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Garni Barkhoudarian, Julian T. Hoff, and B. Gregory Thompson

✓ Propionibacteria are known to play a part in postneurosurgical infections, primarily those involving ventricular shunts. Nevertheless, little is known about the association between dural allografts and propionibacterium infections.

Two patients underwent craniotomy for supratentorial meningiomas and each received a dural allograft. Both patients subsequently presented with delayed epidural fluid collections several weeks after surgery. Propionibacterium species was cultured in samples from both patients. The allografts were removed and the patients were treated with appropriate antibiotic agents; one patient underwent an interval craniectomy. Both patients demonstrated neuroimaging and clinical improvement after surgery and antiobiotic therapy.

These cases demonstrate the association of propionibacterium infections with dural allografts. Furthermore, in patients with latent and indolent infections, Propionibacterium spp. should be suspected and treated appropriately.

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Brendan Fong, Garni Barkhoudarian, Patrick Pezeshkian, Andrew T. Parsa, Quinton Gopen, and Isaac Yang

Vestibular schwannomas are histopathologically benign tumors arising from the Schwann cell sheath surrounding the vestibular branch of cranial nerve VIII and are related to the NF2 gene and its product merlin. Merlin acts as a tumor suppressor and as a mediator of contact inhibition. Thus, deficiencies in both NF2 genes lead to vestibular schwannoma development. Recently, there have been major advances in our knowledge of the molecular biology of vestibular schwannomas as well as the development of novel therapies for its treatment. In this article the authors comprehensively review the recent advances in the molecular biology and characterization of vestibular schwannomas as well as the development of modern treatments for vestibular schwannoma. For instance, merlin is involved with a number of receptors including the CD44 receptor, EGFR, and signaling pathways, such as the Ras/raf pathway and the canonical Wnt pathway. Recently, merlin was also shown to interact in the nucleus with E3 ubiquitin ligase CRL4DCAF1. A greater understanding of the molecular mechanisms behind vestibular schwannoma tumorigenesis has begun to yield novel therapies. Some authors have shown that Avastin induces regression of progressive schwannomas by over 40% and improves hearing. An inhibitor of VEGF synthesis, PTC299, is currently in Phase II trials as a potential agent to treat vestibular schwannoma. Furthermore, in vitro studies have shown that trastuzumab (an ERBB2 inhibitor) reduces vestibular schwannoma cell proliferation. With further research it may be possible to significantly reduce morbidity and mortality rates by decreasing tumor burden, tumor volume, hearing loss, and cranial nerve deficits seen in vestibular schwannomas.

Open access

Michael B. Avery, Regin Jay Mallari, Garni Barkhoudarian, and Daniel F. Kelly

OBJECTIVE

The authors’ objective was to compare the indications, outcomes, and anatomical limits of supraorbital (SO) and mini-pterional (MP) craniotomies in patients with intra- and extraaxial brain tumors, and to assess approach selection, utility of endoscopy, and surgical field overlap.

METHODS

A retrospective analysis was conducted of all brain tumor patients who underwent an SO or MP approach. The analyzed characteristics included pathology, endoscopy use, extent of resection, length of stay (LOS), and complications. On the basis of preoperative MRI data, tumor heatmaps were constructed to compare surgical access provided by both routes, including coronal projection heatmaps for parasellar tumors.

RESULTS

From 2007 to 2020, 158 patients underwent 173 (84.8%) SO craniotomies and 30 patients underwent 31 (15.2%) MP craniotomies; 71 (34.8%) procedures were reoperations. Of these 204 operations, 110 (63.6%) SO and 21 (67.7%) MP approaches were for extraaxial tumors (meningiomas in 65% and 76.2%, respectively). Gliomas and metastases together represented 84.1% and 70% of intraaxial tumors accessed with SO and MP approaches, respectively. Overall, 56.1% of tumors accessed with the SO approach and 41.9% of those accessed with the MP approach were in the parasellar region. Axial projection heatmaps showed that SO access extended along the entire ipsilateral and medial contralateral anterior cranial fossa, parasellar region, ipsilateral sylvian fissure, medial middle cranial fossa, and anterior midbrain, whereas MP access was limited to the ipsilateral middle cranial fossa, sylvian fissure, lateral parasellar region, and posterior aspect of anterior cranial fossa. Coronal projection heatmaps showed that parasellar access extended further superiorly with the SO approach compared with that of the MP approach. Endoscopy was utilized in 98 (56.6%) SO craniotomies and 7 (22.6%) MP craniotomies, with further tumor resection in 48 (49%) and 5 (71.4%) cases, respectively. Endoscope-assisted tumor removal was clustered in areas that were generally at farther distances from the craniotomy or in angled locations such as the cribriform plate region where microscopic visualization is limited. Gross-total or near-total resection was achieved in 120/173 (69%) SO approaches and 21/31 (68%) MP approaches. Major complications occurred in 11 (6.4%) SO approaches and 1 (3.2%) MP approach (p = 0.49). The median LOS decreased to 2 days in the last 2 years of the study.

CONCLUSIONS

This clinical experience suggests the SO and MP craniotomies are versatile, safe, and complementary approaches for tumors located in the anterior and middle cranial fossae and perisylvian and parasellar regions. The SO route, used in 85% of cases, achieved greater overall reach than the MP route. Both approaches may benefit from expanded visualization with endoscopy.

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Andrew S. Little, Daniel F. Kelly, and Garni Barkhoudarian

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John A. Cowan Jr., Garni Barkhoudarian, Lynda J. S. Yang, and B. Gregory Thompson

✓ The authors present a case in which a posterior communicating artery (PCoA) infundibulum progressed into an aneurysm in a patient with Alagille syndrome (arteriohepatic dysplasia). The 3-mm PCoA infundibulum had been noted on angiography studies obtained 5 years earlier, prior to clip occlusion of a basilar tip aneurysm. Recently, the patient presented to the emergency department with the sudden onset of headache and decreased mental status. A computerized tomography scan of the head with three-dimensional angiography revealed no gross subarachnoid hemorrhage, but did demonstrate a 5-mm PCoA aneurysm. Lumbar puncture demonstrated xanthochromia and a large quantity of red blood cells. The patient underwent open surgery for aneurysm clip occlusion and obtained a good recovery.

This case illustrates the small but growing number of examples of infundibulum progression. It also indicates the need for a close follow up in patients with congenital abnormalities that may pose an increased risk for what has traditionally been considered a benign lesion.

Free access

Andrew Conger, Fan Zhao, Xiaowen Wang, Amalia Eisenberg, Chester Griffiths, Felice Esposito, Ricardo L. Carrau, Garni Barkhoudarian, and Daniel F. Kelly

OBJECTIVE

The authors previously described a graded approach to skull base repair following endonasal microscopic or endoscope-assisted tumor surgery. In this paper they review their experience with skull base reconstruction in the endoscopic era.

METHODS

A retrospective review of a single-institution endonasal endoscopic patient database (April 2010–April 2017) was undertaken. Intraoperative CSF leaks were graded based on size (grade 0 [no leak], 1, 2, or 3), and repair technique was documented across grades. The series was divided into 2 epochs based on implementation of a strict perioperative antibiotic protocol and more liberal use of permanent and/or temporary buttresses; repair failure rates and postoperative meningitis rates were assessed for the 2 epochs and compared.

RESULTS

In total, 551 operations were performed in 509 patients for parasellar pathology, including pituitary adenoma (66%), Rathke’s cleft cyst (7%), meningioma (6%), craniopharyngioma (4%), and other (17%). Extended approaches were used in 41% of cases. There were 9 postoperative CSF leaks (1.6%) and 6 cases of meningitis (1.1%). Postoperative leak rates for all 551 operations by grade 0, 1, 2, and 3 were 0%, 1.9%, 3.1%, and 4.8%, respectively. Fat grafts were used in 33%, 84%, 97%, and 100% of grade 0, 1, 2, and 3 leaks, respectively. Pedicled mucosal flaps (78 total) were used in 2.6% of grade 0–2 leaks (combined) and 79.5% of grade 3 leaks (60 nasoseptal and 6 middle turbinate flaps). Nasoseptal flap usage was highest for craniopharyngioma operations (80%) and lowest for pituitary adenoma operations (2%). Two (3%) nasoseptal flaps failed. Contributing factors for the 9 repair failures were BMI ≥ 30 (7/9), lack of buttress (4/9), grade 3 leak (4/9), and postoperative vomiting (4/9). Comparison of the epochs showed that grade 1–3 repair failures decreased from 6/143 (4.1%) to 3/141 (2.1%) and grade 1–3 meningitis rates decreased from 5 (3.5%) to 1 (0.7%) (p = 0.08). Prophylactic lumbar CSF drainage was used in only 4 cases (< 1%), was associated with a higher meningitis rate in grades 1–3 (25% vs 2%), and was discontinued in 2012. Comparison of the 2 epochs showed increase buttress use in the second, with use of a permanent buttress in grade 1 and 3 leaks increasing from 13% to 55% and 32% to 76%, respectively (p < 0.001), and use of autologous septal/keel bone as a permanent buttress in grade 1, 2, and 3 leaks increasing from 15% to 51% (p < 0.001).

CONCLUSIONS

A graded approach to skull base repair after endonasal surgery remains valid in the endoscopic era. However, the technique has evolved significantly, with further reduction of postoperative CSF leak rates. These data suggest that buttresses are beneficial for repair of most grade 1 and 2 leaks and all grade 3 leaks. Similarly, pedicled flaps appear advantageous for grade 3 leaks, while CSF diversion may be unnecessary and a risk factor for meningitis. High BMI should prompt an aggressive multilayered repair strategy. Achieving repair failure and meningitis rates lower than 1% is a reasonable goal in endoscopic skull base tumor surgery.

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Charles H. Cho, Garni Barkhoudarian, Liangge Hsu, Wenya Linda Bi, Amir A. Zamani, and Edward R. Laws

Object

Identification of the normal pituitary gland is an important component of presurgical planning, defining many aspects of the surgical approach and facilitating normal gland preservation. Magnetic resonance imaging is a proven imaging modality for optimal soft-tissue contrast discrimination in the brain. This study is designed to validate the accuracy of localization of the normal pituitary gland with MRI in a cohort of surgical patients with pituitary mass lesions, and to evaluate for correlation between presurgical pituitary hormone values and pituitary gland characteristics on neuroimaging.

Methods

Fifty-eight consecutive patients with pituitary mass lesions were included in the study. Anterior pituitary hormone levels were measured preoperatively in all patients. Video recordings from the endoscopic or microscopic surgical procedures were available for evaluation in 47 cases. Intraoperative identification of the normal gland was possible in 43 of 58 cases. Retrospective MR images were reviewed in a blinded fashion for the 43 cases, emphasizing the position of the normal gland and the extent of compression and displacement by the lesion.

Results

There was excellent agreement between imaging and surgery in 84% of the cases for normal gland localization, and in 70% for compression or noncompression of the normal gland. There was no consistent correlation between preoperative pituitary dysfunction and pituitary gland localization on imaging, gland identification during surgery, or pituitary gland compression.

Conclusions

Magnetic resonance imaging proved to be accurate in identifying the normal gland in patients with pituitary mass lesions, and was useful for preoperative surgical planning.

Free access

Hasan A. Zaidi, Kenneth De Los Reyes, Garni Barkhoudarian, Zachary N. Litvack, Wenya Linda Bi, Jordina Rincon-Torroella, Srinivasan Mukundan Jr., Ian F. Dunn, and Edward R. Laws Jr.

OBJECTIVE

Endoscopic skull base surgery has become increasingly popular among the skull base surgery community, with improved illumination and angled visualization potentially improving tumor resection rates. Intraoperative MRI (iMRI) is used to detect residual disease during the course of the resection. This study is an investigation of the utility of 3-T iMRI in combination with transnasal endoscopy with regard to gross-total resection (GTR) of pituitary macroadenomas.

METHODS

The authors retrospectively reviewed all endoscopic transsphenoidal operations performed in the Advanced Multimodality Image Guided Operating (AMIGO) suite from November 2011 to December 2014. Inclusion criteria were patients harboring presumed pituitary macroadenomas with optic nerve or chiasmal compression and visual loss, operated on by a single surgeon.

RESULTS

Of the 27 patients who underwent transsphenoidal resection in the AMIGO suite, 20 patients met the inclusion criteria. The endoscope alone, without the use of iMRI, would have correctly predicted extent of resection in 13 (65%) of 20 cases. Gross-total resection was achieved in 12 patients (60%) prior to MRI. Intraoperative MRI helped convert 1 STR and 4 NTRs to GTRs, increasing the number of GTRs from 12 (60%) to 16 (80%).

CONCLUSIONS

Despite advances in visualization provided by the endoscope, the incidence of residual disease can potentially place the patient at risk for additional surgery. The authors found that iMRI can be useful in detecting unexpected residual tumor. The cost-effectiveness of this tool is yet to be determined.

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Jai Deep Thakur, Regin Jay Mallari, Alex Corlin, Samantha Yawitz, Weichao Huang, Amy Eisenberg, Walavan Sivakumar, Howard R. Krauss, Chester Griffiths, Garni Barkhoudarian, and Daniel F. Kelly

OBJECTIVE

Increased lifespan has led to more elderly patients being diagnosed with meningiomas. In this study, the authors sought to analyze and compare patients ≥ 65 years old with those < 65 years old who underwent minimally invasive surgery for meningioma. To address surgical selection criteria, the authors also assessed a cohort of patients managed without surgery.

METHODS

In a retrospective analysis, consecutive patients with meningiomas who underwent minimally invasive (endonasal, supraorbital, minipterional, transfalcine, or retromastoid) and conventional surgical treatment approaches during the period from 2008 to 2019 were dichotomized into those ≥ 65 and those < 65 years old to compare resection rates, endoscopy use, complications, and length of hospital stay (LOS). A comparator meningioma cohort of patients ≥ 65 years old who were observed without surgery during the period from 2015 to 2019 was also analyzed.

RESULTS

Of 291 patients (median age 60 years, 71.5% females, mean follow-up 36 months) undergoing meningioma resection, 118 (40.5%) were aged ≥ 65 years and underwent 126 surgeries, including 20% redo operations, as follows: age 65–69 years, 46 operations; 70–74 years, 40 operations; 75–79 years, 17 operations; and ≥ 80 years, 23 operations. During 2015–2019, of 98 patients referred for meningioma, 67 (68%) had surgery, 1 (1%) had radiosurgery, and 31 (32%) were observed. In the 11-year surgical cohort, comparing 173 patients < 65 years versus 118 patients ≥ 65 years old, there were no significant differences in tumor location, size, or outcomes. Of 126 cases of surgery in 118 elderly patients, the approach was a minimally invasive approach to skull base meningioma (SBM) in 64 cases (51%) as follows: endonasal 18, supraorbital 28, minipterional 6, and retrosigmoid 12. Endoscope-assisted surgery was performed in 59.5% of patients. A conventional approach to SBM was performed in 15 cases (12%) (endoscope-assisted 13.3%), and convexity craniotomy for non–skull base meningioma (NSBM) in 47 cases (37%) (endoscope-assisted 17%). In these three cohorts (minimally invasive SBM, conventional SBM, and NSBM), the gross-total/near-total resection rates were 59.5%, 60%, and 91.5%, respectively, and an improved or stable Karnofsky Performance Status score occurred in 88.6%, 86.7%, and 87.2% of cases, respectively. For these 118 elderly patients, the median LOS was 3 days, and major complications occurred in 10 patients (8%) as follows: stroke 4%, vision decline 3%, systemic complications 0.7%, and wound infection or death 0. Eighty-three percent of patients were discharged home, and readmissions occurred in 5 patients (4%). Meningioma recurrence occurred in 4 patients (3%) and progression in 11 (9%). Multivariate regression analysis showed no significance of American Society of Anesthesiologists physical status score, comorbidities, or age subgroups on outcomes; patients aged ≥ 80 years showed a trend of longer hospitalization.

CONCLUSIONS

This analysis suggests that elderly patients with meningiomas, when carefully selected, generally have excellent surgical outcomes and tumor control. When applied appropriately, use of minimally invasive approaches and endoscopy may be helpful in achieving maximal safe resection, reducing complications, and promoting short hospitalizations. Notably, one-third of our elderly meningioma patients referred for possible surgery from 2015 to 2019 were managed nonoperatively.

Free access

Tyler Lazaro, Visish M. Srinivasan, Maryam Rahman, Ashok Asthagiri, Garni Barkhoudarian, Lola B. Chambless, Peter Kan, Ganesh Rao, Brian V. Nahed, and Akash J. Patel

OBJECTIVE

Neurosurgical education in the US has changed significantly as a consequence of the novel coronavirus (COVID-19) pandemic. Institutional social distancing requirements have resulted in many neurosurgical programs utilizing video conferencing for educational activities. However, it is unclear how or if these practices should continue after the pandemic. The objective of this study was to characterize virtual education in neurosurgery and understand how it should be utilized after COVID-19.

METHODS

A 24-question, 3-part online survey was administered anonymously to all 117 US neurosurgical residency programs from May 15, 2020, to June 15, 2020. Questions pertained to the current use of virtual conferencing, preferences over traditional conferences, and future inclinations. The Likert scale (1 = strongly disagree, 3 = neutral, 5 = strongly agree) was used. Comparisons were calculated using the Mann-Whitney U-test. Statistical significance was set at 0.05.

RESULTS

One-hundred eight responses were recorded. Overall, 38 respondents (35.2%) were attendings and 70 (64.8%) were trainees. Forty-one respondents (38.0%) indicated attending 5–6 conferences per week and 70 (64.8%) attend national virtual conferences. When considering different conference types, there was no overall preference (scores < 3) for virtual conferences over traditional conferences. In regard to future use, respondents strongly agreed that they would continue the practice at some capacity after the pandemic (median score 5). Overall, respondents agreed that virtual conferences would partially replace traditional conferences (median score 4), whereas they strongly disagreed with the complete replacement of traditional conferences (median score 1). The most common choices for the partial replacement of tradition conferences were case conferences (59/108, 55%) and board preparation (64/108, 59%). Lastly, there was a significant difference in scores for continued use of virtual conferencing in those who attend nationally sponsored conferences (median score 5, n = 70) and those who do not (median score 4, n = 38; U = 1762.50, z = 2.97, r = 0.29, p = 0.003).

CONCLUSIONS

Virtual conferences will likely remain an integral part of neurosurgical education after the COVID-19 pandemic has abated. Across the country, residents and faculty report a preference for continued use of virtual conferencing, especially virtual case conferences and board preparation. Some traditional conferences may even be replaced with virtual conferences, in particular those that are more didactic. Furthermore, nationally sponsored virtual conferences have a positive effect on the preferences for continued use of virtual conferences.