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.

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.

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.

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.