Browsing by Author "Patel, Ajay"

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    Brainstem metastases treated with Gamma Knife stereotactic radiosurgery: the Indiana University Health experience
    (Future Medicine:, 2018-01) Patel, Ajay; Mohammadi, Homan; Dong, Tuo; Shiue, Kevin Ren-Yeh; Frye, Douglas; Le, Yi; Ansari, Shaheryar; Watson, Gordon A.; Miller, James C.; Lautenschlaeger, Tim; Medicine, School of Medicine
    Brainstem metastases offer a unique challenge in cancer treatment, yet stereotactic radiosurgery (SRS) has proven to be an effective modality in treating these tumors. This report discusses the clinical outcomes of patients with brainstem metastases treated at Indiana University with Gamma Knife (GK) radiosurgery from 2008 to 2016. 19 brainstem metastases from 14 patients who had follow-up brain imaging were identified. Median tumor volume was 0.04 cc (range: 0.01-2.0 cc). Median prescribed dose was 17.5 Gy to the 50% isodose line (range: 14-22 Gy). Median survival after GK SRS treatment to brainstem lesion was 17.2 months (range: 2.8-45.6 months). The experience at Indiana University confirms the safety and efficacy of range of GK SRS prescription doses (14-22 Gy) to brainstem metastases.
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    Standard work tools for dynamic stereoelectroencephalography using ROSA: naming convention and perioperative planning
    (JNS, 2021-04) Bakr, Salma M.; Patel, Ajay; Zaazoue, Mohamed A.; Wagner, Kathryn; Lam, Sandi K.; Curry, Daniel J.; Raskin, Jeffrey S.; Neurological Surgery, School of Medicine
    OBJECTIVE The grid-based orthogonal placement of depth electrodes (DEs), initially defined by Jean Talairach and Jean Bancaud, is known as stereo-electroencephalography (sEEG). Although acceptance in the United States was initially slow, advances in imaging and technology have spawned a proliferation of North American epilepsy centers offering sEEG. Despite publications highlighting minimal access techniques and varied indications, standard work for phase I targeted DE has not been defined. In this article, the authors propose the term “dynamic sEEG” and define standard work tools and related common data elements to promote uniformity in the field. METHODS A multidisciplinary approach from July to August 2016 resulted in the production of 4 standard work tools for dynamic sEEG using ROSA: 1) a 34-page illustrated manual depicting a detailed workflow; 2) a planning form to collocate all the phase I data; 3) a naming convention for DEs that encodes the data defining it; and 4) a reusable portable perioperative planning and documentation board. A retrospective review of sEEG case efficiency was performed comparing those using standard work tools (between July 2016 and April 2017) with historical controls (between March 2015 and June 2016). The standard work tools were then instituted at another epilepsy surgery center, and the results were recorded. RESULTS The process for dynamic sEEG was formally reviewed, including anesthesia, positioning, perioperative nursing guidelines, surgical steps, and postoperative care for the workflow using cranial fixation and ROSA-guided placement. There was a 40% improvement in time per electrode, from 44.7 ± 9.0 minutes to 26.9 ± 6.5 minutes (p = 0.0007) following the development and use of the manual, the naming convention, and the reusable portable perioperative planning and documentation board. This standardized protocol was implemented at another institution and yielded a time per electrode of 22.3 ± 4.4 minutes. CONCLUSIONS The authors propose the term dynamic sEEG for stereotactic depth electrodes placed according to phase I workup data with the intention of converting to ablation. This workflow efficiency can be optimized using the standard work tools presented. The authors also propose a novel naming convention that encodes critical data and allows portability among providers. Use of a planning form for common data elements optimizes research, and global adoption could facilitate multicenter studies correlating phase I modality and seizure onset zone identification.
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    Toxicity of Radiosurgery for Brainstem Metastases
    (Elsevier, 2018) Patel, Ajay; Dong, Tuo; Ansari, Shaheryar; Cohen-Gadol, Aaron; Watson, Gordon; de Moraes, Fabio Ynoe; Nakamura, Masaki; Murovic, Judith; Chang, Steven D.; Hatiboglu, Mustafa Aziz; Chung, Caroline; Miller, James; Lautenschlaeger, Tim; Radiation Oncology, School of Medicine
    Background Although stereotactic radiosurgery (SRS) is an effective modality in the treatment of brainstem metastases (BSM), radiation-induced toxicity remains a critical concern. To better understand how severe or life-threatening toxicity is affected by the location of lesions treated in the brainstem, a review of all available studies reporting SRS treatment for BSM was performed. Methods Twenty-nine retrospective studies investigating SRS for BSM were reviewed. Results The rates of grade 3 or greater toxicity, based on the Common Terminology Criteria for Adverse Events, varied from 0 to 9.5% (mean 3.4 ± 2.9%). Overall, the median time to toxicity after SRS was 3 months, with 90% of toxicities occurring before 9 months. A total of 1243 cases had toxicity and location data available. Toxicity rates for lesions located in the medulla were 0.8% (1/131), compared with midbrain and pons, respectively, 2.8% (8/288) and 3.0% (24/811). Conclusions Current data suggest that brainstem substructure location does not predict for toxicity and lesion volume within this cohort with median tumor volumes 0.04–2.8 cc does not predict for toxicity.