Citations

OBJECTIVE Sylvian fissure dissection following subarachnoid hemorrhage (SAH) is a challenging but fundamental skill in microneurosurgery, and one that has become increasingly difficult to develop during residency, given the overarching management trends. The authors describe a novel rodent model for simulation of sylvian fissure dissection and cerebrovascular bypass under SAH conditions. METHODS A standardized microvascular anastomosis model comprising rat femoral arteries and veins was used for the experimental framework. In the experimental protocol, following exposure and skeletonization of the vessels, extensive, superficial (1- to 2-mm) soft-tissue debridement was conducted and followed by wound closure and delayed reexploration at intervals of 7, 14, and 28 days. Two residents dissected 1 rat each per time point (n = 6 rats), completing vessel skeletonization followed by end-to-end artery/vein anastomoses. Videos were reviewed postprocedure to assess scar score and relative difficulty of dissection by blinded raters using 4-point Likert scales. RESULTS At all time points, vessels were markedly invested in friable scar, and exposure was subjectively assessed as a reasonable surrogate for sylvian fissure dissection under SAH conditions. Scar score and relative difficulty of dissection both indicated 14 days as the most challenging time point. CONCLUSIONS The authors’ experimental model of femoral vessel skeletonization, circumferential superficial soft-tissue injury, and delayed reexploration provides a novel approximation of sylvian fissure dissection and cerebrovascular bypass under SAH conditions. The optimal reexploration interval appears to be 7–14 days. To the authors’ knowledge, this is the first model of SAH simulation for microsurgical training, particularly in a live animal system.

OBJECTIVE Steno-occlusive diseases of the cerebral vasculature have been associated with cognitive decline. The authors performed a systematic review of the existing literature on intracranial steno-occlusive disease, including intracranial atherosclerosis and moyamoya disease (MMD), to determine the extent and quality of evidence for the effect of revascularization on cognitive performance. METHODS A systematic search of PubMed/MEDLINE, the Thomson Reuters Web of Science Core Collection, and the KCI Korean Journal Database was performed to identify randomized controlled trials (RCTs) in the English-language literature and observational studies that compared cognitive outcomes before and after revascularization in patients with steno-occlusive disease of the intracranial vasculature, from which data were extracted and analyzed. RESULTS Nine papers were included, consisting of 2 RCTs and 7 observational cohort studies. Results from 2 randomized trials including 142 patients with symptomatic intracranial atherosclerotic steno-occlusion found no additional benefit to revascularization when added to maximal medical therapy. The certainty in the results of these trials was limited by concerns for bias and indirectness. Results from 7 observational trials including 282 patients found some cognitive benefit for revascularization for symptomatic atherosclerotic steno-occlusion and for steno-occlusion related to MMD in children. The certainty of these conclusions was low to very low, due to both inherent limitations in observational studies for inferring causality and concerns for added risk of bias and indirectness in some studies. CONCLUSIONS The effects of revascularization on cognitive performance in intracranial steno-occlusive disease remain uncertain due to limitations in existing studies. More well-designed randomized trials and observational studies are needed to determine if revascularization can arrest or reverse cognitive decline in these patients.

Abstract Cavernous malformations (CM) of the anterior midbrain are best reached through an orbitozygomatic (OZ) approach with removal of the orbital rim and wide Sylvian fissure dissection. Our surgical video demonstrates this approach to resect a ruptured CM in a 36-yr-old woman who presented with headaches, left face and left arm paresthesias/weakness, and right-sided partial oculomotor nerve (CN III) palsy. Initial magnetic resonance imaging (MRI) showed a midbrain CM, and the patient was managed conservatively. However, 1 wk later, she presented again with worsened left arm and leg weakness and complete CN III palsy. Seven Tesla MRI demonstrated a larger hematoma, and the CM with new mass effect and upper pons extension. The patient underwent a right modified OZ craniotomy and Sylvian fissure split under guidance of intraoperative neuronavigation and with neuromonitoring. The carotid-oculomotor triangle and the Liliequist membrane were dissected to access the midbrain, and CN III was identified and followed posteriorly to the midbrain. Confirmed with neuronavigation, a longitudinal incision of the midbrain was performed, and the CM was encountered. The hematoma and CM were debulked and removed in a piece-meal fashion, leaving hemosiderin-stained brain intact to prevent unnecessary additional damage to the midbrain. Postoperative MRI confirmed gross-total resection, and the patient's weakness recovered substantially. In this video, we demonstrate that the brainstem is no longer forbidden surgical territory, and show how the use of neuronavigation for surgical planning, positioning, and approach, in addition to the understanding of safe entry zones and meticulous microsurgical technique have made safe and effective surgery on the brainstem possible.

Abstract BACKGROUND Flow diversion (FD) is effective for treatment of intracranial internal carotid artery (ICA) aneurysms. OBJECTIVE To determine whether carotid siphon (CS) geometry influences the efficacy of FD when employed for ICA aneurysms. METHODS Outcomes of a consecutive series of patients with ICA aneurysms treated with FD were retrospectively reviewed. CS anatomy was quantified through measurement of the posterior, anterior, and anterosuperior bend angles in accordance with previously described methodology. The relationship of CS geometry to likelihood of incomplete aneurysm occlusion at 1 yr after treatment was assessed with multivariate logistic regression analysis. RESULTS There were 167 ICA aneurysms in 164 patients treated with FD during the study period. The mean age of our cohort was 55.7 yr (standard deviation [SD]: 12.3) and a majority of patients were female (145/164, 86.8%). Anterior (47.4 degrees vs 8.5, P < .001) and anterosuperior bend angles (100.9 vs 76.5, P = .002) were significantly greater in aneurysms that required repeat FD after initial treatment. On multivariate logistic regression analysis, increasing patient age (unit odds ratio [OR]: 1.05, 95% confidence interval [CI] 1.01-1.08; P = .003) and anterior bend angle ≥–3.5 (OR: 2.47, 95% CI 1.04-5.86; P = .046) were associated with increased odds of incomplete aneurysm occlusion at 1 yr after treatment. CONCLUSION These findings suggest that variations in CS anatomy may influence the efficacy of FD treatment and should be analyzed prior to offering FD for treatment of ICA aneurysms. Further investigation into the hemodynamic effects of CS geometry is warranted.

Neuromodulation and deep brain stimulation (DBS) have been increasingly used in many neurological ailments, including essential tremor, Parkinson’s disease, epilepsy, and more. Yet for many patients and practitioners the desire to utilize these therapies is met with caution, given the need for craniotomy, lead insertion through brain parenchyma, and, at many times, bilateral invasive procedures. Currently endovascular therapy is a standard of care for emergency thrombectomy, aneurysm treatment, and other vascular malformation/occlusive disease of the cerebrum. Endovascular techniques and delivery catheters have advanced greatly in both their ability to safely reach remote brain locations and deliver devices. In this review the authors discuss minimally invasive endovascular delivery of devices and neural stimulating and recording from cortical and DBS targets via the neurovascular network.

Abstract We present a case of a patient with pseudotumor cerebri (PC) and transverse/sigmoid junction sinus (TSJS) stenosis treated with stenting venoplasty. A 54-yr-old man with a history of hypertension, hyperlipidemia, and chronic obstructive pulmonary disease presented with subacute onset of progressive headaches, blurred vision, and papilledema. He was clinically diagnosed with PC. Left TSJS stenosis was suspected on magnetic resonance venography and confirmed with digital subtraction angiography and venography. During angiography, venous pressures were measured along the intracranial venous system revealing a significant drop compared with pressures obtained from the superior sagittal and sigmoid sinuses. For 7 d prior to venous sinus stenting, he was prescribed antiplatelet therapy with aspirin (350 mg/d) and clopidogrel (75 mg/d). Patient consent was obtained prior to performing the procedure; institutional board approval is not required for the report of a single case. Under conscious sedation and systemic heparinization, the patient underwent endovascular stenting of the left TSJS with an open-cell carotid stent (Precise 7 × 40 mm; Cordis, Milpitas, California). Successful left TSJS reconstruction transpired with no procedure-related complications. The patient was discharged home 1 d postprocedure. After 2 mo of dual antiplatelet therapy, clopidogrel was discontinued. At the 1-yr follow-up, he had resolution of papilledema and notably less intense headaches. Venous sinus stenting is an effective endovascular treatment for symptomatic patients with PC and sinus stenosis. Venous pressure measurement is imperative for patient selection. Adequate venous access with a 6-French guide catheter into the sigmoid sinus and an intermediate catheter into the transverse sinus is crucial to navigate a stent through the acute angles of the TSJS and jugular vein.

Abstract Mechanical thrombectomy has become the standard of care for management of most acute large-vessel occlusion (LVO) strokes. Most intracranial occlusions are located in the middle cerebral and internal carotid arteries. We present a unique case of acute occlusion of an azygous anterior cerebral artery (ACA). A 59-yr-old man with known hypertension and alcoholism presented with right hemiparesis, right facial palsy, aphasia, and dysarthria. His initial National Institutes of Health Stroke Scale (NIHSS) score was 20. Computed tomographic angiography and perfusion imaging demonstrated acute bilateral ACA occlusion with viable penumbra and preserved cerebral blood volume. The patient was not a candidate for intravenous tissue plasminogen activator because he presented with a wake-up stroke. After consent was obtained from his family, the patient was taken urgently for endovascular recanalization. Digital subtraction angiography confirmed acute azygous ACA occlusion. Under conscious sedation, the patient underwent mechanical thrombectomy with a stent retriever and a large-bore aspiration catheter. Successful revascularization (thrombolysis in cerebral infarction [TICI] grade 3) of the azygous ACA and both A2 arteries was obtained after 2 attempts and the use of a different stent retriever (first a 3 × 30 mm Trevo [Stryker Neurovascular, Kalamazoo, Michigan] and then a 4 × 40 mm Solitaire Platinum [Medtronic, Dublin, Ireland]). A reperfusion catheter was used during both attempts. No procedure-related complications occurred. The patient was discharged to a rehabilitation facility 3 d after the procedure with an NIHSS score of 2. In this video, we present the operative nuances of an uncommon location of LVO and its endovascular management.

OBJECTIVE De novo aneurysms are rare entities periodically discovered during follow-up imaging. Little is known regarding the frequency with which these lesions form or the time course. This systematic review and meta-analysis was undertaken to estimate the incidence of de novo aneurysms and to determine risk factors for aneurysm formation. METHODS The authors searched multiple databases for studies of patients with unruptured and ruptured aneurysms describing the rate of de novo aneurysm formation. The primary outcome was incidence of de novo aneurysm formation. A meta-analysis was performed using a random-effects model. The authors examined the associations of multiple aneurysms, prior subarachnoid hemorrhage, smoking, sex, age at presentation, and hypertension with de novo aneurysm formation. RESULTS The meta-analysis included 14,968 aneurysm patients who received imaging follow-up from 35 studies. The overall incidence of de novo aneurysm formation was 2% (95% CI 2%–3%) over a mean follow-up time of 8.3 years. The estimated incidence density was 0.3%/patient-year. There was no statistically significant difference in rates of de novo aneurysm formation between patients who had ruptured aneurysms and those with unruptured aneurysms. In 8 studies, 11.2% of de novo aneurysms were found in patients with ≤ 5 years of follow-up and 88.8% were found at > 5 years. The mean time to rupture for de novo aneurysms was 10 years. CONCLUSIONS This systematic review demonstrates that formation of de novo aneurysms is rare. Overall, routine screening for de novo aneurysms is likely to be of low yield and could be performed at time intervals of at least 5 to 10 years.

Abstract Middle cerebral artery (MCA) aneurysms often have an irregular morphology that might require creative clipping techniques even in the case of small aneurysms. In this video, we illustrate the case of a patient with an incidental but very irregular MCA aneurysm. The presence of 2 separate, asymmetric lobes was dealt with by utilizing the “interlocking” clip technique in which a regular clip is used to obliterate 1 portion of the aneurysm and a fenestrated clip, with the ring of the fenestration circling the body of the first clip, is used to obtain obliteration of the other lobe. This patient also had a contralateral internal carotid artery occlusion, and we discuss the pitfalls of temporary clipping in such a situation.