Left A1 Research Articles

Abstract 1122‐000164: Peri‐embolization Use of Stent Retrievers as a Rescue Tool in Patients with Subarachnoid Hemorrhage

Introduction : Coil migration after endovascular embolization of intracranial aneurysms is one of the periprocedural complications in 2–6% of patients. Stent retriever use is well‐established in treatment of ischemic stroke but has not been well established to address coil retrieval as rescue therapy. We describe three cases with successful removal of migrated coils using stent retrievers. Methods : A retrospective review at a single center university hospital was performed for all Neuro‐endovascular case log from December 2018 to November 2020. Cases of coil migration were reviewed and coil retraction with Stent Retriever with successful coil mass extraction was considered an endpoint. Number of attempts, types of stent retrievers used and time taken for extraction were noted. Results : Case 1: 56‐year‐old female presented with ruptured tri‐lobed 4 × 3 mm Anterior communicating artery aneurysm. Hunt and Hess (H&H) Grade 2. Modified Fisher scale (MFS) 4. Underwent primary coil embolization. Two 2mmx2cm Galaxy Orbit coils were deployed within aneurysm. During deployment of third coil the first two coils displaced out of the aneurysm migrating into left A2 segment. Stryker’s Trevo 3 × 20 mm stent retriever was used for retrieval of coils however they dislodged at the left internal carotid artery (ICA) terminus and migrated distally into the left middle cerebral artery (MCA) M2 superior division. Subsequently, Medtronic’s Solitaire 4 × 40 mm stent retriever was successfully deployed retrieving the migrated coils with full recanalization. Case 2: 64‐year‐old female presented with ruptured 3 × 5.3 mm right posterior communicating artery (Pcom) aneurysm. H&H 5 and MFS 4. Underwent primary coil embolization with placement of Galaxy Orbit 2.5mmx3.5cm coil. On follow up run, coil mass had migrated into the origin of right fetal Pcom. Migrated coil was successfully retrieved using Stryker’s 4 × 40 mm stent retriever with complete recanalization. Case 3: 65‐year‐old female with presented ruptured 8.5 × 6.8 mm right supraclinoid ICA irregular aneurysm. H&H Grade 1. MFS 3. Underwent primary coil embolization with one Galaxy coil (5mm x 10cm) with plan for future flow diversion. Two weeks later, patient experienced acute neurological worsening with new left sided hemiparesis and right gaze deviation. Imaging revealed acute occlusion of right middle cerebral artery M1 segment occlusion with thrombosed migrated coil. Patient underwent retrieval of the coil and superimposed thrombus utilizing Stryker’s Trevo (4*30 mm) stent retriever with resultant full recanalization. Conclusions : These cases demonstrate successful endovascular mechanical removal of migrated coils using stent retrievers. They add to the limited experience of stent retrievers utilization as effective tools for dealing with such complications.

Musicianship and melodic predictability enhance neural gain in auditory cortex during pitch deviance detection.

When listening to music, pitch deviations are more salient and elicit stronger prediction error responses when the melodic context is predictable and when the listener is a musician. Yet, the neuronal dynamics and changes in connectivity underlying such effects remain unclear. Here, we employed dynamic causal modeling (DCM) to investigate whether the magnetic mismatch negativity response (MMNm)—and its modulation by context predictability and musical expertise—are associated with enhanced neural gain of auditory areas, as a plausible mechanism for encoding precision‐weighted prediction errors. Using Bayesian model comparison, we asked whether models with intrinsic connections within primary auditory cortex (A1) and superior temporal gyrus (STG)—typically related to gain control—or extrinsic connections between A1 and STG—typically related to propagation of prediction and error signals—better explained magnetoencephalography responses. We found that, compared to regular sounds, out‐of‐tune pitch deviations were associated with lower intrinsic (inhibitory) connectivity in A1 and STG, and lower backward (inhibitory) connectivity from STG to A1, consistent with disinhibition and enhanced neural gain in these auditory areas. More predictable melodies were associated with disinhibition in right A1, while musicianship was associated with disinhibition in left A1 and reduced connectivity from STG to left A1. These results indicate that musicianship and melodic predictability, as well as pitch deviations themselves, enhance neural gain in auditory cortex during deviance detection. Our findings are consistent with predictive processing theories suggesting that precise and informative error signals are selected by the brain for subsequent hierarchical processing.

An MRI study of typical anatomical variants of the anterior communicating artery complex.

This magnetic resonance imaging study examined the most frequent anatomical variants of the anterior communicating artery (ACoA) complex of the cerebral arterial circle, and aimed to determine whether they were associated with ACoA complex aneurysm. The study enrolled 669 patients. Using three-dimensional time-of-flight magnetic resonance angiography, 617 patients were classified into the following groups based on the anatomical variation in the ACoA complex: no ACoA complex anomaly; ACoA complex aneurysm; and vascular anomaly distant from the cerebral arterial circle. Of the 617 classified subjects, the classical anatomical description applied to 48.73% in the no ACoA complex anomaly group and 37.5% in the ACoA complex aneurysm group. One variant (left anterior cerebral artery segment A1 hypoplasia) was significantly more frequent in the ACoA complex aneurysm group. There was no sex difference in the prevalence of any variant. Anatomical variants of the ACoA complex of the cerebral arterial circle were found in almost half of the subjects. One variant seemed to be associated with a higher likelihood of an aneurysm, but causality could not be inferred.

Bubbles and Troubles: A Case of Azygous ACA with Bilateral ICA Aneurysm, Besides the Usual Distal ACA Aneurysm

Azygous ACA is one of the rare anatomic variants of anterior cerebral artery. Predisposition to aneurysm development is attributed to the alteration in flow dynamics. Such hemodynamic alteration is most commonly seen in the anterior circulation, causing distal ACA aneurysm to be the most commonly associated vascular pathology. Although neurosurgical literature is replete with anatomical reports of such cases, there has been no case reports where bilateral ICA aneurysms are also present with the distal ACA aneurysm. In this case, the presence of hypoplastic left A1 segment might predispose the other segments of Circle of Willis to hemodynamic alterations. Thus, whenever one comes across an azygous ACA in association with an additional anomaly he should be vigilant enough to look for other pathologies beyond the commonly encountered distal ACA aneurysm. The presence of azygous ACA also poses a technical challenge due to the risk of ischemic insult to anterior regions of bilateral hemispheres during temporary clipping of the single A2 trunk. In addition to it, the presence of a hypoplastic A1 segment also makes the approach to the giant aneurysm in ICA segment more technically demanding as cross flow is not adequate. So, the presence of multiple anatomic anomalies not just increases the number of vascular pathologies but also enhances the challenges that the surgeon has to face in planning the strategic approach to tackle all the lesions.

Artificial Neural Network for Predicting the Safe Temporary Artery Occlusion Time in Intracranial Aneurysmal Surgery.

Background. Temporary artery clipping facilitates safe cerebral aneurysm management, besides a risk for cerebral ischemia. We developed an artificial neural network (ANN) to predict the safe clipping time of temporary artery occlusion (TAO) during intracranial aneurysm surgery. Method. We devised a three-layer model to predict the safe clipping time for TAO. We considered age, the diameter of the right and left middle cerebral arteries (MCAs), the diameter of the right and left A1 segment of anterior cerebral arteries (ACAs), the diameter of the anterior communicating artery, mean velocity of flow at the right and left MCAs, and the mean velocity of flow at the right and left ACAs, as well as the Fisher grading scale of brain CT scans as the input values for the model. Results. This study included 125 patients: 105 patients from a retrospective cohort for training the model and 20 patients from a prospective cohort for validating the model. The output of the neural network yielded up to 960 s overall safe clipping time for TAO. The input values with the greatest impact on safe TAO were mean velocity of blood at left MCA and left ACA, and Fisher grading scale of brain CT scan. Conclusion. This study presents an axillary framework to improve the accuracy of the estimated safe clipping time interval of temporary artery occlusion in intracranial aneurysm surgery.

Auditory cortex hyperconnectivity before rTMS is correlated with tinnitus improvement

IntroductionRepetitive transcranial magnetic stimulation (rTMS) has been used as a potential treatment for tinnitus; however, its effectiveness is variable and unpredictable. We hypothesized that resting-state functional connectivity before rTMS may be correlated with rTMS treatment effectiveness. MethodsWe applied 1-Hz rTMS to the left primary auditory (A1) and dorsolateral prefrontal cortices (DLPFC) of 10 individuals with tinnitus and 10 age-matched controls. Resting-state functional magnetic resonance imaging (fMRI) studies were performed approximately one week before rTMS. Seed-based connectivity analyses were conducted for each individual, with seed regions as rTMS target areas. ResultsCompared to controls, the left superior temporal areas showed significantly increased positive connectivity with the left A1 and negative connectivity with the left DLPFC in the tinnitus group. The left frontoparietal and right cerebellar areas showed significantly increased negative connectivity with the left A1 and positive connectivity with the left DLPFC. Seed-based hyperconnectivity was correlated with tinnitus improvement (pre-rTMS vs. 2-week post-rTMS Tinnitus Handicap Inventory scores). Tinnitus improvement was significantly correlated with left A1 hyperconnectivity; however, no correlation was observed with left DLPFC connectivity. Positive rTMS outcomes were associated with significantly increased positive connectivity in bilateral superior temporal areas and significantly increased negative connectivity in bilateral frontal areas. ConclusionsOur results suggest that oversynchronisation of left A1 connectivity before rTMS of the left A1 and DLPFC is associated with treatment effectiveness.

In Situ Side-to-Side Pericallosal-Pericallosal Artery and Callosomarginal-Callosomarginal Artery Bypasses for Complex Distal Anterior Cerebral Artery Aneurysms: A Technical Note.

Despite surgical and endovascular technical improvements over the last decades, the treatment of complex aneurysms of the distal anterior cerebral artery (ACA) is very challenging for both vascular neurosurgeons and interventional neuroradiologists. Furthermore, the interpersonal anatomic variability requires, most of the time, a tailored planning. To describe a novel technique of bypasses in the territory of ACA to protect the brain territory distal to the aneurysm. A 53-yr-old male with a large complex fusiform aneurysm of the left distal A2 segment of the ACA, involving the origin of the callosomarginal and pericallosal arteries, was judged not suitable for a single procedure (endovascular or neurosurgical). Two side-to-side bypasses were performed in a single surgery to connect the pericallosal and callosomarginal arteries of both sides, distally to the aneurysm. Subsequently, an endovascular embolization of the aneurysm was achieved with coils. The patency of the microanastomoses, performed in the anterior interhemispheric fissure, was positively evaluated intraoperatively with indocyanine green and fluorescein videoangiography. The aneurysm sac, together with proximal A2 segment, was completely occluded with platinum coils. At the last follow-up, computed tomography angiography confirmed the patency of both bypasses, without any sign of aneurysm recanalization. The patients never complained of any focal neurological deficits or worsening of clinical status. We present an elegant and innovative solution to completely protect the distal ACA territory in cases of complex aneurysm involving the origin of both callosomarginal and pericallosal arteries.

Enlarged anterior communicating artery masquerading as intracranial aneurysm

Background. The anterior communicating artery (ACoA) complex consists of the ACoA, the pre-and post-communicating segments of the anterior cerebral artery, and the recurrent artery of Heubner. It is the most common site for anatomical variations in the circle of Willis. Such variations can mimic intracranial aneurysms.
 Case description. A 30-year-old female presented with recurrent episodes of extreme headache and bilateral tinnitus. A brain computed tomography (CT) scan showed no significant lesions, while her CT-angiography (CTA) showed an enlarged vascular lesion at the ACoA, raising the suspicion for an ACoA aneurysm. A repeated CTA revealed a rare anatomical variation with a pattern of cross dominance in the ACoA complex; the left A1 and right A2 were dominant-enlarged, resulting in an enlargement of the ACoA. The presence of an ACoA aneurysm was hence excluded and the patient was managed conservatively. At 6-month follow-up, CTA showed no new findings. 
 Conclusion. ACoA enlargement can result from unequal hemodynamics around the ACoA complex, which may be mistaken for an aneurysm. A thorough study of the imaging data is of pivotal importance and may change the management strategy.

Changes in the Auditory Association Cortex in Dementing Illnesses.

To evaluate the relationship between degree of cognitive impairment and gray-matter density changes in the auditory cortex. Retrospective case-control. Six hundred sixty-three patients of a tertiary referral center cognitive disorders clinic. Magnetic resonance imaging. Ratios of gray matter density of the primary auditory cortex (A1) to whole brain and auditory association cortex (AAC) to whole brain in patients with Alzheimer's disease (AD) compared with mild cognitive impairment (MCI) and patients with a mini-mental state exam (MMSE) scores ≤25 versus >25. After multivariate analysis, a statistically significant difference between AAC to brain ratios for patients with a MMSE ≤25 (n = 325) compared with >25 (n = 269) was found, with values -0.03 (95% CI -0.04 to -0.02, p < 0.0001) on the left and -0.04 (95% CI -0.06 to -0.03, p < 0.0001) on the right. The adjusted average difference of left and right AAC to brain ratios between AD patients (n = 218) compared with MCI patients (n = 121) was also statistically significant, at -0.03 (95% CI -0.05 to -0.01, p = 0.004) and -0.05 (95% CI -0.07 to -0.03, p < 0.0001), respectively. There was no statistically significant difference in the left or right A1 to brain ratios between the MMSE groups or between the AD and MCI groups. The AAC for patients with MMSE ≤25 and for those with AD shows decreased gray matter density when compared with patients with better cognitive function. No difference was detected in A1, raising the possibility that patients may have intact neural hearing, but impaired ability to interpret sounds.

Reduced auditory steady state responses in autism spectrum disorder

BackgroundAuditory steady state responses (ASSRs) are elicited by clicktrains or amplitude-modulated tones, which entrain auditory cortex at their specific modulation rate. Previous research has reported reductions in ASSRs at 40 Hz for autism spectrum disorder (ASD) participants and first-degree relatives of people diagnosed with ASD (Mol Autism. 2011;2:11, Biol Psychiatry. 2007;62:192–197).MethodsUsing a 1.5 s-long auditory clicktrain stimulus, designed to elicit an ASSR at 40 Hz, this study attempted to replicate and extend these findings. Magnetencephalography (MEG) data were collected from 18 adolescent ASD participants and 18 typically developing controls.ResultsThe ASSR localised to bilateral primary auditory regions. Regions of interest were thus defined in left and right primary auditory cortex (A1). While the transient gamma-band response (tGBR) from 0-0.1 s following presentation of the clicktrain stimulus was not different between groups, for either left or right A1, the ASD group had reduced oscillatory power at 40 Hz from 0.5 to 1.5 s post-stimulus onset, for both left and right A1. Additionally, the ASD group had reduced inter-trial coherence (phase consistency over trials) at 40 Hz from 0.64-0.82 s for right A1 and 1.04-1.22 s for left A1.LimitationsIn this study, we did not conduct a clinical autism assessment (e.g. the ADOS), and therefore, it remains unclear whether ASSR power and/or ITC are associated with the clinical symptoms of ASD.ConclusionOverall, our results support a specific reduction in ASSR oscillatory power and inter-trial coherence in ASD, rather than a generalised deficit in gamma-band responses. We argue that this could reflect a developmentally relevant reduction in non-linear neural processing.

Anterior Communicating Artery Complex Aneurysms Are Caused by the Asymmetric Anterior Cerebral Arteries

Background: Rupture of anterior communicating artery complex (AcomAC) aneurysms is a common cause of haemorrhagic brain strokes. Ability to predict development of aneurysms in advance would allow stroke prevention. Asymmetry of the components of cerebral basal arterial network (CBAN) could alter hemodynamics and may contribute to formation of aneurysms. The asymmetric diameter ratio of first segments of anterior cerebral arteries (A1s), correlates with the occurrence of the AcomAC aneurysms. Materials and Methods: Cerebral Computed Tomography Angiography (CTA) scans of 166 adult patients of both sexes were studied. The internal diameters of the right and left A1 segments of anterior cerebral arteries, perpendicular to the long axis of the vessels were measured. Positions and presence or absence of aneurysms in AcomAC were recorded in each individual case. The ratio of the larger to the smaller A1 diameters was determined as a measure of the asymmetry of A1 segments of anterior cerebral arteries (ACAs). Findings: The risk of development of aneurysms in AcomAC was much greater (risk 80%, odds ratio = 47·3) when one A1 segment's radius was at least 50% larger (i.e. 2·25 times greater cross-sectional area) than the other. The risk of development of aneurysms was just 7·8%, if the A1 asymmetric ratio was less than 1·5 (odds ratio = 0·02). Conclusion: The asymmetry ratio of the A1 segments of anterior cerebral arteries is a good predictor for the development of aneurysms in the AcomAC region. Funding Statement: The authors stated: None. Declaration of Interests: The authors declare that there is no conflict of interests. Ethics Approval Statement: The use of images and accompanying information was approved for research purposes by the University of Adelaide Human Research Ethics Board (approval number: H2014-176). Patients’ personal details, have not been copied, documented, or included in this research.

The Comparison of the Right and Left Sigmoid Sinus Cross-Sectional Areas in Fetal Period and the Factors Affecting the Venous Dominance.

Skull base is an important and a challenging area for surgeons. Success in skull base surgery depends on various factors such as pre-operative evaluation, appropriate surgical technique, anesthesia duration, intraoperative neuromonitorization and wound care. This study was performed in the Anatomy dissection laboratory of M.U. Medical Faculty (Ethical committee approval number 2010-103). Twelve fetuses between 17-33 gestational weeks fixed with formaldehyde were enrolled to the study. This study was planned to investigate the cross sectional areas of the sigmoid sinus in three levels to compare the right-left sides and the probable relationship among the levels in fetuses to further delineate the developmental factors on jugular foramen asymmetry. The cross-sectional measurements of sigmoid sinus lumen were done on 3 levels which are described as A1 level; sinodural angle, A2 level; the midpoint between the sinodural angle and endocranial orifice and A3 level as the entrance (endo-cranial orifice) of the jugular foramen. There is a strong positive correlation between left (L) A1 and L A2 and also the same for L A1 and right (R) A2. These strong and positive correlations are all valid between L A2-L A3, L A2-R A2, L A2-R A3, L A3-R A3, R A1-R A2. Multicenter studies would be beneficial to investigate the topic with greater number of fetuses also on the different regions for genetic differences.

Laminar Organization of FM Direction Selectivity in the Primary Auditory Cortex of the Free-Tailed Bat.

We studied the columnar and layer-specific response properties of neurons in the primary auditory cortex (A1) of six (four females, two males) anesthetized free-tailed bats, Tadarida brasiliensis, in response to pure tones and down and upward frequency modulated (FM; 50 kHz bandwidth) sweeps. In addition, we calculated current source density (CSD) to test whether lateral intracortical projections facilitate neuronal activation in response to FM echoes containing spectrally distant frequencies from the excitatory frequency response area (FRA). Auditory responses to a set of stimuli changing in frequency and level were recorded along 64 penetrations in the left A1 of six free-tailed bats. FRA shapes were consistent across the cortical depth within a column and there were no obvious differences in tuning properties. Generally, response latencies were shorter (<10 ms) for cortical depths between 500 and 600 μm, which might correspond to thalamocortical input layers IIIb–IV. Most units showed a stronger response to downward FM sweeps, and direction selectivity did not vary across cortical depth. CSD profiles calculated in response to the CF showed a current sink located at depths between 500 and 600 μm. Frequencies lower than the frequency range eliciting a spike response failed to evoke any visible current sink. Frequencies higher than the frequency range producing a spike response evoked layer IV sinks at longer latencies that increased with spectral distance. These data support the hypothesis that a progressive downward relay of spectral information spreads along the tonotopic axis of A1 via lateral connections, contributing to the neural processing of FM down sweeps used in biosonar.

Anatomical variations and dimensions of arteries in the anterior part of the circle of Willis.

The aim of this study was to investigate different anatomic variations and dimensions of anterior part of the circle of Willis (CW) and their prevalence on Kosovo's population. This is an observational descriptive and retrospective study performed at the University Clinical Centre, Clinic of Radiology. The three-dimensional time-of-flight technique was used for magnetic resonance angio- graphy imaging to evaluate the anatomy of the CW in 513 adults without clinical manifestations for cerebrovascular disease. The diameters of arteries of the CW were measured and variations were recorded. The complete anterior part of CW was found in 64.3% of cases, more evident in female at about 66% than male 62.2%. Morphologic variations of the ACA1 are agenesis or hypoplasia in 5.65%, fusion of the anterior cerebral arteries (ACAs) on a short distance in 6.5% and fusion of the ACA on a long distance in 2.5%, median ACA is presented in 11 examined patients or 2.1%. Normal anterior communicating artery (ACoA) was seen in 68.2%, hypoplasia or absence 15.66%, double ACoA in 0.6% and fenestrations in 3.89%. The mean calibrations of the vessels were measured as 2.04 mm in right A1, 2.06 mm in left A1 and 1.16 mm of ACoA. While, 14.1 mm length of right A1, 13.87 mm of left A1 and 2.99 mm of ACoA. Knowledge of the variations and diameter of the anterior part of the CW has a great importance in determination of anatomical variations and diameter in general populations, also, in interventional radiology for various endovascular interventions as well as during anatomy lessons.

Microsurgical Clip Placement for a Giant Anterior Communicating Artery Aneurysm With Intraluminal Thrombus: 2-Dimensional Operative Video

Giant brain aneurysms account for approximately 5% of all intracranial aneurysms. Although treatment modalities can vary widely, none is ideal for every patient. Endovascular treatment is usually preferred, especially when the large size of the aneurysm limits visualization of the brain parenchyma and parent vessels that arise from the aneurysm, making surgical clip placement across the neck a difficult task. However, despite the higher chances of morbidity, microsurgery is an effective treatment modality due to lower recurrence rates. Surgically, a wide neck, calcifications, or atheroma are complicating factors to be considered while planning the best treatment. Thus, with an appropriate case selection, a favorable outcome is feasible in most cases. Here, we present the case of a 27-yr-old female who presented with a severe headache for 7 mo and 3 mo of progressive left temporal vision loss, which was confirmed by visual field perimetry using the Humphrey visual field analyzer. Magnetic resonance angiography and digital subtraction cerebral angiography showed an anterior communicating artery complex inferiorly and medially oriented aneurysm measuring 25.4×16.5 mm, with a 3 mm neck. It was fed by the right A1, associated with a hypoplastic left A1, incorporating the proximal right and left A2 segments, with an intraluminal thrombus and causing mass effect on the optic chiasm and hypothalamus. This video demonstrates the microsurgical steps required to perform this operation, through a right orbitozygomatic craniotomy. At a 3-mo follow-up, the patient was neurological intact without complaints. The patient signed the Institutional Consent Form, which allows the use of his/her images and videos for any type of medical publications in conferences and/or scientific articles.

Preliminary study of auditory cortex resting-state fMRI features for adult post-lingual deafness

Objective: To understand the auditory cortex resting-state fMRI features for adult post-lingual deafness.Method: The author performed functional connectivity analysis on the study subjects with resting-state fMRI,the region of interest(ROI) of which were based separately on the left and right sides of primary auditory cortex. The data were collected from 8 cases with severe or above sensorineurally post-lingual deafness,compared to a control group of 8 cases with normal hearing. Result: When ROI were based on the left A1 areas of all subjects, the main activating area in the control group was bilateral superior temporal gyrus(STG), while the post-lingual deafness group included the bilateral STG, pre-central gyri, left Transverse temporal gyrus(TTG), post-central gyri and right TTG (P<0.01); when ROI were based on the right A1 areas of all subjects, the main activating area in the control group was the bilateral STG, while the post-lingual deafness group included the bilateral STG, right precentral gyri and post-central gyr i(P<0.01). The data showed statistical significance(P<0.05). Conclusion: After hearing loss functional reorganization takes place in the brains of adults with post-lingual deafness, resulting in possible enhancement of visual sense, tactile sense and other sensory systems in order to compensate information acquisition in daily life. .

Intraoperative microsurgical anatomy of the anterior communicating artery complex harbouring an anterior cerebral territory aneurysm.

The vascular anatomy of the anterior communicating artery complex (ACAC), the most frequent site of occurrence of aneurysms, is complex and associated with many anatomical and morphological variations. The aim of this study was to determine the anatomical variations of ACAC in the Indian population. This was an observational study. Sixty-two patients of ACAC aneurysms were subjected to clipping, and intraoperative microsurgical details were analyzed. Twenty-two (35.48%) patients had anatomical and morphological variations that were more common on the right side. Right A1 was hypoplastic in 5 (8.06%), aplastic in 2 (3.22%), and tortuous in 1 (1.61%) patient. Left A1 was aplastic in 3 (4.83%), hypoplastic in 1 (1.61%) and prominent in 2 (3.22%) patients. One patient (1.61%) had a prominent left A2 segment and 2 (3.22%) had a prominent right A1 and A2 segment. Two patients (3.22%) had fenestration of the ACAC and 3 (4.83%) had the median artery of corpus callosum. The recurrent artery of Heubner was identified in only 44 (70.96%) patients, and in these patients, distinct anatomical variations were noted. Eleven patients were found to present with a parent vessel anomaly, having a total of 23 (mean, 2.09) perforators arising from ACAC, whereas those without a parent vessel anomaly had a total of 57 (mean, 1.11) perforators. This difference was statistically significant. The ACAC region is the area of highest anatomical and morphological variability. This variability is even more exhaustive when associated with aneurysmal formation. A sound anatomical knowledge of the perforators and their preservation during the surgical management of the ACAC is of paramount importance for ensuring a good clinical outcome of patients.

Side-to-Side Bypass between Bilateral Distal Anterior Cerebral Arteries and Surgical Trapping of a Pseudoaneurysm from the Anterior Communicating Artery: Lessons Learnt

Background:Treatment options for a ruptured anterior communicating artery (ACoA) pseudoaneurysm are limited. In most cases trapping of the ACoA is the best treatment option. Occasionally, bypass surgery is warranted to ensure blood flow to the contralateral anterior cerebral artery (ACA) in cases with one dominant A1. We report a case of an ACoA pseudoaneurysm presenting with delayed subarachnoid hemorrhage following surgical clipping of an unruptured ACoA aneurysm, with a review of the literature.Case description:A 74-year-old female had undergone surgical clipping of a 1.2-cm-sized unruptured ACoA aneurysm through the left supraorbital keyhole approach. During the operation, there had been a small tear between the aneurysm neck and the right proximal A2, and the tear point was controlled by clipping of the tear site. One month later, she was admitted again because of subarachnoid hemorrhage. Cerebral angiography showed a probable pseudoaneurysm from the previous tear site. The patient had a dominant left A1 with a right A1 aplasia. The pseudoaneurysm was treated with side-to-side bypass between the distal ACAs and subsequent trapping of the ACoA harboring a pseudoaneurysm. Both the distal ACAs were preserved; however, post-hemorrhagic neurological sequelae remained.Conclusions:Side-to-side bypass between distal ACAs and surgical trapping of the ACoA for the ruptured ACoA pseudoaneurysm was a good rescue option to prevent rebleeding and preserve blood supply to the contralateral ACA territory.

Hemodynamic ischemia of the anterior choroidal artery and reversal by carotid artery stenting 10 years after ipsilateral superficial temporal artery-middle cerebral artery bypass for symptomatic left middle cerebral artery stenosis.

The pathogenesis of anterior choroidal artery (AChA) territory infarction includes various mechanisms, but hemodynamic causes are rare and difficult to diagnose. 77- year-old man, who had moderate left ICA stenosis and he had treated with STA-MCA bypass surgery for severe symptomatic left MCA stenosis 10 years earlier, was admitted with right hemiparesis and confused state. On admission, magnetic resonance imaging and angiography demonstrated patent bypass, but severe stenosis of left ICA with no opacification of the left AChA and A1 portion of the left ACA. Diffusionweighted imaging demonstrated ischemic lesion in the left corona radiata. Together with clinical findings, hemodynamic ischemia of the AChA region was suspected and left carotid artery stenting resulted in prompt improvement of symptoms. Hemodynamic ischemia of the AChA territory is rare, however, should be considered as a potential target of treatment when the ipsilateral ICA, A1 and M1 show stenoocclusive lesions.

In Situ Left Azygous Anterior Cerebral Artery to Right Pericallosal Artery Bypass for Treatment of a Giant Right A1/2 Aneurysm: 2-Dimensional Operative Video.

Here we present a 46-yr-old man with recurrent syncopal episodes thought to be of cardiac origin. He was eventually found to harbor a giant, partially thrombosed, saccular aneurysm arising from the A1/A2 segment of the right anterior cerebral artery with foramen of Monro obstruction and a trapped left-sided ventricular system. An azygous left A2 artery segment supplied both callosomarginal arteries. We performed an in situ side-to-side anastomosis between the distal left azygous anterior cerebral artery and the right pericallosal artery, which was previously supplied by the right A1. The right A1 was clip ligated, and the aneurysm evacuated with an ultrasonic aspirator. Postoperatively, the patient did well with no recurrence of the aneurysm and resolution of his preoperative obstructive hydrocephalus. He continues to be independent>7 yr post surgery. His 6-mo follow-up angiogram revealed a patent bypass.