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Benjamin K. Hendricks and Aaron A. Cohen-Gadol

Epidermoid cysts or tumors comprise 1% of intracranial tumors with a predilection for the cerebellopontine angle or parasellar cisterns. These tumors are derived from an ectopic ectodermal implant seeded between fusing ectodermal surfaces. This results in a benign proliferation of stratified squamous epithelium along a cyst wall with a lumen composed of hyperkeratotic material derived from the desquamating cells. Surgical intervention is the treatment of choice for symptomatic patients. There is no role for radiotherapy or chemotherapy in the treatment of these lesions, including for residual or recurrent disease. The inherent adhesion of the proliferating epithelial lining to surrounding neurovascular structures significantly complicates attempts at gross-total resection. Epidermoid tumors or cysts are rarely reported within the third ventricular region. In this video, the authors demonstrate the technique of right-sided posterior interhemispheric transcallosal approach for maximal resection of a complex recurrent third ventricular epidermoid tumor with lateral ventricular extension.

The video can be found here: https://youtu.be/wbXp7mc0vT4.

Open access

Benjamin K. Hendricks and Aaron A. Cohen-Gadol

Surgery within the posterior cranial fossa uniquely requires excellence in microsurgical technique, given the complexity of the neurovascular structures housed within this region. Arteriovenous malformations (AVMs) within this region represent the greatest surgical challenge because of the difficulty in resecting an AVM completely while preserving the highly eloquent surrounding structures. The AVM in this video exemplifies a surgeon’s “most challenging case,” a surgery that spanned two stages, including 14 hours of resection, but concluded with complete resection despite the complexity of deep arterial and dural feeders.

The video can be found here: https://youtu.be/WNBuwFHSrQ0

Free access

Benjamin K. Hendricks, Aaron A. Cohen-Gadol, and James C. Miller

Glioblastoma (GBM) is the most common primary brain tumor and carries a grave prognosis. Despite years of research investigating potentially new therapies for GBM, the median survival rate of individuals with this disease has remained fairly stagnant. Delivery of drugs to the tumor site is hampered by various barriers posed by the GBM pathological process and by the complex physiology of the blood-brain and blood–cerebrospinal fluid barriers. These anatomical and physiological barriers serve as a natural protection for the brain and preserve brain homeostasis, but they also have significantly limited the reach of intraparenchymal treatments in patients with GBM.

In this article, the authors review the functional capabilities of the physical and physiological barriers that impede chemotherapy for GBM, with a specific focus on the pathological alterations of the blood-brain barrier (BBB) in this disease. They also provide an overview of current and future methods for circumventing these barriers in therapeutic interventions. Although ongoing research has yielded some potential options for future GBM therapies, delivery of chemotherapy medications across the BBB remains elusive and has limited the efficacy of these medications.

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Roxanna M. Garcia, Taemin Oh, Tyler S. Cole, Benjamin K. Hendricks, and Michael T. Lawton

OBJECTIVE

Proximity of brainstem cavernous malformations (BSCMs) to tracts and cranial nerve nuclei make it costly to transgress normal tissue in accessing the lesion or disrupting normal tissue adjacent to the lesion in the separation plane. This interplay between tissue sensitivity and extreme eloquence makes it difficult to avoid leaving a remnant on occasion. Recurrences require operative intervention, which may increase morbidity, lengthen recovery, and add to overall costs. An approximately 20-year experience with patients with recurrent BSCM lesions following primary microsurgical resection was reviewed.

METHODS

A prospectively maintained database of 802 patients who underwent microsurgical resection of cerebral cavernous malformations during 1997–2018 was queried to identify 213 patients with BSCMs. A retrospective chart review was conducted for patients with recurrent BSCM after primary resection who required a second surgery.

RESULTS

Fourteen of 213 patients (6.6%) underwent repeat resection for recurrent BSCM. Thirty-four hemorrhagic events were observed among these 14 patients over 576 patient-years (recurrent hemorrhage rate, 5.9% per year; median discrete hemorrhagic events, 2; median time to rehemorrhage, 897 days). BSCM occurred in the pons in 10 cases, midbrain in 2 cases, and medulla in 2 cases. A blind spot in the operative corridor was the most common cause of residual BSCM (9 patients). All recurrent BSCMs were removed completely, although 2 patients each required 2 operations to treat recurrence. Twelve patients had unchanged or improved modified Rankin Scale scores at last clinical evaluation compared with admission, and 2 patients had worse scores. Recurrence was more common among patients who were operated on in the first versus the second half of the series (8.5% vs 4.7%).

CONCLUSIONS

The 6.6% rate of BSCM recurrence requiring reoperation reflects the fine lines between complete resection and recurrence and between safe and harmful surgery. The detection of remnants is difficult postoperatively and remains so even at 6 months when the resection bed has healed. The 5.9% annual hemorrhage risk associated with recurrent BSCM in this experience is consistent with that reported for unoperated BSCMs. The right-angle method helps to anticipate blind spots and meticulously inspect the resection cavity for residual BSCM during surgery. A low percentage of recurrent BSCM (5%–10%) ensures ongoing effort toward an acceptable balance of safety and completeness.

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Colin J. Przybylowski, Benjamin K. Hendricks, Fabio A. Frisoli, Xiaochun Zhao, Claudio Cavallo, Leandro Borba Moreira, Sirin Gandhi, Nader Sanai, Kaith K. Almefty, Michael T. Lawton, and Andrew S. Little

OBJECTIVE

Recently, the prognostic value of the Simpson resection grading scale has been called into question for modern meningioma surgery. In this study, the authors analyzed the relationship between Simpson resection grade and meningioma recurrence in their institutional experience.

METHODS

This study is a retrospective review of all patients who underwent resection of a WHO grade I intracranial meningioma at the authors’ institution from 2007 to 2017. Binary logistic regression analysis was used to assess for predictors of Simpson grade IV resection and postoperative neurological morbidity. Cox multivariate analysis was used to assess for predictors of tumor recurrence. Kaplan-Meier analysis and log-rank tests were used to assess and compare recurrence-free survival (RFS) of Simpson resection grades, respectively.

RESULTS

A total of 492 patients with evaluable data were included for analysis, including 394 women (80.1%) and 98 men (19.9%) with a mean (SD) age of 58.7 (12.8) years. The tumors were most commonly located at the skull base (n = 302; 61.4%) or the convexity/parasagittal region (n = 139; 28.3%). The median (IQR) tumor volume was 6.8 (14.3) cm3. Simpson grade I, II, III, or IV resection was achieved in 105 (21.3%), 155 (31.5%), 52 (10.6%), and 180 (36.6%) patients, respectively. Sixty-three of 180 patients (35.0%) with Simpson grade IV resection were treated with adjuvant radiosurgery. In the multivariate analysis, increasing largest tumor dimension (p < 0.01) and sinus invasion (p < 0.01) predicted Simpson grade IV resection, whereas skull base location predicted neurological morbidity (p = 0.02). Tumor recurrence occurred in 63 patients (12.8%) at a median (IQR) of 36 (40.3) months from surgery. Simpson grade I resection resulted in superior RFS compared with Simpson grade II resection (p = 0.02), Simpson grade III resection (p = 0.01), and Simpson grade IV resection with adjuvant radiosurgery (p = 0.01) or without adjuvant radiosurgery (p < 0.01). In the multivariate analysis, Simpson grade I resection was independently associated with no tumor recurrence (p = 0.04). Simpson grade II and III resections resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01) but similar RFS compared with Simpson grade IV resection with adjuvant radiosurgery (p = 0.82). Simpson grade IV resection with adjuvant radiosurgery resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01).

CONCLUSIONS

The Simpson resection grading scale continues to hold substantial prognostic value in the modern neurosurgical era. When feasible, Simpson grade I resection should remain the goal of intracranial meningioma surgery. Simpson grade IV resection with adjuvant radiosurgery resulted in similar RFS compared with Simpson grade II and III resections.

Free access

Todd J. Wannemuehler, Kolin E. Rubel, Benjamin K. Hendricks, Jonathan Y. Ting, Troy D. Payner, Mitesh V. Shah, and Aaron A. Cohen-Gadol

OBJECTIVE

Craniopharyngiomas have historically been resected via transcranial microsurgery (TCM). In the last 2 decades, the extended endoscopic endonasal (transtuberculum) approach to these tumors has become more widely accepted, yet there remains controversy over which approach leads to better outcomes. The purpose of this study is to determine whether differences in outcomes were identified between TCM and extended endoscopic endonasal approaches (EEEAs) in adult patients undergoing primary resection of suprasellar craniopharyngiomas at a single institution.

METHODS

A retrospective review of all patients who underwent resection of their histopathologically confirmed craniopharyngiomas at the authors' institution between 2005 and 2015 was performed. Pediatric patients, revision cases, and patients with tumors greater than 2 standard deviations above the mean volume were excluded. The patients were divided into 2 groups: those undergoing primary TCM and those undergoing a primary EEEA. Preoperative patient demographics, presenting symptoms, and preoperative tumor volumes were determined. Extent of resection, tumor histological subtype, postoperative complications, and additional outcome data were obtained. Statistical significance between variables was determined utilizing Student t-tests, chi-square tests, and Fisher exact tests when applicable.

RESULTS

After exclusions, 21 patients satisfied the aforementioned inclusion criteria; 12 underwent TCM for resection while 9 benefitted from the EEEA. There were no significant differences in patient demographics, presenting symptoms, tumor subtype, or preoperative tumor volumes; no tumors had significant lateral or prechiasmatic extension. The extent of resection was similar between these 2 groups, as was the necessity for additional surgery or adjuvant therapy. CSF leakage was encountered only in the EEEA group (2 patients). Importantly, the rate of postoperative visual improvement was significantly higher in the EEEA group than in the TCM group (88.9% vs 25.0%; p = 0.0075). Postoperative visual deterioration only occurred in the TCM group (3 patients). Recurrence was uncommon, with similar rates between the groups. Other complication rates, overall complication risk, and additional outcome measures were similar between these groups as well.

CONCLUSIONS

Based on this study, most outcome variables appear to be similar between TCM and EEEA routes for similarly sized tumors in adults. The multidisciplinary EEEA to craniopharyngioma resection represents a safe and compelling alternative to TCM. The authors' data demonstrate that postoperative visual improvement is statistically more likely in the EEEA despite the increased risk of CSF leakage. These results add to the growing evidence that the EEEA may be considered the approach of choice for resection of select confined primary craniopharyngiomas without significant lateral extension in centers with experienced surgeons. Further prospective, multiinstitutional collaboration is needed to power studies capable of fully evaluating indications and appropriate approaches for craniopharyngiomas.

Restricted access

Douglas A. Hardesty, Michael A. Mooney, Benjamin K. Hendricks, Joshua S. Catapano, Scott T. Brigeman, Michael A. Bohl, John P. Sheehy, and Andrew S. Little

OBJECTIVE

Hospital readmission and the reduction thereof has become a major quality improvement initiative in organized medicine and neurosurgery. However, little research has been performed on why neurosurgical patients utilize hospital emergency rooms (ERs) with or without subsequent admission in the postoperative setting.

METHODS

This study was a retrospective, single-center review of data for all surgical cranial procedures performed from July 2013 to July 2016 in patients who survived to discharge. The study was approved by the institutional review board of the participating medical center.

RESULTS

The authors identified 7294 cranial procedures performed during 6596 hospital encounters in 5385 patients. The rate of postoperative ER utilization within 30 days after surgical hospitalization across all procedure types was 13.1 per 100 surgeries performed. The two most common chief complaints were pain (30.7%) and medical complication (18.2%). After identification of relevant surgical and patient factors with univariable analysis, a multivariable backward elimination logistic regression model was constructed in which Ommaya reservoir placement (OR 2.65, p = 0.0008) and cranial CSF shunt placement (OR 1.40, p = 0.0001) were associated with increased ER utilization. Deep brain stimulation electrode placement (OR 0.488, p = 0.0004), increasing hospital length of stay (OR 0.935, p < 0.0001), and increasing patient age (OR 0.988, p < 0.0001) were associated with lower rates of postoperative ER utilization. One-half (50%) of ER visit patients were readmitted to the hospital. New/worsening neurological deficit chief complaint (OR 1.99, p = 0.0088), fever chief complaint (OR 2.41, p = 0.0205), altered mentation chief complaint (OR 2.71, p = 0.0002), patient chronic kidney disease (OR 3.31, p = 0.0037), brain biopsy procedure type (OR 3.50, p = 0.0398), and wound infection chief complaint (OR 31.4, p = 0.0008) were associated with increased rates of readmission to the hospital from the ER in multivariable analysis.

CONCLUSIONS

The authors report the rates of and reasons for ER utilization in a large cohort of postoperative cranial neurosurgical patients. Factors identified were associated with both increased and decreased use of the ER after cranial surgery, as well as variables associated with readmission to the hospital after postoperative ER visitation. These findings may direct future quality improvement via prospective implementation of care pathways for high-risk procedures.

Restricted access

Benjamin K. Hendricks, James S. Yoon, Kurt Yaeger, Christopher P. Kellner, J Mocco, Reade A. De Leacy, Andrew F. Ducruet, Michael T. Lawton, and Justin R. Mascitelli

OBJECTIVE

Wide-necked aneurysms (WNAs) are a variably defined subset of cerebral aneurysms that require more advanced endovascular and microsurgical techniques than those required for narrow-necked aneurysms. The neurosurgical literature includes many definitions of WNAs, and a systematic review has not been performed to identify the most commonly used or optimal definition. The purpose of this systematic review was to highlight the most commonly used definition of WNAs.

METHODS

The authors searched PubMed for the years 1998–2017, using the terms “wide neck aneurysm” and “broad neck aneurysm” to identify relevant articles. All results were screened for having a minimum of 30 patients and for clearly stating a definition of WNA. Reference lists for all articles meeting the inclusion criteria were also screened for eligibility.

RESULTS

The search of the neurosurgical literature identified 809 records, of which 686 were excluded (626 with < 30 patients; 60 for lack of a WNA definition), leaving 123 articles for analysis. Twenty-seven unique definitions were identified and condensed into 14 definitions. The most common definition was neck size ≥ 4 mm or dome-to-neck ratio < 2, which was used in 49 articles (39.8%). The second most commonly used definition was neck size ≥ 4 mm, which was used in 26 articles (21.1%). The rest of the definitions included similar parameters with variable thresholds. There was inconsistent reporting of the precise dome measurements used to determine the dome-to-neck ratio. Digital subtraction angiography was the only imaging modality used to study the aneurysm morphology in 87 of 122 articles (71.3%).

CONCLUSIONS

The literature has great variability regarding the definition of a WNA. The most prevalent definition is a neck diameter of ≥ 4 mm or a dome-to-neck ratio of < 2. Whether this is the most appropriate and clinically useful definition is an area for future study.

Free access

Zoe E. Teton, Rachel S. Freedman, Samuel B. Tomlinson, Joseph R. Linzey, Alvin Onyewuenyi, Anadjeet S. Khahera, Benjamin K. Hendricks, and Aaron A. Cohen-Gadol

OBJECTIVE

The advent of the internet and the popularity of e-learning resources has promoted a shift in medical and surgical education today. The Neurosurgical Atlas has sought to capitalize on this shift by providing easily accessible video and online education to its users on an international scale. The rising popularity of social media has provided new avenues for expanding that global reach, and the Atlas has sought to do just that. In this study, the authors analyzed user demographics and web traffic patterns to quantify the international reach of the Atlas and examined the potential impact of social media platforms on the expansion of that reach.

METHODS

Twitter, Facebook, and Instagram metrics were extracted using each respective service’s analytics tool from the date of their creation through October 2019. Google Analytics was used to extract website traffic data from September 2018 to September 2019 and app data from January 2019 to October 2019. The metrics extracted included the number of platform users/followers, user demographic information, percentage of new versus returning visitors, and a number of platform-specific values.

RESULTS

Since the authors’ previous publication in 2017, annual website viewership has more than doubled to greater than 500,000 viewing sessions in the past year alone; international users accounted for more than 60% of the visits. The Atlas Twitter account, established in August 2012, has more than 12,000 followers, primarily hailing from the United States, the United Kingdom, Canada, and Saudi Arabia. The Atlas Facebook account, established in 2013, has just over 13,000 followers, primarily from India, Egypt, and Mexico. The Atlas Instagram account (established most recently, in December 2018) has more than 16,000 followers and the highest percentage (31%) of younger users (aged 18–24 years). The Atlas app was officially launched in May 2019, largely via promotion on the Atlas social media platforms, and has since recorded more than 60,000 viewing sessions, 80% of which were from users outside the United States.

CONCLUSIONS

The Neurosurgical Atlas has attempted to leverage the many e-learning resources at its disposal to assist in spreading neurosurgical best practice on an international scale in a novel and comprehensive way. By incorporating multiple social media platforms into its repertoire, the Atlas is able to ensure awareness of and access to these resources regardless of the user’s location or platform of preference. In so doing, the Atlas represents a novel way of advancing access to neurosurgical educational resources in the digital age.