Sonolucent Cranial Implants: A Window into the Future of Management of Neurosurgical Patients? A Systematic Review and Cost Analysis.

BACKGROUND: Computeed tomography (CT) is a cornerstone of the identification and management of acute changes in neurosurgery patients. In addition to the monetary expense of CT scans, further costs are incurred due to the time of patient transport and radiation exposure. Ultrasounds (USs)offer a safe, inexpensive, and bedside alternative to CT but obstacles remain due to decreased penetrance in the adult skull. Sonolucent Cranial Implants (SCIs) offer a window for USs to view intracranial architectures. METHODS: The authors performed a PRISMA guidelines-based systematic review of the literature. Information was extracted from included articles in regards to illness pathology, US imaging feasibility, comparison to standard imaging, infections, and revisions. Costs were collected in regards to price of implant and follow-up imaging. RESULTS: A total of 226 articles resulted, of which 5 were included in the study. Ninety non-duplicate patients who received SCIs were analyzed. The pathologies of included patients is as follows: 51 patients were after extracranial-intracranial bypass, 37 after ventriculoperitoneal shunt placement for hydrocephalus, 1 after tumor resection, and 1 after cranioplasty following decompressive hemicraniectomy. All studies noted feasibility of US and comparability to standard imaging following SCI placement. Follow-up imaging with trans-sonolucent cranial implant ultrasound was estimated to save up to $4,000 per patient depending on the procedure. CONCLUSIONS: Initial studies suggest that US imaging through SCIs is a safe and efficacious alternative to CT imaging in neurosurgical patients. Cost analysis suggests that SCI and subsequent US can offer a cost savings compared with current treatment.

The Evolution of Laser-Induced Thermal Therapy for the Treatment of Gliomas.

Laser-induced thermal therapy (LITT) has evolved over the past two decades to treat a number of intracranial pathologies. Although it initially emerged as a salvage treatment of surgically inoperable tumors or recurrent lesions that had exhausted more conventional treatments, it is now being used as a primary, first-line treatment in certain instances with outcomes comparable to traditional surgical resection. The authors discuss the evolution of LITT in the treatment of gliomas and future directions, which may further enhance the efficacy of this procedure.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Brainstem Pathologies.

OBJECTIVE: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive and effective treatment option that can potentially treat deep-seated pathologies in cases without safe open surgical corridors. In the present report, we have described our experience using MRgLITT for brainstem pathologies. METHODS: A retrospective medical record review and analysis were conducted for all patients who had undergone MRgLITT for pathologies within or closely surrounding the brainstem between 2011 and 2020. The patients had undergone stereotactic laser placement in the operating suite and were transported to the magnetic resonance imaging suite for laser ablation with real-time monitoring. The demographics, operative parameters, and complications were recorded. RESULTS: A total of 12 patients had undergone MRgLITT for brainstem pathologies. The average age of the patients was 47.6 years (range, 4-75 years). The pathologies included both primary and metastatic intracranial tumors. The average preablation volume of the targets was 2.4 ± 0.50 cm3. The average ablation time was 324.3 ± 60.7 seconds, and the average postablation volume was 2.92 ± 0.53 cm3. One perioperative mortality was directly related to the procedure and 7 patients developed postoperative deficits. Two patients had experienced a recurrence after MRgLITT and opted to undergo additional alternative treatment. CONCLUSIONS: The brainstem represents formidable territory even for minimally invasive procedures. The overall morbidity and mortality has remained high, and the probability of achieving a meaningful outcome must be carefully assessed.

Real-time navigation guidance with intraoperative CT imaging for pedicle screw placement using an augmented reality head-mounted display: a proof-of-concept study.

OBJECTIVE: Augmented reality (AR) has the potential to improve the accuracy and efficiency of instrumentation placement in spinal fusion surgery, increasing patient safety and outcomes, optimizing ergonomics in the surgical suite, and ultimately lowering procedural costs. The authors sought to describe the use of a commercial prototype Spine AR platform (SpineAR) that provides a commercial AR head-mounted display (ARHMD) user interface for navigation-guided spine surgery incorporating real-time navigation images from intraoperative imaging with a 3D-reconstructed model in the surgeon's field of view, and to assess screw placement accuracy via this method. METHODS: Pedicle screw placement accuracy was assessed and compared with literature-reported data of the freehand (FH) technique. Accuracy with SpineAR was also compared between participants of varying spine surgical experience. Eleven operators without prior experience with AR-assisted pedicle screw placement took part in the study: 5 attending neurosurgeons and 6 trainees (1 neurosurgical fellow, 1 senior orthopedic resident, 3 neurosurgical residents, and 1 medical student). Commercially available 3D-printed lumbar spine models were utilized as surrogates of human anatomy. Among the operators, a total of 192 screws were instrumented bilaterally from L2-5 using SpineAR in 24 lumbar spine models. All but one trainee also inserted 8 screws using the FH method. In addition to accuracy scoring using the Gertzbein-Robbins grading scale, axial trajectory was assessed, and user feedback on experience with SpineAR was collected. RESULTS: Based on the Gertzbein-Robbins grading scale, the overall screw placement accuracy using SpineAR among all users was 98.4% (192 screws). Accuracy for attendings and trainees was 99.1% (112 screws) and 97.5% (80 screws), respectively. Accuracy rates were higher compared with literature-reported lumbar screw placement accuracy using FH for attendings (99.1% vs 94.32%; p = 0.0212) and all users (98.4% vs 94.32%; p = 0.0099). The percentage of total inserted screws with a minimum of 5° medial angulation was 100%. No differences were observed between attendings and trainees or between the two methods. User feedback on SpineAR was generally positive. CONCLUSIONS: Screw placement was feasible and accurate using SpineAR, an ARHMD platform with real-time navigation guidance that provided a favorable surgeon-user experience.

Endoscope-Assisted Retromastoid Intradural Suprameatal Approach for Trigeminal Schwannoma.

BACKGROUND AND INTRODUCTION: Dumbbell trigeminal schwannoma is the second most common type of intracranial schwannomas. OBJECTIVE: Herein, we are describing and presenting a video of left trigeminal dumbbell schwannoma with a predominant posterior fossa component (modified Samii's grade C1), operated through left Retromastoid Intradural Suprameatal Approach (RISA). We demonstrate a step by step technique of a previously defined procedure for educational purpose. SURGICAL TECHNIQUE: The patient was placed in the right lateral position, and left retromastoid craniotomy was done. Dura was opened based on transverse and sigmoid sinus to expose tumors in the suprameatal region. The tumor removed piecemeal under the microscope, and later endoscope was introduced to identify and remove the residual tumor in the superolateral part of Meckel's cave. RESULTS: The patient had an uneventful recovery. CONCLUSION: Trigeminal schwannoma with a predominantly posterior fossa component can be excised through retromastoid sub-occipital craniotomy. Endoscopic-assisted microsurgery should be considered in all skull base tumors. Aim for complete excision, but safe maximal resection with GKRS for residual can be considered in difficult cases.

Cognard Grade IV Tentorial Dural Arteriovenous Fistula Presenting as Trigeminal Neuralgia: Endovascular Management.

Tentorial dural arteriovenous fistulas have an increased risk of rupture and hemorrhage, and therefore require urgent treatment to occlude the fistula and proximal venous drainage. This is usually accomplished via endovascular treatment. We present a case of a Cognard grade IV dural arteriovenous fistula that presented as trigeminal neuralgia. This video showcases the angiographic vascular composition of the lesion with main feeders coming from the middle meningeal artery and the tentorial artery of Bernasconi and Cassinari. Details, benefits, and risks of the procedure were thoroughly discussed with the patient and consent was obtained prior to the procedure. We performed endovascular Onyx embolization through a distal branch of the right middle meningeal artery. We were able to successfully occlude the lesion using Onyx embolization and the patient had significant improvement of her pretreatment trigeminal neuralgia.

Rapid Recovery of Cranial Nerve Deficits After Anterior Petrosal (Kawase) Approach for Medically Refractory Petrous Apicitis.

BACKGROUND: The mainstay treatment for petrous apicitis (Gradenigo's syndrome) is medical management with antibiotics, steroids, and placement of pressure equalization tubes. The role for surgery is limited as second-line treatment if conservative methods have failed. CASE DESCRIPTION: We report 2 cases of medically refractory petrous apicitis presenting with progressive cranial neuropathies who underwent petrous apex resection and debridement via an anterior petrosal (Kawase) approach. Both patients had improvement of their preoperative cranial nerve deficits within 24-48 hours of surgery, that previously did not improve after 2 weeks of medical management. CONCLUSIONS: To our knowledge, the use of the Kawase approach for petrous apicitis has not been previously reported. In addition, we postulate that surgical intervention can potentially result in quicker recovery of preexisting cranial nerve deficits in medically refractory petrous apicitis. This raises the potential role of earlier surgical intervention.

Outcomes and Spectrum of Major Neurovascular Events Among COVID-19 Patients: A 3-Center Experience.

BACKGROUND: Preliminary data suggest that Coronavirus Disease-2019 (COVID-19) is associated with hypercoagulability and neurovascular events, but data on outcomes is limited. OBJECTIVE: To report the clinical course and outcomes of a case series of COVID-19 patients with a variety of cerebrovascular events. METHODS: We performed a multicentric, retrospective chart review at our three academic tertiary care hospitals, and identified all COVID-19 patients with cerebrovascular events requiring neuro-intensive care and/or neurosurgical consultation. RESULTS: We identified 26 patients between March 1 and May 24, 2020, of whom 12 (46%) died. The most common event was a large-vessel occlusion (LVO) in 15 patients (58%), among whom 8 died (8/15, 53%). A total of 9 LVO patients underwent mechanical thrombectomy, of whom 5 died (5/9, 56%). A total of 7 patients (27%) presented with intracranial hemorrhage. Of the remaining patients, 2 had small-vessel occlusions, 1 had cerebral venous sinus thrombosis, and another had a vertebral artery dissection. Acute Respiratory Distress Syndrome occurred in 8 patients, of whom 7 died. Mortalities had a higher D-dimer on admission (mean 20 963 ng/mL) than survivors (mean 3172 ng/mL). Admission Glasgow Coma Scale (GCS) score was poor among mortalities (median 7), whereas survivors had a favorable GCS at presentation (median 14) and at discharge (median 14). CONCLUSION: COVID-19 may be associated with hemorrhage as well as ischemia, and prognosis appears poorer than expected-particularly among LVO cases, where outcome remained poor despite mechanical thrombectomy. However, a favorable neurological condition on admission and lower D-dimer may indicate a better outcome.

Parasitic infections of the spine: case series and review of the literature.

OBJECTIVEAlthough parasitic infections are endemic to parts of the developing world and are more common in areas with developing economies and poor sanitary conditions, rare cases may occur in developed regions of the world.METHODSArticles eligible for the authors' literature review were initially searched using PubMed with the phrases "parasitic infections" and "spine." After the authors developed a list of parasites associated with spinal cord infections from the initial search, they expanded it to include individual diagnoses, using search terms including "neurocysticercosis," "schistosomiasis," "echinococcosis," and "toxoplasmosis."RESULTSTwo recent cases of parasitic spinal infections from the authors' institution are included.CONCLUSIONSKey findings on imaging modalities, laboratory studies suggestive of parasitic infection, and most importantly a thorough patient history are required to correctly diagnose parasitic spinal infections.

Magnetic Resonance-Guided Laser-Induced Thermal Therapy for the Treatment of Progressive Enhancing Inflammatory Reactions Following Stereotactic Radiosurgery, or PEIRs, for Metastatic Brain Disease.

BACKGROUND: In patients who have previously undergone maximum radiation for metastatic brain tumors, a progressive enhancing inflammatory reaction (PEIR) that represents either tumor recurrence or radiation necrosis, or a combination of both, can occur. Magnetic resonance-guided laser-induced thermal therapy (LITT) offers a minimally invasive treatment option for this problem. OBJECTIVE: To report our single-center experience using LITT to treat PEIRs after radiosurgery for brain metastases. METHODS: Patients with progressive, enhancing reactions at the site of prior radiosurgery for metastatic brain tumors and who had a Karnofsky performance status of ≥70 were eligible for LITT. The primary endpoint was local control. Secondary end points included dexamethasone use and procedure-related complications. RESULTS: Between 2010 and 2017, 59 patients who underwent 74 LITT procedures for 74 PEIRs met inclusion criteria. The mean pre-LITT PEIR size measured 3.4 ± 0.4 cm3. At a median follow-up of 44.6 wk post-LITT, the local control rate was 83.1%. Most patients were weaned off steroids post-LITT. Patients experiencing a post-LITT complication were more likely to remain on steroids indefinitely. The rate of new permanent neurological deficit was 3.4%. CONCLUSION: LITT is an effective treatment for local control of PEIRs after radiosurgery for metastatic brain disease. When possible, we recommend offering LITT once PEIRs are identified and prior to the initiation of high-dose steroids for symptom relief.

Volumetric trends of progressive in-field recurrences after stereotactic radiosurgery of metastatic intracranial tumors.

OBJECTIVE: Local recurrence after stereotactic radiosurgery for brain metastasis is a well-known problem. We analyzed volumetric trends from the time of radiosurgery to time of treatment to understand progression behavior. METHODS: A retrospective review of patients who underwent treatment for post-radiation progressive lesions was performed. Volumetric trends were obtained by plotting individual lesion volumes from the post-radiation nadir volume to volume at treatment and then fitted to exponential decay or linear regressions. RESULTS: Twenty-eight post-radiation recurrences demonstrated exponential growth and thirteen followed a linear pattern. For lesions exhibiting exponential growth, the average nadir volume was 0.26cm3 (SEM=0.06) at an average of 298 days before treatment and mean volume at treatment was 2.39cm3 (SEM=0.33). The average adjusted R2 was 0.94 (SEM=0.013) and doubling factor was 68.60days (SEM=12.55). In the linear growth cohort, the mean nadir volume was 1.43cm3 (SEM=0.25) at an average of 158 days before treatment and average volume at treatment was 6.90cm3 (SEM=1.43). The mean R2 was 0.92 (SEM=0.02) and average growth rate was 0.034cm3/day. Majority of lesions from primary non-small cell lung cancer (81%) and breast cancer (63%) followed exponential growth. CONCLUSIONS: Exponential and linear regressions are accurate representations of post-radiation progression behavior and may be valuable in understanding the growth patterns for recurrences ultimately requiring treatment.

Low Yield of Cerebral Angiography in Adequately Occluded Aneurysms After Flow Diversion.

BACKGROUND: Flow diversion has emerged as a highly effective treatment for intracranial aneurysms. OBJECTIVE: To assess the yield of further angiographic follow-up in aneurysms that have achieved adequate occlusion after treatment with the Pipeline Embolization Device (PED; Medtronic Inc, Dublin, Ireland). METHODS: This is a single-institution, retrospective study. Inclusion criteria were as follows: (1) patients with 1 or more aneurysms treated with PED, (2) available short-term (<12 mo) follow-up digital subtraction angiography (DSA), (3) complete (100%) or near-complete (>95%) occlusion on short-term follow-up DSA, and (4) available further angiographic follow-up (DSA, Magnetic Resonance Angiography (MRA), or Computed Tomography Angiography (CTA)). RESULTS: A total of 146 patients were identified. Aneurysm size was 8.4 ± 5.1 mm on average. Mean angiographic follow-up time was 29.7 ± 12.2 mo. On short-term follow-up DSA images, 132 (90.4%) had complete aneurysm occlusion and 14 (9.6%) had near-complete occlusion. Four patients (3%) had further DSA follow-up alone, 30 patients (21%) had further DSA and MRA/CTA follow-up, and 112 patients (76%) had further MRA/CTA follow-up alone. On further angiographic follow-up (DSA, MRA, and/or CTA), no patient had a decrease in the degree of aneurysm occlusion (recurrence) or required retreatment. Of the 14 patients with near-complete occlusion on initial DSA images, 7 patients (50%) progressed to complete aneurysm occlusion on further angiographic follow-up. CONCLUSION: This study did not find any diagnostic yield in repeating cerebral angiography in adequately occluded aneurysms with the PED. We do not recommend repeat angiographic follow-up once aneurysms have achieved complete occlusion with the PED unless clinically warranted.

Off-label uses of the Pipeline embolization device: a review of the literature.

The Pipeline embolization device (PED) is the most widely used flow diverter in endovascular neurosurgery. In 2011, the device received FDA approval for the treatment of large and giant aneurysms in the internal carotid artery extending from the petrous to the superior hypophyseal segments. However, as popularity of the device grew and neurosurgeons gained more experience, its use has extended to several other indications. Some of these off-label uses include previously treated aneurysms, acutely ruptured aneurysms, small aneurysms, distal circulation aneurysms, posterior circulation aneurysms, fusiform aneurysms, dissecting aneurysms, pseudoaneurysms, and even carotid-cavernous fistulas. The authors present a literature review of the safety and efficacy of the PED in these off-label uses.

The Role of MRgLITT in Overcoming the Challenges in Managing Infield Recurrence After Radiation for Brain Metastasis.

Radiation necrosis and tumor recurrence are common sequelae after radiation therapy for brain metastasis. The differentiation of radiation necrosis and recurrent brain metastases continues to remain a difficult task despite a number of diagnostic methods. Techniques including magnetic resonance imaging, diffusion-weighted imaging, nuclear studies, and the gold standard of biopsy have all been studied for their effectiveness in accurately diagnosing the postradiation condition. Various specific treatment options of the distinct pathologies are available with the general theory that recurrences require more immediate treatment whereas radiation necrosis can be observed until symptomatic before intervention. This further emphasizes the necessity to accurately diagnose the condition to start appropriate and effective treatment. Despite both pathologies being pathophysiologically distinct, controversies exist as to whether there should be a distinction made at all or if the two can be perceived as a single condition if treatment and presentation are similar enough. Furthermore, a single treatment option such as magnetic resonance-guided, laser-induced thermal therapy (MRgLITT) can be used, potentially eliminating the need to differentiate the 2 entities because it successfully treats both conditions while being minimally invasive. ABBREVIATIONS: ADC, apparent diffusion coefficientDWI, diffusion-weighted imagingFDG, fluorodeoxyglucoseMET, 11C-labeled methionineMRgLITT, magnetic resonance-guided, laser-induced thermal therapyMRS, magnetic resonance spectroscopySPECT, single-photon emission computed tomographyT/N, ratio of tumor tissue to normal tissueVEGF, vascular endothelial growth factor.

Intracranial MR-guided laser-induced thermal therapy: single-center experience with the Visualase thermal therapy system.

OBJECTIVE MR-guided laser-induced thermal therapy (MRgLITT) can be used to treat intracranial tumors, epilepsy, and chronic pain syndromes. Here, the authors report their single-center experience with 102 patients, the largest series to date in which the Visualase thermal therapy system was used. METHODS A retrospective analysis of all patients who underwent MRgLITT between 2010 and 2014 was performed. Pathologies included glioma, recurrent metastasis, radiation necrosis, chronic pain, and epilepsy. Laser catheters were placed stereotactically, and ablation was performed in the MRI suite. Demographics, operative parameters, length of hospital stay, and complications were recorded. Thirty-day readmission rates were calculated by using the standard method according to America's Health Insurance Plans Center for Policy and Research guidelines. RESULTS A total of 133 lasers were placed in 102 patients who required intervention for intracranial tumors (87 patients), chronic pain syndrome (cingulotomy, 5 patients), or epilepsy (10 patients). The procedure was completed in 98% (100) of these patients. Ninety-two patients (90.2%) had undergone previous treatment for their intracranial tumors. The average (± SD) total procedural time was 170.5 ± 34.4 minutes, and the mean laser-on time was 8.7 ± 6.8 minutes. The average intensive care unit (ICU) and hospital stays were 1.8 and 3.6 days, respectively, and the median length of stay for both the ICU and the hospital was 1 day. By postoperative Day 1, 54% of the patients (n = 55) were neurologically stable for discharge. There were 27 cases of morbidity, including new-onset neurological deficits, and 2 perioperative deaths. Fourteen patients (13.7%) developed new deficits after the MRgLITT procedure, and of those 14 patients, 64.3% (n = 9) had complete resolution of deficits within 1 month, 7.1% (n = 1) had partial resolution of symptoms within 1 month, 14.3% (n = 2) had not had resolution of symptoms at the most recent follow-up, and 14.3% (n = 2) died without resolution of symptoms. The 30-day readmission rate was 5.6% CONCLUSIONS MRgLITT, although minimally invasive, must be used with caution. Thermal damage to critical and eloquent structures can occur despite MRI guidance. Once the learning curve is overcome, the overall procedural complication rate is low, and most patients can be discharged within 24 hours, with a relatively low readmission rate. In cases in which they occurred, most neurological deficits were temporary. The therapeutic role of MRgLITT in various intracranial diseases will require larger and more rigorous studies.