From Operating Room to Courtroom: Analyzing Malpractice Trajectories in Cranial Neurosurgery.

BACKGROUND AND OBJECTIVES: Nearly all neurosurgeons in the United States will be named defendants in a malpractice claim before retirement. We perform an assessment of national malpractice trends in cranial neurosurgery to inform neurosurgeons on current outcomes, trends over time, benchmarks for malpractice coverage needs, and ways to mitigate lawsuits. METHODS: The Westlaw Edge and LexisNexis databases were searched to identify medical malpractice cases relating to open cranial surgery between 1987 and 2023. Extracted data included date of verdict, jurisdiction, outcome, details of sustained injuries, and any associated award/settlement figures. RESULTS: Of 1550 cases analyzed, 252 were identified as malpractice claims arising from open cranial surgery. The median settlement amount was $950 000 and the average plaintiff ruling was $2 750 000. The highest plaintiff ruling resulted in an award of $28.1 million. Linear regression revealed no significant relationship between year and defendant win (P-value = .43). After adjusting for inflation, award value increased with time (P-value = .01). The most common cranial subspecialties were tumor (67 cases, 26.6%), vascular (54 cases, 21.4%), infection (23 cases, 9.1%), and trauma (23 cases, 9.1%). Perioperative complications was the most common litigation category (96 cases, 38.1%), followed by delayed treatment (40 cases, 15.9%), failure to diagnose (38 cases, 15.1%), and incorrect choice of procedure (29 cases, 11.5%). The states with most claims were New York (40 cases, 15.9%), California (24 cases, 9.5%), Florida (21 cases, 8.3%), and Pennsylvania (20 cases, 7.9%). CONCLUSION: Although a stable number of cases were won by neurosurgeons, an increase in award sizes was observed in the 37-year period assessed. Perioperative complications and delayed treatment/diagnosis were key drivers of malpractice claims.

Pilot trial of perampanel on peritumoral hyperexcitability and clinical outcomes in newly diagnosed high-grade glioma.

Background: Glutamatergic neuron-glioma synaptogenesis and peritumoral hyperexcitability promote glioma growth in a positive feedback loop. The objective of this study was to evaluate the feasibility and estimated effect sizes of the AMPA-R antagonist, perampanel, on intraoperative electrophysiologic hyperexcitability and clinical outcomes. Methods: An open-label trial was performed comparing perampanel to standard of care (SOC) in patients undergoing resection of newly-diagnosed radiologic high-grade glioma. Perampanel was administered as a pre-operative loading dose followed by maintenance therapy until progressive disease or up to 12-months. SOC treatment involved levetiracetam for 7-days or as clinically indicated. The primary outcome of hyperexcitability was defined by intra-operative electrocorticography high frequency oscillation (HFO) rates. Seizure-freedom and overall survival (OS) were estimated by the Kaplan-Meier method. Tissue concentrations of perampanel, levetiracetam, and metabolites were measured by mass spectrometry. Results: HFO rates were similar between perampanel-treated and SOC cohorts. The trial was terminated early after interim analysis for futility, and outcomes assessed in 11 patients (7 perampanel-treated, 4 SOC). Over a median 281 days of post-enrollment follow-up, 27% of patients had seizures, including 14% treated with perampanel and 50% treated with SOC. OS in perampanel-treated patients was similar to a glioblastoma reference cohort (p=0.81). Glutamate concentrations in surface biopsies were positively correlated with HFO rates in adjacent electrode contacts and were not significantly associated with treatment assignment or drug concentrations. Conclusions: A peri-operative loading regimen of perampanel was safe and well-tolerated, with similar peritumoral hyperexcitability as in levetiracetam-treated patients. Maintenance anti-glutamatergic therapy was not observed to impact survival outcomes.

Landmine Injury Resulting in Comminuted Lumbar Facet Fracture as a Cause of Lumbar Stenosis and Spondylolisthesis.

Lumbar facet fractures are rarely reported and have been linked to sports and spine surgery. We describe the case of a 77-year-old patient who sustained an injury from multiple landmine blasts during the Vietnam War. He had low back pain since that time, which was initially managed conservatively. However, the pain progressed over decades to severe neurogenic claudication that greatly restricted his quality of life. Neuroimaging revealed the presence of bone fragments impinging on the spinal canal at the L5/6 level (transitional anatomy) that resulted from a comminuted fracture of the lumbar facet at the inferior articular process. We performed an L5/6 decompressive laminectomy, with removal of these fragments, and posterior instrumented fusion, with substantial improvement in symptoms. This case illustrates a unique mechanism of lumbar facet fracture and the biomechanic origination, natural history, and optimal treatment of this entity. We expand on the spectrum of lumbosacral injuries associated with the combat blast injury that have only increased in prevalence in recent conflicts.

Brain tumors in United States military veterans.

BACKGROUND: Comprehensive analysis of brain tumor incidence and survival in the Veteran population has been lacking. METHODS: Veteran data were obtained from the Veterans Health Administration (VHA) Medical Centers via VHA Corporate Data Warehouse. Brain tumor statistics on the overall US population were generated from the Central Brain Tumor Registry of the US data. Cases were individuals (≥18 years) with a primary brain tumor, diagnosed between 2004 and 2018. The average annual age-adjusted incidence rates (AAIR) and 95% confidence intervals were estimated per 100 000 population and Kaplan-Meier survival curves evaluated overall survival outcomes among Veterans. RESULTS: The Veteran population was primarily white (78%), male (93%), and between 60 and 64 years old (18%). Individuals with a primary brain tumor in the general US population were mainly female (59%) and between 18 and 49 years old (28%). The overall AAIR of primary brain tumors from 2004 to 2018 within the Veterans Affairs cancer registry was 11.6. Nonmalignant tumors were more common than malignant tumors (AAIR:7.19 vs 4.42). The most diagnosed tumors in Veterans were nonmalignant pituitary tumors (AAIR:2.96), nonmalignant meningioma (AAIR:2.62), and glioblastoma (AAIR:1.96). In the Veteran population, survival outcomes became worse with age and were lowest among individuals diagnosed with glioblastoma. CONCLUSIONS: Differences between Veteran and US populations can be broadly attributed to demographic composition differences of these groups. Prior to this, there have been no reports on national-level incidence rates and survival outcomes for Veterans. These data provide vital information that can drive efforts to understand disease burden and improve outcomes for individuals with primary brain tumors.

Late Subacute Cerebral Hematoma Mimicking a Metastasis on PSMA PET/CT.

ABSTRACT: A 64-year-old man with history of prostate cancer was found to have rising prostate-specific antigen after radical prostatectomy. 18 F-DCFPyL PET/CT demonstrated a prostate-specific membrane antigen-avid brain lesion in the left frontal lobe and no other findings to account for rising prostate-specific antigen. Brain MRI demonstrated a small intraparenchymal hematoma with late subacute features in this location. The patient reported a seizure 3 weeks before but was otherwise asymptomatic, and neurologic examination was normal. Follow-up MRI demonstrated gradual decrease in size of the hematoma without treatment.

Price Transparency for Cervical Spinal Fusion Among High-Performing Spine Centers in the United States.

BACKGROUND AND OBJECTIVES: As of January 1, 2021, all US hospitals are required by the Hospital Price Transparency Final Rule (HPTFR) to publish standard charges for all items and services, yet the state of price transparency for cervical spinal fusion is unknown. Here, we assess the nationwide price transparency landscape for cervical spinal fusion among high-performing spine centers in the United States. METHODS: In this cross-sectional economic evaluation, we queried publicly available price transparency websites of 332 "high-performing" spine centers, as defined by the US News and World Report. We extracted variables including gross charges for cervical spinal fusion, payor options, price reporting methodology, and prices relevant to consumers including listed cash prices and minimum and maximum negotiated charges. RESULTS: While nearly all 332 high-performing spine surgery centers (99.4%) had an online cost estimation tool, the HPTFR compliance rate was only 8.4%. Gross charges for cervical spinal fusion were accessible for 68.1% of hospitals, discounted cash prices for 46.4% of hospitals, and minimum and maximum charges for 10.8% of hospitals. There were large IQRs for gross charges ($48 491.98-$99 293.37), discounted cash prices ($26 952.25-$66 806.63), minimum charges ($10 766.11-$21 248.36), and maximum charges ($39 280.49-$89 035.35). There was geographic variability in the gross charges of cervical spinal fusion among high-performing spine centers within and between states. There was a significant association between "excellent" discharge to home status and lower mean gross charges. CONCLUSION: Although online cost reporting has drastically increased since implementation of the HPTFR, data reported for cervical spinal fusion remain inadequate and difficult to interpret by both providers and patients.

Incidence, treatment and outcomes of coronary artery dissection during percutaneous coronary intervention.

BACKGROUND: Coronary artery dissection is a feared and potentially life-threatening complication of percutaneous coronary intervention (PCI). METHODS: We examined the clinical, angiographic, and procedural characteristics, and outcomes of coronary dissection at a tertiary care institution. RESULTS: Between 2014 and 2019, unplanned coronary dissection occurred in 141 of 10,278 PCIs (1.4%). Median patient age was 68 (60, 78) years, 68% were men, and 83% had hypertension. The prevalence of diabetes (29%), and prior PCI (37%) was high. Most target vessels were significantly diseased: 48% had moderate/severe tortuosity and 62% had moderate/severe calcification. The most common cause of dissection was guidewire advancement (30%), followed by stenting (22%), balloon angioplasty (20%), and guide-catheter engagement (18%). TIMI flow was 0 in 33% and 1-2 in 41% of cases. Intravascular imaging was used in 17% of the cases. Stenting was used to treat the dissection in 73% of patients. There was no consequence of dissection in 43% of patients. Technical and procedural success was 65% and 55%, respectively. In-hospital major adverse cardiovascular events occurred in 23% of patients: 13 (9%) had an acute myocardial infarction (MI), 3 (2%) had emergency coronary artery bypass graft surgery, and 10 (7%) died. During a mean follow up of 1612 days, 28 (20%) patients died, and the rate of target lesion revascularization was 11.3% (n=16). CONCLUSION: Coronary artery dissection is an infrequent complication of PCI, but is associated with adverse clinical outcomes, such as death and acute MI.

Clinical characterization of the mutational landscape of 24,639 real-world samples from patients with myeloid malignancies.

Myeloid neoplasms represent a broad spectrum of hematological disorders for which somatic mutation status in key driver genes is important for diagnosis, prognosis and treatment. Here we summarize the findings of a targeted, next generation sequencing laboratory developed test in 24,639 clinical myeloid samples. Data were analyzed comprehensively and as part of individual cohorts specific to acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and myeloproliferative neoplasms (MPN). Overall, 48,015 variants were detected, and variants were found in all 50 genes in the panel. The mean number of mutations per patient was 1.95. Mutation number increased with age (Spearman's rank correlation coefficient, ρ = 0.29, P < 0.0001) and was higher in patients with AML than MDS or MPN (Student's t-test, P < 0.0001). TET2 was the most common mutation detected (19.1% of samples; 4,695/24,639) including 7.7% (1,908/24,639) with multi-hit TET2 mutations. Mutation frequency was correlated between patients with cytopenias and MDS (Spearman's, ρ = 0.97, P < 2.2×10-16) with the MDS diagnostic gene SF3B1 being the only notable outlier. This large retrospective study shows the utility of NGS testing to inform clinical decisions during routine clinical care and highlights the mutational landscape of a broad population of myeloid patients.

Intraoperative hypovolemia as a possible precipitating factor for pituitary apoplexy: a case report.

BACKGROUND: Pituitary apoplexy is acute infarction with or without hemorrhage of the pituitary gland. It is a rare but potentially life-threatening emergency that most commonly occurs in the setting of pituitary adenoma. The mechanisms underlying pituitary apoplexy are not well understood, but are proposed to include factors of both hemodynamic supply and adenoma demand. In the case of patients with known pituitary macroadenomas undergoing major surgery for other indications, there is a theoretically increased risk of apoplexy in the setting of "surgical stress." However, risk stratification of patients with nonfunctioning pituitary adenomas prior to major surgery is challenging because the precipitating factors for pituitary apoplexy are not completely understood. Here we present a case in which intraoperative hypovolemia is a possible mechanistic precipitating factor for pituitary apoplexy. CASE PRESENTATION: A 76-year-old patient with a known hypofunctioning pituitary macroadenoma underwent nephrectomy for renal cell carcinoma, during which there was significant intraoperative blood loss. He became symptomatic with ophthalmoplegia on the second postoperative day, and was diagnosed with pituitary apoplexy. He was managed conservatively with cortisol replacement therapy, and underwent therapeutic anticoagulation 2 months after pituitary apoplexy for deep vein thrombosis. His ophthalmoplegia slowly resolved over months of follow-up. Pituitary apoplexy did not recur with therapeutic anticoagulation. CONCLUSIONS: When considering the risk of surgery in patients with a known pituitary macroadenoma, an operation with possible high-volume intraoperative blood loss may have increased risk of pituitary apoplexy because intraoperative hypovolemia may precipitate ischemia, infarction, and subsequent hemorrhage. This may be particularly relevant in the cases of elective surgery. Additionally, we found that we were able to therapeutically anticoagulate a patient 2 months after pituitary apoplexy for the management of deep vein thrombosis without recurrence of pituitary apoplexy.

The current state of glioma data registries.

Background: The landscape of glioma research has evolved in the past 20 years to include numerous large, multi-institutional, database efforts compiling either clinical data on glioma patients, molecular data on glioma specimens, or a combination of both. While these strategies can provide a wealth of information for glioma research, obtaining information regarding data availability and access specifications can be challenging. Methods: We reviewed the literature for ongoing clinical, molecular, and combined database efforts related to glioma research to provide researchers with a curated overview of the current state of glioma database resources. Results: We identified and reviewed a total of 20 databases with data collection spanning from 1975 to 2022. Surveyed databases included both low- and high-grade gliomas, and data elements included over 100 clinical variables and 12 molecular data types. Select database strengths included large sample sizes and a wide variety of variables available, while limitations of some databases included complex data access requirements and a lack of glioma-specific variables. Conclusions: This review highlights current databases and registries and their potential utility in clinical and genomic glioma research. While many high-quality resources exist, the fluid nature of glioma taxonomy makes it difficult to isolate a large cohort of patients with a pathologically confirmed diagnosis. Large, well-defined, and publicly available glioma datasets have the potential to expand the reach of glioma research and drive the field forward.

Intracranial Facial Schwannomas: Multiple Distinct Entities Necessitating Tailored Management.

OBJECTIVE: Facial nerve (FN) schwannomas are extremely rare. According to their origin and involved segment(s), they constitute distinct subtypes. Intact FN function presents a management challenge, particularly in the cerebellopontine angle cisternal subtype that masquerades as a vestibular schwannoma. Fascicular-sparing technique with subtotal resection can maintain a good FN function. This study focuses on management to maintain good FN function. METHODS: A retrospective analysis of a cohort of 13 patients harboring FN schwannoma. Patient demographics, clinical findings, imaging, surgical intervention, and outcomes were analyzed. RESULTS: Five women and 8 men, with an average age of 55.3 years (39-75 years), harbored 6 cisternal, 2 ganglion, and 5 combined tumors. Average tumor size was 28.3 mm (16-50 mm). Eleven patients underwent surgery. Seven patients had fascicle-sparing technique, 5 of whom maintained their preoperative FN function, whereas 2 patients with near-total removal had a deterioration in FN function. Two patients with preoperative complete facial paralysis had gross total removal with interposition nerve graft. CONCLUSIONS: FN schwannomas management is individualized according to the subtype and the FN function at presentation. When FN function is normal, observation can be applied for prolonged period of time. At the early sign of deterioration, sub- or near-total resection with fascicle sparing technique can be performed. The cisternal subtype masquerade as vestibular schwannoma and should be recognized at the initial exposure by the appearance of finely splayed nerve fascicles at the perimetry of the tumor which elicits a motor response at low threshold stimulation.

Rotational Thromboelastometry-Guided Venoarterial Extracorporeal Membrane Oxygenation in the Treatment of Amniotic Fluid Embolism.

Amniotic fluid embolism (AFE) is a rare and often fatal complication of pregnancy that occurs during the puerperium. The low incidence of AFE has resulted in few large studies, which makes evidence-based management of AFE challenging. The use of extracorporeal membrane oxygenation (ECMO) has been reported but is limited by availability and challenges managing anticoagulation. In this report, we detail the case of a 29-year-old female who suffered from an AFE leading to cardiac arrest and disseminated intravascular coagulopathy. She was treated with protocolized A-OK (adenosine, ondansetron, and ketorolac), emergency c-section, cardiopulmonary resuscitation, massive blood transfusion, and rotational thromboelastometry-guided ECMO, allowing her to forgo initial anticoagulation. After a prolonged rehabilitation with initial poor neurological status, she made a complete recovery. In this report, we describe the protocols that contributed to her recovery and detail management of complicated AFE for other clinicians.

Incidence, Treatment, and Outcomes of Coronary Artery Perforation During Percutaneous Coronary Intervention.

OBJECTIVES: To examine the incidence, treatment and outcomes of perforation during percutaneous coronary intervention (PCI). BACKGROUND: Coronary perforation is a potentially life-threatening PCI complication. METHODS: We examined the clinical, angiographic, and procedural characteristics, management, and outcomes of coronary perforation at a tertiary care institution. RESULTS: Between 2014 and 2019, perforation occurred in 70 of 10,278 PCIs (0.7%). Patient age was 71 ± 12 years, 66% were men, and 30% had prior coronary artery bypass graft surgery. Among perforation cases, the prevalence of chronic total occlusions was 33%, moderate/severe calcification was 66% and moderate/severe tortuosity was 41%. The frequency of Ellis class 1, 2, and 3 perforations was 14%, 50%, and 36%, respectively. Most (n = 51; 73%) were large vessel perforations, 16 (23%) were distal vessel perforations and 3 (4%) were collateral vessel perforations (1 septal and 2 epicardial). Hypotension occurred in 26%, pericardial effusion in 36% and tamponade in 13%; 47% of perforations did not have clinical consequences. Perforations were most often treated with prolonged balloon inflation (63%), reversal of anticoagulation (39%), and covered stent implantation (33%). Technical and procedural success were 73% and 60%, respectively, and major periprocedural adverse cardiac events occurred in 21% of the patients. Three patients (4%) required emergent CABG surgery and four (6%) died. CONCLUSIONS: Coronary perforation is an infrequent complication of PCI. Most perforations are large vessel perforations and often require further intervention. The incidence of death or emergent cardiac surgery is low.

Salvage brachytherapy for multiply recurrent metastatic brain tumors: A matched case analysis.

Background: Patients with recurrent brain metastases who have exhausted external radiation options pose a treatment challenge in the setting of advances in systemic disease control which have improved quality of life and survival. Brachytherapy holds promise as salvage therapy given its ability to enforce surgical cytoreduction and minimize regional toxicity. This study investigates the role of salvage brachytherapy in maintaining local control for recurrent metastatic lesions. Methods: We retrospectively reviewed our institution's experience with brachytherapy in patients with multiply recurrent cerebral metastases who have exhausted external radiation treatment options (14 cases). The primary outcome of the study was freedom from local recurrence (FFLR). To capture the nuances of tumor biology, we compared FFLR achieved by brachytherapy to the preceding treatment for each patient. We further compared the response to brachytherapy in patients with lung cancer (8 cases) against a matched cohort of maximally radiated lung brain metastases (10 cases). Results: Brachytherapy treatment conferred significantly longer FFLR compared to prior treatments (median 7.39 vs 5.51 months, P = .011) for multiply recurrent brain metastases. Compared to an independent matched cohort, brachytherapy demonstrated superior FFLR (median 8.49 vs 1.61 months, P = .004) and longer median overall survival (11.07 vs 5.93 months, P = .055), with comparable side effects. Conclusion: Brachytherapy used as salvage treatment for select patients with a multiply recurrent oligometastatic brain metastasis in the setting of well-controlled systemic disease holds promise for improving local control in this challenging patient population.

ARHGEF-10 gene mutation presenting as orbital inflammatory syndrome.

Rho guanine nucleotide exchange factor 10 (ARHGEF-10) is a RHO GTPase that has a role for neural morphogenesis, however its effect on the eyes remains unknown. Here, we report a 44-year-old man who presented with eyelid swelling along with a history of bilateral hand contractures, high-arched feet and muscle wasting, who was found to have an ARHGEF-10 mutation. Neuroimaging was significant for numerous nerve-based cystic abnormalities in the bilateral orbits and throughout the neuraxis, and an orbital biopsy revealed S-100 and SOX-10 positive lesion consistent with pseudocysts. While the role of ARHGEF-10 remains unclear, further research is warranted to further describe its clinical manifestations.

Longitudinal Temperament Pathways to ADHD Between Childhood and Adolescence.

The current investigation extended prior cross-sectional mapping of etiological factors, transdiagnostic effortful and affective traits, and ADHD symptoms to longitudinal pathways extending from two etiological domains: polygenic and prenatal risk. Hypotheses were (1) genetic risk for ADHD would be related to inattentive ADHD symptoms in adolescence and mediated by childhood effortful control; (2) prenatal smoking would be related to hyperactive-impulsive ADHD symptoms during childhood and mediated by childhood surgency; and (3) there would be age-related variation, such that mediation of genetic risk would be larger for older than younger ages, whereas mediation of prenatal risk would be larger in earlier childhood than at later ages. Participants were 849 children drawn from the Oregon ADHD-1000 Cohort, which used a case control sample and an accelerated longitudinal design to track development from childhood (at year 1 ages 7-13) through adolescence (at year 6 ages 13-19). Results showed the mediational pathway from prenatal smoking through surgency to hyperactivity-impulsivity at Year 1 was significant (indirect effect estimate = .053, p < .01). The mediational pathway from polygenic risk through effortful control to inattention at Year 6 was also significant (indirect effect estimate = .084, p < .01). Both results were independent of the association between inattention and hyperactivity-impulsivity and control for the alternative etiological input and held across parent- and teacher-report of ADHD symptoms. In line with dual pathway models of ADHD, early prenatal risk for hyperactivity-impulsivity appears to operate through surgency, while polygenic genetic risk for inattention appears mediated by effortful control.

Syringomyelia From Extramedullary Compression: Resolution After Microsurgical Resection of a High-Cervical Spine Schwannoma: 2-Dimensional Operative Video.

Syringomyelia with compression at the foramen magnum is a well-studied subject with a pathophysiological hypothesis explaining syrinx development and treatment.1,2 However, compression of the cervical cord, as in cervical spondylosis, can also lead to cavitation in the spinal cord.3,4 Although the association of intramedullary spinal cord tumors with syringomyelia is well known,5 the association of extramedullary tumors with syringomyelia is scarcely reported, and it is of unknown mechanism and uncertain outcomes regarding syrinx resolution. Syringomyelia is reported to be associated with intramedullary spinal schwannoma.6 However, spinal schwannomas are by and large extramedullary tumors that produce deficits through compressive radiculopathy or myelopathy. The association of extramedullary schwannomas with syringomyelia is extremely rare. In this article, we present a patient with an extramedullary high-cervical schwannoma causing significant syringomyelia who underwent microsurgical resection of the schwannoma, with subsequent total resolution of the syringomyelia. The patient consented for surgery. Images from Lancet 1969 at 6:36 in video Reprinted from The Lancet, Vol. 294, Bernard Williams, The Distending Force in the Production of "Communicating Syringomyelia," Pages 189-193, Copyright 1969, with permission from Elsevier.

Sugita-Kobayashi Maneuver for Preservation of Large Bridging Veins in the Interhemispheric Approach: 2-Dimensional Operative Video.

Giants of neurosurgery have made contributions that might at times seem to be minor maneuvers but have a major impact on safe surgery, such as Sugita and Kobayashi's description of the preservation of the bridging sagittal veins.1 The interhemispheric approach is haunted by risk to the bridging veins and resultant venous infarction. At the midsegment, this could produce devastating neurological deficits.2 This is an especially critical factor in falcine meningiomas in which the location of the tumor narrows the options for the surgical corridor, particularly if an additional falcine margin, "Grade Zero" resection, is to be performed.3 Detailed preoperative neuroimaging workup is required to plan the appropriate surgical strategy and minimize risk for venous complications. This may include magnetic resonance or computed tomography venogram, dynamic computed tomography angiography,4 or in some cases formal angiography to assess the relationship with the superior sagittal sinus, the anatomy of parasagittal bridging veins in relation to the lesion, and the patterns of collateral venous drainage. While bridging veins may be displaced, compressed, or obscured by tumor involvement,5 microsurgical technique can facilitate the safe identification and preservation of this crucial anatomy. Bridging veins are separated from the underlying cortex to a distance from the sinus, allowing for improved relaxation of the ipsilateral cortex, without venous compromise.1,6 Herein, we demonstrate a case of a large falcine meningioma with a "Grade Zero" resection, with mobilization of the parasagittal bridging veins to develop the interhemispheric surgical corridor. The patient consented for surgery.