Previously, 36 patients (72%) had undergone at least one craniotomy and four patients (8%) had received fractionated external beam radiation therapy. Stereotactic radiosurgery was the primary treatment modality in 16 patients (32%) with symptomatic tumors demonstrated by neuroimaging. Computer imaging-generated isodose plans (with one to five irradiation isocenters) for single-treatment irradiation gave optimal (≥ 50% isodose line) coverage in 44 patients (88%). The proximity of cranial nerves or vascular, pituitary, and brain-stem structures to the often convoluted tumor mass was crucial to dose selection. Serial imaging studies were evaluated in all 50 patients. Twenty-four patients were examined between 12 and 36 months after treatment; 13 (54%) showed a reduction in tumor volume while nine (38%) showed no change. Of 26 patients evaluated between 6 and 12 months after treatment, four showed a decrease in tumor size while 22 showed no change. Two patients (both with large tumors that received suboptimal irradiation) had delayed tumor growth outside the radiosurgical treatment volume. The actuarial 2-year tumor growth control rate was 96%. Between 3 and 12 months after radiosurgery, three patients developed delayed neurological deficits that gradually improved, compatible with delayed radiation injury. Although extended follow-up monitoring over many years will be necessary to fully evaluate treatment, to date stereotactic radiosurgery has proved to be a relatively safe and effective therapy for selected patients with symptomatic meningiomas, including those who failed surgical resection. Radiosurgery was an effective primary treatment alternative for those patients whose advanced age, medical condition, or high-risk tumor location mitigated against surgical resection.

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Douglas Kondziolka and L. Dade Lunsford

✓ Stereotactic aspiration is a valuable surgical alternative for colloid cysts when used alone or in conjunction with microsurgical resection. Since 1981, the authors have performed computerized tomography (CT)-guided stereotactic aspiration as the initial procedure in 22 patients with colloid cysts; stereotactic aspiration alone was successful in 11 patients (50%). Of the 11 patients in whom aspiration failed, stereotactic endoscopic resection was attempted in three and was successful in one. Seven patients required a craniotomy and microsurgical removal of the cyst performed via a transcortical approach.

The preoperative CT appearance in eight cases of a hypodense or isodense cyst correlated favorably with successful aspiration of the cyst in six patients. A hyperdense appearance on the preoperative CT scan in 14 cases was associated with subtotal aspiration in 13 patients; five required craniotomy for removal. Preoperative magnetic resonance (MR) imaging in eight patients provided excellent anatomical definition of the cyst and its relationship to other structures of the third ventricle, but it was not possible to correlate successful aspiration with cyst appearance on MR images with short or long relaxation time sequences. The authors' 9-year experience suggests that preoperative CT studies accurately determine size, predict viscosity, and help to define a group of colloid cyst patients for whom stereotactic cyst aspiration will likely be successful. Unsuccessful stereotactic aspiration was related to two features: the high viscosity of the intracystic colloid material (nine patients), or deviation of the cyst away from the aspiration needle due to small cyst volume (two patients). Because of its simplicity and low risk, stereotactic surgery can be offered to selected patients as the initial procedure of choice. Craniotomy can be reserved for those whose imaging studies predict failure or for those whose cyst cannot be aspirated.

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L. Dade Lunsford, Douglas Kondziolka, John C. Flickinger, David J. Bissonette, Charles A. Jungreis, Ann H. Maitz, Joseph A. Horton and Robert J. Coffey

✓ Stereotactic radiosurgery successfully obliterates carefully selected arteriovenous malformations (AVM's) of the brain. In an initial 3-year experience using the 201-source cobalt-60 gamma knife at the University of Pittsburgh, 227 patients with AVM's were treated. Symptoms at presentation included prior hemorrhage in 143 patients (63%), headache in 104 (46%), and seizures in 70 (31%). Neurological deficits were present in 102 patients (45%). Prior surgical resection (resulting in subtotal removal) had been performed in 36 patients (16%). In 47 selected patients (21%), embolization procedures were performed in an attempt to reduce the AVM size prior to radiosurgery. The lesions were classified according to the Spetzler grading system: 64 (28%) were Grade VI (inoperable), 22 (10%) were Grade IV, 90 (40%) were Grade III, 43 (19%) were Grade II, and eight (4%) were Grade I. With the aid of computer imaging-integrated isodose plans for single-treatment irradiation, total coverage of the AVM nidus was possible in 216 patients (95%). The location and volume of the AVM were the most important factors for the selection of radiation dose. Magnetic resonance (MR) imaging was performed at 6-month intervals in 161 patients. Seventeen patients who had MR evidence of complete obliteration underwent angiography within 3 months of imaging: in 14 (82%) complete obliteration was confirmed. Complete angiographic obliteration was confirmed in 37 (80%) of 46 patients at 2 years, the earliest confirmation being 4 months (mean 17 months) after radiosurgery. The 2-year obliteration rates according to volume were: all eight (100%) AVM's less than 1 cu cm; 22 (85%) of 26 AVM's of 1 to 4 cu cm; and seven (58%) of 12 AVM's greater than 4 cu cm. Magnetic resonance imaging revealed postirradiation changes in 38 (24%) of 161 patients at a mean interval of 10.2 months after radiosurgery; only 10 (26%) of those 38 patients were symptomatic. In the entire series, two patients developed permanent new neurological deficits believed to be treatment-related. Two patients died of repeat hemorrhage at 6 and 23 months after treatment during the latency interval prior to obliteration.

Stereotactic radiosurgery is an important method to obliterate AVM's, especially those previously considered inoperable. Success and complication risks are related to the AVM location and the volume treated.