Isolated unilateral thalamic venous infarct in a toddler.

Isolated deep cerebral venous thrombosis (CVT), especially involving only the right thalamus, is one of the rarest forms of intracranial venous thrombosis in a child. The anatomy and flow patterns of the deep cerebral venous system are complex and usually, the thrombosis of the internal cerebral veins (ICV) results in thalamic infarction bilaterally. The focal infections, thalamic tumours and vascular malformations may have overlapping clinicoradiological patterns. The treating team should be able to recognise the atypical phenotypes of the deep CVT at the earliest, which can facilitate apt treatment and obviate the need for unnecessary investigations and interventions. We present a rare case of an isolated right thalamic acute venous infarct secondary to bilateral ICV thrombosis in a toddler who was successfully managed by timely diagnosis and with only conservative therapy.

Isolated acute pseudobulbar palsy with infarction of artery of percheron: case report and literature review.

INTRODUCTION: Pseudobulbar palsy (PBP) is characterized by supranuclear lesions in the corticobulbar pathway. Neoplasia, inflammatory, demyelinating, and stroke are possible etiologies of this disorder. CASE REPORT: We report an elderly female who presented with dysarthria. She was dysarthric with a hypernasal voice, no apraxia or aphasia was observed. Tongue movements were slow with limited amplitude. Her soft palate dropped bilaterally; gag reflex was present. Also, she reported swallowing difficulty and choking with her saliva. Bilateral vertical and horizontal gaze were intact to either voluntary or oculocephalic movements. A cranial CT scan was suggestive of artery of Percheron (AOP) infarction. Brain magnetic resonance imaging showed hypersignal on diffusion-weighted and T2-weighted images and hyposignal on apparent diffusion coefficient in both thalami. CT angiography scan revealed an AOP originating from the left posterior cerebral artery. The swallowing study with a videofluoroscopic demonstrated oral and pharyngeal phases with severe dysfunction. CONCLUSION: To the authors' knowledge, there are two cases of individuals with artery of Percheron infarction who developed PBP associated with other clinical syndromes. Still, isolated PBP following infarction of Percheron's artery was not reported. We hypothesized that the PBP may have occurred because of the existence of vascular territory variations in the perforating arteries that arise from the AOP.

Infarto da artéria de Percheron: relato de caso / Percheron´s artery infarction: a case report

O infarto da artéria de Percheron é uma apresentação rara de acidente vascular cerebral, caracterizado principalmente por isquemia talâmica bilateral. A apresentação clinica desse infarto se apresenta de maneira inesperada e variável. Relata-se um caso de um paciente masculino, idoso, acometido por diversas comorbidades, admitido na emergência em coma e hemiplégico a direita, demonstrando acometimento neurológico. A condição clínica do paciente variou durante a hospitalização, apresentando melhora do quadro neurológico focal e midríase fixa à direita, levando a um diagnóstico tardio. Paciente evoluiu ao óbito devido a causas não neurológicas.

The artery of Percheron infarct is a rare presentation of stroke, featured mainly by thalamic bilateral ischemia. The clinical presentation of this infarct is unexpected and variable. It's reported a case of a male patient, elderly, affected with several comorbidities, admitted to the emergency in comatose state and right hemiplegic, proving neurological involvement. The patient's clinical condition has fluctuated throughout the hospitalization presenting improvement of the focal neurologic implication and right mydriasis, culminating in a lagged diagnosis. Patient's death due to non neurologic causes.

Blepharospasm With Photophobia Secondary to Midbrain Tuberculoma and Thalamic Infarct.

INTRODUCTION: Blepharospasm is a type of focal dystonia and categorized into primary and secondary forms, based on whether or not a cause can be established. Secondary blepharospasm is uncommon and can be associated with underlying brain lesions. Photophobia is a prominent complaint in blepharospasm patients. We are reporting a case of secondary blepharospasm with photophobia in a patient who had underlying midbrain tuberculoma and thalamic infarcts. This type of presentation has not been reported to the best of our knowledge. CASE REPORT: A 26-year-old man presented to us with the complaint of increased blinking and involuntary closure of both eyes for 1 year. He had a past history of tubercular meningitis 16 years back when he presented with bilateral ptosis, left up gaze palsy and right hemiparesis suggestive of Weber syndrome. His magnetic resonance images of the brain were suggestive of multiple intracranial tuberculomas, thalamic infarcts, and noncommunicating hydrocephalus. Following treatment he recovered significantly with no residual neurological deficit except mild bilateral ptosis. His recent magnetic resonance images of the brain was suggestive of calcified granuloma in the midbrain and chronic left thalamic lacunar infarcts. He was treated with injection Onabotulinum toxin and his symptoms improved significantly. CONCLUSIONS: Our patient had tuberculoma in the midbrain and chronic infarcts in the thalamus, and both lesions may cause blepharospasm and photophobia independently, so it is difficult to ascertain the causative lesion in our patient. However, it is possible that these heterogenous lesions are all part of a single functionally connected brain network and further studies are required to confirm this hypothesis.

Holmes Tremor due to Artery of Percheron Infarct: Clinical Case and Treatment Using Deep Brain Stimulation of the Vim and ZI Targets.

Background: Holmes tremor (HT) arises from disruption of the cerebellothalamocortical pathways. A lesion can interrupt the projection at any point, resulting in this tremor. We describe a case of HT due to the rare artery of Percheron infarct and its successful treatment using deep brain stimulation. Case report: A 62-year-old woman with a right medial cerebral peduncle and bilateral thalamic stroke developed HT. Ventral intermediate nucleus (Vim) zona incerta (ZI) deep brain stimulation (DBS) surgery was performed, with improvement in her tremor. Discussion: Our case supports the theory that the more caudal ZI target in combination with Vim is beneficial in treating poorly DBS-responsive tremors such as HT.

Effect of intravoxel incoherent motion on diffusion parameters in normal brain.

At very low diffusion weighting the diffusion MRI signal is affected by intravoxel incoherent motion (IVIM) caused by dephasing of magnetization due to incoherent blood flow in capillaries or other sources of microcirculation. While IVIM measurements at low diffusion weightings have been frequently used to investigate perfusion in the body as well as in malignant tissue, the effect and origin of IVIM in normal brain tissue is not completely established. We investigated the IVIM effect on the brain diffusion MRI signal in a cohort of 137 radiologically-normal patients (62 male; mean age = 50.2 ±â€¯17.8, range = 18 to 94). We compared the diffusion tensor parameters estimated from a mono-exponential fit at b = 0 and 1000 s/mm2 versus at b = 250 and 1000 s/mm2. The asymptotic fitting method allowed for quantitative assessment of the IVIM signal fraction f* in specific brain tissue and regions. Our results show a mean (median) percent difference in the mean diffusivity of about 4.5 (4.9)% in white matter (WM), about 7.8 (8.7)% in cortical gray matter (GM), and 4.3 (4.2)% in thalamus. Corresponding perfusion fraction f* was estimated to be 0.033 (0.032) in WM, 0.066 (0.065) in cortical GM, and 0.033 (0.030) in the thalamus. The effect of f* with respect to age was found to be significant in cortical GM (Pearson correlation ρ â€‹= â€‹0.35, p â€‹= â€‹3*10-5) and the thalamus (Pearson correlation ρ = 0.20, p = 0.022) with an average increase in f* of 5.17*10-4/year and 3.61*10-4/year, respectively. Significant correlations between f* and age were not observed for WM, and corollary analysis revealed no effect of gender on f*. Possible origins of the IVIM effect in normal brain tissue are discussed.

Left Thalamus Arteriovenous Malformation Secondary to Radiation Therapy of Original Vermian Arteriovenous Malformation: Case Report.

A 70-year-old gentleman with history of hypothyroidism, hyperlipidemia, hypertension, and right superior cerebellar aneurysm presented to the neurosurgery service in 2008 with vertigo. Diagnostic cerebral angiography performed that year demonstrated a vermian arteriovenous malformations (AVM). The patient underwent stereotactic proton beam radiosurgery, which resulted in a decrease in flow and size of the lesion, and the patient was lost to follow-up. Now at the age of 80, the patient presented with acute gait instability. Cerebral angiogram demonstrated his stable vermian AVM and a new 1.1 cm AVM nidus in the region of the left posterior thalamus. Although AVMs are often described as congenital lesions, there is a growing body of literature suggesting that AVMs can grow, spontaneously regress, and even arise de novo in response to some insult. Understanding what leads to the growth, remodeling, regression, and hemorrhage of AVMs is crucial in order to better direct therapeutic endeavors. We would argue that this patient's AVM is secondary to endothelial cell damage from radiation therapy. Radiation can cause endothelial cell injury and upregulation of factors, such as vascular endothelial growth factor and transforming growth factor beta expression, which are implicated in AVM development pathways. We believe that this patient's new AVM is secondary to entrance radiation dosing affecting the thalamus during radiation therapy for the original vermian AVM.

Deep Venous Thrombosis with Decreased Cerebral Blood Flow to the Thalamus was Completely Restored by Factor Xa Inhibitor.

BACKGROUND: Cerebral venous thrombosis is rare and an uncommon cause of stroke and has diverse etiologies and varied clinical presentations. Here, we report 2 cases of deep cerebral venous thrombosis. CASE DESCRIPTION: A 64-year-old woman presented with cerebral venous thrombosis due to a hypercoagulable state associated with ovarian tumor. On initial fluid-attenuated inversion recovery and diffusion-weighted imaging, there was a diffuse high-intensity lesion in the bilateral thalamus. Computed tomography angiography showed occlusion of the straight sinus, vein of Galen, and internal cerebral vein. Single-photon emission computed tomography showed decreased cerebral blood flow in the bilateral thalamus. After 3 weeks of factor Xa inhibitor therapy, the patient's consciousness gradually improved and eventually became clear enough to leave the hospital. She had no neurological deficit. Another patient was a 47-year-old man who presented with splitting headache and drowsiness. Magnetic resonance venography confirmed deep thrombosis of the vein of Galen. He completely recovered after 4 weeks of factor Xa inhibitor therapy. CONCLUSIONS: This study reports on 2 rare cases of decreased cerebral blood flow in the bilateral thalamus on single-photon emission computed tomography, which improved following the administration of factor Xa inhibitor.

Stereotactic radiosurgery for arteriovenous malformations of the basal ganglia and thalamus: an international multicenter study.

OBJECTIVE: Arteriovenous malformations (AVMs) of the basal ganglia (BG) and thalamus are associated with elevated risks of both hemorrhage if left untreated and neurological morbidity after resection. Therefore, stereotactic radiosurgery (SRS) has become a mainstay in the management of these lesions, although its safety and efficacy remain incompletely understood. The aim of this retrospective multicenter cohort study was to evaluate the outcomes of SRS for BG and thalamic AVMs and determine predictors of successful endpoints and adverse radiation effects. METHODS: The authors retrospectively reviewed data on patients with BG or thalamic AVMs who had undergone SRS at eight institutions participating in the International Gamma Knife Research Foundation (IGKRF) from 1987 to 2014. Favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RICs). Multivariable models were developed to identify independent predictors of outcome. RESULTS: The study cohort comprised 363 patients with BG or thalamic AVMs. The mean AVM volume and SRS margin dose were 3.8 cm3 and 20.7 Gy, respectively. The mean follow-up duration was 86.5 months. Favorable outcome was achieved in 58.5% of patients, including obliteration in 64.8%, with rates of post-SRS hemorrhage and permanent RIC in 11.3% and 5.6% of patients, respectively. Independent predictors of favorable outcome were no prior AVM embolization (p = 0.011), a higher margin dose (p = 0.008), and fewer isocenters (p = 0.044). CONCLUSIONS: SRS is the preferred intervention for the majority of BG and thalamic AVMs. Patients with morphologically compact AVMs that have not been previously embolized are more likely to have a favorable outcome, which may be related to the use of a higher margin dose.

Síndrome de Percheron / Percheron syndrome

El infarto talámicoparamediano bilateral sincrónico,llamado habitualmente infarto de la arteria de Percheron, se considera infrecuente y de difícil diagnóstico clínico. Se presenta a una paciente de 50 años, con infarto talámico bilateral, que presentó un cuadro de desorientación, visión borrosa y doble en horas de la mañana, sin referir pérdida de conciencia. En la tomografía axial computarizada de cráneo simple se evidenció una hipodensidad talámica bilateral, compatible con un infarto agudo a este nivel, por oclusión de la arteria de Percheron. Es importante el reconocimiento de esta variante anatómica para establecer el mecanismo del infarto talámico bilateral.

Artery of Percheron infarction: a case report.

BACKGROUND: The artery of Percheron is a rare anatomic variant of arterial supply to the paramedian thalamus and rostral midbrain, and occlusion of the artery of Percheron results in bilateral paramedian thalamic infarcts with or without midbrain involvement. Acute artery of Percheron infarcts represent 0.1 to 2% of total ischemic stroke. However, of thalamic strokes, occlusion of artery of Percheron is the cause in 4 to 35% of cases. Early diagnosis of artery of Percheron infarction can be challenging because it is infrequent and early computed tomography or magnetic resonance imaging may be negative. Thus, it can be confused with other neurological conditions such as tumors and infections. CASE PRESENTATION: This is a retrospective case study of a 56-year-old white man admitted to Umeå University Hospital and diagnosed with an artery of Percheron infarction. Medical records and the neuroradiological database were reviewed, and the diagnosis was made based on typical symptoms and radiological findings of artery of Percheron infarction. We report the case of a 56-year-old man with a history of overconsumption of alcohol who was found in his home unconscious and hypothermic. He had a Reaction Level Scale-85 score of 4. He developed ventricular fibrillation on arrival at our emergency department, and cardiopulmonary resuscitation successfully restored sinus rhythm within an estimated 2 minutes of onset. He was then put on cardiopulmonary bypass for rewarming. The initial head computed tomography performed on admission was wrongly assessed as unremarkable. Bilateral ischemia in the paramedian thalamic nuclei and pons were first documented on a follow-up computed tomography on day 24 after hospitalization. He died on day 35 after hospitalization. CONCLUSIONS: Artery of Percheron infarcts are rare. The radiological diagnosis can initially often be judged as normal and in combination with variability in the neurological symptoms it is a rather difficult condition to diagnose. For these reasons few clinicians have much experience with this type of infarct, which may delay diagnosis and initiation of appropriate treatment.

Delayed symptomatic haemorrhage from the remnants of a thalamic arteriovenous malformation after previous angiographic cure with radiotherapy.

In 1995 a 16-year old girl was diagnosed with a large left thalamic AVM that was considered unsuitable for microsurgical resection and was treated with radiotherapy twice, which led to angiographic cure. She re-presented 19 years after initial treatment with a symptomatic acute thalamic haemorrhage. Her digital subtraction angiography was negative for arterio-venous shunting. MRI/MRA showed cystic change with adjacent contrast enhancement in the region of the previously irradiated arteriovenous malformation. The patient underwent an interhemispheric transcallosal resection of the left thalamic haemorrhagic lesion via a contralateral craniotomy. Intra-operatively there was a cystic cavity filled with blood products in association with thrombosed, calcified vessels as well as actively filling vessels. Histologically there were aggregated abnormal blood vessels with a dilated lumen and surrounded by brain parenchyma. Some of the vessel walls were thickened with fibrosis and some were arterialised with presence of elastin fibres. Potential mechanisms for the delayed haemorrhage are discussed.

[Cryptogenic stroke in a young patient with heart disease and kidney failure]. / Ictus criptogenico en un paciente joven con cardiopatia y fallo renal.

INTRODUCTION: Fabry's disease is an infrequent metabolic pathology linked to the X chromosome which causes a wide variety of signs and symptoms. CASE REPORT: A 39-year-old male who was admitted to our stroke unit with right-side hemiparesis (1 + 0) and dysarthria (1). The score on the National Institute of Health Stroke Scale was 2. The patient presented angiokeratomas in both thighs. A computerised axial tomography scan of the head showed left thalamic acute infarction. The duplex scan of the supra-aortic trunks was normal, and the transcranial Doppler reflected a generalised increase in the pulsatility indices. Transthoracic echocardiography showed left ventricular hypertrophy and left atrial dilatation. He was discharged five days later, with antiaggregating medication but asymptomatic. The prolonged Holter-electrocardiogram recording showed paroxysmal atrial fibrillation. One notable value in the urine analysis was microalbuminuria of 281 mg/L. In view of the multi-organic involvement and the family history, a study for Fabry's disease was performed. Activity of the enzyme alpha-galactosidase A was diminished, and the presence of a mutation in the GLA gene was found. The patient's brother, who suffered from kidney failure and atrial fibrillation, was positive for this mutation. The patient is on treatment with agalsidase beta. CONCLUSIONS: Fabry's disease must be suspected in young males with heart disease, stroke or peripheral neuropathy, skin lesions, kidney failure and a history of cases in the family. Hormone replacement therapy must be established at an early stage, as it can improve the prognosis.

TITLE: Ictus criptogenico en un paciente joven con cardiopatia y fallo renal.Introduccion. La enfermedad de Fabry es una patologia metabolica infrecuente ligada al cromosoma X, que provoca una amplia variedad de signos y sintomas. Caso clinico. Varon de 39 antilde;os que ingreso en nuestra unidad de ictus con hemiparesia derecha (1 + 0) y disartria (1). La puntuacion en la National Institute of Health Stroke Scale era de 2. Presentaba angioqueratomas en ambos muslos. La tomografia axial computarizada craneal mostraba un infarto agudo talamico izquierdo. El duplex de los troncos supraaorticos era normal, y el Doppler transcraneal reflejaba un aumento generalizado de los indices de pulsatilidad. El ecocardiograma transtoracico mostraba hipertrofia ventricular izquierda y dilatacion de la auricula izquierda. Recibio el alta cinco dias despues, asintomatico, con antiagregacion. El registro Holter-electrocardiografico prolongado mostraba fibrilacion auricular paroxistica. En la analitica de orina destacaba microalbuminuria de 281 mg/L. En vista de la afectacion multiorganica y la historia familiar, se curso estudio de enfermedad de Fabry. La actividad de la enzima alfa-galactosidasa-A se encontro disminuida, y se demostro la presencia de una mutacion en el gen GLA. Su hermano, que padecia insuficiencia renal y fibrilacion auricular, fue positivo para dicha mutacion. El paciente se encuentra en tratamiento con agalsidasa beta. Conclusiones. La enfermedad de Fabry debe sospecharse en varones jovenes con cardiopatia, ictus o neuropatia periferica, lesiones cutaneas, fallo renal e historia de familiares afectos. El tratamiento hormonal sustitutivo debe comenzarse precozmente, ya que puede mejorar el pronostico.

Novel Anatomic Classification of Spontaneous Thalamic Hemorrhage Classified by Vascular Territory of Thalamus.

BACKGROUND: Spontaneous thalamic hemorrhage has increased in incidence in recent years. Analysis of the characteristics of thalamic hemorrhage was based on the vascular territories of the thalamus. METHODS: Retrospective analysis included 303 consecutive patients with spontaneous thalamic hemorrhage. Thalamic hemorrhage was classified into 4 types: anterior type (supplied mainly by the tuberothalamic artery), medial (mainly paramedian thalamic-subthalamic artery), lateral (mainly thalamogeniculate artery), and posterior (mainly posterior choroidal artery). The baseline characteristics, complications, and functional outcomes were assessed. RESULTS: The anterior type was found in 10 patients (3.3%), the medial type in 47 (15.5%), the lateral type in 230 (75.9%), and the posterior type in 16 (5.3%). Intracerebral hemorrhage volume was smallest in the anterior type, and significantly smaller than in the medial (P = 0.002) and lateral types (P < 0.001). Intraventricular hemorrhage (IVH) or acute hydrocephalus was significantly associated with the medial type (P < 0.01 or P < 0.01, respectively). Non-IVH or non-acute hydrocephalus was significantly associated with the anterior (P < 0.05 or P < 0.05, respectively) and lateral (P < 0.05 or P < 0.05, respectively) types. Emergency surgery was correlated only with the medial type (P < 0.01). The independent predictors of poor outcome were age (odds ratio [OR], 1.07; P = 0.002), admission National Institutes of Health Stroke Scale score (OR, 1.32; P < 0.001), and type of thalamic hemorrhage (OR, 2.08; P = 0.038). CONCLUSIONS: The present study proposed a novel anatomic classification of thalamic hemorrhage according to the major thalamic vascular territories.

Thalamic cavernous malformations.

Cavernous malformations of the thalamus represent a particularly complex subset of cavernous malformations because of the highly eloquent nature of the involved tissue and their deep location. The decision about whether to operate on any individual lesion depends on the specific location of the lesion within the thalamus, the nature of the patient's symptoms, and the patient's history. When surgery is recommended, the approach must be chosen carefully. Each part of the thalamus is reached by a different surgical approach. These approaches include the orbitozygomatic approach to the anteroinferior thalamus, the anterior interhemispheric transcallosal approach to the medial thalamus, the anterior contralateral interhemispheric transcallosal approach to the lateral thalamus, the posterior interhemispheric transcallosal approach to the posterosuperior thalamus, the parieto-occipital transventricular approach to the lateral posteroinferior thalamus, and the suboccipital supracerebellar infratentorial/transtentorial approach to the medial posteroinferior thalamus. Careful attention to safe entry zones and image guidance can allow safe removal of these lesions when necessary.

MRI venous architecture of the thalamus.

PURPOSE: Our purpose is to describe the thalamic veins using a novel approach named venous gliography in cases with primary or secondary gliomas of the thalamus. Venous gliography is defined by authors as a method to visualize veins on MRI Brain T1-weighted post contrast scans containing gliomas which have induced regional venous congestion. METHODS: Routine clinical MR Imaging studies were reviewed to assess the presence of thalamic veins in 29 glioma cases. In addition, confocal reconstruction techniques (Anatom-e and Osirix) were used in cases that had thin sections (1.0-1.5mm) post contrast T1 weighted sequences. Multiplanar MIP and confocal volume rendered images were generated to evaluate the thalamic veins in those cases. RESULTS: Using venous gliography and confocal reconstruction techniques, two patterns in the venous architecture of the thalamus were documented. First, the branching pattern created by the tributaries of the internal cerebral vein, namely the superior thalamic vein and the anterior thalamic vein, which together formed the superior group of thalamic veins. Second, the pattern created by the un-branched vertically oriented veins, namely the inferior thalamic veins and the posterior thalamic veins, which joined the basal vein of Rosenthal and constituted the inferior group of thalamic veins. CONCLUSIONS: Venous gliography combined with the use of confocal reconstruction techniques provided a novel approach to display the thalamic veins that are usually not seen. The understanding of the venous architecture is mandated by the recent research where veins have taken on an important role in the perivenular spread of gliomas.

Artery of Percheron infarction after endoscopic pituitary surgery.

Infarction in the artery of Percheron territory is a rare phenomenon in which occlusion of an unpaired perforating artery arising from the P1 segment on one side results in infarcts in the bilateral paramedian thalami with or without midbrain infarcts. We describe the case of a 40-year-old male who developed this complication following re-exploratory trans-sphenoidal surgery for a pituitary adenoma. In this first report of its kind in endoscopic pituitary surgery, the pathogenesis and clinico-radiological features of this rare vascular event are discussed.

Bilateral thalamic developmental venous variations (DVVs) draining into same internal cerebral vein: a case report and review with emphasis on DVVs with outflow restriction.

Developmental venous variations (DVVs) are anatomic variations of normal transmedullary veins which are often discovered incidentally. Although they are accepted as benign compensatory venous drainage systems, they may become symptomatic or clinically significant due to flow-related causes. The fragile venous drainage systems increase vulnerability to in-out flow alterations. Increased inflow or decreased outflow causes rise in venous pressure, which may subsequently produce ischemic symptoms. Obstruction or stenosis of the collector vein is the most common cause of decreased outflow of a DVV. However, in the absence of collecting vein stenosis, venous hypertension may still exist due to volume overload. In case of multiple DVVs with single combined drainage pathway, functional outflow restriction may occur due to diminished capability of the vessel to adapt to pressure changes. In this report, we present a case with bilateral thalamic DVVs, which cause parenchymal amorphous calcification and drain into the left internal cerebral vein. A review of the literature on DVVs with outflow restriction including pathophysiological mechanisms is also discussed.

Endovascular parent artery occlusion of proximal posterior cerebral artery aneurysms: a report of two cases.

We report two cases of proximal posterior cerebral artery (PCA) aneurysms treated with endovascular parent artery occlusion (PAO) with coils. In both cases, selective injection from the 4 F distal access catheter clearly showed the perforating arteries arising from the PCA. Case No 1, a 49-year-old woman, was successfully treated with preservation of a paramedian artery. Case No 2, a 54-year-old woman, was treated in the same manner. The patient underwent extensive thalamic infarction after the procedure because of paramedian artery occlusion. Endovascular PAO with coils is feasible for proximal PCA aneurysms; however, preservation of perforating arteries arising from the PCA is mandatory.