Identifying the Sylvian Triangle on CT angiography: A technique for detecting distal middle cerebral artery occlusions.

Medium vessel occlusions (MeVOs), defined as occlusion of the M2/M3 and A2/A3 segments of the middle cerebral artery (MCA) and anterior cerebral artery, can be challenging to visualize on CT angiography (CTA) and MR angiography (MRA), given the anatomic complexity of the mid- and distal intracranial vasculature and smaller vessel caliber (Leary MC, Kidwell CS, Villablanca JP, et al. Validation of computed tomographic MCA "dot" sign: an angiographic correlation study. Stroke 2003; 34: 2636-2640; Luijten SPR, Wolff L, Duvekot MHC, et al. Diagnostic performance of an algorithm for automated large vessel occlusion (LVO) detection on CTA. J Neurointerv Surg 2022; 14: 794-798). In turn, the appearance of a sudden vessel cutoff in these vascular distributions on CTA or MRA is not always straightforward and may represent true occlusion, variant anatomy, and/or artifact (Leary MC, Kidwell CS, Villablanca JP, et al. Validation of computed tomographic MCA "dot" sign: an angiographic correlation study. Stroke 2003; 34: 2636-2640; Luijten SPR, Wolff L, Duvekot MHC, et al. Diagnostic performance of an algorithm for automated LVO detection on CTA. J Neurointerv Surg 2022; 14: 794-798). Given the importance of rapidly establishing an accurate diagnosis in the setting of stroke, combined with recent clinical trials and movements promoting the efficacy of endovascular therapeutic approaches to treat MeVOs, it remains imperative to detect such occlusions accurately and quickly on imaging. In turn, we present five imaging patterns of the Sylvian Triangle on sagittal reformatted images from CTA Head examinations, which our practice has utilized to assess patency of the M2 and M3 divisions. This approach is rapidly deployable and can be utilized by radiology and non-radiology healthcare providers alike, thus facilitating rapid and accurate diagnosis of MeVO, timely evaluation of candidacy for endovascular therapy, and ultimately supporting favorable door-to-intervention time and successful patient outcomes.

Endovascular Management of Intracranial Vertebral Artery Dissection: Technical Nuances for the Preservation of Posterior Inferior Cerebellar Artery and Basilar Artery.

BACKGROUND: The treatment of intracranial vertebral artery dissection (VAD) can be challenging. OBJECTIVE: To evaluate the clinical presentation, endovascular treatment techniques, and prognostic outcome of patients diagnosed with intracranial VAD at our institution. METHODS: A retrospective analysis of 35 patients who were diagnosed with VAD at our institution over 17-yr period (2001-2017) is presented. A total of 27 patients with a total of 30 affected arteries underwent endovascular treatment, and their outcome was evaluated. RESULTS: Of the 35 total patients with VAD, 15 presented with headache, 12 with focal neurological deficits, 2 with neck pain, 2 with dizziness, 1 with syncope, and 3 after trauma. Of the 30 dissected arteries, 18 were treated with deconstruction and 12 were treated with stent reconstruction. Treatment method was determined by the dominance of the affected artery and location relative to the ipsilateral posterior inferior cerebellar artery (PICA) and the basilar artery. Deconstructive techniques were utilized in all cases of hypoplastic artery dissection and the majority of codominant artery dissections, whereas reconstruction was performed on the majority of dominant artery dissections. Rupture did not impact treatment technique. Four patients demonstrated post-treatment infarcts, and another 1 patient died because of intraparenchymal bleed. The remaining 22 patients demonstrated favorable clinical outcome. None of the patients developed recanalization or needed retreatment till the last follow-up. CONCLUSION: This study suggests that endovascular treatment of intracranial VAD with deconstruction or stent reconstruction based on the patients anatomy, particularly vessel dominance and location with respect to PICA, is feasible and effective though the revascularization procedures still has its role in selected cases.

Neuroendovascular Cerebral Sinus Stenting in Idiopathic Intracranial Hypertension.

Idiopathic intracranial hypertension (IIH) is a rare, ill-understood disease of significant morbidity. Because the pathophysiology is poorly understood, treatment protocols are not uniform and are directed towards alleviating the most common symptoms: headache and visual loss. In this review, we analyze 25 case series, all of which included IIH patients (n = 408) who were treated with placement of a venous sinus stent. Among 342 patients who had headache, 240 patients (70.2%) had improvement or resolution of headache after the stent insertion. Of the 217 patients documented to have visual problems, visual acuity was improved or stabilized in 161 patients (74.2%). Of the 304 patients with papilledema, 257 showed resolution or improved (84.5%). Of the 124 patients who presented with pulsatile tinnitus, it was resolved in 110 patients (88.7%) after stent placement. Endovascular management of dural sinus stenosis is therefore clinically efficacious in patients with IIH who have failed medical and surgical therapy.

Updates in the Management of Cerebral Infarctions and Subarachnoid Hemorrhage Secondary to Intracranial Arterial Dissection: A Systematic Review.

OBJECTIVE: Intracranial arterial dissection (IAD) is a rare cerebrovascular disease that is likely underdiagnosed because of the inherent difficulty of visualizing the subtle radiographic signs of the pathologic small intracranial arteries. No widespread consensus exists on the treatment of IAD, and thus it is often managed empirically because of the absence of major randomized controlled trials. In this study, we conducted a systematic review to evaluate the management and treatment options for IAD. METHODS: We performed a systematic review in accordance with the PRISMA guidelines using the following databases: MEDLINE (PubMed) and Cochrane Library. Included studies were limited to human patients with dissections in intracranial vessels only. RESULTS: A total of 82 studies were included in this systematic review. The most common complications of IAD were cerebral infarction and subarachnoid hemorrhage, and thus, patients with IAD can be subdivided into those presenting with either ischemia or hemorrhage, respectively. Those with ischemia were predominantly managed with antiplatelet therapy, whereas patients presenting with hemorrhage often were amenable to treatment with endovascular techniques. CONCLUSIONS: Given these findings, clinicians should prescribe antiplatelet therapy for patients with IAD presenting with ischemia and consider endovascular treatment for those presenting with hemorrhage. However, further investigation is required given the heterogeneity of methods and reporting outcomes in the investigated studies.

Volumetric Trends Associated with MR-guided Stereotactic Laser Amygdalohippocampectomy in Mesial Temporal Lobe Epilepsy.

OBJECTIVE: Magnetic resonance (MR)-guided stereotactic laser amygdalohippocampectomy is a minimally invasive procedure for the treatment of refractory epilepsy in patients with mesial temporal sclerosis. Limited data exist on post-ablation volumetric trends associated with the procedure. METHODS: 10 patients with mesial temporal sclerosis underwent MR-guided stereotactic laser amygdalohippocampectomy. Three independent raters computed ablation volumes at the following time points: pre-ablation (PreA), immediate post-ablation (IPA), 24 hours post-ablation (24PA), first follow-up post-ablation (FPA), and greater than three months follow-up post-ablation (>3MPA), using OsiriX DICOM Viewer (Pixmeo, Bernex, Switzerland). Statistical trends in post-ablation volumes were determined for the time points. RESULTS: MR-guided stereotactic laser amygdalohippocampectomy produces a rapid rise and distinct peak in post-ablation volume immediately following the procedure. IPA volumes are significantly higher than all other time points. Comparing individual time points within each raters dataset (intra-rater), a significant difference was seen between the IPA time point and all others. There was no statistical difference between the 24PA, FPA, and >3MPA time points. A correlation analysis demonstrated the strongest correlations at the 24PA (r=0.97), FPA (r=0.95), and 3MPA time points (r=0.99), with a weaker correlation at IPA (r=0.92). CONCLUSION: MR-guided stereotactic laser amygdalohippocampectomy produces a maximal increase in post-ablation volume immediately following the procedure, which decreases and stabilizes at 24 hours post-procedure and beyond three months follow-up. Based on the correlation analysis, the lower inter-rater reliability at the IPA time point suggests it may be less accurate to assess volume at this time point. We recommend post-ablation volume assessments be made at least 24 hours post-selective ablation of the amygdalohippocampal complex (SLAH).

Mechanical thrombectomy - is time still brain? The DAWN of a new era.

PURPOSE: The purpose of this study is to review the history of treatments for acute ischemic stroke, examine developments in endovascular therapy, and discuss the future of the management of acute ischemic stroke. METHODS: A selective review of recent clinical trials for the treatment of acute ischemic stroke was conducted. RESULTS: We reviewed completed trials of the management of acute ischemic stroke including intravenous thrombolytics, intraarterial thrombolytics, and thrombectomy. We also assessed the future direction of research by reviewing ongoing clinical trials. CONCLUSIONS: The advancement of endovascular treatment for stroke has led to improved morbidity and mortality for patients. Future challenges include delivering these treatments to stroke centers worldwide.

Accuracy of Laser Placement With Frameless Stereotaxy in Magnetic Resonance-Guided Laser-Induced Thermal Therapy.

BACKGROUND: As magnetic resonance-guided laser-induced thermal therapy (MRgLITT) becomes more accepted, there needs to be an evaluation of the techniques required to achieve accurate laser placement. OBJECTIVE: To report our experience with frameless stereotaxy and the ability to achieve accurate laser placements. We also evaluate the variables associated with proper placement. METHODS: We performed a retrospective analysis from 3 years of MRgLITT. Demographics and operational parameters, including trajectory length, target alignment error, registration error, and radial error were recorded and compared. Blinded review was used for completeness of ablation. RESULTS: In the study, 90 laser placements were evaluated for 72 cases. Trajectory length and target alignment error was 95.3 ± 26.0 mm and 0.7 ± 0.3 mm, respectively. Significant differences existed in registration error between 4 (0.6 ± 0.3 mm) and 5 (0.5 ± 0.2 mm) skull pins (P = .04), but no significant decreases in registration error as additional skull pins were registered. Fifteen laser placements resulted in subtotal ablations. The overall radial error using frameless stereotaxy was 0.9 ± 1.6 mm. In the study, 65% of lasers were exactly on the planned trajectory. Of the 30 that were not, the radial error = 2.6 ± 1.9 mm. Radial error of subtotal laser ablations was 0.5 ± 0.9 (range, 0-2.8 mm) and was not significantly different from 0.8 ± 1.7 (range, 0-7.1 mm) radial error of lasers with total ablations (P = .52). Lasers with radial error >0 mm resulted in an incomplete ablation in 26.7% of cases. CONCLUSION: Skull pin-based frameless stereotaxy for MRgLITT results in consistent accuracy, with the majority of cases resulting in complete ablations. A significant proportion of lasers with RE >0 mm still result in complete ablations.

Treatment of a supratentorial primitive neuroectodermal tumor using magnetic resonance-guided laser-induced thermal therapy.

Supratentorial primitive neuroectodermal tumors (PNETs) are rare tumors that carry a poorer prognosis than those arising from the infratentorial compartment (such as medulloblastoma). The overall prognosis for these patients depends on several factors including the extent of resection, age at diagnosis, CSF dissemination, and site in the supratentorial space. The authors present the first case of a patient with a newly diagnosed supratentorial PNET in which cytoreduction was achieved with MR-guided laser-induced thermal therapy. A 10-year-old girl presented with left-sided facial weakness and a large right thalamic mass extending into the right midbrain. The diagnosis of supratentorial PNET was made after stereotactic biopsy. Therapeutic options for this lesion were limited because of the risks of postoperative neurological deficits with resection. The patient underwent MR-guided laser-induced thermal ablation of her tumor. Under real-time MR thermometry, thermal energy was delivered to the tumor at a core temperature of 90°C for a total of 960 seconds. The patient underwent follow-up MR imaging at regular intervals to evaluate the tumor response to the thermal ablation procedure. Initial postoperative scans showed an increase in the size of the lesion as well as the amount of the associated edema. Both the size of the lesion and the edema stabilized by 1 week and then decreased below preablation levels at the 3-month postsurgical follow-up. There was a slight increase in the size of the lesion and associated edema at the 6-month follow-up scan, presumably due to concomitant radiation she received as part of her postoperative care. The patient tolerated the procedure well and has had resolution of her symptoms since surgery. Further study is needed to assess the role of laser-induced thermal therapy for the treatment of intracranial tumors. As such, it is a promising tool in the neurosurgical armamentarium. Postoperative imaging has shown no evidence of definitive recurrence at the 6-month follow-up period, but longer-term follow-up is required to assess for late recurrence.

Acute multiple sclerosis lesion: conversion of restricted diffusion due to vasogenic edema.

It is widely accepted that acute demyelinating plaques in patients with multiple sclerosis (MS) demonstrate increased apparent diffusion coefficient (ADC) and increased diffusion weighted imaging (DWI) signals on MRI. These imaging characteristics in acute MS lesions have been postulated to be due to peripheral vasogenic edema that typically increases the ADC. This assumption is commonly used to differentiate stroke from MS lesions since acute and subacute stroke lesions demonstrate increased DWI signal with reduced ADC due to acute cytotoxic edema. We report a case of active relapsing-remitting MS with two new symptomatic contrast-enhancing lesions. The lesions had reduced diffusion on the ADC map in the early acute phase of MS exacerbation. The reduced ADC signal was subsequently "converted" to increased ADC signal that coincided with the development of profound peripheral vasogenic edema seen on T2-weighted images. To our knowledge, this is the first serial MRI study describing decreased ADC signal in the early acute phase of contrast-enhancing MS lesion. The implications of decreased diffusion in the acute phase of MS lesions for the disease pathogenesis are discussed.

Endovascular treatment of a ruptured giant serpentine aneurysm of the superior cerebellar artery in a patient with a Chiari II malformation.

We present a case of a ruptured giant serpentine aneurysm (GSA) of the superior cerebellar artery in a patient with a Chiari II malformation. The fusiform aneurysm was successfully treated with endovascular parent artery occlusion of the GSA by using detachable coils.