Intraoperative motor-evoked potential monitoring during coil embolization for anterior choroidal artery aneurysms

False-Negative Motor-Evoked Potential Due to Contrast-Induced Encephalopathy During Coil Embolization for Intracranial Aneurysm: A Case Report

Contrast-induced encephalopathy (CIE) is a rare neurological complication that can occur following the use of contrast media during angiographic procedures. It can lead to neurological deficits, such as motor weakness. Transcranial motor-evoked potential (TcMEP) monitoring is commonly used to detect pyramidal tract disorders during embolization for intracranial aneurysms. However, it remains unclear whether TcMEP monitoring is effective in cases of motor weakness associated with CIE. We present a case of a false-negative motor-evoked potential caused by CIE during coil embolization for unruptured internal carotid artery aneurysms. A 68-year-old woman with dizziness underwent an MRI, which revealed multiple unruptured cerebral aneurysms, including a right anterior choroidal artery aneurysm (Ach AAn) and a posterior communicating artery aneurysm (Pcom AAn). Coil embolization was performed for the right Ach AAn and Pcom AAn with intraoperative TcMEP monitoring under general anesthesia. Throughout the procedure, no abnormalities were detected in the TcMEP monitoring. A total of 360 mL of contrast medium was used. After regaining consciousness, the patient experienced left hemiplegia and unilateral spatial neglect. Cerebral angiography revealed no missing branches, including those of the Ach A and Pcom A. MRI showed no acute ischemic or hemorrhagic changes. However, CT revealed CIE. The left hemiplegia and unilateral spatial neglect gradually improved and were completely resolved by postoperative day four. This case suggests that CIE-associated motor weakness may not be detected by intraoperative TcMEP monitoring. Therefore, in patients who develop motor weakness immediately after coil embolization for intracranial aneurysms without changes in TcMEP, brain CT should be performed to exclude CIE.

Total Intravenous Anesthesia Protocol for Decreasing Unacceptable Movements during Cerebral Aneurysm Clipping with Motor-Evoked Potential Monitoring: A Historical Control Study and Meta-Analysis

Injury can occur during intraoperative transcranial motor-evoked potential (MEP) monitoring caused by patient movement related to insufficient neuromuscular blocking agent use. Here, we evaluated the incidence of unacceptable movements in patients undergoing intraoperative MEP monitoring following our anesthetic protocol. We reviewed the anesthesia records of 419 patients who underwent unruptured cerebral aneurysm clipping with intraoperative MEP monitoring. The anesthetic protocol included target-controlled infusion with a fixed effect-site propofol concentration of 3 μg/mL and an adjustable effect-site remifentanil concentration of 10-12 ng/mL. We compared our findings of the intraoperative parameters and incidence of spontaneous movement and respiration with those of published meta-analysis studies. Spontaneous movement and respiration occurred in one (0.2%) patient each. The meta-analysis included six studies. The pooled proportions of spontaneous movement and respiration were 6.9% (95% confidence interval [CI], 1.3-16.5%) and 4.1% (95% CI, 0.5-14.1%), respectively. The proportion of spontaneous movement in our study was significantly lower than that in previous studies (p = 0.013), with no significant difference in spontaneous respiration (p = 0.097). Following our center's anesthesia protocol during cerebral aneurysm clipping resulted in a low incidence of spontaneous respiration and movement, indicating its safety for patients undergoing intraoperative MEP monitoring.

Treatment of Ruptured Anterior Choroidal Artery Aneurysms by Acute Coiling Followed by Flow Diversion

BACKGROUND

Flow-diverter treatments are successful endovascular treatments in protecting important perforating branches during aneurysm treatments. Because these treatments are performed under antiplatelet therapy, acute flow-diverter treatments in ruptured aneurysms are still controversial. Acute coiling followed by flow diversion has emerged as an intriguing and feasible treatment option for ruptured anterior choroidal artery aneurysm treatment. As a single-center retrospective case series study, this study reported the clinical and angiographic results of staged endovascular treatment in patients with a ruptured anterior choroidal aneurysm.

METHODS

This is a single-center retrospective case series study between March 2011 and May 2021. Patients with ruptured anterior choroidal aneurysm received flow-diverter therapy in a different session after acute coiling. Patients treated with primary coiling or only flow diversion were excluded. Preoperative demographic and presenting symptoms, aneurysm morphology, perioperative and postoperative complications, and long-term clinical and angiographic outcome as measured using the modified Rankin Scale and O'Kelly Morata Grading scale and also Raymond-Roy occlusion classification respectively.

RESULTS

Sixteen patients underwent coiling in the acute phase to undergo flow diversion later. The mean maximum aneurysm diameter is 5.44 ± 3.39 mm. All patients had a subarachnoid hemorrhage and were treated acutely between days 0 and 3 of acute bleeding. The mean age at the presentation was 54.12 ± 12 years (32-73 years). Two patients (12.5%) had minor ischemic complications, which are seen on magnetic resonance angiography as clinically silent infarcts, after the procedure. One patient (6.2%) had a technical complication with the flow-diverter shortening and deployed a second flow diverter telescopically. No mortality or permanent morbidity was reported. The mean interval time between the 2 treatments was 24.06 ± 11.83 days. All patients were followed up with digital subtraction angiography; 14/16 patients (87.5%) had aneurysms that were completely occluded and 2/16 (12.5%) showed near-complete occlusion. Mean follow-up was 16.62 ± 3.22 months; all patients had modified Rankin Scale scores ≤2; 14/16 (87.5%) had a total occlusion 14/16 (87.5%) had near-complete occlusion. None of the patients had retreatment or rebleeding.

CONCLUSIONS

Staged treatment of ruptured anterior choroidal artery aneurysms with acute coiling and flow-diverter treatment after recovery from subarachnoid hemorrhage is safe and effective. In this series, no cases of rebleeding occurred during the interval between coiling and flow diversion. Staged treatment should be considered a valid option in patients with challenging ruptured anterior choroidal aneurysms.

Infundibular Widening of Angiographically Invisible Duplicate Anterior Choroidal Artery Mimicking Typical Anterior Choroidal Artery Aneurysm

A diagnosis of an intracranial aneurysm depends on the angiographic configuration and should be cautiously differentiated from aneurysm mimics. In cases of duplicate anterior choroidal arteries (AChAs), infundibular widening of the distal minor AChA can be an aneurysm mimic. If the minor AChA with a smaller diameter is obscured angiographically due to poor contrast filling, an associated infundibular widening beside the proximal large AChA can misinterpreted as a typical AChA aneurysm in angiograms. The authors report on two such cases of duplicate AChAs with infundibular widening presenting like a typical AChA aneurysm in angiograms. Surgical exploration revealed a perforating artery emitting from the dome of the saccular lesion, confirming infundibular widening of a duplicate AChA. No reparative procedure was applied to the infundibular widening in a 48-year-old man, while two vascular outpouchings from the infundibular widening were clipped preserving the duplicate AChA in a 55-year-old woman.

Endovascular Treatment and Angiographic Characteristics of Aneurysms at the Origin of the Anterior Choroidal Artery

Background

The information available about the variations and anatomy of the anterior choroidal artery (AchA) with aneurysm at the origin of the vessel and the outcomes of endovascular treatment (EVT) for AchA aneurysms is incomplete.

Materials and Methods

A retrospective study of 54 consecutive patients who were admitted to our hospital with a diagnosis of AchA aneurysm and treated with EVT was performed. The variations and anatomy of the AchA and the outcomes of EVT for AchA aneurysms were analyzed.

Result

The 54 patients were aged 35-82 years (mean age, 56.1 ± 19.7 years) and included 32 females (59.3%, 32/54). Regarding AchA anatomy, 63.5% of AchAs had a typical S-shaped course. The diameter of the AchA origin averaged 0.8 ± 0.3 mm. Of all the AchA aneurysms, 51.9% were ruptured. The diameter of AchA aneurysms averaged 4.1 ± 2.4 mm. Moreover, 40.7% of 54 cases had multiple aneurysms. EVT was assisted with stenting for 25.9% of 54 AchA aneurysms. An immediate Modified Raymond-Roy Classification grade of I was obtained in 96.3% of AchA aneurysm cases. After EVT, the ischemic complication rate was 13%. In total, 83% of patients had good outcomes, with a Glasgow Outcome Scale score of 4-5. Follow-up angiography showed acceptable treatment results in this study.

Conclusion

The study showed that the AchA had a complex angiographic anatomy in cases with aneurysms at the origin of the vessel and that the anatomical features can be helpful in EVT. EVT for aneurysms at the origin of the AchA had good outcomes.