Editorial. Toward reducing futile recanalization in stroke: automated prediction of final infarct volume
Muhammad Waqas and Elad I. Levy
High-intensity focused ultrasound: past, present, and future in neurosurgery
Syed A. Quadri, Muhammad Waqas, Inamullah Khan, Muhammad Adnan Khan, Sajid S. Suriya, Mudassir Farooqui, and Brian Fiani
Since Lynn and colleagues first described the use of focused ultrasound (FUS) waves for intracranial ablation in 1942, many strides have been made toward the treatment of several brain pathologies using this novel technology. In the modern era of minimal invasiveness, high-intensity focused ultrasound (HIFU) promises therapeutic utility for multiple neurosurgical applications, including treatment of tumors, stroke, epilepsy, and functional disorders. Although the use of HIFU as a potential therapeutic modality in the brain has been under study for several decades, relatively few neuroscientists, neurologists, or even neurosurgeons are familiar with it. In this extensive review, the authors intend to shed light on the current use of HIFU in different neurosurgical avenues and its mechanism of action, as well as provide an update on the outcome of various trials and advances expected from various preclinical studies in the near future. Although the initial technical challenges have been overcome and the technology has been improved, only very few clinical trials have thus far been carried out. The number of clinical trials related to neurological disorders is expected to increase in the coming years, as this novel therapeutic device appears to have a substantial expansive potential. There is great opportunity to expand the use of HIFU across various medical and surgical disciplines for the treatment of different pathologies. As this technology gains recognition, it will open the door for further research opportunities and innovation.
Sovereign immunity and its implications for neurosurgery
Rimal H. Dossani, Muhammad Waqas, Michael J. Meyer, Felix Chin, Hamid H. Rai, Rameez Dossani, Anshara Munir Dossani, and Muhammad Riaz
The proportion of neurosurgeons facing a malpractice suit each year is highest among all medical and surgical specialties. It is critical for neurosurgeons to understand local malpractice laws because they vary among states. Sovereign immunity, as described in the 11th constitutional amendment, provides absolute immunity to states from being sued by their residents and by other states. A state may waive its sovereign immunity, however, and substitute itself as the defendant in place of a state-employed physician in the court of law. This means that a physician working for a state-funded hospital may not be liable to a malpractice suit. Further provisions of the law allow the state not to pay indemnity beyond a certain limit, which discourages plaintiff attorneys from pursuing indemnity charges against physicians working for state-funded institutions. In this review, the authors describe the concept of sovereign immunity and its implications for the practice of neurosurgery.
First reported single-surgeon transpalpebral hybrid approach for indirect cavernous carotid fistula: illustrative case
Justin M. Cappuzzo, Ammad A. Baig, William Metcalf-Doetsch, Muhammad Waqas, Andre Monteiro, and Elad I. Levy
Failure to reach the cavernous sinus after multiple transvenous attempts, although rare, can be challenging for neurointerventionists. The authors sought to demonstrate technical considerations and nuances of the independent performance of a novel hybrid surgical and endovascular transpalpebral approach through the superior ophthalmic vein (SOV) for direct coil embolization of an indirect carotid cavernous fistula (CCF), and they review salient literature regarding the transpalpebral approach.
An illustrative case, including patient history and presentation, was reviewed. PubMed, MEDLINE, and Embase databases were searched for articles published between January 1, 2000, and September 30, 2021, that reported ≥1 patient with a CCF treated endovascularly via the SOV approach. Data extracted included sample size, treatment modality, surgical technique, performing surgeon specialty, and procedure outcome. The authors’ case illustration demonstrates the technique for the hybrid transpalpebral approach. For the review, 273 unique articles were identified; 14 containing 74 treated patients fulfilled the inclusion criteria. Oculoplastic surgery was the most commonly involved specialty (5 of 14 studies), followed by ophthalmology (3 of 14). Coiling alone was the treatment of choice in 12 studies, with adjunctive use of Onyx (Medtronic) in 2.
The authors’ technical case description, video, illustrations, and review provide endovascular neurosurgeons with a systematic guide to conduct the procedure independently.
Deployment of distal posterior cerebral artery flow diverter in tortuous anatomy
Kunal Vakharia, Stephan A. Munich, Muhammad Waqas, Swetadri Vasan Setlur Nagesh, and Elad I. Levy
Progressive deconstruction with flow diversion using a Pipeline embolization device (PED; Medtronic) can be utilized to promote thrombosis of broad-based fusiform aneurysms. Current flow diverters require a 0.027-inch microcatheter for deployment. The authors present a patient with a fusiform P2–3 junction posterior cerebral artery aneurysm in which they demonstrate the importance of haptics in microwire manipulation to recognize large-vessel anatomy versus perforator anatomy that may overlap, especially when access is needed in distal tortuous circulations. In addition, the authors demonstrate the need for appropriate visualization before PED deployment. Postembolization runs demonstrated optimal wall apposition with contrast stasis within the aneurysm dome.
The video can be found here: https://youtu.be/8kfsSvN3XqM.
Stent anchor technique to reduce microcatheter loop for stent-assisted coiling of anterior communicating artery aneurysm
Kunal Vakharia, Stephan A. Munich, Michael K. Tso, Muhammad Waqas, and Elad I. Levy
Stent-assisted coiling offers a potential solution for coil embolization of broad-based aneurysms. Challenges associated with navigating a microcatheter beyond these aneurysms sometimes require looping the microcatheter within the aneurysm dome. Reducing microcatheter loops within domes can be difficult, and anchor techniques have been described, including balloon anchor, stent-retriever anchor, and stent anchor techniques. The authors present a patient requiring stent-assisted coiling of an anterior communicating artery aneurysm in whom a stent anchor technique was used to reduce a microcatheter loop within an aneurysm dome before coil embolization. Postembolization angiographic runs showed complete coil occlusion of the aneurysm with approximately 35% packing density.
The video can be found here: https://youtu.be/zHR1ZOArUro.
Evolution of the patient-first approach: a dual-trained, single-neurosurgeon experience with 2002 consecutive intracranial aneurysm treatments
Muhammad Waqas, Andre Monteiro, Justin M. Cappuzzo, Vincent M. Tutino, and Elad I. Levy
The paradigm for intracranial aneurysm (IA) treatment is shifting toward a hybrid approach involving open and endovascular techniques. The authors chronicled the evolution of IA treatment by retrospectively examining a large series of IA cases treated by a single dual-trained neurosurgeon, focusing on evolving technology relative to the choice of treatment options, perioperative morbidity, and mortality.
The aneurysm database at the authors’ institution was searched to identify consecutive patients treated with endovascular or open microsurgical approaches by one neurosurgeon during an 18-year time span. Patients were included regardless of IA rupture status, location or morphology, or treatment modality. Data collected were baseline clinical characteristics, aneurysm size, treatment modality, operative complications, in-hospital mortality, and retreatment rate.
A total of 1858 patients with 2002 IA treatments were included in the study. Three-hundred fifty IAs (17.5%) were ruptured. Open microsurgery was performed in 504 aneurysms (25.2%) and endovascular surgery in 1498 (74.8%). Endovascular IA treatments trended toward a growing use of flow diversion during the last 11 years. In-hospital mortality was 1.7% overall, including 7.0% in ruptured and 0.5% in unruptured cases. The overall complication rate was 3.3%, including 3.4% for microsurgical cases and 3.3% for endovascular cases. The rate of retreatment was 3.6% after clipping and 10.7% for endovascular treatment.
This study demonstrates complementary use of open and endovascular approaches for IA treatment. By customizing treatment to the patient, comparable rates of procedural complications, mortality, and retreatment were achieved for both endovascular and microsurgical approaches.
FRED flow diversion with LVIS protection of large posterior communicating artery aneurysm: the "FRELVIS" technique
Steven B. Housley, Justin M. Cappuzzo, Muhammad Waqas, Andre Monteiro, Elad I. Levy, and Adnan H. Siddiqui
Treatment of wide-necked posterior communicating artery (PCoA) aneurysms is extremely challenging, especially in fetal posterior cerebral artery (PCA) configurations. This technical video demonstrates the nuances of an innovative use of flow diversion to treat a recurrent wide-necked PCoA aneurysm. This middle-aged patient presented with recurrence of a previously ruptured, coil-embolized PCoA aneurysm. Initial attempts at Comaneci-assisted coiling were unsuccessful because the coil herniated into the middle cerebral artery (MCA). Therefore, a low-profile visualized intraluminal support (LVIS) was placed in the fetal PCA across the aneurysm ostium and a flow diverter was placed in the internal carotid artery and MCA to constitute a Y-construct.
The video can be found here: https://stream.cadmore.media/r10.3171/2022.7.FOCVID2262
Evaluating a 3D deep learning pipeline for cerebral vessel and intracranial aneurysm segmentation from computed tomography angiography–digital subtraction angiography image pairs
Tatsat R. Patel, Aakash Patel, Sricharan S. Veeturi, Munjal Shah, Muhammad Waqas, Andre Monteiro, Ammad A. Baig, Nandor Pinter, Elad I. Levy, Adnan H. Siddiqui, and Vincent M. Tutino
Computed tomography angiography (CTA) is the most widely used imaging modality for intracranial aneurysm (IA) management, yet it remains inferior to digital subtraction angiography (DSA) for IA detection, particularly of small IAs in the cavernous carotid region. The authors evaluated a deep learning pipeline for segmentation of vessels and IAs from CTA using coregistered, segmented DSA images as ground truth.
Using 50 paired CTA-DSA images, the authors trained (n = 27), validated (n = 3), and tested (n = 20) a deep learning model (3D DeepMedic) for cerebrovasculature segmentation from CTA. A landmark-based coregistration algorithm was used for registration and upsampling of CTA images to paired DSA images. Segmented vessels from the DSA were used as the ground truth. Accuracy of the model for vessel segmentation was evaluated using conventional metrics (dice similarity coefficient [DSC]) and vessel segmentation–specific metrics, like connectivity-area-length (CAL). On the test cases (20 IAs), 3 expert raters attempted to detect and segment IAs. For each rater, the authors recorded the rate of IA detection, and for detected IAs, raters segmented and calculated important IA morphology parameters to quantify the differences in IA segmentation by raters to segmentations by DeepMedic. The agreement between raters, DeepMedic, and ground truth was assessed using Krippendorf’s alpha.
In testing, the DeepMedic model yielded a CAL of 0.971 ± 0.007 and a DSC of 0.868 ± 0.008. The model prediction delineated all IAs and resulted in average error rates of < 10% for all IA morphometrics. Conversely, average IA detection accuracy by the raters was 0.653 (undetected IAs were present to a significantly greater degree on the ICA, likely due to those in the cavernous region, and were significantly smaller). Error rates for IA morphometrics in rater-segmented cases were significantly higher than in DeepMedic-segmented cases, particularly for neck (p = 0.003) and surface area (p = 0.04). For IA morphology, agreement between the raters was acceptable for most metrics, except for the undulation index (α = 0.36) and the nonsphericity index (α = 0.69). Agreement between DeepMedic and ground truth was consistently higher compared with that between expert raters and ground truth.
This CTA segmentation network (DeepMedic trained on DSA-segmented vessels) provides a high-fidelity solution for CTA vessel segmentation, particularly for vessels and IAs in the carotid cavernous region.
Mechanical thrombectomy versus intravenous thrombolysis for distal large-vessel occlusion: a systematic review and meta-analysis of observational studies
Muhammad Waqas, Cathleen C. Kuo, Rimal H. Dossani, Andre Monteiro, Ammad A. Baig, Modhi Alkhaldi, Justin M. Cappuzzo, Elad I. Levy, and Adnan H. Siddiqui
While several studies have compared the feasibility and safety of mechanical thrombectomy (MT) for distal large-vessel occlusion (LVO) strokes in patients, few studies have compared MT with intravenous thrombolysis (IVT) alone. The purpose of this systematic review was to compare the effectiveness and safety between MT and standard medical management with IVT alone for patients with distal LVOs.
PubMed, Google Scholar, Embase, Scopus, Web of Science, Ovid Medline, and Cochrane Library were searched in order to identify studies that directly compared MT with IVT for distal LVOs (anterior cerebral artery A2, middle cerebral artery M3–4, and posterior cerebral artery P2–4). Primary outcomes of interest included a modified Rankin Scale (mRS) score of 0 to 2 at 90 days posttreatment, occurrence of symptomatic intracerebral hemorrhage (sICH), and all-cause mortality at 90 days posttreatment.
Four studies representing a total of 381 patients were included in this meta-analysis. The pooled results indicated that the proportion of patients with an mRS score of 0 to 2 at 90 days (OR 1.16, 95% CI 0.23–5.93; p = 0.861), the occurrence of sICH (OR 2.45, 95% CI 0.75–8.03; p = 0.140), and the mortality rate at 90 days (OR 1.73, 95% CI 0.66–4.55; p = 0.263) did not differ between patients who underwent MT and those who received IVT alone.
The meta-analysis did not demonstrate a significant difference between MT and standard medical management with regard to favorable outcome, occurrence of sICH, or 90-day mortality. Prospective clinical trials are needed to further compare the efficacy of MT with IVT alone for distal vessel occlusion.