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L. Dade Lunsford

cessation or tumor volume reduction ( Fig. 2 ). Tumor growth outside the radiation field occurred in two of three patients with malignant meningiomas. Fig. 2. Graph showing tumor control rates after stereotactic radiosurgery for meningiomas at the University of Pittsburgh. The 4-year actuarial tumor control rate for 94 benign meningiomas was 92%. We recently evaluated the efficacy and safety of stereotactic radiosurgery in a series of 34 patients with growing or recurrent cavernous sinus meningiomas. 3 Of interest, 62% of neurological deficits detected in

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Huai-che Yang, Hideyuki Kano, Nasir Raza Awan, L. Dade Lunsford, Ajay Niranjan, John C. Flickinger, Josef Novotny Jr., Jagdish P. Bhatnagar and Douglas Kondziolka

T he incidence of clinically recognized vestibular schwannomas (acoustic neuromas) is approximately 1:100,000 in the US population. 2 Because these lesions are generally benign tumors, the goals of treatment include long-term tumor control and maintenance of existing cranial nerve function. Stereotactic radiosurgery is a safe and effective tool in patients with vestibular schwannoma. 1 , 3–5 , 9 , 11 , 13–15 , 19 The role of SRS in the management of large vestibular schwannomas (> 3 cm) remains controversial. The potential for AREs and lack of rapid volume

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Hideyuki Kano, John C. Flickinger, Aya Nakamura, Rachel C. Jacobs, Daniel A. Tonetti, Craig Lehocky, Kyung-Jae Park, Huai-che Yang, Ajay Niranjan and L. Dade Lunsford

M anagement of large-volume arteriovenous malformations (AVMs) poses significant challenges to patients and physicians. For such AVMs, selected centers began to stage treatment volumes of the AVM using stereotactic radiosurgery (SRS). To date few published reports exist to validate the long-term results of this strategy. 1 , 3 , 9 , 12 , 18 , 19 The obliteration response of an AVM depends on radiation dose and volume, but for larger volumes, the dose must be reduced to decrease radiation-related brain injury. In 1992, we began to stage anatomical components of

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Douglas Kondziolka and L. Dade Lunsford

neurological deterioration. Although our stereotactic technique has been previously published, 15 we will summarize it briefly here. After application of the stereotactic frame, * a contrast-enhanced CT scan with 5-mm axial sections through the third and lateral ventricles was performed using a dedicated intraoperative CT scanner. Preaspiration cyst volume measurements were made from the CT scans. 18 Either a percutaneous twist-drill hole or a burr hole was made, and a 1.8-mm probe was advanced to the target, usually 3 to 5 mm past the center of the cyst to allow for

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subarachnoid space supplied by first-division trigeminal fibers) and occasionally in lower divisions of the face. 4. Regardless of the divisions of the trigeminal nerve affected by pain, the trigeminal cistern varies from 0.15 to 0.45 ml, with a median volume of 0.3 ml. 4 Glycerol injected without definition of the trigeminal cistern may extravasate through the porus of Meckel's cave into the subarachnoid space of the posterior fossa. Volumes of glycerol injected without due consideration of the patient's individual cisternal volume will increase the risks of a

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Changing concepts in the treatment of colloid cysts

An 11-year experience in the CT era

Walter A. Hall and L. Dade Lunsford

preoperative CT scan with 5-mm axial sections through the third ventricle was obtained after the administration of intravenous contrast material. Reformatted imaging in coronal and sagittal planes was performed to define the lesions. Volume determinations were made using the cursor track ball and region-of-interest techniques available on the CT scanner. 17 Fig. 1. Preoperative computerized tomography scans demonstrating colloid cysts of the third ventricle in seven patients who had stereotaxic aspiration as the initial surgical treatment. Aspiration and

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L. Dade Lunsford, Geoffrey Levine and Lewis W. Gumerman

of the short penetrance of the rays and ideal dosimetry, strictly betaemitting isotopes such as yttrium-90, rhenium-186, and phosphorus-32 ( 32 P) have been selected for this purpose. Accurate determination of the cyst volume is mandatory for 32 P dosimetry. Despite the widespread use of computerized tomography (CT) as a superior diagnostic device to clearly delineate the cystic tumor, at present an isotope dilution technique using technetium-99m ( 99m Tc) sulfur colloid has remained the benchmark for the determination of intraoperative cyst volume. 1, 10 High

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Elizabeth Tyler-Kabara, Douglas Kondziolka, John C. Flickinger and L. Dade Lunsford

ventricle wall ( Fig. 1 ). After surgery the patient continued to exhibit mild neurocognitive deficits. She was referred to us for stereotactic radiosurgery to treat the residual tumor. Radiosurgery was performed using the Leksell gamma knife (Elekta Instruments, Atlanta, GA). A combination of five 14-mm isocenters was used to deliver a dose to the tumor margin of 14 Gy and a maximum dose of 28 Gy. The residual tumor volume measured 7.9 cm 3 . Subsequent imaging studies demonstrated complete regression of the contrast-enhancing tumor mass ( Fig. 1 ). Now, 53 months after

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

nine cases and multiple irradiation isocenters in 41 ( Fig. 1 ). Five isocenters of irradiation were used in four patients, and four isocenters were used in another four. Forty-four patients (88%) were treated at the 50% isodose line or greater, to take advantage of the sharp fall-off of the radiation field outside the target volume. 49 The mean dose delivered to the tumor margin was 16.98 Gy (range 10 to 25 Gy). A scatterplot of tumor volume versus dose to the margin for all 50 tumors is presented in Fig. 2 . TABLE 2 Radiosurgical dosimetry in 50 patients

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Satoshi Maesawa, John C. Flickinger, Douglas Kondziolka and L. Dade Lunsford

associated with incomplete nidus obliteration in 45 patients who underwent repeated AVM radiosurgery. 22 For a number of reasons, the residual nidus was identified outside the field (treatment volume) of the initial radiosurgery in many patients. In the remaining patients in whom the persistent nidus was within the field, no obvious cause (relative radiobiological resistance) was found. In initiating the present study, we questioned how factors associated with treatment failure at the first radiosurgery might impact on repeated radiosurgery. We hypothesized that the