Superselective Provocative Test with Propofol Using Motor-Evoked Potential Monitoring for Managing Cerebral Arteriovenous Malformations Fed by the Anterior Choroidal Artery

Endovascular treatment for brain arteriovenous malformations via the anterior choroidal artery for casting Onyx-18

Background: Few studies have investigated the safety of endovascular treatment (EVT) for brain arteriovenous malformations (BAVMs) via the anterior choroidal artery (AchA); therefore, this topic is worth studying further. Materials and methods: This was a retrospective study of 18 consecutive patients with BAVMs that were treated via the AchA with Onyx casting. Clinical and angiographic data were collected from the patients and analyzed. Results: The ages of the 18 patients ranged from 13 to 67 years (mean 39.2 ± 14.7 years), and eight patients were male (44.4%, 8/18). All patients had intracranial hemorrhages, including 2 with previous hemorrhages. All 18 BAVMs were mainly fed by the AchA and were treated via the AchA as the route for casting Onyx-18. Of the 13 single-trunk AchAs, after EVT, all proximal segments were preserved. For the 5 double-trunk AchAs, EVT was performed via the lower trunk; the proximal segments of the lower trunk were occluded for 2 of these AchAs. Among the 18 BAVMs, 16 niduses were embolized to different degrees, as were twelve associated aneurysms. Five (27.8%, 5/18) of the 18 patients experienced complications, and appropriate management was provided. During long-term follow-up, 14 (77.8%, 14/18) patients achieved good outcomes. Conclusion: EVT for BAVMs via the AchA has significant risks, but overall, good long-term outcomes were achieved in approximal 80% of the patients. This study highlights the potential of this technique for embolizing BAVMs via the AchA.

Case Study of a Complex Neurovascular Disorder: Choroidal Arteriovenous Malformation

This study conducts an in-depth analysis of the management of a complex arteriovenous malformation (AVM) in a 44-year-old individual, who initially manifested with acute left hemiparesis and progressively declined into a comatose state. Diagnostic neuroimaging identified a substantial right fronto-temporal intraparenchymal hematoma via a CT scan. Cerebral angiography further elucidated a choroidal AVM originating from the anterior choroidal artery, accompanied by intranidal aneurysms. The elected treatment strategy was the surgical excision of the AVM. The procedure achieved complete removal of the intracranial AVM, situated in a neurologically sensitive region, leading to notable neurological recovery. This study thoroughly explores and critically evaluates a wide spectrum of treatment approaches for intracranial arteriovenous malformations, including novel endovascular therapies. Despite extensive discourse on AVM in contemporary literature, this report is among the few documenting the treatment of a choroidal AVM via a microsurgical technique, and highlights various therapeutic options.

Role of the anterior choroidal artery in the endovascular treatment of brain arteriovenous malformations

The anterior choroidal artery (AchA) is a very important vessel that supplies certain crucial structures that have poor collateral circulation. When the AchA is recruited to supply brain arteriovenous malformations (BAVMs), can the AchA act as a safe path through which endovascular treatment (EVT) be performed? As few studies or reports have investigated this matter, we performed a review to expound upon the role of the AchA in the EVT of BAVMs. In this review, we discussed the anatomy and variation of the AchA, the angioarchitecture of BAVMs fed by the AchA, the status of EVT for BAVMs and its associated problems and their solutions, the choice of embolic materials, new EVT techniques, the complications and prognoses of EVT through the AchA, etc. The review revealed that although EVT of BAVMs through the AchA is challenging and can result in unpredictable complications, it may be an appropriate option prior to surgery and radiation therapies or serve as a curative procedure. A complete and thorough understanding of the functional anatomy and variant of the AchA and proper EVT techniques are crucial for successful embolization of BAVMs via the AchA.

Endovascular treatment of an infectious aneurysm using the selective provocative test and transcranial motor evoked potential monitoring under general anesthesia: a case report

The selective provocative test (SPT) under local anesthesia aids in protecting against ischemic complications during endovascular treatment. However, the use of this test under general anesthesia is not well described. Herein, we present a case of a 51-year-old man with a ruptured fusiform aneurysm in the middle cerebral artery M4 segment, which was thought to possibly supply the motor cortex. Internal trapping of the affected vessel and aneurysm by endovascular intervention was successfully performed after SPT using transcranial motor evoked potential (MEP) monitoring under general anesthesia. Transcranial MEP is suitable for neurological assessment during SPT under general anesthesia.

Endovascular Treatment of Posterior Cerebral Artery Trunk Aneurysm: The Status Quo and Dilemma

The posterior cerebral artery (PCA) is an important artery that can be divided into four segments (P1-4): segments P1-2 are proximal segments, and segments P3-4 are distal segments. Various aneurysms can occur along the PCA trunk. True saccular aneurysms are rare, and most PCA trunk aneurysms are dissecting. Sometimes, the PCA trunk can give rise to flow-related aneurysms in association with high-flow arteriovenous shunt diseases or moyamoya disease and internal carotid artery occlusion. Some PCA trunk aneurysms require treatment, especially ruptured or large/giant aneurysms. Recently, endovascular treatment (EVT) has become the mainstream treatment for PCA trunk aneurysms, and it mainly involves reconstructive or deconstructive techniques. Traditional EVT includes selective coiling with/without stent or balloon assistance and parent artery occlusion (PAO). For proximal aneurysms, the PCA should be preserved. For distal aneurysms, PAO can be performed. However, during EVT, preservation of the PCA must naturally be the prime objective. Recently, flow-diverting stents have been used and are a revolutionary treatment for unruptured dissecting aneurysms of the PCA trunk. Despite the associated complications, EVT remains an effective method for treating PCA trunk aneurysms and can result in a good prognosis.

Super-selective balloon test occlusion with electrophysiological monitoring to occlude angiographically invisible posterior communicating artery perforators with unruptured aneurysm

Balloon test occlusion (BTO) can predict the ischemic complication risk associated with arterial occlusion. We present a case of an unruptured, broad-necked internal carotid artery-posterior communicating artery (PcomA) aneurysm that was successfully embolized after super-selective BTO of fetal PcomA with electrophysiological monitoring. The proximal portion of the PcomA was internally occluded without causing major neurological deficits, although we observed a small new infarction in the ipsilateral anterior thalamus postoperatively. We recognized small perforators arising from the proximal PcomA during a previous clipping surgery. Super-selective BTO with electrophysiological monitoring could be useful for functional preservation after infarction from angiographically invisible perforators.

Pharmacologic Provocative Testing in Combination With Intraoperative Neurophysiologic Monitoring During Arteriovenous Malformation Embolization

OBJECTIVE

To review our use of pharmacologic provocative testing (PT) and intraoperative neurophysiologic monitoring (IONM) during endovascular embolization for eloquent arteriovenous malformations (AVMs), and better define their clinical utility.

METHODS

This is a prospective study between 1 June 2018 and 1 June 2020. Prior to endovascular embolization, superselective PTs with propofol injection were performed. The PT results were assessed by IONM. The impact of different doses of propofol on PT results was compared.

RESULTS

Under general anesthesia, 111 PTs and 48 endovascular embolizations were performed in 22 patients. For the initial 48 PTs before planned embolization, 38 PTs with 5 mg propofol were negative and repeat PTs with 7 mg propofol were also negative. For the remaining 10 positive PTs, the microcatheter tip was adjusted to an alternative site until repeat PTs were negative to ensure a subsequent safe embolization. In comparison, 5-mg-propofol PT results were consistent with 7-mg-propofol PTs in larger-sized feeders, whereas for smaller-sized vessels, 3-mg-propofol PT results were consistent with 5-mg-propofol PTs. The negative predictive value of PTs was 97.9% (47 of 48), as only 1 of the 48 embolizations with negative PTs resulted in postoperative hemorrhage and none of the other 47 embolizations led to a postoperative neurologic deficit.

CONCLUSIONS

PTs and IONM are valuable techniques to predict neurologic deficits and improve procedure decision-making during AVM embolization under general anesthesia. A 5-mg dose of propofol may be sufficient for PTs in larger-sized feeders and a 3-mg dose may be sufficient in smaller-sized feeding branches.

Motor Evoked Potential Warning Criteria in Supratentorial Surgery: A Scoping Review

During intraoperative monitoring of motor evoked potentials (MEP), heterogeneity across studies in terms of study populations, intraoperative settings, applied warning criteria, and outcome reporting exists. A scoping review of MEP warning criteria in supratentorial surgery was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). Sixty-eight studies fulfilled the eligibility criteria. The most commonly used alarm criteria were MEP signal loss, which was always a major warning sign, followed by amplitude reduction and threshold elevation. Irreversible MEP alterations were associated with a higher number of transient and persisting motor deficits compared with the reversible changes. In almost all studies, specificity and Negative Predictive Value (NPV) were high, while in most of them, sensitivity and Positive Predictive Value (PPV) were rather low or modest. Thus, the absence of an irreversible alteration may reassure the neurosurgeon that the patient will not suffer a motor deficit in the short-term and long-term follow-up. Further, MEPs perform well as surrogate markers, and reversible MEP deteriorations after successful intervention indicate motor function preservation postoperatively. However, in future studies, a consensus regarding the definitions of MEP alteration, critical duration of alterations, and outcome reporting should be determined.

Clinical importance of the anterior choroidal artery: a review of the literature

The anterior choroidal artery (AChA) is a critical artery in brain physiology and function. The AChA is involved in many diseases, including aneurysm, brain infarct, Moyamoya disease (MMD), brain tumor, arteriovenous malformation (AVM), etc. The AChA is vulnerable to damage during the treatment of these diseases and is thus a very important vessel. However, a comprehensive systematic review of the importance of the AChA is currently lacking. In this study, we used the PUBMED database to perform a literature review of the AChA to increase our understanding of its role in neurophysiology. Although the AChA is a small thin artery, it supplies an extremely important region of the brain. The AChA consists of cisternal and plexal segments, and the point of entry into the choroidal plexus is known as the plexal point. During treatment for aneurysms, tumors, AVM or AVF, the AChA cisternal segments should be preserved as a pathway to prevent the infarction of the AChA target region in the brain. In MMD, a dilated AChA provides collateral flow for posterior circulation. In brain infarcts, rapid treatment is necessary to prevent brain damage. In Parkinson disease (PD), the role of the AChA is unclear. In trauma, the AChA can tear and result in intracranial hematoma. In addition, both chronic and non-chronic branch vessel occlusions in the AChA are clinically silent and should not deter aneurysm treatment with flow diversion. Based on the data available, the AChA is a highly essential vessel.

Curative and adjunctive AVM Onyx embolization of AVMs through the choroidal arteries

Objective The anterior or posterior choroidal artery is often recruited to supply deep location arteriovenous malformations (AVMs). This study is to report curative and adjunctive AVM Onyx embolization through these arteries. Methods This study retrospectively reviewed six patients with cerebral AVMs who underwent endovascular embolization through the choroidal arteries between October 2015 and October 2016. Embolization was performed as a curative procedure in five patients and adjunctive procedure in one patient. Results Four patients underwent embolization through the anterior choroidal artery (AchA), and two patients underwent embolization through the lateral posterior choroidal artery (LPchA). One of the four patients in whom embolization was from the AchA (distal to the plexal point) developed transient hemiparesis. Complete obliteration was confirmed by angiography at the last follow-up in five patients. Conclusions Onyx embolization of cerebral AVMs through the choroidal arteries is possible as a curative or adjunctive procedure.