Understanding Geospatial Trends in Lumbar Fusion Incidence and Technique in Medicare Populations.

STUDY DESIGN: Retrospective study with epidemiologic analysis of public Medicare data. OBJECTIVE: This study seeks to utilize geospatial analysis to identify distinct trends in lumbar fusion incidence and techniques in Medicare populations. SUMMARY OF BACKGROUND DATA: With an aging population and new technologies, lumbar fusion is an increasingly common procedure. There is controversy, however, regarding which indications and techniques achieve optimal outcomes, leading to significant intersurgeon variation and potential national disparities in care. MATERIALS AND METHODS: Medicare billing datasets were supplemented with Census Bureau socioeconomic data from 2013 to 2020. These databases listed lumbar fusions billed to Medicare by location, specialty, and technique. Hotspots and coldspots of lumbar fusion incidence and technique choice were identified with county-level analysis and compared with Mann-Whitney U . A linear regression of fusion incidence and a logistic regression of lumbar fusion hotspots/coldspots were also calculated. RESULTS: Between 2013 and 2020, 624,850 lumbar fusions were billed to Medicare. Lumbar fusion hotspots performed fusions at nearly five times the incidence of coldspots (101.6-21.1 fusions per 100,000 Medicare members) and were located in the Midwest, Colorado, and Virginia while coldspots were in California, Florida, Wisconsin, and the Northeast. Posterior and posterolateral fusion were the most favored techniques, with hotspots in the Northeast. Combined posterior and posterolateral fusion and posterior interbody fusion was the second most favored technique, predominantly in Illinois, Missouri, Arkansas, and Colorado. CONCLUSIONS: The geographic distribution of lumbar fusions correlates with variations in residency training, fellowship, and specialty. The geospatial patterning in both utilization and technique reflects a lack of consensus in the application of lumbar fusion. The strong variance in utilization is a potentially worrying finding that could suggest that the nonstandardization of lumbar fusion indication has led to both overtreatment and undertreatment across the nation. LEVEL OF EVIDENCE: Level 3-retrospective.

Microsurgical intraluminal obliteration of type IV perimedullary arteriovenous fistula with an in situ hemostatic agent: illustrative case.

BACKGROUND: Spinal arteriovenous fistulas (SAVFs) are underdiagnosed entities that can lead to severe morbidity from spinal cord dysfunction or hemorrhage. Treatment options include endovascular embolization or direct surgical obliteration at the level of the arteriovenous shunt. The authors present a case of intraluminal microsurgical access for occlusion with a hemostatic agent of a type IV SAVF near the conus medullaris as an alternative to clip occlusion to avoid nerve root compromise. OBSERVATIONS: Temporary microsurgical clipping of the SAVF led to nerve root compromise detected via intraoperative monitoring. Instead, the authors advanced elongated pieces of a hemostatic agent directly into the arterial lumen via arteriotomy to create direct obliteration of the fistula without intraoperative monitoring changes. LESSONS: In patients unable to tolerate clipping of the SAVF because of nerve root involvement and neurophysiological signal decline, open access of the vessels and direct intraluminal obliteration using a hemostatic agent should be considered as an alternative method of fistula occlusion.

Single-Stage Titanium Mesh Cranioplasty for the Treatment of Depressed Skull Fractures.

BACKGROUND: Historically, depressed skull fractures that warranted surgery were treated in 2 stages: the first stage involved debridement and craniectomy, followed by the second stage of delayed cranioplasty. More recently, single-stage autologous cranioplasty has been proven to be safe. However, there is a paucity of literature regarding single-stage titanium mesh cranioplasty when autologous repair is not possible. METHODS: A retrospective review identified 22 patients who underwent single-stage titanium mesh cranioplasty for the acute treatment of comminuted depressed skull fractures. Fracture location, fracture etiology, timing of surgery, neurologic complications, infection, and cosmetic deformity were recorded. Average follow-up was 9 months. RESULTS: The mean age of the patients was 34 years (range: 3-77); 83% were male. Seventeen (77%) involved the frontal bone, with 7 (32%) involving the frontal sinus. Eighteen (82%) had open defects at presentation. Sixteen (73%) were neurologically normal. Average time from presentation to repair was 11 hours (range: 1-28 hours). There were no neurologic worsening, seizures, or infections postoperatively. Antibiotic prophylaxis was prescribed in 13 cases (57%). One patient required revision surgery for persistent cosmetic deformity. CONCLUSIONS: Autologous cranioplasty for depressed skull fractures is not always possible especially in cases of significant comminution. From our case series, single-stage titanium mesh cranioplasty appears to be a safe option.

Trends in Technology for Pedicle Screw Placement: A Temporal Meta-Analysis.

STUDY DESIGN: Systematic Review. OBJECTIVE: We sought to determine which method of the pedicle screw (PS) placement is most accurate and understand how the development of subsequent generations of robotic systems has changed placement accuracy over time. SUMMARY OF BACKGROUND DATA: Previous studies have demonstrated the success of robotic PS placement, but how this accuracy compares to other methods is unclear. METHODS: A systematic review following PRISMA Guidelines was performed on articles published between January 2000 and August 2021, comparing PS insertion methods with at least 10 screws per study arm. Single and multiple-arm trials were included. Data were extracted for patient outcomes, including optimal PS placement, misplacement, and accuracy. The logit-event rate of misplacement was calculated for each study. P values were adjusted for multiple comparisons using the Tukey post hoc correction. RESULTS: Our search revealed 127 studies, and 156 comparative arms, with 77,360 pedicle screws placed using five different modalities. Meta-regression of pooled accuracy revealed no significant changes in PS accuracy over time for freehand, 2D fluoroscopic navigation, 3D fluoroscopic navigation, and computed tomography navigation. Robotic navigation had a significant increase in accuracy over time ( P =0.036). Pooled misplacement rates were also compared across all modalities. Robotics was found to have the lowest rates of misplacement for PS compared to freehand ( P =0.0015) and 2D fluoroscopic navigation ( P =0.026). CONCLUSION: Our analysis is the largest study to date on pedicle screw placement. Pedicle screw placement through robotics was found to be superior due to its low misplacement rates compared with other modalities. Intraoperative 3D fluoroscopic navigation was found to have comparable misplacement rates. In addition, pedicle screw placement accuracy with robotics has continued to improve over time. This speaks to both the stability of the technology and the potential for continued improvement with new and more accurate robotic systems.

Posterior fossa ischemic infarction: single-center retrospective review of non-surgical and surgical cases.

Cerebellar ischemic stroke (CIS) is a morbid neurological event, with potentially fatal consequences. There is currently no objective standard of care regarding when surgical procedures are required for this entity. We retrospectively reviewed 763 patients with CIS, 247 patients of which had a stroke larger than 1 cm in greatest dimension on cranial imaging. In this subgroup, 11% of patients received ventriculostomy, 12% suboccipital craniectomy, and 9% mechanical endovascular thrombectomy. Various clinical and radiographic variables were examined for relationship to surgical procedures, 30-day mortality rate, and modified Rankin scores. The smallest volume of stroke requiring a surgical procedure was 15.5 mL3 (BrainLab Software). Patients receiving surgical procedures had a higher incidence of multi-territory infarctions, hydrocephalus, cistern compression, 4th ventricular compression, as well as younger age, lower admission GCS, higher admission NIHSS, and higher 30-day mortality/disability. Patients deemed to require surgical procedures for CIS have a higher expected morbidity and mortality than those not requiring surgery. Various clinical and radiographic variables, including stroke volume, can be used to guide selection of patients requiring surgery.

Perioperative prophylaxis for surgical site infections in pediatric spinal surgery: a systematic review and network meta-analysis.

OBJECTIVE: Postoperative infections in pediatric spinal surgery commonly occur and necessitate reoperation(s). However, pediatric-specific infection prophylaxis guidelines are not available. This network meta-analysis compares perioperative prophylaxis methods including Betadine irrigation, saline irrigation, intrawound vancomycin powder, combination therapy (Betadine, vancomycin, gentamicin, and cefuroxime), Betadine irrigation plus vancomycin powder, and no intervention to determine the most efficacious prevention method. METHODS: A systematic review was performed by searching the PubMed, EBSCO, Scopus, and Web of Science databases for peer-reviewed articles published prior to February 2022 comparing two or more infection prophylaxis methods in patients younger than 22 years of age. Data were extracted for treatment modalities, patient demographics, and patient outcomes such as total number of infections, surgical site infections, deep infections, intraoperative blood loss, operative time, follow-up time, and postoperative complications. Quality and risk of bias was assessed using National Institutes of Health tools. A network meta-analysis was performed with reduction of infections as the primary outcome. RESULTS: Overall, 10 studies consisting of 5164 procedures were included. There was no significant difference between prophylactic treatment options in reduction of infection. However, three treatment options showed significant reduction in total infection compared with no prophylactic treatment: Betadine plus vancomycin (OR 0.22, 95% CI 0.09-0.54), vancomycin (OR 3.26, 95% CI 1.96-5.44), and a combination therapy (Betadine, vancomycin, gentamicin, and cefuroxime) (OR 0.24, 95% CI 0.07-0.75). P-Score hierarchical ranking estimated Betadine plus vancomycin to be the superior treatment to prevent total infections, deep infections, and surgical site infections (P-score 0.7876, 0.7175, and 0.7291, respectively). No prophylaxis treatment-related complications were reported. CONCLUSIONS: The results of this network meta-analysis show the strongest support for Betadine plus vancomycin as a method to reduce infections following pediatric spinal surgery. There was heterogeneity among studies and inconsistent outcome reporting; however, three effective treatment options are identified.

Use of balloon-assisted nasal access to augment endoscopic endonasal transsphenoidal approach: illustrative case.

BACKGROUND: Pituitary adenoma is a neurosurgical pathology commonly resected via endoscopic endonasal approach. Septal and nasal passage anatomy can affect the surgical corridor and may require septoplasty or other techniques for expansion. OBSERVATIONS: The authors presented a case of pituitary macroadenoma with septal deviation with use of balloon-assisted nasal access for surgery. LESSONS: This technique enhanced surgical width of field and instrument maneuverability via septal medialization for successful tumor resection.

Temporary Posterior C1-C2 Instrumentation without Fusion for Treatment of Displaced Atlantoaxial Fractures.

OBJECTIVE: To describe open reduction internal fixation (ORIF) with posterior C1-C2 instrumentation without fusion to treat displaced atlantoaxial fractures with later instrumentation removal. METHODS: A retrospective review identified 14 patients (mean age 44 years) with displaced atlantoaxial fractures treated with ORIF without fusion. Patient demographics, fracture morphology, trauma etiology, instrumentation levels, timing of hardware removal, and complications were collected. Patients were maintained in a cervical collar, and healing was confirmed via imaging before instrumentation removal. RESULTS: Fractures included type III odontoid, C2 pars, C1 ring, and complex C1 or C2 fractures. All cases used C1 lateral mass screws and C2 pars or pedicle screws with a C1 cross-link. Two patients had C3 lateral mass screws. All patients showed fracture healing on imaging within 4 months after ORIF. Instrumentation removal was performed in 13 patients. No complications were noted. CONCLUSIONS: Displaced atlantoaxial fractures have been traditionally managed with halo-vest immobilization closed reduction or ORIF with fusion. ORIF without fusion and subsequent hardware removal is an alternative approach. This strategy preserves mobility at C1-C2, avoids halo-vest immobilization, and appears to be a safe option for treatment of atlantoaxial fractures.

Chyle leak occurring after vagal nerve stimulator implantation in a child.

Vagus nerve stimulation is a therapy indicated for some patients with medically-refractory epilepsy. Typical risks of this procedure include infection, hoarseness, vocal cord dysfunction, and hardware malfunction. Chyle leak via injury to the thoracic duct is a known complication of thoracic and head and neck surgeries-though less so in the neurosurgical literature. In severe cases, chyle leak can lead to nutritional deficiencies and immunosuppression. Management of chyle leak includes low-fat diet and pharmacological suppression of chyle production with medications such as octreotide. If leak is persistent, surgical exploration with attempted ligation of lymphatic structures is performed.

Simulation of proximal catheter occlusion and design of a shunt tap aspiration system.

PURPOSE: Total and partial proximal catheter occlusions are well-known complications of ventriculoperitoneal shunts (VPS). When this occurs, surgeons often attempt to perform a shunt tap. However, the degree of obstruction in a proximal catheter that ultimately leads to shunt malfunction is unknown. METHODS: We developed a benchtop model to simulate proximal catheter occlusion with two hydrostatic reservoirs connected by a VPS catheter system. The Centurion compass device was used to measure pressure across the valve digitally. Wires of varying diameters (equalling different occlusion percentages) were inserted into the catheter's proximal end to stimulate obstruction. A mock shunt tap aspiration was then performed by incorporating a pressure transducer. RESULTS: As a general trend, pressure reading on the device decreases as occlusion increases. At higher levels of occlusion (> 45%), the blockage begins to significantly impede the flow through the catheter, and the pressure drops at a faster rate compared with lower occlusion percentages. The pressure reading converges quickly to 0 with increasing blockage after about 70%. The Centurion compass is able to detect large changes in pressure as evidenced by the major differences in pressure readings between no occlusion, 45%, and 84%. The shunt will not function at 84%. In order to determine the threshold for occlusion beyond which fluid cannot be withdrawn, we tested five levels of occlusion (0%, 33%, 63%, 84%, and 100%) at various aspiration pressures and determined that fluid can still be produced with 0-84% occlusion, but no fluid could be produced at 100% occlusion. CONCLUSIONS: We developed a model of proximal shunt obstruction and found that cerebrospinal fluid (CSF) flow through a VPS is unaffected up to 33% occlusion, begins to become impaired at 45% occlusion, and is miniscule at 84% occlusion. Shunt aspiration was not possible at 84% occlusion. Pressure measured at the reservoir is accurate and correlates with intracranial pressure (ICP) up to approximately 60% proximal occlusion. With partial occlusion up to 70%, ventricular pressure will dictate shunt function.

Prognostic Indices for Predicting Facial Nerve Outcome following the Resection of Large Acoustic Neuromas.

This study analyzes the simple ratio of anterior-to-posterior extension of large (>2.5 cm) acoustic neuromas relative to the internal auditory canal (ICA; anterior-posterior [A/P] index) as a tool for predicting risk of facial nerve (FN) injury. In total, 105 patients who underwent microsurgical resection for large acoustic neuromas were analyzed retrospectively. House-Brackmann (HB) scores were assessed immediately postoperatively, at 1 month, and at 1 year. Lateral-medial, inferior-superior, A/P, and maximum diameters were measured from preoperative magnetic resonance images. These measurements and the A/P index were analyzed using univariable and multivariable statistical models to assess relationship to FN outcomes. The retrosigmoid, translabyrinthine, and combined approaches were used, and the extent of resection was evaluated. For every 1 standard deviation increase in the A/P index, a patient was 3.87 times more likely have a higher postoperative HB score ( p < 0.0001). Accordingly, for every 1-mm increase anterior to the IAC, a patient was 16% more likely have a higher postoperative HB score ( p < 0.001). After controlling for tumor size, a patient was still 3.82 times more likely have a higher postoperative HB score for every 1 standard deviation increase in the A/P index ( p < 0.0001). While larger tumor size trended toward worse postoperative HB scores, it was not statistically significant. Our prognostic index may be useful to assess the risk of FN injury preoperatively for large acoustic neuromas, while also providing information about the tumor-nerve relationship.

Identification of Preoperative and Intraoperative Risk Factors for Complications in the Elderly Undergoing Elective Craniotomy.

BACKGROUND: Neurosurgical patients are aging as the general population is becoming older. METHODS: A retrospective review of patients ≥65 years of age who underwent an elective craniotomy from 2007 to 2015 to identify risk factors for 30-day morbidity/mortality was conducted. Key preoperative variables included age, comorbidities, and functional status based on the Karnofsky Performance Status score and modified Rankin Scale score. Outcome variables included long-term care (LTC) complications, neurologic complications, systemic/infectious complications, length of stay, functional outcomes, and mortality. RESULTS: A total of 286 patients ≥65 years underwent elective craniotomy at Loyola University Medical Center over 8 years. Seventy-two patients had a preoperative neurologic deficit and 95 had a systemic morbidity before surgery. Postoperative neurologic and systemic morbidity was 14% and 23%, respectively. 7% of patients experienced a LTC complication and 5 patients (1.7%) died. Worse preoperative scores on both the Karnofsky Performance Status and modified Rankin Scale predicted increased length of stay and mortality (P < 0.05). Univariable and multivariable analyses showed that patients with preoperative motor deficit, altered mental status, congestive heart failure, smoking history, and chronic steroid use were all more likely to have an LTC complication, and increased anesthesia time and estimated blood loss increased risk for LTC, neurologic, and systemic/infectious complications. CONCLUSIONS: This study identifies factors that predict perioperative complications for elderly patients undergoing elective craniotomies, particularly congestive heart failure, smoking history, chronic steroid use, anesthesia time, and estimated blood loss. Age alone should not preclude elective craniotomy.

Deterministic Tractography of the Descending Tract of the Spinal Trigeminal Nerve Using Diffusion Tensor Imaging.

BACKGROUND AND PURPOSE: Pain information from the face enters the pons via the trigeminal nerve before creating an anatomical "elbow" that turns caudally into the spinal trigeminal tract (SpTV). Visualization of the descending tract of the trigeminal nerve as it begins its descent from the nerve root entry zone (NREZ) in the pons would improve the accuracy of current procedures aimed at altering or lesioning the trigeminal nerve within the brainstem. The focus of this study was to develop a standardized protocol using diffusion tensor imaging (DTI) and deterministic tractography methods to image the SpTV. There are currently no standard techniques used to visualize the trigeminal nerve using DTI. METHODS: DTI and tractography were performed on 20 patients: 17 with trigeminal neuralgia (TN), 1 with hemifacial spasm, 1 with a facial nerve tumor, and 1 with an arteriovenous malformation. A standardized protocol was developed using regions of interest (ROIs) located at the SpTV, as determined by a brainstem atlas, and the NREZ. RESULTS: Using our standardized protocol, the descending tract of the trigeminal nerve was successfully visualized in all 20 patients. Trigeminal fibers entered the pons at the NREZ and descended through the SpTV. The accuracy of the visualized tract was confirmed through coregistration with a stereotactic atlas and anatomical scan. CONCLUSION: A successful, robust DTI imaging and postprocessing protocol of the SpTV contributes to our understanding of its anatomical distribution within the brainstem and is a potentially new neurosurgical planning tool.

Microsurgical Pontine Descending Tractotomy in Cases of Intractable Trigeminal Neuralgia.

BACKGROUND: Current treatment strategies in patients with trigeminal neuralgia (TN) include trials of medical therapy and surgical intervention, when necessary. In some patients, pain is not adequately managed with these existing strategies. OBJECTIVE: To present a novel technique, ventral pontine trigeminal tractotomy via retrosigmoid craniectomy, as an adjunct treatment in TN when there is no significant neurovascular compression. METHODS: We present a nonrandomized retrospective comparison between 50 patients who lacked clear or impressive arterial neurovascular compression of the trigeminal nerve as judged by preoperative magnetic resonance imaging and intraoperative observations. These patients had intractable TN unresponsive to previous treatment. Trigeminal tractotomy was performed either alone or in conjunction with microvascular decompression. Stereotactic neuronavigation was used during surgery to localize the descending tract via a ventral pontine approach for descending tractotomy. RESULTS: Follow-up was a mean of 44 months. At first follow-up, 80% of patients experienced complete relief of their pain, and 18% had partial relief. At the most recent follow-up, 74% of patients were considered a successful outcome. Only 1 (2%) patient had no relief after trigeminal tractotomy. Of those with multiple sclerosis-related TN, 87.5% experienced successful relief of pain at their latest follow-up. CONCLUSION: While patient selection is a significant challenge, this procedure represents an option for patients with TN who have absent or equivocal neurovascular compression, multiple sclerosis-related TN, or recurrent TN.