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Venous angiomas (developmental venous anomalies) are vascular malformations increasingly recognized in general neurosurgical or neurological practice. They are associated with intracranial hemorrhage, seizures, or progressive neurological deficits or found as incidental findings in patients who present with headaches or have neuroimaging studies for investigation of unrelated neurological disorders. Since venous angiomas drain normal cerebral tissue within a functionally normal arterial territory, resection can lead to venous infarction. This report studies 27 patients with venous angiomas, all of whom had conservative treatment. The venous angioma was considered to be responsible for the onset of neurological symptoms in 14 patients (7 with hemorrhage, 3 with hemorrhage and seizures, 2 with seizures, one with an extrapyramidal movement disorder, and one with motor deficit). Thirteen patients had incidental lesions (8 with headache, and 5 with unrelated neurological symptoms). Ten venous angiomas were in the posterior fossa; seven in the cerebellum. Location did not correlate with symptomatic presentation. No patient with hemorrhage required surgical evacuation of the hematoma. No patient died or had significant morbidity during the follow-up interval (mean of 3.7 years). Venous angiomas are low flow, low resistance vascular malformations, many of which are not associated with neurological sequelae. Our series supports the concept that surgical removal or radiosurgical obliteration should not be performed unless a patient has a second life threatening hemorrhage.

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.

Despite conventional multimodality treatment (surgery and fractionated radiation therapy), recurrence and clinical progression of cranial base chordomas and chondrosarcomas are common. The malignant behavior of these tumors is a result of their critical location, locally aggressive nature, and high recurrence rate. To explore the role of radiosurgery in the treatment of these skull base neoplasms, we assessed its use in four patients with chordoma and two with chondrosarcoma. In five of the patients, radiosurgery was used as adjuvant therapy for residual or recurrent tumors after surgical debulking, and in one patient with a chordoma, it was the primary treatment. No patient received fractionated external beam radiotherapy. All tumors were less than 30 mm in diameter and were treated with 20 Gy to the tumor margin. Skull base computed tomography and magnetic resonance images were essential to define the anatomic relationships between tumor and adjacent basal structures. During follow-up (mean, 22 mo; range, 8-36 mo), we found no progression of the treated tumor volume in any patient. Neurological deficits before treatment improved in three patients; the other three patients remained in stable neurological condition. Serial follow-up imaging studies demonstrated that two patients showed reduction in tumor size and four patients had no tumor growth. In one patient, a metastatic parietal lobe chondrosarcoma developed and was treated by microsurgery. Another patient showed tumor progression outside of the radiosurgical treatment volume. Our results attest to the value of stereotactic radiosurgery as an adjuvant or primary treatment for selected patients with chordoma or chondrosarcoma and demonstrate its potential advantages over standard fractionated irradiation. Analysis of the long-term clinical and imaging effects after radiosurgery is warranted.

Stereotactic radiosurgery using the gamma unit represents a unique neurosurgical treatment method for the management of selected intracranial vascular malformations and tumors. During a closed-skull single-session procedure that focuses 201 individual beams of gamma irradiation, a high-radiation dose is delivered to the lesion, with a steep dose fall-off peripherally. In order to maintain accuracy of delivery, the target must remain fixed in space; hence the skull is engaged by rigid external fixation during treatment. In this report, we document the first extracranial lesion treated with radiosurgery, a recurrent squamous cell carcinoma of Rosenmuller's fossa, and discuss the possible role of radiosurgery in carefully selected head and neck malignancies.

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 (greater than or equal to 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.

Eighty-five patients with acoustic neurinomas underwent stereotactic radiosurgery with the gamma unit at the University of Pittsburgh (Pittsburgh, PA) during its first 30 months of operation. Neuroimaging studies performed in 40 patients with more than 1 year follow-up showed that tumors were smaller in 22 (55%), unchanged in 17 (43%), and larger in one (2%). The 2-year actuarial rates for preservation of useful hearing and any hearing were 46% and 62%, respectively. Previously undetected neuropathies of the trigeminal (n = 12) and facial nerves (n = 14) occurred 1 week to 1 year after radiosurgery (median, 7 and 6 months, respectively), and improved at median intervals of 13 and 8 months, respectively, after onset. Hearing loss was significantly associated with increasing average tumor diameter (P = 0.04). No deterioration of any cranial nerve function has yet developed in seven patients with average tumor diameters less than 10 mm. Radiosurgery is an important treatment alternative for selected acoustic neurinoma patients.

Fifty patients with meningiomas were treated during the initial 30 months experience using the 201 source cobalt-60 gamma knife at the University of Pittsburgh. The most frequent site of origin was the skull base. Stereotactic radiosurgery was the primary treatment modality in 16 (32%) patients with symptomatic tumors demonstrated by neuroimaging. Thirty-six patients (72%) had undergone at least one craniotomy, and 4 patients (8%) previously had fractionated external beam radiation therapy. The proximity of cranial nerves, vascular, pituitary and brainstem structures to the often convoluted tumor mass was crucial to dose selection. Follow-up imaging studies and clinical analysis of patients were performed at 6-month intervals. The actuarial 2-year tumor control rate was 96%. Only 2 patients have shown delayed tumor growth outside the radiosurgical treatment volume. To date, stereotactic radiosurgery proved to be a relatively safe and effective therapy for selected patients with symptomatic meningiomas, either as an adjuvant treatment to prior resection, or as a primary treatment alternative for patients whose advanced age, medical condition or high-risk tumor location mitigated against surgical resection.