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Zachary A. Seymour, Penny K. Sneed, Nalin Gupta, Michael T. Lawton, Annette M. Molinaro, William Young, Christopher F. Dowd, Van V. Halbach, Randall T. Higashida and Michael W. McDermott

for AVMs to surgical series is not straightforward, as total AVM volume rather than SM grade is the most important factor for SRS risk stratification. 5 Select small AVMs (< 10 ml) have a 3-year obliteration rate of 70%–95%. 18 , 27 , 28 Single-session SRS for the treatment of SM Grade I–II AVMs using a median radiation dose of 22 Gy can have an obliteration rate as high as 90% at 5 years. 16 Radiation dose and treatment volume play important roles in the rates of AVM obliteration; Pan et al. reported only a 25% overall obliteration rate at 40 months for single

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Nader Sanai and Michael W. McDermott

postoperative pseudomeningocele. The galea and skin were each closed separately with running suture. Results Patient and Tumor Demographics Eight tumors (67%) were right-sided and 4 (33%) were left-sided. The most common location was along the posterior fossa convexity (in 5 patients [42%]), followed by the CPA (in 4 [33%]) and the petrous face (in 3 [25%]). The mean tumor volume was 72.6 cm 3 (range 8–131 cm 3 ), and the median maximal tumor diameter was 4.9 cm. Microsurgical and Clinical Outcome Three patients (25%) underwent preoperative embolization, and

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Kurtis I. Auguste and Michael W. McDermott

either Septra DS (one tablet twice daily; King Pharmaceuticals, Inc., Bristol, TN) or oral clindamycin (300 mg three times per day). All patients remained in the hospital for the duration of the antibiotic irrigation treatment. Dressings, tubing, and wound and neurological status were checked twice daily by a physician and every 2 hours by the nursing staff. Nurses also recorded the volume of irrigation fluid passing into and out of the craniotomy site on a 2-hour basis. With the infusion solution hung from mobile intravenous fluid stands, patients were able to

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William T. Curry, Michael W. McDermott, Bob S. Carter and Fred G. Barker II

T here is increasing evidence that the ratio of patient mortality and morbidity is lower when complex medical or surgical procedures are performed at high-volume centers and when they are performed by high-volume physician providers. For example, the in-hospital mortality rate is lower when cardiovascular operations, 9 complex cancer operations, 7, 21 and surgical excision of acoustic neuromas 6 are performed at high-volume hospitals or by high-volume surgeons. A lower mortality rate and a shorter length of hospital stay after craniotomies for brain tumors

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Adib A. Abla, William Caleb Rutledge, Zachary A. Seymour, Diana Guo, Helen Kim, Nalin Gupta, Penny K. Sneed, Igor J. Barani, David Larson, Michael W. McDermott and Michael T. Lawton

(approximately 3 cm in diameter) require reductions in the marginal dose below 16 Gy to avoid adverse radiation complications, 19 while 16-, 18-, and 20-Gy marginal doses are associated with 70%, 80%, and 90% obliteration rates for AVMs overall. 22 Volume-staged SRS (VS-SRS) is a newer strategy that divides a large AVM into 2 or 3 smaller portions that are treated at separate stages enabling each portion to receive a higher dose. 12 , 22 The higher dose may be associated with a greater likelihood of response, while the separation of stages by months and proper alignment of

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Nader Sanai, Mei-Yin Polley, Michael W. McDermott, Andrew T. Parsa and Mitchel S. Berger

location. The institutional review board of the University of California, San Francisco approved this retrospective study. All patients gave written informed consent for the procedure; however, because of the study's retrospective nature, the requirement for informed consent for this study was waived by the institutional review board. Tumor Volume and EOR The EOR was determined by comparing MR imaging studies obtained before surgery with those obtained within 48 hours after surgery. A 3D volumetric measurement of pre- and postoperative MR imaging studies was

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Roberto C. Heros

took place at hospitals where there is a higher volume of meningioma surgery and when the surgery was performed by surgeons who perform higher volumes of this type of operation. In a previous editorial I addressed the limitations of studies such as this, which are based on national administrative databases. In this paper the authors provide an excellent discussion of the limitations and potential pitfalls of their study. The authors have masterfully used all the data at their disposal to adjust the results, eliminating as many potential sources of bias as possible

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Yaping Joyce Liao, William P. Dillon, Cynthia T. Chin, Michael W. McDermott and Jonathan C. Horton

abdominal cavity. However, tracer clearance can occur rapidly in a patient with a normally functioning shunt, especially if a large tracer volume is administered or the patient is crying or upright during the procedure. For this reason, a radionuclide study cannot always differentiate reliably between a shunt that is overdraining and one that is working properly. In our patient, the lack of anterograde flow of 99m Tc from the shunt reservoir to the abdomen in the first shuntogram was interpreted as evidence for shunt obstruction. Had distal obstruction been present

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Nader Sanai, Michael E. Sughrue, Gopal Shangari, Kenny Chung, Mitchel S. Berger and Michael W. McDermott

by the temporal convexity (28 lesions [20%]), median convexity (24 lesions [17%]), and posterior convexity (15 lesions [11%]). The mean tumor volume was 146.3 cm 3 (range 1–512 cm 3 ), and 95% of all tumors had a maximal diameter of at least 3 cm ( Fig. 1 ). TABLE 2: Lesion characteristics Characteristic No. lt-sided/rt-sided 72:69 mean vol in cm 3 (range) 146.3 (1–512) median max tumor dimension in cm 5.2 tumor location on convexity dura (%)  anterior 74 (52)  posterior 15 (11)  temporal 28 (20

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Michael E. Sughrue, Martin J. Rutkowski, Derick Aranda, Igor J. Barani, Michael W. McDermott and Andrew T. Parsa

Object

Although there is a considerable volume of literature available on the treatment of patients with cavernous sinus meningiomas (CSMs), most of the data regarding tumor control and survival come from case studies or single-institution series. The authors performed a meta-analysis of reported tumor control and survival rates of patients described in the published literature, with an emphasis on specific prognostic factors.

Methods

The authors systematically analyzed the published literature and found more than 3000 patients treated for CSMs. Separate meta-analyses were performed to calculate pooled rates of recurrence and cranial neuropathy after 1) gross-total resection, 2) subtotal resection without adjuvant postoperative radiotherapy or radiosurgery, and 3) stereotactic radiosurgery (SRS) alone. Results were expressed as pooled proportions, and random-effects models were used to incorporate any heterogeneity present to generate a pooled proportion. Individual studies were weighted using the inverse variance method, and 95% CIs for each group were calculated from the pooled proportions.

Results

A total of 2065 nonduplicated patients treated for CSM met inclusion criteria for the analysis. Comparisons of the 95% CIs for recurrence of these 3 cohorts revealed that SRS-treated patients experienced improved rates of recurrence (3.2% [95% CI 1.9–4.5%]) compared with either gross-total resection (11.8% [95% CI 7.4–16.1%]) or subtotal resection alone (11.1% [95% CI 6.6–15.7%]) (p < 0.01). The authors found that the pooled mixed-effects rate of cranial neuropathy was markedly higher in patients undergoing resection (59.6% [95% CI 50.3–67.5%]) than for those undergoing SRS alone (25.7% [95% CI 11.5–38.9%]) (p < 0.05).

Conclusions

Radiosurgery provided improved rates of tumor control compared with surgery alone, regardless of the subjective extent of resection.