Posterior Communicating Artery Aneurysm Research Articles

Comment on "Failure of the Pipeline Embolization Device in Posterior Communicating Artery Aneurysms Associated with a Fetal Posterior Cerebral Artery".

Comment on "Failure of the Pipeline Embolization Device in Posterior Communicating Artery Aneurysms Associated with a Fetal Posterior Cerebral Artery".

Response to: Comment on "Failure of the Pipeline Embolization Device in Posterior Communicating Artery Aneurysms Associated with a Fetal Posterior Cerebral Artery".

Response to: Comment on "Failure of the Pipeline Embolization Device in Posterior Communicating Artery Aneurysms Associated with a Fetal Posterior Cerebral Artery".

Remote multifocal bleeding points producing a Sylvian subpial hematoma during endovascular coiling of an acutely ruptured cerebral aneurysm

Subpial hematoma is a rare type of intracranial hemorrhage with a poor prognosis. A new mechanism to explain subpial Sylvian hematoma formation in acute post-aneurysmal subarachnoid hemorrhage (SAH) was observed...

Ruptured intracranial aneurysm in patients with osteogenesis imperfecta: 2 familial cases and a systematic review of the literature

ObjectiveOsteogenesis imperfecta is an inherited connective tissue disorder that causes bone fragility. Vascular complications have been described, but only few cases of ruptured intracranial aneurysm have been reported. Materials and methodsWe first described 2 familial cases of ruptured intracranial aneurysm and then conducted a systematic review of the literature. ResultsA mother and her daughter with a typical history of osteogenesis imperfecta presented with subarachnoid hemorrhage, which was related to a posterior communicating artery aneurysm in both cases. The mother had early rebleeding and died. The aneurysm was excluded by coiling in the daughter. Despite occurrence of hydrocephalus and delayed cerebral ischemia, she had an excellent functional outcome. A systematic review of the literature identified seven additional cases. None of the cases were in fact familial. All patients had a previous medical history of multiple fractures. Seven aneurysms were resolved, three by surgical clipping and four by endovascular procedure. No periprocedural complication was reported. One patient died prematurely and 6 experienced good functional outcome. ConclusionsWe report the first familial cases of aneurysmal subarachnoid hemorrhage in osteogenesis imperfecta patients. Intracranial aneurysms are probably linked to a collagen pathology, which is at the origin of osteogenesis imperfecta. In cases of aneurysmal subarachnoid hemorrhage in an osteogenesis imperfecta family, intracranial aneurysm screenings in the relatives showing osteogenesis imperfecta should be considered.

Association between anatomical variations of the posterior communicating artery and the presence of aneurysms

Objectives: Posterior communicating artery aneurysms (PcoAA) account for 30–35% of intracranial aneurysms. The anatomical factors involved in the formation of PCoAA are poorly known. The study aimed to investigate the anatomical variations in the posterior communicating artery (PcoAs) and the presence of PCoAA.Methods: All 154 patients hospitalized from January 2008 to December 2013 at the department of neurology of our hospital were included in this study; 76 were confirmed with PCoAA upon cerebral angiography and 78 were confirmed without cranial artery aneurysm (controls). According to the blood supply pattern, variations of the PCoAA were classified as Type P0, P-I, or P-II. The angles of C7 and C6 of the internal carotid artery on each side were analyzed.Results: Compared with controls, patients with PCoAA had a higher frequency of abnormal posterior communicating artery (Types P-I and P-II) (p < 0.001). The angles of C7 and C6 on the contralateral side in the PCoAA group were significantly greater than on the affected side, and significantly lesser than in controls (p < 0.001). There was no difference in the angle between the culprit artery and the contralateral one.Discussion: Abnormal PCoAs (Types P-I and P-II) might be more vulnerable to PCoAA development, and Type P-II was the most vulnerable. There was a correlation between the angles of C7 and C6 part of the internal carotid artery and the presence of symptomatic PCoAA, with smaller angles being associated with increased frequency of symptomatic PCoAA.

Aneurysms with persistent patency after treatment with the Pipeline Embolization Device

The Pipeline Embolization Device (PED) was approved for the treatment of intracranial aneurysms from the petrous to the superior hypophyseal segment of the internal carotid artery. However, since its approval, its use for treatment of intracranial aneurysms in other locations and non-sidewall aneurysms has grown tremendously. The authors report on a cohort of 15 patients with 16 cerebral aneurysms that incorporated an end vessel with no significant distal collaterals, which were treated with the PED. The cohort includes 7 posterior communicating artery aneurysms, 5 ophthalmic artery aneurysms, 1 superior cerebellar artery aneurysm, 1 anterior inferior cerebellar artery aneurysm, and 2 middle cerebral artery aneurysms. None of the aneurysms achieved significant occlusion at the last follow-up evaluation (mean 24 months). Based on these observations, the authors do not recommend the use of flow diverters for the treatment of this subset of cerebral aneurysms.

Application of LVIS stents in very small intracranial aneurysms

To investigate the safety and short-term efficacy of stent on 17 patients with very small intracranial aneurysms. A total of 17 patients with very small intracranial aneurysms were treated by LVIS stent from October 2014 to November 2015. The location, size of the aneurysms and the branch around aneurysms were evaluated by digital subtraction angiography (DSA). The metal coverage for aneurysms was enhanced by using deployment technology ("compression" mode). The safety and efficacy were assessed after operation. LVIS stents-assisted treatments for very small aneurysms were carried out in 17 cases, including 7 cases of paraclinoid aneurysms, 4 cases of posterior communicating artery aneurysms, 3 cases of anterior communicating artery aneurysms, 2 cases of carotid bifurcation aneurysms, 1 case of the superior cerebellar artery aneurysm. The stents for 17 patients with very small intracranial aneurysms were released completely (100%); Raymond grade I embolization was seen in 13 cases (76.5%); Raymond grade II embolization was seen in 4 cases (23.5%); during the follow up from a month to a year, 16 patients showed good curative effect (with the mRS score at 0-2), 1 showed poor effect (with the mRS score at 3-6), and the efficacy rate was 94.1%; no perioperative hemorrhagic and ischemic complications happened. LVIS stent-assisted therapy for very small intracranial aneurysms by using deployment technology was safe and feasible, which can significantly improve the embolization rate for very small aneurysms.

The causes and strategies for intraoperative rupture during clipping the anterior circulation aneurysms

To investigate the causes and strategies for intraoperative rupture during clipping the anterior circulation aneurysms. Nineteen patients with anterior circulation aneurysms ruptured during clipping, who admitted to the Department of Neurosurgery, Henan Provincial People's Hospital from November 2012 to February 2014, were enrolled. Their clinical data were analyzed retrospectively to summarize the causes and strategies for intraoperative rupture. The aneurysms ruptured during predissection in 2 cases (10.5%), during dissection in 11 cases (57.9%) and during clip application in 6 cases (31.6%). There was no residual aneurysm confirmed by postoperative CTA in 17 patients. One case with posterior communicating artery aneurysm cannot be clipped because of the serious avulsion of the aneurysm neck during clipping. The aneurysm was trapped and the patient paralysed on one side after operation. One case died postoperative 8 days because of severe cerebral edema, whose aneurysm ruptured during predissection. The Glasgow Outcome Scale (GOS) of three months after operation showed good recovery in 11, moderate recovery in 5, severe disability in 2, and death in 1 cases, respectively. Adequate preoperative evaluation for the risk factors of intraoperative rupture and excellent microsurgical techniques can prevent intraoperative rupture of intracranial aneurysms. Controlling the bleeding quickly and dissecting and clipping the aneurysm after definitely know the anatomy of the aneurysm and surrounding vasculature could be the keys to deal with intraoperative aneurysm rupture.

Giant Posterior Communicating Artery Aneurysm Presenting as Trigeminal Neuralgia

We report an extremely rare case of trigeminal neuralgia (TN) caused by a giant posterior communicating artery aneurysm. We describe the case of a 73-year-old man who suffered disabling TN, which was deeply exacerbated when he laid down. Computed tomography angiography and digital angiography revealed an unruptured giant posterior left communicating artery aneurysm projecting to the posterior fossa and contacting the trigeminal root. The size and projection of the aneurysm seemed responsible for both the neuralgia itself and its peculiar clinical characteristic of exacerbation when the patient laid down. The aneurysm was surgically clipped, then opened and emptied to decompress the trigeminal root. The patient reported an immediate complete remission of the neuralgia. The finding of TN secondary to aneurysms is rare but even more in the case of a posterior communicating aneurysm. The clinical clue that should alert physicians about the presence of an aneurysm as the cause of TN is exacerbation of pain by adopting a supine position. Due to the high risk of rupture associated with giant and symptomatic aneurysms, we believe that treatment should be aggressive in this case, not only to solve the symptomatic TN but also to avoid the risk of aneurysm rupture in the future. The treatment selection between surgical clipping or endovascular coiling with or without stenting, depends on patient's clinical condition and the size and shape of the aneurysm.

Resolution of third nerve palsy despite persistent aneurysmal mass effect after flow diversion embolization of posterior communicating artery aneurysms

Posterior communicating artery (PCOM) aneurysms may cause third nerve palsies. The optimal treatment with clipping versus coiling remains controversial. Here we report on two cases of resolution of third nerve palsy after flow diversion embolization of large and giant PCOM aneurysms without adjuvant coil placement. The resolution of third nerve palsy was not preceded by significant shrinkage of the aneurysmal sac on MRI. However, one patient showed resolution of T2-weighted signal abnormalities in the midbrain and mesial temporal lobe despite a similar size of the aneurysm. Therefore, flow diversion embolization of a PCOM aneurysm may resolve oculomotor nerve palsies through decreasing arterial pulsations against the nerve or midbrain.

Patency of the posterior communicating artery following treatment with the Pipeline Embolization Device.

OBJECTIVE The Pipeline Embolization Device (PED) has become an effective treatment strategy for some cerebral aneurysms. Concerns regarding the patency of branch arteries have been raised. The objective of this study was to assess the patency of the posterior communicating artery (PCoA) following treatment of PCoA aneurysms using the PED. METHODS All patients with PCoA aneurysms treated with the PED who had angiographic follow-up were retrospectively identified. The patency of the PCoA at follow-up was evaluated by 2 authors who were not involved in the intervention. Univariate and multivariate analyses were performed to identify factors associated with the following: 1) PCoA patency versus no or diminished flow, and 2) PCoA patency and diminished flow versus PCoA occlusion. RESULTS Thirty patients with an angiographic follow-up of 6 months were included. Aneurysm obliteration was achieved in 25 patients (83.3%). The PCoA was patent in 7 patients (23.3%), had diminished flow in 7 patients (23.3%), and was occluded in 16 patients (53.3%). In the univariate analysis of outcome, there was a trend for aneurysms with incomplete occlusion, aneurysms not previously treated, those with presence of a fetal PCoA, and those with an artery coming from the aneurysm to have higher odds of the PCoA remaining patent. In univariate and multivariate analyses of factors associated with outcome, fetal PCoA and presence of an artery coming from the aneurysm were associated with the PCoA remaining open with or without diminished flow. No patients had symptoms related to PCoA occlusion. CONCLUSIONS Occlusion and diminished flow through the PCoA is common following PED treatment of PCoA aneurysms. However, it is clinically insignificant in most cases.

Feasibility of simultaneous sodium fluorescein and indocyanine green injection in neurosurgical procedures

ObjectiveThe objective of this study is to assess the feasibility of simultaneous Sodium Fluorescein (SF) and Indocyanine Green (ICG) injection during neurosurgical procedures. Patients and methodsThree patients harboring a high-grade glioma (HGG) were retrospectively identified in the surgical database of the Neurosurgical Unit 2 at the Foundation IRCCS Istituto Neurologico C. Besta in Milan, by having received intraoperatively both SF for tumor resection and ICG for vasculature angiographic studies in the same surgical procedure. We identified 2 males and 1 female (age range 25–60). Lesions were located in the left temporo-polar area and hippocampus (1 case), right superior frontal gyrus (1 case), left supplementary motor area (1 case). All the three lesions showed Magnetic Resonance Imaging (MRI) characteristics of HGG and, for this reason, in all patients a fluorescein-guided tumor removal was proposed. In the same surgical procedure ICG videoangiography was considered necessary in order to study arterial and venous vasculature, given by the strict relation of the tumor with an unexpected Posterior Communicating Artery (PComA) aneurysm in one case and with cortical drainage veins complexes in the other two cases. In all cases a microscope equipped with both YELLOW560 and IR800 integrated filters (Pentero 900, Carl Zeiss, Oberkorchen, Germany) was used. Fluorescein was i.v. injected at a dose of 5mg/kg immediately after patient intubation. ICG was i.v. injected in bolus on demand of the operating surgeon at a dose of 12.5mg. ResultsNo side-effects related to simultaneous injection of SF and ICG were identified. In all three cases, the use of SF allowed to better visualize the tumor areas during surgical removal, thus leading to a radical resection until no macroscopic appearance of residual tumor mass and no fluorescence was visible in the surgical cavity. ICG videoangiography confirmed the patency of branches of internal carotid artery after clipping of an unexpected small PComA aneurysm found intraoperatively during tumor removal in one case, while in patient 2 and 3 it allowed to evaluate patency and study flow pattern in cortical drainage veins that were intimately related to the tumors and the way of the surgical approach. Postoperative MRI showed a Gross Total Resection of the tumors in all cases. ConclusionsThis study showed for the first time the feasibility of intravenous SF injection and ICG videoangiography in the same surgical procedure. The presence of different fluorescence filters on the same surgical microscope allows the surgeon to recognize and safely resect the tumor and simultaneously evaluate local brain vascularization.

Aneurysm Location as a Prognostic Outcome Factor After Subarachnoid Hemorrhage From Internal Carotid Artery Aneurysms and Potential Impact for Further Experimental Subarachnoid Hemorrhage Models

Prognostic factors of favorable and unfavorable clinical outcome after aneurysmal subarachnoid hemorrhage (SAH) are still not completely known. We retrospectively analyzed the aneurysm location as a factor for patients' outcome after aneurysmal SAH. We retrospectively selected patients from our prospectively collected database with aneurysm at the carotid bifurcation artery (n= 23) and posterior communicating artery (n= 170). Outcome was assessed using the modified Rankin Scale (mRS) (favorable [mRS score, 0-2] vs. unfavorable [mRS score, 3-6]) 6 months after SAH. A good clinical admission status (World Federation of Neurological Surgery grade I-III) has a significant influence on mRS score after SAH. In univariate analysis, advanced age, Fisher grade 3, early hydrocephalus, severity of cerebral vasospasm (CVS), longer stay on the intensive care unit, and posterior communicating artery aneurysms were associated with an unfavorable outcome. Multivariate analysis showed 4 prognostic factors for a favorable outcome: good admission status (odds ratio [OR], 10.8); aneurysms of carotid bifurcation artery (OR, 4.3); absence of mild or severe CVS (OR, 3.4); and patients age less than 55 years (OR, 2.1). Despite the usual prognostic factors (good admission status, younger age, absence of CVS) for a favorable outcome after SAH, the aneurysm location (carotidbifurcation artery) itself seems to be a prognostic factor. Also, aneurysms of the carotid bifurcation artery showed less occurrence of an early hydrocephalus, which is an indicator for the presence of an early brain injury. According to these results, we question if experimental animal models (especially the endovascular model using the perforation of the carotid bifurcation artery) have to be re-evaluated.

Difference in Aneurysm Characteristics between Patients with Familial and Sporadic Aneurysmal Subarachnoid Haemorrhage.

ObjectPatients with familial intracranial aneurysms (IA) have a higher risk of rupture than patients with sporadic IA. We compared geometric and morphological risk factors for aneurysmal rupture between patients with familial and sporadic aneurysmal subarachnoid hemorrhage (aSAH) to analyse if these risk factors contribute to the increased rupture rate of familial IA.MethodsGeometric and morphological aneurysm characteristics were studied on CT-angiography in a prospectively collected series of patients with familial and sporadic aSAH, admitted between September 2006 and September 2009, and additional patients with familial aSAH retrieved from the prospectively collected database of familial IA patients of our center. Odds ratios (OR) with corresponding 95% confidence intervals (95% CI) were calculated to compare the aneurysm characteristics between patients with familial and sporadic aSAH.ResultsWe studied 67 patients with familial and 184 with sporadic aSAH. OR’s for familial compared with sporadic aSAH were for oval shape 1.16(95%CI:0.65–2.09), oblong shape 0.26(95%CI:0.03–2.13), irregular shape 0.83(95%CI:0.47–1.49), aspect ratio ≥ 1.6 0.94(95%CI:0.54–1.66), contact with the perianeurysmal environment (PAE) 1.15(95%CI:0.56–2.40), deformation by the PAE 1.05(95%CI:0.47–2.35) and for dominance of the posterior communicating artery (PCoA) in case of PCoA aneurysms 1.97(95% CI:0.50–7.83).ConclusionsThe geometric and morphological risk factors for aneurysm rupture do not have a higher prevalence in familial than in sporadic aSAH and thus do not explain the increased risk of IA rupture in patients with familial IA. We recommend further search for other potential risk factors for rupture of familial IA, such as genetic factors.

Characteristic analysis of hemodynamics for trunk aneurysm of posterior communicating artery

Objective To study the hemodynamic characteristics of the difference between the trunk aneurysm of posterior communicating artery (PCoA) and the internal carotid artery (ICA)-PCoA aneurysm. Methods A total of 15 patients with trunk aneurysm of PCoA (11 ruptured aneurysms, 4 unruptured aneurysms, for short PCoA trunk group) treated at the Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University from January 2014 to June 2015 were studied retrospectively. The 15 patients with ICA-PCoA aneurysm with approximately the same size and the same rupture state at the same time were used as a matched control group. A numerical simulation analysis was conducted for individual three-dimensional digital subtraction angiography (DSA) images of the patients using the method of computational fluid dynamics. The differences of hemodynamic parameters of the aneurysms were compared between the 2 groups. Results The PCoA trunk aneurysms were in accordance with the blood flow pattern of the lateral aneurysms, and the ICA-PCoA aneurysms were in accordance with the flow blood pattern of the aneurysms at the bifurcations. The hemodynamic parameters in the PCoA trunk group vs. the control group: The wall shear stress (WSS) of the PCoA trunk group and the control group was 0.48±0.08 and 0.63±0.07 respectively. The percentage of the low WSS area (LSA) was 23.20±6.94% and 4.50±2.29% respectively. There were significant differences (P=0.022, P=0.008). The oscillatory shear index (OSI) of the two groups was 0.0233±0.0071 and 0.0158±0.0044 respectively. There was no significant difference (P=0.411). The WSS of the ruptured group (n=22) and the unruptured group (n=8) was 0.45±0.05 and 0.84±0.08 respectively, and LSA was 18.22±5.11% and 1.84±1.76% respectively. There was significant difference (P<0.001, P=0.006). The OSI of the two groups was 0.0234±0.0054 and 0.0091±0.0027 respectively. There was no significant difference (P=0.132). Conclusion The low WSS may be one of the reasons for the high risk of PCoA trunk aneurysm rupture. Key words: Intracranial aneurysms; Aneurysm, ruptured; Hemodynamics; Posterior communicating artery; Computational fluid dynamics

Carotid siphon morphology: Is it associated with posterior communicating aneurysms?

Posterior communicating artery (PComA) aneurysm seems to behave uniquely compared with other intracranial aneurysms at different locations. The association between the morphology of the carotid siphon and PComA aneurysms is not well known. This study aimed to investigate whether the anatomical characteristics of the carotid siphon are associated with the formation and rupture of PComA aneurysms. One hundred and thirty-two patients were retrospectively reviewed in a monocentric case-control study. Sixty-seven consecutive patients with PComA aneurysms were included in the case group, and 65 patients with anterior circulation aneurysm situated in other intracranial locations were included in the control group, matched by age and sex. Morphological characteristics of the carotid siphon were analyzed using angiography images. A univariate analysis was used to investigate the association between the morphological characteristics and the formation of PComA aneurysms. Furthermore, a subgroup analysis within the case group compared ruptured and non-ruptured PComA aneurysms. Patients with PComA aneurysm had a significantly (1.31 ± 0.70 vs. 0.82 ± 0.46; P < 0.001) larger PComA. No association was observed between the morphological characteristics of the carotid siphon and the presence of a PComA aneurysm. Likewise, subgroup analysis showed no significant association between morphological characteristics of the carotid siphon and aneurysm rupture. This case-control study shows that the carotid siphon morphology seems not to be related to PComA aneurysm formation or rupture.

Clinical study of the relationship between Willis arterial loop variation and intracranial aneurysms

Objective To explore the relationship between the changes of the cerebral arterial circle of Willis and the occurrence of intracranial aneurysms in the diagnosis of digital angiography. Methods From December 2014 to January 2014, 144 cases of intracranial aneurysms were treated in the First Affiliated Hospital of Luzhou Medical University. According to the location of the aneurysm of all patients, the patients were divided into the anterior communicating artery and the posterior communicating artery aneurysms. The relationship between two groups of patients was compared by the sex, age, and the length of the intracranial aneurysms. The relationship was analyzed between the Willis ring and the intracranial aneurysms. The sensitivity and specificity were compared with the surgical results. Results A total of 144 cases of intracranial aneurysms were detected by digital angiography, 68 patients in anterior communicating artery aneurysms, and posterior communicating artery aneurysm in 76 cases. There were no significant differences in sex distribution, age distribution, and length of tumor in the patients with anterior communicating artery aneurysms and the patients with a group of patients with a posterior communicating artery aneurysm. The anterior communicating artery aneurysm group, A1 segment of slender or absence rate was up to 79.41%, and communicating artery aneurysm group A1 segment of slender or absence rate was only 52.63%, two groups were compared with statistical significance (P 0.05). Conclusions Digital angiography can be more accurate in the diagnosis of intracranial aneurysms. Anterior communicating artery aneurysm occurrence is closely related to A1 segment of slender, and absent and bilateral embryo brain artery. Communicating artery aneurysms is more closely related to unilateral embryonic brain artery. Key words: Circle of willis/PA/RA; Tomography, X-ray computed; Intracranial aneurysm/PA/RA

Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms.

Background and PurposeThe conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA) aneurysms.Materials and MethodsIn 129 PCoA aneurysms (85 ruptured, 44 unruptured), clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms.ResultsWhile univariate analyses showed that the size of aneurysm dome, aspect ratio (AR), size ratio (SR), dome-to-neck ratio (DN), inflow angle (IA), normalized wall shear stress (NWSS) and percentage of low wall shear stress area (LSA) were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p < 0.001) and LSA (OR = 1.393, p = 0.041).ConclusionsHemodynamics and morphology were related to rupture status of intracranial aneurysms. Higher IA and LSA were identified as discriminators for rupture status of PCoA aneurysms.

Spontaneous Acute Subdural Hemorrhage with Rupture of Intracranial Aneurysm: A Series of Two Cases and Review of Literature

We present a rare series of two cases of spontaneous intracranial aneurysmal hemorrhage associated with acute subdural hematoma. One patient was having ruptured anterior communicating artery aneurysm and acute subdural hematoma with no evidence of subarachnoid hemorrhage and the other patient presented with subarachnoid hemorrhage with bleeding in subdural, intraparenchymal, and intraventricular location with rupture of posterior communicating artery aneurysm. In this report, we are describing the pathophysiology and radiological features of subdural hematoma with aneurysm bleed.

Real-Time Evaluation of Anterior Choroidal Artery Patency During Aneurysm Clipping.

Inadvertent occlusion of the anterior choroidal artery during aneurysm clipping can cause a disabling stroke in minutes. We evaluate the clinical utility of direct cortical motor evoked potential (MEP) monitoring during aneurysm clipping, as a real-time assessment of arterial patency, prior to performing indocyanine green videoangiography. Direct cortical MEPs were recorded in seven patients undergoing surgery for aneurysms that involved or abutted the anterior choroidal artery. The aneurysms clipped in those seven patients included four anterior choroidal artery aneurysms and six posterior communicating artery aneurysms. Serial MEP recordings were performed during the intradural dissection, aneurysm exposure, and clip placement. A significant change in MEPs after clip placement would prompt immediate inspection and removal or repositioning of the clip. If the clip placement appeared satisfactory and MEP recordings were stable, then an intraoperative indocyanine green videoangiogram was performed to confirm obliteration of the aneurysm and patency of the arteries. Seven patients underwent successful clipping of anterior choroidal artery aneurysms and posterior communicating artery aneurysms using direct cortical MEP monitoring, with good clinical and radiographic outcomes. In six patients, no changes in MEP amplitudes were observed following permanent clip placement. In one patient, a profound decrease in MEP amplitude occurred 220 seconds after placement of a permanent clip on a large posterior communicating aneurysm. An inspection revealed that the anterior choroidal artery was kinked. The clip was immediately removed, and the MEP signals returned to baseline shortly thereafter. A clip was then optimally placed, and the patient awoke without neurologic deficit. Direct cortical MEPs are a useful adjunct to standard electrophysiologic monitoring in aneurysm surgery, particularly when the anterior choroidal artery or lenticulostriate arteries are at risk. When these arteries are occluded, infarction may occur before the occlusion is detected by indocyanine green videoangiography or intraoperative angiography. The use of MEPs allows real-time detection of ischemia to subcortical motor pathways.