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Vivek Mehta, Joshua Bakhsheshian, Amir H. Dorafshar, and Edward S. Ahn

The authors describe the case of a boy with Muenke syndrome, an autosomal dominant disorder associated with craniosynostosis. The family history was significant for syndromic craniosynostosis in the patient’s maternal grandmother, who died in adulthood after a craniofacial reconstruction. The patient, her grandson, underwent craniofacial reconstruction surgery at the age of 9 months and developed upward transtentorial herniation. Imaging findings revealed remote cerebellar hemorrhage after a large quantity of supratentorial CSF was drained during postoperative Day 1. The clinical course was further complicated by cerebral sinus thrombosis, which was diagnosed after a fourth surgical procedure. Upward transtentorial herniation can occur when a significant increase in intracranial pressure in the posterior fossa causes displacement of the central lobule and superior surfaces of the cerebellum upward through the incisura tentorii. This is a rare but well-documented phenomenon that commonly occurs in the setting of an expansive posterior fossa lesion or excessive supratentorial CSF loss. To help clinicians recognize and prevent this rare but potentially fatal complication, the authors review the postulated mechanisms by which this process may occur.

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Joshua Bakhsheshian, Nader S. Dahdaleh, Shayan Fakurnejad, Justin K. Scheer, and Zachary A. Smith

Object

The overall evidence for nonoperative management of patients with traumatic thoracolumbar burst fractures is unknown. There is no agreement on the optimal method of conservative treatment. Recent randomized controlled trials that have compared nonoperative to operative treatment of thoracolumbar burst fractures without neurological deficits yielded conflicting results. By assessing the level of evidence on conservative management through validated methodologies, clinicians can assess the availability of critically appraised literature. The purpose of this study was to examine the level of evidence for the use of conservative management in traumatic thoracolumbar burst fractures.

Methods

A comprehensive search of the English literature over the past 20 years was conducted using PubMed (MEDLINE). The inclusion criteria consisted of burst fractures resulting from a traumatic mechanism, and fractures of the thoracic or lumbar spine. The exclusion criteria consisted of osteoporotic burst fractures, pathological burst fractures, and fractures located in the cervical spine. Of the studies meeting the inclusion/exclusion criteria, any study in which nonoperative treatment was used was included in this review.

Results

One thousand ninety-eight abstracts were reviewed and 447 papers met inclusion/exclusion criteria, of which 45 were included in this review. In total, there were 2 Level-I, 7 Level-II, 9 Level-III, 25 Level-IV, and 2 Level-V studies. Of the 45 studies, 16 investigated conservative management techniques, 20 studies compared operative to nonoperative treatments, and 9 papers investigated the prognosis of conservative management.

Conclusions

There are 9 high-level studies (Levels I–II) that have investigated the conservative management of traumatic thoracolumbar burst fractures. In neurologically intact patients, there is no superior conservative management technique over another as supported by a high level of evidence. The conservative technique can be based on patient and surgeon preference, comfort, and access to resources. A high level of evidence demonstrated similar functional outcomes with conservative management when compared with open surgical operative management in patients who were neurologically intact. The presence of a neurological deficit is not an absolute contraindication for conservative treatment as supported by a high level of evidence. However, the majority of the literature excluded patients with neurological deficits. More evidence is needed to further classify the appropriate burst fractures for conservative management to decrease variables that may impact the prognosis.

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Martin H. Pham, Joshua Bakhsheshian, Patrick C. Reid, Ian A. Buchanan, Vance L. Fredrickson, and John C. Liu

OBJECTIVE

Freehand placement of C2 instrumentation is technically challenging and has a learning curve due the unique anatomy of the region. This study evaluated the accuracy of C2 pedicle screws placed via the freehand technique by neurosurgical resident trainees.

METHODS

The authors retrospectively reviewed all patients treated at the LAC+USC Medical Center undergoing C2 pedicle screw placement in which the freehand technique was used over a 1-year period, from June 2016 to June 2017; all procedures were performed by neurosurgical residents. Measurements of C2 were obtained from preoperative CT scans, and breach rates were determined from coronal reconstructions on postoperative scans. Severity of breaches reflected the percentage of screw diameter beyond the cortical edge (I = < 25%; II = 26%–50%; III = 51%–75%; IV = 76%–100%).

RESULTS

Neurosurgical residents placed 40 C2 pedicle screws in 24 consecutively treated patients. All screws were placed by or under the guidance of Pham, who is a postgraduate year 7 (PGY-7) neurosurgical resident with attending staff privileges, with a PGY-2 to PGY-4 resident assistant. The authors found an average axial pedicle diameter of 5.8 mm, axial angle of 43.1°, sagittal angle of 23.0°, spinal canal diameter of 25.1 mm, and axial transverse foramen diameter of 5.9 mm. There were 17 screws placed by PGY-2 residents, 7 screws placed by PGY-4 residents, and 16 screws placed by the PGY-7 resident. The average screw length was 26.0 mm, with a screw diameter of 3.5 mm or 4.0 mm. There were 7 total breaches (17.5%), of which 4 were superior (10.0%) and 3 were lateral (7.5%). There were no medial breaches. The breaches were classified as grade I in 3 cases (42.9%), II in 3 cases (42.9%), III in 1 case (14.3%), and IV in no cases. There were 3 breaches that occurred via placement by a PGY-2 resident, 3 breaches by a PGY-4 resident, and 1 breach by the PGY-7 resident. There were no clinical sequelae due to these breaches.

CONCLUSIONS

Freehand placement of C2 pedicle screws can be done safely by neurosurgical residents in early training. When breaches occurred, they tended to be superior in location and related to screw length choice, and no breaches were found to be clinically significant. Controlled exposure to this unique anatomy is especially pertinent in the era of work-hour restrictions.

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Ilya Lekht, Noah Brauner, Joshua Bakhsheshian, Ki-Eun Chang, Mittul Gulati, Mark S. Shiroishi, Edward G. Grant, Eisha Christian, and Gabriel Zada

OBJECTIVE

Intraoperative contrast-enhanced ultrasound (iCEUS) offers dynamic imaging and provides functional data in real time. However, no standardized protocols or validated quantitative data exist to guide its routine use in neurosurgery. The authors aimed to provide further clinical data on the versatile application of iCEUS through a technical note and illustrative case series.

METHODS

Five patients undergoing craniotomies for suspected tumors were included. iCEUS was performed using a contrast agent composed of lipid shell microspheres enclosing perflutren (octafluoropropane) gas. Perfusion data were acquired through a time-intensity curve analysis protocol obtained using iCEUS prior to biopsy and/or resection of all lesions.

RESULTS

Three primary tumors (gemistocytic astrocytoma, glioblastoma multiforme, and meningioma), 1 metastatic lesion (melanoma), and 1 tumefactive demyelinating lesion (multiple sclerosis) were assessed using real-time iCEUS. No intraoperative complications occurred following multiple administrations of contrast agent in all cases. In all neoplastic cases, iCEUS replicated enhancement patterns observed on preoperative Gd-enhanced MRI, facilitated safe tumor debulking by differentiating neoplastic tissue from normal brain parenchyma, and helped identify arterial feeders and draining veins in and around the surgical cavity. Intraoperative CEUS was also useful in guiding a successful intraoperative needle biopsy of a cerebellar tumefactive demyelinating lesion obtained during real-time perfusion analysis.

CONCLUSIONS

Intraoperative CEUS has potential for safe, real-time, dynamic contrast-based imaging for routine use in neurooncological surgery and image-guided biopsy. Intraoperative CEUS eliminates the effect of anatomical distortions associated with standard neuronavigation and provides quantitative perfusion data in real time, which may hold major implications for intraoperative diagnosis, tissue differentiation, and quantification of extent of resection. Further prospective studies will help standardize the role of iCEUS in neurosurgery.

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Ben A. Strickland, Robert C. Rennert, Joshua Bakhsheshian, Sebina Bulic, Adrian J. Correa, Arun Amar, Joseph Carey, and Jonathan J. Russin

Surgical revascularization continues to play an important role in the management of complex intracranial aneurysms and ischemic cerebrovascular disease. Graft spasm is a common complication of bypass procedures and can result in ischemia or graft thrombosis. The authors here report on the first clinical use of botulinum toxin to prevent graft spasm following extracranial-intracranial (EC-IC) bypass. This technique was used in 3 EC-IC bypass surgeries, 2 for symptomatic carotid artery occlusions and 1 for a ruptured basilar tip aneurysm. In all 3 cases, the harvested graft was treated ex vivo with botulinum toxin before the anastomosis was performed. Post-bypass vascular imaging demonstrated patency and the absence of spasm in all grafts. Histopathological analyses of treated vessels did not show any immediate endothelial or vessel wall damage. Postoperative angiograms were without graft spasm in all cases. Botulinum toxin may be a reasonable option for preventing graft spasm and maintaining patency in cerebral revascularization procedures.

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Kristine Ravina, Ben A. Strickland, Robert C. Rennert, Vance Fredrickson, Joshua Bakhsheshian, Mark Chien, William Mack, Arun Amar, and Jonathan J. Russin

Fusiform aneurysms of the vertebral artery (VA) involving the posterior inferior cerebellar artery (PICA) origin are uncommon and challenging. The anterior spinal artery (ASA) commonly originates from a unilateral ramus just distal to the PICA. Occlusion of an unpaired ASA can result in bilateral medial medullary syndrome. The authors propose a treatment paradigm for ASA preservation based on the artery’s proximity to fusiform VA aneurysms, and they present 3 representative cases. In the first case, they performed a V3-PICA bypass using an interposition graft and then performed endovascular coil embolization of the parent VA. A complete occlusion of the aneurysm and VA was complicated by ASA thrombosis. The subsequent cases were treated with PICA-PICA bypass and subsequent endovascular embolization of the VA. Filling of the sole angiographic ASA remote from the aneurysm was preserved in both cases. The anatomy of the ASA is the most critical determinant of treatment recommendations for fusiform VA aneurysms involving PICA. When the ASA originates from the aneurysm, proximal occlusion with or without a PICA bypass is suggested. In cases in which the ASA is removed from the aneurysm, the authors recommend revascularization followed by endovascular sacrifice. When the aneurysm is immediately adjacent to the ASA, revascularization and open trapping should be considered.

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Shane Shahrestani, Ben A. Strickland, Joshua Bakhsheshian, William J. Mack, Arthur W. Toga, Nerses Sanossian, Yu-Chong Tai, and Gabriel Zada

OBJECTIVE

Spontaneous intracerebral hemorrhage occurs in an estimated 10% of stroke patients, with high rates of associated mortality. Portable diagnostic technologies that can quickly and noninvasively detect hemorrhagic stroke may prevent unnecessary delay in patient care and help rapidly triage patients with ischemic versus hemorrhagic stroke. As such, the authors aimed to develop a rapid and portable eddy current damping (ECD) hemorrhagic stroke sensor for proposed in-field diagnosis of hemorrhagic stroke.

METHODS

A tricoil ECD sensor with microtesla-level magnetic field strengths was constructed. Sixteen gelatin brain models with identical electrical properties to live brain tissue were developed and placed within phantom skull replicas, and saline was diluted to the conductivity of blood and placed within the brain to simulate a hemorrhage. The ECD sensor was used to detect modeled hemorrhages on benchtop models. Data were saved and plotted as a filtered heatmap to represent the lesion location. The individuals performing the scanning were blinded to the bleed location, and sensors were tangentially rotated around the skull models to localize blood. Data were also used to create heatmap images using MATLAB software.

RESULTS

The sensor was portable (11.4-cm maximum diameter), compact, and cost roughly $100 to manufacture. Scanning time was 2.43 minutes, and heatmap images of the lesion were produced in near real time. The ECD sensor accurately predicted the location of a modeled hemorrhage in all (n = 16) benchtop experiments with excellent spatial resolution.

CONCLUSIONS

Benchtop experiments demonstrated the proof of concept of the ECD sensor for rapid transcranial hemorrhagic stroke diagnosis. Future studies with live human participants are warranted to fully establish the feasibility findings derived from this study.

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Ben A. Strickland, Joshua Lucas, Brianna Harris, Edwin Kulubya, Joshua Bakhsheshian, Charles Liu, Bozena Wrobel, John D. Carmichael, Martin Weiss, and Gabriel Zada

OBJECTIVE

Cerebrospinal fluid (CSF) rhinorrhea is among the most common complications following transsphenoidal surgery for sellar region lesions. The aim of this study was to review the authors’ institutional experience in identifying, repairing, and treating CSF leaks associated with direct endonasal transsphenoidal operations.

METHODS

The authors performed a retrospective review of cases involving surgical treatment of pituitary adenomas and other sellar lesions at the University of Southern California between December 1995 and March 2016. Inclusion criteria included all pathology of the sellar region approached via a direct microscopic or endoscopic endonasal transsphenoidal approach. Demographics, pathology, intraoperative and postoperative CSF leak rates, and other complications were recorded and analyzed. A literature review of the incidence of CSF leaks associated with the direct endonasal transsphenoidal approach to pituitary lesions was conducted.

RESULTS

A total of 1002 patients met the inclusion criteria and their cases were subsequently analyzed. Preoperative diagnoses included pituitary adenomas in 855 cases (85.4%), Rathke’s cleft cyst in 94 (9.4%), and other sellar lesions in 53 (5.2%). Lesions with a diameter ≥ 1 cm made up 49% of the series. Intraoperative repair of an identified CSF leak was performed in 375 cases (37.4%) using autologous fat, fascia, or both. An additional 92 patients (9.2%) underwent empirical sellar reconstruction without evidence of an intraoperative CSF leak. Postoperative CSF leaks developed in 26 patients (2.6%), including 13 (1.3% of the overall group) in whom no intraoperative leak was identified. Among the 26 patients who developed a postoperative CSF leak, 13 were noted to have intraoperative leak and underwent sellar repair while the remaining 13 did not have an intraoperative leak or sellar repair. No patients who underwent empirical sellar repair without an intraoperative leak developed a postoperative leak. Eight patients underwent additional surgery (0.8% reoperation rate) for CSF leak repair, and 18 were successfully treated with lumbar drainage or lumbar puncture alone. The incidence of postoperative CSF rhinorrhea in this series was compared with that in 11 other reported series that met inclusion criteria, with incidence rates ranging between 0.6% and 12.1%.

CONCLUSIONS

In this large series, half of the patients who developed postoperative CSF rhinorrhea had no evidence of intraoperative CSF leakage. Unidentified intraoperative CSF leaks and/or delayed development of CSF fistulas are equally important sources of postoperative CSF rhinorrhea as the lack of employing effective CSF leak repair methods. Empirical sellar reconstruction in the absence of an intraoperative CSF leak may be of benefit following resection of large tumors, especially if the arachnoid is thinned out and herniates into the sella.

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Eisha A. Christian, Joshua Bakhsheshian, Ben A. Strickland, Vance L. Fredrickson, Ian A. Buchanan, Martin H. Pham, Andrew Cervantes, Michael Minneti, Bozena B. Wrobel, Steven Giannotta, and Gabriel Zada

OBJECTIVE

Competency in endoscopic endonasal approaches (EEAs) to repair high-flow cerebrospinal fluid (CSF) leaks is an essential component of the neurosurgical training process. The objective of this study was to demonstrate the feasibility of a simulation model for EEA repair of anterior skull base CSF leaks.

METHODS

Human cadaveric specimens were utilized with a perfusion system to simulate a high-flow CSF leak. Neurological surgery residents (postgraduate year 3 or greater) performed a standard EEA to repair a CSF leak using a combination of fat, fascia lata, and pedicled nasoseptal flaps. A standardized 5-point Likert questionnaire was used to assess the knowledge gained, techniques learned, degree of safety, benefit of CSF perfusion during repair, and pre- and posttraining confidence scores.

RESULTS

Intrathecal perfusion of fluorescein-infused saline into the ventricular/subarachnoid space was successful in 9 of 9 cases. The addition of CSF reconstitution offered the residents visual feedback for confirmation of intraoperative CSF leak repair. Residents gained new knowledge and a realistic simulation experience by rehearsing the psychomotor skills and techniques required to repair a CSF leak with fat and fascial grafts, as well as to prepare and rotate vascularized nasoseptal flaps. All trainees reported feeling safer with the procedure in a clinical setting and higher average posttraining confidence scores (pretraining 2.22 ± 0.83, posttraining 4.22 ± 0.44, p < 0.001).

CONCLUSIONS

Perfusion-based human cadaveric models can be utilized as a simulation training model for repairing CSF leaks during EEA.

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Shane Shahrestani, Nolan J. Brown, Tasha S. Nasrollahi, Ben A. Strickland, Joshua Bakhsheshian, Jacob J. Ruzevick, Ilaria Bove, Ariel Lee, Ugochi A. Emeh, John D. Carmichael, and Gabriel Zada

OBJECTIVE

Although pituitary adenomas (PAs) are common intracranial tumors, literature evaluating the utility of comorbidity indices for predicting postoperative complications in patients undergoing pituitary surgery remains limited, thereby hindering the development of complex models that aim to identify high-risk patient populations. We utilized comparative modeling strategies to evaluate the predictive validity of various comorbidity indices and combinations thereof in predicting key pituitary surgery outcomes.

METHODS

The Nationwide Readmissions Database was used to identify patients who underwent pituitary tumor operations (n = 19,653) in 2016–2017. Patient frailty was assessed using the Johns Hopkins Adjusted Clinical Groups (ACG) System. The Charlson Comorbidity Index (CCI) and Elixhauser Comorbidity Index (ECI) were calculated for each patient. Five sets of generalized linear mixed-effects models were developed, using as the primary predictors 1) frailty, 2) CCI, 3) ECI, 4) frailty + CCI, or 5) frailty + ECI. Complications of interest investigated included inpatient mortality, nonroutine discharge (e.g., to locations other than home), length of stay (LOS) within the top quartile (Q1), cost within Q1, and 1-year readmission rates.

RESULTS

Postoperative mortality occurred in 73 patients (0.4%), 1-year readmission was reported in 2994 patients (15.2%), and nonroutine discharge occurred in 2176 patients (11.1%). The mean adjusted all-payer cost for the procedure was USD $25,553.85 ± $26,518.91 (Q1 $28,261.20), and the mean LOS was 4.8 ± 7.4 days (Q1 5.0 days). The model using frailty + ECI as the primary predictor consistently outperformed other models, with statistically significant p values as determined by comparing areas under the curve (AUCs) for most complications. For prediction of mortality, however, the frailty + ECI model (AUC 0.831) was not better than the ECI model alone (AUC 0.831; p = 0.95). For prediction of readmission, the frailty + ECI model (AUC 0.617) was not better than the frailty model alone (AUC 0.606; p = 0.10) or the frailty + CCI model (AUC 0.610; p = 0.29).

CONCLUSIONS

This investigation is to the authors’ knowledge the first to implement mixed-effects modeling to study the utility of common comorbidity indices in a large, nationwide cohort of patients undergoing pituitary surgery. Knowledge gained from these models may help neurosurgeons identify high-risk patients who require additional clinical attention or resource utilization prior to surgical planning.