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Open access

Introduction. Use of the exoscope in neurosurgery

Constantinos G. Hadjipanayis, Libby K. Infinger, Martin Lehecka, Gustavo Pradilla, and Gabriel Zada

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Effect of cerebral arteriovenous malformation location on outcomes of repeat, single-fraction stereotactic radiosurgery: a matched-cohort analysis

Georgios Mantziaris, Stylianos Pikis, Chloe Dumot, Sam Dayawansa, Roman Liscak, Jaromir May, Cheng-Chia Lee, Huai-Che Yang, Nuria Martínez Moreno, Roberto Martinez Álvarez, L. Dade Lunsford, Ajay Niranjan, Zhishuo Wei, Priyanka Srinivasan, Lilly W. Tang, Ahmed M. Nabeel, Wael A. Reda, Sameh R. Tawadros, Khaled Abdel Karim, Amr M. N. El-Shehaby, Reem M. Emad Eldin, Ahmed Hesham Elazzazi, Selcuk Peker, Yavuz Samanci, Varun Padmanaban, Francis J. Jareczek, James McInerney, Kevin M. Cockroft, David Mathieu, Salman Aldakhil, Juan Diego Alzate, Douglas Kondziolka, Manjul Tripathi, Joshua D. Palmer, Rituraj Upadhyay, Michelle Lin, Gabriel Zada, Cheng Yu, Christopher P. Cifarelli, Daniel T. Cifarelli, Ahmed Shaaban, Zhiyuan Xu, and Jason P. Sheehan

OBJECTIVE

Patients with deep-seated arteriovenous malformations (AVMs) have a higher rate of unfavorable outcome and lower rate of nidus obliteration after primary stereotactic radiosurgery (SRS). The aim of this study was to evaluate and quantify the effect of AVM location on repeat SRS outcomes.

METHODS

This retrospective, multicenter study involved 505 AVM patients managed with repeat, single-session SRS. The endpoints were nidus obliteration, hemorrhage in the latency period, radiation-induced changes (RICs), and favorable outcome. Patients were split on the basis of AVM location into the deep (brainstem, basal ganglia, thalamus, deep cerebellum, and corpus callosum) and superficial cohorts. The cohorts were matched 1:1 on the basis of the covariate balancing score for volume, eloquence of location, and prescription dose.

RESULTS

After matching, 149 patients remained in each cohort. The 5-year cumulative probability rates for favorable outcome (probability difference −18%, 95% CI −30.9 to −5.8%, p = 0.004) and AVM obliteration (probability difference –18%, 95% CI –30.1% to −6.4%, p = 0.007) were significantly lower in the deep AVM cohort. No significant differences were observed in the 5-year cumulative probability rates for hemorrhage (probability difference 3%, 95% CI –2.4% to 8.5%, p = 0.28) or RICs (probability difference 1%, 95% CI –10.6% to 11.7%, p = 0.92). The median time to delayed cyst formation was longer with deep-seated AVMs (deep 62 months vs superficial 12 months, p = 0.047).

CONCLUSIONS

AVMs located in deep regions had significantly lower favorable outcomes and obliteration rates compared with superficial lesions after repeat SRS. Although the rates of hemorrhage in the latency period and RICs in the two cohorts were comparable, delayed cyst formation occurred later in patients with deep-seated AVMs.

Open access

Tumor characteristics guiding selection of channel-based versus open microscopic approaches for resection of atrial intraventricular meningiomas: patient series

Jeffrey J Feng, Stephanie K Cheok, Mark S Shiroishi, and Gabriel Zada

BACKGROUND

Atrial intraventricular meningiomas (AIMs) are relatively rare and typically deep-seated tumors that can mandate resection. Compared with transsulcal or transcortical open microscopic approaches, port- or channel-based exoscopic approaches have facilitated a less invasive alternative of tumor access and resection. The authors present a case series of seven patients with AIMs who underwent open microscopic versus channel-based exoscopic resection by a senior neurosurgeon at their institution between 2012 and 2022 to understand patient and tumor features that lent themselves to selection of a particular approach.

OBSERVATIONS

In the patients harboring three AIMs selected for channel-based resection, the average AIM diameter (2.9 vs 5.2 cm) was smaller, the AIMs were deeper from the cortical surface (2.5 vs 1.1 cm), and the patients had a shorter average postoperative length of stay (3.3 vs 5.8 days) compared with the four patients who underwent open resection. Gross-total resection was achieved in all cases. Complications for both groups included transient homonymous hemianopsia and aphasia. No recurrences were identified over the follow-up period.

LESSONS

The authors demonstrate that channel-based exoscopic resection is safe and effective for AIMs 3 cm in diameter and over 2 cm deep. This may help guide neurosurgeons in future approach selection based on tumor features, including size/volume, location, and depth from cortical surface.

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Management of growth hormone–secreting pituitary adenomas causing acromegaly: a practical review of surgical and multimodal management strategies for neurosurgeons

Stephanie K. Cheok, John D. Carmichael, and Gabriel Zada

This review aimed to highlight the history, diagnostic criteria, preoperative prognostic factors, surgical management, and multimodal adjuvant therapies recommended to provide a comprehensive and multifaceted understanding of and clinical approach to treating growth hormone–secreting pituitary adenomas (GHPAs) in patients with acromegaly. The authors collated and reviewed published studies, many written by skull base neurosurgeons, endocrinologists, and radiation oncologists with expertise in pituitary adenoma management, to produce a practical and contemporary update pertaining to the optimal management of acromegaly for neurosurgeons. Acromegaly is a debilitating disease for which surgery can be curative in more than two-thirds of patients. Recent rates of hormonal remission by the authors’ group and others following the resection of GHPAs are on the order of 70%–80%, and these increase to more than 85% with the addition of medical therapy in a minority of patients who do not achieve remission with surgery alone. Most tumors are accessible via a direct endoscopic endonasal transsphenoidal approach, which can be augmented with a variety of extended approaches to gain access to suprasellar, clival, and parasellar compartments as needed. Preoperative growth hormone levels, cavernous sinus invasion, and pituitary adenoma consistency are important factors in determining the extent of resection. In most patients with residual or recurrent disease, medical therapy (e.g., somatostatin analogs and dopamine agonists) can be used to help achieve hormonal remission. Repeat surgery can be safely performed in most cases if needed, whereas stereotactic radiosurgery is usually reserved for medically resistant tumors in surgically inaccessible compartments. The neurosurgeon has a primary and often definitive role in the management of acromegaly. The involvement of an integrated and multidisciplinary team consisting of experts from neurosurgery, otolaryngology, endocrinology, and radiation oncology optimizes the chances for a biochemical cure, even in large and aggressive GHPAs.

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Association between county-level socioeconomic status and the incidence of and surgical treatment for pituitary adenoma

David J. Cote, Carol Kruchko, Jill S. Barnholtz-Sloan, Gabriel Zada, Joseph L. Wiemels, and Quinn T. Ostrom

OBJECTIVE

The objective of this study was to evaluate the association between county-level socioeconomic status (SES) and the incidence of and surgical treatment for pituitary adenoma (PA).

METHODS

Using the Centers for Disease Control and Prevention’s National Program of Cancer Registries and the National Cancer Institute’s Surveillance, Epidemiology, and End Results database, the authors identified the average annual age-adjusted incidence rates and calculated odds ratios (ORs) for surgical treatment of PA, stratified by a county-level index for SES, race/ethnicity, metropolitan status, and other confounders.

RESULTS

From 2006 to 2018, 167,121 PA cases were identified. There was no significant trend in the incidence of PA by county-level SES overall (incidence rate ratio [IRR] 0.98, 95% CI 0.96–1.00, p = 0.05, comparing highest to lowest quintile of SES). Among Asian or Pacific Islander (API; IRR 0.82, 95% CI 0.71–0.95, p = 0.007) and American Indian/Alaska Native (AIAN) participants (IRR 0.82, 95% CI 0.71–0.95, p = 0.009), the incidence of PA was statistically significantly lower with higher SES, while among Black individuals, the incidence of PA was higher with higher SES (IRR 1.10, 95% CI 1.05–1.15, p < 0.001, comparing 5th to 1st quintile of SES). Higher SES quintile was associated with surgical treatment of PA (OR 1.04, 95% CI 0.99–1.09, comparing highest to lowest quintile, p value for trend = 0.02). Males were more likely than females to undergo surgery (OR 1.50, 95% CI 1.47–1.53, p < 0.001), and Black (OR 0.89, 95% CI 0.86–0.91, p < 0.001) and AIAN individuals (OR 0.88, 95% CI 0.78–0.99, p = 0.04) were less likely to undergo surgery than White individuals, whereas API individuals were more likely to undergo surgery (OR 1.15, 95% CI 1.09–1.21, p < 0.001).

CONCLUSIONS

Higher county-level SES in the US was associated with a higher incidence of PA among Black individuals, but not among White individuals, while API and AIAN individuals had a lower PA incidence with higher SES. After multivariable adjustment, higher county-level SES was associated with surgical treatment of PA, and White and API individuals were significantly more likely to undergo surgery than Black or AIAN individuals.

Free access

Comparison of preoperative versus postoperative treatment dosimetry plans of single-fraction stereotactic radiosurgery for surgically resected brain metastases

Stephanie K. Cheok, Cheng Yu, Jeffrey J. Feng, Robert G. Briggs, Frances Chow, Lindsay Hwang, Jason C. Ye, Frank J. Attenello, David Tran, Eric Chang, and Gabriel Zada

OBJECTIVE

Stereotactic radiosurgery (SRS) for operative brain metastasis (BrM) is usually administered 1 to 6 weeks after resection. Preoperative versus postoperative timing of SRS delivery related to surgery remains a critical question, as a pattern of failure is the development of leptomeningeal disease (LMD) in as many as 35% of patients who undergo postoperative SRS or the occurrence of radiation necrosis. As they await level I clinical data from ongoing trials, the authors aimed to bridge the gap by comparing postoperative with simulated preoperative single-fraction SRS dosimetry plans for patients with surgically resected BrM.

METHODS

The authors queried their institutional database to retrospectively identify patients who underwent postoperative Gamma Knife SRS (GKSRS) after resection of BrM between January 2014 and January 2021. Exclusion criteria were prior radiation delivered to the lesion, age < 18 years, and prior diagnosis of LMD. Once identified, a simulated preoperative SRS plan was designed to treat the unresected BrM and compared with the standard postoperative treatment delivered to the resection cavity per Radiation Therapy Oncology Group (RTOG) 90–05 guidelines. Numerous comparisons between preoperative and postoperative GKSRS treatment parameters were then made using paired statistical analyses.

RESULTS

The authors’ cohort included 45 patients with a median age of 59 years who were treated with GKSRS after resection of a BrM. Primary cancer origins included colorectal cancer (27%), non–small cell lung cancer (22%), breast cancer (11%), melanoma (11%), and others (29%). The mean tumor and cavity volumes were 15.06 cm3 and 12.61 cm3, respectively. In a paired comparison, there was no significant difference in the planned treatment volumes between the two groups. When the authors compared the volume of surrounding brain that received 12 Gy or more (V12Gy), an important predictor of radiation necrosis, 64% of patient plans in the postoperative SRS group (29/45, p = 0.008) recorded greater V12 volumes. Preoperative plans were more conformal (p < 0.001) and exhibited sharper dose drop-off at the lesion margins (p = 0.0018) when compared with postoperative plans.

CONCLUSIONS

Comparison of simulated preoperative and delivered postoperative SRS plans administered to the BrM or resection cavity suggested that preoperative SRS allows for more highly conformal lesional coverage and sharper dose drop-off compared with postoperative plans. Furthermore, V12Gy was lower in the presurgical GKSRS plans, which may account for the decreased incidence of radiation necrosis seen in prior retrospective studies.

Open access

Endoscopic endonasal approach for MRI–Negative Cushing’s microadenoma

Jeffrey J. Feng, Stephanie K. Cheok, Alexander G. Chartrain, John D. Carmichael, Mark S. Shiroishi, William J. Mack, and Gabriel Zada

A 54-year-old male with a history of diabetes mellitus type 2 for 12 years and hypertension was seen in the clinic due to poorly controlled diabetes. Inferior petrosal sinus sampling (IPSS) confirmed Cushing’s disease with primary adrenocorticotropic hormone (ACTH)–secreting pituitary adenoma on the right. However, 3T and subsequent 7T MRI showed no visible tumor. An endoscopic transsphenoidal approach was selected to explore the pituitary gland and resect the presumed microadenoma. Tumor was identified in the lateral recess along the right medial cavernous sinus wall and gross-total resection (GTR) was performed. The normal pituitary gland was preserved, and the patient went into remission.

The video can be found here: https://stream.cadmore.media/r10.3171/2023.4.FOCVID2324

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ChatGPT versus the neurosurgical written boards: a comparative analysis of artificial intelligence/machine learning performance on neurosurgical board–style questions

Benjamin S. Hopkins, Vincent N. Nguyen, Jonathan Dallas, Pavlos Texakalidis, Max Yang, Alex Renn, Gage Guerra, Zain Kashif, Stephanie Cheok, Gabriel Zada, and William J. Mack

Free access

Adjuvant versus on-progression Gamma Knife radiosurgery for residual nonfunctioning pituitary adenomas: a matched-cohort analysis

Georgios Mantziaris, Stylianos Pikis, Tomas Chytka, Roman Liščák, Kimball Sheehan, Darrah Sheehan, Selcuk Peker, Yavuz Samanci, Shray K. Bindal, Ajay Niranjan, L. Dade Lunsford, Rupinder Kaur, Renu Madan, Manjul Tripathi, Dhiraj J. Pangal, Ben A. Strickland, Gabriel Zada, Anne-Marie Langlois, David Mathieu, Ronald E. Warnick, Samir Patel, Zayda Minier, Herwin Speckter, Zhiyuan Xu, Rithika Kormath Anand, and Jason P. Sheehan

OBJECTIVE

Radiological progression occurs in 50%–60% of residual nonfunctioning pituitary adenomas (NFPAs). Stereotactic radiosurgery (SRS) is a safe and effective management option for residual NFPAs, but there is no consensus on its optimal timing. This study aims to define the optimal timing of SRS for residual NFPAs.

METHODS

This retrospective, multicenter study involved 375 patients with residual NFPAs managed with SRS. The patients were divided into adjuvant (ADJ; treated for stable residual NFPA within 6 months of resection) and progression (PRG) cohorts (treated for residual NFPA progression). Factors associated with tumor progression and clinical deterioration were analyzed.

RESULTS

Following propensity-score matching, each cohort consisted of 130 patients. At last follow-up, tumor control was achieved in 93.1% of patients in the ADJ cohort and in 96.2% of patients in the PRG cohort (HR 1.6, 95% CI 0.55–4.9, p = 0.37). Hypopituitarism was associated with a maximum point dose of > 8 Gy to the pituitary stalk (HR 4.5, 95% CI 1.6–12.6, p = 0.004). No statistically significant difference was noted in crude new-onset hypopituitarism rates (risk difference [RD] = −0.8%, p > 0.99) or visual deficits (RD = −2.3%, p = 0.21) between the two cohorts at the last follow-up. The median time from resection to new hypopituitarism was longer in the PRG cohort (58.9 vs 29.7 months, p = 0.01).

CONCLUSIONS

SRS at residual NFPA progression does not appear to alter the probability of tumor control or hormonal/visual deficits compared with adjuvant SRS. Deferral of radiosurgical management to the time of radiological progression could significantly prolong the time to radiosurgically induced pituitary dysfunction. A lower maximum point dose (< 8 Gy) to the pituitary stalk portended a more favorable chance of preserving pituitary function after SRS.

Free access

From white to blue light: evolution of endoscope-assisted intracranial tumor neurosurgery and expansion to intraaxial tumors

Jacob Ruzevick, Tyler Cardinal, Dhiraj J. Pangal, Ilaria Bove, Ben Strickland, and Gabriel Zada

OBJECTIVE

Intraoperative use of the endoscope to assist in visualization of intracranial tumor pathology has expanded with increasing surgeon experience and improved instrumentation. The authors aimed to study how advancements in endoscopic technology have affected the evolution of endoscope use, with particular focus on blue light–filter modification allowing for discrimination of fluorescent tumor tissue following 5-ALA administration.

METHODS

A retrospective analysis of patients undergoing craniotomy for tumor resection at a single institution between February 2012 and July 2021 was performed. Patients were included if the endoscope was used for diagnostic tumor cavity inspection or therapeutic assistance with tumor resection following standard craniotomy and microsurgical tumor resection, with emphasis on those cases in which blue light endoscopy was used. Medical records were queried for patient demographics, operative reports describing the use of the endoscope and extent of resection, associations with tumor pathology, and postoperative outcomes. Preoperative and postoperative MR images were reviewed for radiographic extent of resection.

RESULTS

A total of 52 patients who underwent endoscope-assisted craniotomy for tumor were included. Thirty patients (57.7%) were men and the average age was 52.6 ± 16.1 years. Standard white light endoscopes were used for assistance with tumor resection in 28 cases (53.8%) for tumors primarily located in the ventricular system, parasellar region, and cerebellopontine angle. A blue light endoscope for detection of 5-ALA fluorescence was introduced into our practice in 2014 and subsequently used for assistance with tumor resection in 24 cases (46.2%) (intraaxial: n = 22, extraaxial: n = 2). Beyond the use of the surgical microscope as the primary visualization source, the blue light endoscope was used to directly perform additional tumor resection in 19/21 cases as a result of improved fluorescence detection as compared to the surgical microscope. No complications were associated with the use of the endoscope or with additional resection performed under white or blue light visualization.

CONCLUSIONS

Endoscopic assistance to visualize intracranial tumors had previously been limited to white light, assisting mostly in the visualization of extraaxial tumors confined to intraventricular and cisternal compartments. Blue light–equipped endoscopes provide improved versatility and visualization of 5-ALA fluorescing tissue beyond the capability of the surgical microscope, thereby expanding its use into the realm of intraaxial tumor resections.