Search Results

You are looking at 1 - 7 of 7 items for

  • Author or Editor: Samir Patel x
  • Refine by Access: all x
Clear All Modify Search
Restricted access

Jian-Qiang Lu, Samir Patel, Beverly A. Wilson, Jeffrey Pugh, and Vivek Mehta

Angiocentric glioma is a recently recognized benign brain tumor with unknown histogenesis. Most of these tumors are mitotically low in activity in accord with their benign clinical course. However, increased mitotic activity has been noted in several cases, one of which had an ultimately fatal outcome. Here, the authors present a tumor showing angiocentric glioma and glioblastoma-like features, with recurrence of the lower-grade component after radiotherapy. A 15-year-old boy presented with a 3-month history of progressive left-sided weakness and headache. Magnetic resonance imaging showed a large heterogeneous mass in the right frontal lobe, with mild post-Gd enhancement. A gross-total resection was obtained. Histopathological examination of the resected tissue revealed a tumor with 2 distinct appearances: 1) a mildly to moderately cellular infiltrating tumor with angiocentric glioma characteristics, and 2) a markedly cellular glioblastoma-like tissue with necrosis and microvascular proliferation. The patient received a course of postoperative radiotherapy to 59.4 Gy in 33 fractions administered over the course of 6.5 weeks, but his tumor recurred 4 months after resection. A second resection was then performed. The recurrent tumor exhibited radiation-induced changes and persistent characteristics of angiocentric glioma, but it had fewer malignant features; the mitotic activity was lower, and there was no necrosis or microvascular proliferation. The findings in this case, along with those in several previously reported cases, suggest that angiocentric gliomas may have a malignant variant or malignant transformation. Angiocentric gliomas with malignant features tend to recur, for which surgical intervention followed by radiotherapy and chemotherapy should be offered as a therapeutic option.

Restricted access

Mina G. Safain, Jason P. Rahal, Samir Patel, Alexandra Lauric, Edward Feldmann, and Adel M. Malek

Object

Intracranial atherosclerotic disease (ICAD) carries a high risk of stroke. Evaluation of ICAD has focused on assessing the absolute degree of stenosis, although plaque morphology has recently demonstrated increasing relevance. The authors provide the first report of the use of ultra-high-resolution C-arm cone-beam CT angiography (CBCT-A) in the evaluation of vessel stenosis as well as plaque morphology.

Methods

Between August 2009 and July 2012, CBCT-A was used in all patients with ICAD who underwent catheter-based angiography at the authors' institution (n = 18). Lesions were evaluated for maximum degree of stenosis as well as plaque morphological characteristics (ulcerated, calcified, dissected, or spiculated) via digital subtraction angiography (DSA), 3D-rotational angiography (3DRA), and CBCT-A. The different imaging modalities were compared in their assessment of absolute stenosis as well as their ability to resolve different plaque morphologies.

Results

Lesions were found to have similar degrees of stenosis when utilizing CBCT-A compared with 3DRA, but both 3DRA and CBCT-A differed from DSA in their assessment of the absolute degree of stenosis. CBCT-A provided the most detailed resolution of plaque morphology, identifying a new plaque characteristic in 61% of patients (n = 11) when compared with DSA and 50% (n = 9) when compared with 3DRA. CBCT-A identified all lesion characteristics visualized on DSA and 3DRA.

Conclusions

CBCT-A provides detailed spatial resolution of plaque morphology and may add to DSA and 3DRA in the evaluation of ICAD. Further prospective study is warranted to determine any benefit CBCTA-A may provide in clinical decision making and risk stratification over existing conventional imaging modalities.

Free access

Monica Mureb, Danielle Golub, Carolina Benjamin, Jason Gurewitz, Ben A. Strickland, Gabriel Zada, Eric Chang, Dušan Urgošík, Roman Liščák, Ronald E. Warnick, Herwin Speckter, Skyler Eastman, Anthony M. Kaufmann, Samir Patel, Caleb E. Feliciano, Carlos H. Carbini, David Mathieu, William Leduc, DCS, Sean J. Nagel, Yusuke S. Hori, Yi-Chieh Hung, Akiyoshi Ogino, Andrew Faramand, Hideyuki Kano, L. Dade Lunsford, Jason Sheehan, and Douglas Kondziolka

OBJECTIVE

Trigeminal neuralgia (TN) is a chronic pain condition that is difficult to control with conservative management. Furthermore, disabling medication-related side effects are common. This study examined how stereotactic radiosurgery (SRS) affects pain outcomes and medication dependence based on the latency period between diagnosis and radiosurgery.

METHODS

The authors conducted a retrospective analysis of patients with type I TN at 12 Gamma Knife treatment centers. SRS was the primary surgical intervention in all patients. Patient demographics, disease characteristics, treatment plans, medication histories, and outcomes were reviewed.

RESULTS

Overall, 404 patients were included. The mean patient age at SRS was 70 years, and 60% of the population was female. The most common indication for SRS was pain refractory to medications (81%). The median maximum radiation dose was 80 Gy (range 50–95 Gy), and the mean follow-up duration was 32 months. The mean number of medications between baseline (pre-SRS) and the last follow-up decreased from 1.98 to 0.90 (p < 0.0001), respectively, and this significant reduction was observed across all medication categories. Patients who received SRS within 4 years of their initial diagnosis achieved significantly faster pain relief than those who underwent treatment after 4 years (median 21 vs 30 days, p = 0.041). The 90-day pain relief rate for those who received SRS ≤ 4 years after their diagnosis was 83.8% compared with 73.7% in patients who received SRS > 4 years after their diagnosis. The maximum radiation dose was the strongest predictor of a durable pain response (OR 1.091, p = 0.003). Early intervention (OR 1.785, p = 0.007) and higher maximum radiation dose (OR 1.150, p < 0.0001) were also significant predictors of being pain free (a Barrow Neurological Institute pain intensity score of I–IIIA) at the last follow-up visit. New sensory symptoms of any kind were seen in 98 patients (24.3%) after SRS. Higher maximum radiation dose trended toward predicting new sensory deficits but was nonsignificant (p = 0.075).

CONCLUSIONS

TN patients managed with SRS within 4 years of diagnosis experienced a shorter interval to pain relief with low risk. SRS also yielded significant decreases in adjunct medication utilization. Radiosurgery should be considered earlier in the course of treatment for TN.

Restricted access

Adomas Bunevicius, Mohand Suleiman, Samir Patel, Roberto Martínez Álvarez, Nuria E. Martinez Moreno, Roman Liscak, Jaromir Hanuska, Anne-Marie Langlois, David Mathieu, Christine Mau, Catherine Caldwell, Leonard C. Tuanquin, Brad E. Zacharia, James McInerney, Cheng-Chia Lee, Huai-Che Yang, Jennifer L. Peterson, Daniel M. Trifiletti, Akiyoshi Ogino, Hideyuki Kano, Ronald E. Warnick, Anissa Saylany, Love Y. Buch, John Y. K. Lee, Ben A. Strickland, Gabriel Zada, Eric L. Chang, L. Dade Lunsford, and Jason Sheehan

OBJECTIVE

Radiation-induced meningiomas (RIMs) are associated with aggressive clinical behavior. Stereotactic radiosurgery (SRS) is sometimes considered for selected RIMs. The authors investigated the effectiveness and safety of SRS for the management of RIMs.

METHODS

From 12 institutions participating in the International Radiosurgery Research Foundation, the authors pooled patients who had prior cranial irradiation and were subsequently clinically diagnosed with WHO grade I meningiomas that were managed with SRS.

RESULTS

Fifty-two patients underwent 60 SRS procedures for histologically confirmed or radiologically suspected WHO grade I RIMs. The median ages at initial cranial radiation therapy and SRS for RIM were 5.5 years and 39 years, respectively. The most common reasons for cranial radiation therapy were leukemia (21%) and medulloblastoma (17%). There were 39 multiple RIMs (35%), the mean target volume was 8.61 ± 7.80 cm3, and the median prescription dose was 14 Gy. The median imaging follow-up duration was 48 months (range 4–195 months). RIM progressed in 9 patients (17%) at a median duration of 30 months (range 3–45 months) after SRS. Progression-free survival at 5 years post-SRS was 83%. Treatment volume ≥ 5 cm3 predicted progression (HR 8.226, 95% CI 1.028–65.857, p = 0.047). Seven patients (14%) developed new neurological symptoms or experienced SRS-related complications or T2 signal change from 1 to 72 months after SRS.

CONCLUSIONS

SRS is associated with durable local control of RIMs in the majority of patients and has an acceptable safety profile. SRS can be considered for patients and tumors that are deemed suboptimal, poor surgical candidates, and those whose tumor again progresses after removal.

Restricted access

I. Jonathan Pomeraniec, Zhiyuan Xu, Cheng-Chia Lee, Huai-Che Yang, Tomas Chytka, Roman Liscak, Roberto Martinez-Alvarez, Nuria Martinez-Moreno, Luca Attuati, Piero Picozzi, Douglas Kondziolka, Monica Mureb, Kenneth Bernstein, David Mathieu, Michel Maillet, Akiyoshi Ogino, Hao Long, Hideyuki Kano, L. Dade Lunsford, Brad E. Zacharia, Christine Mau, Leonard C. Tuanquin, Christopher Cifarelli, David Arsanious, Joshua Hack, Ronald E. Warnick, Ben A. Strickland, Gabriel Zada, Eric L. Chang, Herwin Speckter, Samir Patel, Dale Ding, Darrah Sheehan, Kimball Sheehan, Svetlana Kvint, Love Y. Buch, Alexander R. Haber, Jacob Shteinhart, Mary Lee Vance, and Jason P. Sheehan

OBJECTIVE

Stereotactic radiosurgery (SRS) provides a safe and effective therapeutic modality for patients with pituitary adenomas. The mechanism of delayed endocrine deficits based on targeted radiation to the hypothalamic-pituitary axis remains unclear. Radiation to normal neuroendocrine structures likely plays a role in delayed hypopituitarism after SRS. In this multicenter study by the International Radiosurgery Research Foundation (IRRF), the authors aimed to evaluate radiation tolerance of structures surrounding pituitary adenomas and identify predictors of delayed hypopituitarism after SRS for these tumors.

METHODS

This is a retrospective review of patients with pituitary adenomas who underwent single-fraction SRS from 1997 to 2019 at 16 institutions within the IRRF. Dosimetric point measurements of 14 predefined neuroanatomical structures along the hypothalamus, pituitary stalk, and normal pituitary gland were made. Statistical analyses were performed to determine the impact of doses to critical structures on clinical, radiographic, and endocrine outcomes.

RESULTS

The study cohort comprised 521 pituitary adenomas treated with SRS. Tumor control was achieved in 93.9% of patients over a median follow-up period of 60.1 months, and 22.5% of patients developed new loss of pituitary function with a median treatment volume of 3.2 cm3. Median maximal radiosurgical doses to the hypothalamus, pituitary stalk, and normal pituitary gland were 1.4, 7.2, and 11.3 Gy, respectively. Nonfunctioning adenoma status, younger age, higher margin dose, and higher doses to the pituitary stalk and normal pituitary gland were independent predictors of new or worsening hypopituitarism. Neither the dose to the hypothalamus nor the ratio between doses to the pituitary stalk and gland were significant predictors. The threshold of the median dose to the pituitary stalk for new endocrinopathy was 10.7 Gy in a single fraction (OR 1.77, 95% CI 1.17–2.68, p = 0.006).

CONCLUSIONS

SRS for the treatment of pituitary adenomas affords a high tumor control rate with an acceptable risk of new or worsening endocrinopathy. This evaluation of point dosimetry to adjacent neuroanatomical structures revealed that doses to the pituitary stalk, with a threshold of 10.7 Gy, and doses to the normal gland significantly increased the risk of post-SRS hypopituitarism. In patients with preserved pre-SRS neuroendocrine function, limiting the dose to the pituitary stalk and gland while still delivering an optimal dose to the tumor appears prudent.

Restricted access

David T. Asuzu, Adomas Bunevicius, Rithika Kormath Anand, Mohanad Suleiman, Ahmed M. Nabeel, Wael A. Reda, Sameh R. Tawadros, Khaled Abdel Karim, Amr M. N. El-Shehaby, Reem M. Emad Eldin, Tomas Chytka, Roman Liščák, Kimball Sheehan, Darrah Sheehan, Marco Perez Caceres, David Mathieu, Cheng-chia Lee, Huai-che Yang, Piero Picozzi, Andrea Franzini, Luca Attuati, Herwin Speckter, Jeremy Olivo, Samir Patel, Christopher P. Cifarelli, Daniel T. Cifarelli, Joshua D. Hack, Ben A. Strickland, Gabriel Zada, Eric L. Chang, Kareem R. Fakhoury, Chad G. Rusthoven, Ronald E. Warnick, and Jason P. Sheehan

OBJECTIVE

Resection of meningiomas in direct contact with the anterior optic apparatus carries risk of injury to the visual pathway. Stereotactic radiosurgery (SRS) offers a minimally invasive alternative. However, its use is limited owing to the risk of radiation-induced optic neuropathy. Few SRS studies have specifically assessed the risks and benefits of treating meningiomas in direct contact with the optic nerve, chiasm, or optic tract. The authors hypothesized that SRS is safe for select patients with meningiomas in direct contact with the anterior optic apparatus.

METHODS

The authors performed an international multicenter retrospective analysis of 328 patients across 11 institutions. All patients had meningiomas in direct contract with the optic apparatus. Patients were followed for a median duration of 56 months after SRS. Neurological examinations, including visual function evaluations, were performed at follow-up visits. Clinical and treatment variables were collected at each site according to protocol. Tumor volumes were assessed with serial MR imaging. Variables predictive of visual deficit were identified using univariable and multivariable logistic regression.

RESULTS

SRS was the initial treatment modality for 64.6% of patients, and 93% of patients received SRS as a single fraction. Visual information was available for 302 patients. Of these patients, visual decline occurred in 29 patients (9.6%), of whom 12 (41.4%) had evidence of tumor progression. Visual decline in the remaining 17 patients (5.6%) was not associated with tumor progression. Pre-SRS Karnofsky Performance Status predicted visual decline in adjusted analysis (adjusted OR 0.9, 95% CI 0.9–1.0, p < 0.01). Follow-up imaging data were available for 322 patients. Of these patients, 294 patients (91.3%) had radiographic evidence of stability or tumor regression at last follow up. Symptom duration was associated with tumor progression in adjusted analysis (adjusted OR 1.01, adjusted 95% CI 1.0–1.02, adjusted p = 0.02).

CONCLUSIONS

In this international multicenter study, the vast majority of patients exhibited tumor control and preservation of visual function when SRS was used to treat meningioma in direct contact with the anterior optic pathways. SRS is a relatively safe treatment modality for select patients with perioptic meningiomas in direct contact with the optic apparatus.