Comparative Anatomy of the Contralateral Transmaxillary Approach Alone and With Ipsilateral Transpterygoid Extension: Quantitative Insights on Surgical Exposure and Maneuverability in the Petroclival Region.

BACKGROUND AND OBJECTIVES: Beyond qualitative evidence legitimizing endoscopic corridors through contralateral transmaxillary (CTM) and endonasal ipsilateral transpterygoid (ITP) corridors to the petrous apex and petroclival region, surgical feasibility by direct quantitative comparative anatomy is sparse. Our cadaveric study addresses this by performing the CTM approach followed by ITP extension to quantify the extent of petrous apex resection, instrument maneuverability, and working distance to petrous apex. METHODS: Anatomic dissections were performed bilaterally on 5 latex-injected human cadaveric heads (10 petrous bones). After CTM dissections were quantified, the ITP approach was added enlarging initial exposure. Differences were measured with statistical significance when P values are < .05. RESULTS: The mean petrosectomy volume was 0.958 cm3 with CTM and 1.987 cm3 with CTM + ITP, corresponding to 14.53% and 30.52% petrous apex resection, respectively. Craniocaudal instrument mobility was more limited in the lateral extent of dissection compared with the midline for both CTM (8.062° vs 14.416°) and CTM + ITP (5.4° vs 14.4°). The CTM approach achieved the lateral-most dissection at the body of the petrous apex (15.936 mm), with lateralization more limited in the superior petroclival region (9.628 mm) and the inferior petroclival region (8.508 mm). Angle of surgical maneuverability increased superiorly vs inferiorly in the CTM approach (mean 12.596° vs 8.336°, respectively). The CTM approach offered the shortest mean working distance (88.624 mm) to the petroclival region compared with the bi-nares approach (100.5 mm). CTM + ITP achieved greater lateralization in the superior (21.237 mm) and inferior (22.087 mm) aspects of the petroclival region compared with the CTM approach. CONCLUSION: Operative considerations are discussed in accessing target neurovascular structures through the uniquely shaped corridors formed by the CTM or combined CTM + ITP. Allowing mobilization of the internal carotid artery laterally and eustachian tube inferiorly, addition of the ITP allowed for larger petrosectomy than CTM alone, especially in the inferior and lateral aspects of the petrous bone.

Clear neuroimaging margin at the brain-tumor interface is associated with gross total resection and longer survival in non-enhancing diffuse gliomas.

BACKGROUND: This study aimed to determine whether the presence of distinct glioma margins on preoperative imaging is correlated with improved intraoperative identification of tumor-brain interfaces and overall improved surgical outcomes of non-enhancing gliomas. METHODS: This is a retrospective study of all primary glioma resections at our institution between 2000-2020. Tumors with contrast enhancement or with final pathology other than diffuse infiltrative glial neoplasm (WHO II or WHO III) were excluded. Tumors were stratified into two groups: those with distinct radiographical borders between tumor and brain, and those with ill-defined radiographical margins. Multivariate analysis was performed to determine the impact of clear preoperative margins on the primary outcome of gross-total resection. RESULTS: Within the study period, 59 patients met inclusion criteria, of which 31 (53%) had distinct margins. These patients were predominantly younger (37.6 vs. 48.1 years, P=0.007). Tumor and other patient characteristics were similar in both cohorts, including gender, laterality, size, location, tumor type, grade, and surgical adjuncts utilized (P>0.05). Multivariate regression identified that distinct preoperative margins correlated with increased rates of gross total resection (P=0.02). Distinct margins on preoperative neuroimaging also correlated positively with surgeon identification of intra-operative margins (P<0.0001), fewer deaths over the study period (P=0.01), and longer overall survival (P=0.03). CONCLUSIONS: Distinct glioma-parenchyma margins on preoperative imaging are associated with improved surgical resection for diffuse gliomas, as distinct margins may correlate with distinguishable glioma-brain interfaces intraoperatively. Further prospective studies may discover additional clinical uses for these findings.

Novel classification of foramen magnum meningiomas predicted by topographic position relative to neurovascular bundle.

PURPOSE: Proximity to critical neurovascular structures can create significant obstacles during surgical resection of foramen magnum meningiomas (FMMs) to the detriment of treatment outcomes. We propose a new classification that defines the tumor's relationship to neurovascular structures and assess correlation with postoperative outcomes. METHODS: In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor. RESULTS: The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission. CONCLUSION: The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions.

Incidence of Intracranial Melanoma Progression in the Setting of Positive Extracranial Response to Targeted Therapy and Immunotherapy: An Indication for More Frequent Screening in This Population?

Background and objective The incidence of intracranial metastases from melanoma is on the rise. In this study, we aimed to determine the incidence of intracranial disease progression in patients on BRAF/MEK targeted therapy and immunotherapy in the setting of controlled or improving extracranial disease. Methods This was a single-center, retrospective review that involved patients who underwent stereotactic radiosurgery (SRS) for intracranial metastatic melanoma between January 1, 2014, and December 31, 2018. We focused on BRAF/MEK mutation status and dates of treatment with BRAF/MEK targeted therapy, immunotherapy [ipilimumab (Yervoy), nivolumab (Opdivo), or pembrolizumab (Keytruda)], and combination targeted and immunotherapy. Results A total of 51 patients were enrolled: 36 males and 15 females. The average age of the patients was 58.6 years, and 26 among them were BRAF mutation-positive. Seventeen had prior surgery with SRS as adjuvant therapy. The other 34 had SRS as primary treatment. Forty-two patients had extracranial disease present at the time of SRS. There were 34 patients treated with targeted and immune therapy. Overall, 16 patients (47.1%) demonstrated controlled or improving extracranial disease, and 18 (52.9%) demonstrated progressing extracranial disease at the time of SRS. In the subgroup analysis, patients treated with BRAF/MEK targeted therapy demonstrated a 75% rate of extracranial disease control. The extracranial disease was controlled in 43.75% of patients on immunotherapy with intracranial progression, while it was controlled in 30% of patients on both BRAF/MEK targeted therapy and immunotherapy with intracranial progression. Sixteen patients (47.1%) developed intracranial metastasis in our study while having a stable systemic disease with BRAF/MEK targeted therapy, immunotherapy, or a combination of the two. Conclusion Based on our findings, a systemic response to targeted therapy and immunotherapy does not necessarily parallel intracranial protection.

Live-Streaming Surgery for Medical Student Education - Educational Solutions in Neurosurgery During the COVID-19 Pandemic.

OBJECTIVE: The COVID-19 pandemic significantly altered medical student education. The ability for students to be a part of the operating room team was highly restricted. Technology can be used to ensure ongoing surgical education during this time of limited in-person educational opportunities. DESIGN: We have developed an innovative solution of securely live-streaming surgery with real-time communication between the surgeon and students to allow for ongoing education during the pandemic. RESULTS: We successfully live-streamed multiple different types of neurosurgical operations utilizing multiple video sources. This method uses inexpensive, universal equipment that can be implemented at any institution to enable virtual education of medical students and other learners. CONCLUSIONS: This technology has facilitated education during this challenging time. This technological set-up for live-streaming surgery has the potential of improving medical and graduate medical education in the future.

Case-Control Study of Cephalometrics in Patients with Moyamoya.

OBJECTIVE: To determine whether cranial metrics consistently differed between patients with moyamoya and age-, sex-, and race-matched controls. METHODS: Patients diagnosed with moyamoya disease by cerebral angiogram were obtained from a prospectively collected database through the Department of Neurosurgery at the University of Kansas Medical Center. Control patients matched by decade of age, sex, and race were collected through a deidentified hospital database by International Classification of Diseases-9 and 10 codes for ischemic stroke to identify patients with computed tomography angiograms. Imaging studies for both groups were analyzed to obtain 6 skull metrics: maximum anterior to posterior distance, maximum biparietal distance, bregma to occiput distance, right carotid canal diameter (CCD), left CCD, and cephalic index. RESULTS: Forty-five patients were identified in each cohort. Measurements of mean anterior to posterior skull diameter, mean biparietal skull diameter, bregma to occiput distances, and calculated cephalic index did not demonstrate a statistically significant difference between patients with moyamoya and control patients. Right carotid canal mean diameter was 4.8 mm for the moyamoya group and 5.4 mm for the control group, with a significant raw mean difference of -0.61 mm (95% confidence interval, -0.95 to -0.27). Left CCD was 4.7 mm for the moyamoya group and 5.5 mm for the control group, resulting in a significant raw mean difference of -0.76 mm (95% confidence interval, -1.09 to -0.43). CONCLUSIONS: This study identified 2 skull parameters as statistically different in patients with moyamoya compared with a matched control group of patients with ischemic stroke: right CCD and left CCD.

Surgery for traumatic fractures of the upper thoracic spine (T1-T6).

BACKGROUND: The management of traumatic upper thoracic spine fractures (T1-T6) is complex due to the unique biomechanical/physiological characteristics of these levels and the nature of the injuries. They are commonly associated with multiple other traumatic injuries and severe spinal cord injuries. We describe the safety and efficacy of surgery for achieving stability and maintaining reduction of upper thoracic T1-T6 spine fractures. METHODS: We retrospectively analyzed a series of traumatic unstable upper thoracic (T1-T6) spine fractures treated at one institution between 1993 and 2016. All patients were assessed neurologically and underwent complete preoperative radiographic analysis of their T1-T6 spine fractures including assessment of instability. Neurological and radiographic outcomes including fusion rates, kyphotic deformity, and successful reduction of the fracture were evaluated along with hospital length of stay (LOS), intensive care unit LOS, and overall complication rates. RESULTS: There were 43 patients (29 males, 14 females) with an average age of 37.7 years. Between 1993 and 1999, 8 patients were treated with hook/rod constructs, whereas between 1995 and 2016, 35 patients received pedicle screw fixation utilizing intraoperative fluoroscopy or computed tomography (CT) navigation. Forty-three patients had a total of 178 levels fused. In this series, there were no intraoperative vascular or neurological complications. Instrumentation was removed in five patients due to pain, wound infection, or hardware failure. The mean hospital LOS was 21.1 days (range 4-59 days), and there was a 95% fusion rate based on follow-up imaging (X-rays or CT scan). CONCLUSIONS: Surgical treatment of upper thoracic spine fractures (T1-T6), although complex, is safe and effective. Reduction and fixation of these fractures decreases the risk of further neurological complications, allows for earlier mobilization, and correlates with shorter hospital LOS and improved outcomes.

Very Large Metastases to the Brain: Retrospective Study on Outcomes of Surgical Management.

BACKGROUND: The incidence of brain metastases is rising. To our knowledge, no published study focuses exclusively on brain metastases larger than 4 cm. We present our surgical outcomes for patients with brain metastases larger than 4 cm. METHODS: This is a retrospective chart review of inpatient data at our institution from January 2006 to September 2015. Primary end points included overall survival, progression-free survival, and local recurrence rate. RESULTS: Sixty-one patients had a total of 67 brain metastases larger than 4 cm: 52 were supratentorial and 15 were infratentorial. Forty-three patients underwent surgical resection. Average duration of disease freedom after resection was 4.79 months (range, 0-30 months). Excluding patients with residual on immediate postoperative magnetic resonance imaging, the average rate of local recurrence was 7 months (range, 1-14 months). Overall survival after surgery excluding patients who chose palliation in the immediate postoperative period averaged 8.76 months (range, 1-37 months). Thirty-five of 43 patients (81.4%) had stable or improved neurologic examinations postoperatively. Six patients (13.95%) developed surgical complications. There were 3 major complications (6.98%): 2 pseudomeningoceles required intervention and 1 postoperative hematoma required external ventricular drain placement. There were 3 minor complications (6.98%): 1 self-limited pseudomeningocele, 1 subgaleal fluid collection, and 1 postoperative seizure. CONCLUSIONS: Surgery resulted in stable or improved neurologic examination in 81.4% of cases. On statistical analysis, significantly increased overall survival was noted in patients undergoing surgical resection, and those with higher Karnofsky Performance Scale and lower number of brain metastases at presentation. There is a need for further studies to evaluate management of brain metastases larger than 4 cm.

Use of Pipeline™ embolization device for the treatment of traumatic intracranial pseudoaneurysms: Case series and review of cases from literature.

OBJECTIVE: Intracranial traumatic pseudoaneurysms (PSA) are a rare but dangerous subtype of cerebral aneurysm. Reports documenting use of flow-diverting stents to treat traumatic intracranial PSAs are few and lack long-term follow-up. To our knowledge, this is the largest case-series to date demonstrating use of Pipeline Endovascular Device (PED) for traumatic intracranial PSAs. PATIENTS AND METHODS: Retrospective review of 8 intracranial traumatic PSAs in 7 patients treated using only PED placement. Patients were followed clinically and angiographically for at least 6 months. RESULTS: Seven patients with a mean age of 37 years were treated for 8 intracranial pseudo-aneurysms between 2011-2015. Six aneurysms were the result of blunt trauma; 2 were from iatrogenic injury during transsphenoidal surgery. Mean clinical and angiographic follow-up in surviving patients was 15.2 months. In patients with angiographic follow-up, complete occlusion was achieved in all but one patient, who demonstrated near-complete occlusion. No ischemic events or stent-related stenosis were observed. One patient developed a carotid-cavernous fistula after PED, which was successfully retreated with placement of a second PED. There were two mortalities. One was due to suspected microwire perforation remote from the target aneurysm resulting in SAH/IPH. The other was due to a traumatic SDH and brainstem hemorrhage from an unrelated fall during follow-up interval. CONCLUSIONS: Use of PED for treatment of intracerebral PSAs following trauma or iatrogenic injury showed good persistent occlusion, and acceptable complication rate for this high-risk pathology. Risks of this procedure and necessary antiplatelet therapy require appropriate patient selection. Larger prospective studies are warranted.

Early ventral surgical treatment without traction of acute traumatic subaxial cervical spine injuries.

BACKGROUND: Spinal cord decompression after cervical spinal cord injury (SCI) is the standard of care. However, there is a lack of consensus regarding the optimal management of these injuries, including the role of traction and timing of surgery. Here, we report the safety/efficacy of ventral surgery without preoperative traction for intraoperative fracture reduction following acute cervical SCI. METHODS: We prospectively collected a series of patients who sustained acute traumatic subaxial cervical (C3-7) spine fractures between 2004 and 2016. Patients underwent anterior cervical decompression and fusion within 24 h of injury without the utilization of preoperative traction. RESULTS: Thirty-six patients (27 male, 9 female), averaging 35 years of age, sustained 25 motor-vehicle accidents, 4 sports-related injuries, and 7 falls. Fracture dislocations were seen in 26 patients, whereas burst fractures were seen in 10. The majority of injuries occurred at the C4-5 (13 patients) and C5-6 (13 patients) levels. Complete SCI occurred in 10 patients, and incomplete SCI in 26 patients. All patients underwent anterior surgery only; 16 required vertebrectomy in addition to anterior cervical discectomy and fusion. Intraoperative reduction was achieved in all patients using a Cobb elevator or distraction pins without the use of preanesthesia traction. There were no intraoperative complications. Postoperatively, there were one postoperative hematoma, two wound/hardware revisions, one subsequent posterior fusion, and one reoperation anteriorly after screw pullout. The average hospital length of stay was 10.6 days (range 1-39). CONCLUSION: Early direct surgical stabilization/fusion for acute SCI because of subaxial cervical spine fractures is both safe and effective in selected cases when performed anteriorly without preoperative traction in select cases.