[Selection of Appropriate Approaches to Preserve Brain Function for Deep Seated Brain Tumors:Our Experience of Two Posterior Thalamic Cases].

What is the most important factor to achieve successful surgery for deep-seated brain tumors with preservation of brain functions? Definitely, it is to identify the tumor origin site at which a tumor arose and select appropriate surgical approaches that immediately lead directly to the site in the early stage of surgery, minimizing damages of cortices and important white matter bundles, and controlling main arterial supply to the tumor. For this, neurosurgeons must have thorough knowledge of brain anatomy and function, and tailor the best surgical approach for each patient, based on three-dimensional anatomical simulation. For lesions situated in the posterior and lower part of the thalamus and extending to the lateral part, two "cross-court" approaches; the occipital transtentorial/falcine and infratentorial supracerebellar transtentorial approaches, provide a wide corridor to even the lateral aspect of the thalamus and early access to the posterior choroidal arteries, usually main feeders of this territory tumors, without damaging any cerebral cortices and major white matter bundles. Here, we describe the selection of approaches for two representative cases and demonstrate surgical procedures and postoperative courses.

The effects of P2 segment of posterior cerebral artery to thalamus blood supply pattern on gait in cerebral small vessel disease: A 7 T MRI based study.

Gait disturbance is a manifestation of cerebral small vessel disease (CSVD). The posterolateral thalamus (PL), whose blood is mainly supplied by the P2 segment of posterior cerebral artery (P2-PCA), plays pivotal roles in gait regulation. We investigated the influence of the distance between P2-PCA and PL on gait with varying CSVD burden. 71 participants were divided into low and high CSVD burden groups. The distance from P2-PCA to PL was measured using 7 T TOF-MRA and categorized into an immediate or distant PCA-to-thalamus pattern. Functional connectivity (FC) and voxel-based morphometry were assessed to evaluate functional and structural alterations. In the low CSVD burden group, immediate PCA-to-thalamus supply strongly correlates with longer step length and higher wave phase time percent, and exhibited enhanced FCs in left supplementary motor area, right precentral cortex (PreCG.R). While in the high CSVD burden group, no association between PCA-to-thalamus pattern and gait was found, and we observed reduced FC in PreCG.R with immediate PCA-to-thalamus pattern. Higher CSVD burden was associated with decreased gray matter density in bilateral thalamus. However, no significant structural thalamic change was observed between the two types of PCA-to-thalamus patterns in all patients. Our study demonstrated patients with immediate PCA-to-thalamus supply exhibited better gait performance in low CSVD burden populations, which also correlated with enhanced FCs in motor-related cortex, indicating the beneficial effects of the immediate PCA-to-thalamus supply pattern. In the higher burden CSVD populations, the effects of PCA-to-thalamus pattern on gait are void, attributable to the CSVD-related thalamic destruction and impairment of thalamus-related FC.

[A case of bilateral thalamic infarction with the characteristic MRI finding].

A 62-year-old Japanese man with a history of smoking, hypertension and paroxysmal atrial fibrillation presented sudden-onset disturbance of consciousness. He had a fluctuating consciousness, transient apnea, and vertical gaze palsy. Brain diffusion-weighted MRI showed hyperintense signals in the rostral midbrain and bilateral paramedian thalami, and the diagnosis of midbrain and bilateral thalamic infarction was made. The midbrain lesion corresponded with midbrain V sign, a characteristic finding of this infarction. Although there are several other deseases causing bilateral thalamic lesion, this sign is very helpful in distinguishing the disease from others. On the other hand, CT angiography visualized another variant of thalamoperforating arteries instead of Artery of Percheron (AOP), the common variant in bilateral thalamic infarction. This case indicates that other anatomical variants of thalamoperforating arteris besides AOP could cause this infarction.

Artery of Percheron Occlusion in China: A Case Report and Chinese Literature Review.

INTRODUCTION: The artery of Percheron (AOP) is a rare anatomical variant in which bilateral paramedian thalami are supplied by a single vascular branch arising from the P1 segment of the posterior cerebral artery. We present a case of AOP occlusion presenting as loss of consciousness and summarize the literature in Chinese to find the clinical characteristics. CASE REPORT: An 83-year-old woman was found unconscious for 1 day at home and was sent to the hospital the next day. Cerebral magnetic resonance imaging on day 1 of the patient showed a recent bilateral paramedian thalamic infarction. Simultaneously, magnetic resonance angiography found evident artery stenosis of the right P1 segment of the posterior cerebral artery, suggesting that the patient was diagnosed with AOP occlusion. Since the patient has missed the best time for thrombolytic therapy, anticoagulant therapy was given immediately; as the patient was then found to have pulmonary infections, antibiotic therapy was also initiated. The neurological status of this patient improved very slow. In about 2 weeks, the patient becomes more conscious but still could not speak or move. CONCLUSION: Our report suggests that unusual mood disorder and language disorder of aged patients might indicate the AOP occlusion, and cerebral imaging of magnetic resonance imaging (better with magnetic resonance angiography) should be performed to establish the diagnosis of AOP occlusion. The fast and accurate diagnosis of stroke because of AOP occlusion could best benefit the patients.

Percheron Artery-Plus Syndrome: A Syndrome Beyond Stroke Chameleon.

The artery of Percheron (AOP) is an anatomical variant of the thalamoperforating arteries. AOP occlusion can cause bilateral paramedian thalamic infarctions and is referred to as a "stroke chameleon" because it lacks the classic signs of stroke. Coexistence of AOP occlusion and other neurologic disease is rare and can cause disturbance of consciousness. A 78-year-old woman had acute onset of left limb weakness and drowsy consciousness. Brain magnetic resonance angiography (MRA) revealed acute bilateral paramedian thalamic infarctions. However, serum and cerebrospinal fluid (CSF) cryptococcal antigen titers were 1:16 and 1:128, respectively. The CSF culture grew Cryptococcus neoformans. Although consciousness and muscle power improved after treatment, the patient later died of pneumonia. A 68-year-old woman developed acute disturbance of consciousness followed by delirium. Brain MRA revealed acute bilateral paramedian thalamic infarctions. Elevated free thyroxine, anti-thyroperoxidase, and anti-thyroglobulin antibodies were detected. She received 3 days of steroid pulse therapy followed by oral prednisolone. Her consciousness gradually improved after Hashimoto encephalopathy and stroke were controlled. AOP occlusion was diagnosed early in these two patients. However, other concomitant life-threatening diseases could have been overlooked because of the complicated diagnostic determination. Further serum cryptococcal antigen, anti-TPO Ab, and anti-TG Ab surveys might help to exclude cryptococcal meningitis and Hashimoto encephalopathy. CSF study is warranted when central nervous system infection is strongly suspected. This "Percheron artery-plus syndrome" comprises multifaceted disorders beyond the stroke chameleon and requires attention.

Lesion topography of posterior cerebral artery infarcts.

This study analyzed the topography of acute ischemic stroke in the posterior cerebral artery (PCA) territory. We studied 84 patients with unilateral ischemic PCA stroke. Patients were classified according to lesion levels as cortico-subcortical (superficial), combined (cortical and mesodiencephalic) or isolated thalamic. To receive a lesion map, data from acute MR and CT imaging were normalized and labelled automatically by mapping to stereotaxic anatomical atlases. Cortical lesions accounted for 41.7%, combined for 36.9%, and isolated thalamic lesions for 21.4%. The maximum overlay of ischemia and, thus, highest occurrence of PCA ischemic stroke was found in the ventral and medial occipito-temporal cortex and adjacent white matter association tracts. Dorsal and peripheral segments of the occipito-temporo-parietal region were only rarely lesioned. This configuration was similar in both hemispheres. Consistent with this lesion pattern, visual field defects (VFD) were the most frequent signs, followed by sensorimotor signs, dizziness and sopor, cognitive and oculomotor deficits, and ataxia. The three vascular subgroups differed not only by their anatomical lesion profile and lesion load, but also by their clinical manifestation; although patients with combined and thalamic lesions were sigificantly younger, they were more disabled than participants with cortical lesions. VFD were only found in cortical and combined, and oculomotor deficits only in mesodiencephalic lesions. White matter lesions were common in the cortico-subcortical and the combined group. Basal occipito-temporal and calcarine regions, and neighbouring white matter tracts have the highest risk of ischemia in acute PCA stroke.

Artery of Percheron occlusion with first-pass recanalisation of the first segment of posterior cerebral artery.

This is an elderly patient who was found unconscious at home. CT of the head without contrast was unremarkable, while CT angiography of the head and neck revealed a subocclusive thrombus on the precommunicating (P1) segment of the left posterior cerebral artery (PCA). MRI brain revealed bilateral regions of diffusion restriction in the paramedian thalami and bilateral medial mesencephalon. Initial angiography confirmed the presence of a subocclusive thrombus in the P1 segment of the left PCA. Thrombectomy was performed achieving recanalisation of the left PCA and reperfusion of bilateral thalami via a visualised artery of Percheron. Postoperatively, the patient was kept on a daily dose of 325 mg of aspirin. The patient did not improve neurologically. A follow-up MRI brain showed diffusion restriction in the left occipital lobe and petechial haemorrhages in the bilateral thalami. The family eventually opted for palliative measures, and the patient expired on day 14 of admission due to acute respiratory failure from palliative extubating.

Artery of Percheron Infarction: A Characteristic Pattern of Ischemia and Variable Clinical Presentation: A Literature Review.

The Artery of Percheron (AOP) is an uncommon anatomic variant that provides arterial supply to the paramedian region of the thalami and bilaterally to the rostral part of the midbrain; it is a solitary arterial trunk that branches from a proximal segment of the posterior cerebral artery (PCA). Although AOP infarction results in a characteristic pattern of ischemia-namely bilateral paramedian thalamic infarct with or without midbrain involvement-it may cause diagnostic difficulties due to the variety of its clinical presentations and wide differentials, as well as its small diameter and the difficulty of obtaining visualization through diagnostic imaging. Early neuroimaging of AOP infarction and correct diagnosis are mandatory for early initiation of the appropriate treatment and better patient outcomes. In this study, we discuss imaging the patterns of AOP infarction and its differentials and clinical presentation.

Arterial Supply of the Thalamus: A Comprehensive Review.

The thalamus is a deep cerebral structure that is crucial for proper neurological functioning as it transmits signals from nearly all pathways in the body. Insult to the thalamus can, therefore, result in complex syndromes involving sensation, cognition, executive function, fine motor control, emotion, and arousal, to name a few. Specific territories in the thalamus that are supplied by deep cerebral arteries have been shown to correlate with clinical symptoms. The aim of this review is to enhance our understanding of the arterial anatomy of the thalamus and the complications that can arise from lesions to it by considering the functions of known thalamic nuclei supplied by each vascular territory.

Stroke in the artery of percheron territory: the two edges of one diagnosis.

Occlusion of artery of Percheron is a rare condition caused by a peculiar anatomic variation in cerebral blood supply, leading to a bilateral thalamic infarction. Strokes in artery of Percheron account for 0.1% to 2% of all cerebral infarctions. Thalamic area is supplied by the arteries arising directly from the P1 segment of the posterior cerebral artery. However, in 1/3 of cases the supply is provided by a single trunk referred to as artery of Percheron (AOP). Early diagnosis of stroke in AOP can be very challenging due to an ambiguous clinical presentation and the absence of neurovisualization findings. This article presents two clinical cases of stroke in artery of Percheron observed at Lviv Emergency Hospital. Different clinical progression of a cerebrovascular accident contrasted with a similar neurovisualization pattern was a distinctive feature in these patients. Taking into consideration the rarity of this condition and a characteristic clinical presentation, these clinical cases were retrospectively analyzed and compared. A stroke in AOP should be suspected in all patients with symptoms of interrupted blood supply in the vertebrobasilar territory. The diagnosis primarily depends on clinical features; patients with paramedian bilateral thalamic lesions may develop sudden problems with consciousness, vertical gaze palsy and memory disorders. Early diagnosis of this condition allows for more effective therapeutic interventions and improves patient prognosis.

Investigation of risk factors, topographic location and stroke mechanisms of unilateral isolated and posterior cerebral ARTERY thalamic infarcts.

BACKGROUND AND PURPOSE: In this study, we aimed to examine the risk factors, topographic features and stroke mechanisms of acute ischemic unilateral infarcts of thalamus. METHODS: Patient with isolated thalamic infarct and those with posterior cerebral artery (PCA) infarction who were admitted to our hospital between January 2014 and January 2017 with acute unilateral thalamic infarction (TI) were included in this study (isolated thalamic infarction/ isolated TI; thalamic and posterior cerebral artery infarction/PCA+TI). Demographic characteristics and vascular risk factors of the patients were determined. Thalamic infarct areas were recorded topographically as anterior, posteromedial, ventrolateral, posterolateral, more than one area, and variant areas. Stroke mechanism was determined according to the criteria of "Trial of Org 10172 in Acute Stroke Treatment" (TOAST). Patients with isolated TI and PCA TI were compared according to risk factors, stroke mechanism and infarct topography. RESULTS: Forty-three patients with a mean age of 63.3 ± 14.5 years were included in the study. Twenty-eight patients (60.1%) were found to have isolated TI and the remaining 15 patients (34.9%) had PCA+TI. 32.1% of patients with isolated TI had sensory symptoms on presentation, and 60% of patients with PCA-TI had sensorimotor symptoms. The mean age, the mean score on National Institutes of Health Stroke Scale (NIHSS) and the mean frequency of atrial fibrillation were higher in PCA+TI patients than in isolated-TI patients (p: 0.04, p: 0.004, p: 0.02 respectively). 32.6% of the patients had ventrolateral, 30.2% had posteromedial involvement. Ventrolateral topography was seen in 46.7% of the PCA+TI patients, while posteromedial topography was seen in 39.3% of the isolated-TI patients. 53.6% of the isolated-TI had small vessel disease etiology, while 40% of the PCA+TI had cardioembolic etiology, and the other 40% had large artery atherosclerosis. CONCLUSION: Our study showed that the most ommon stroke mechanism in patients with thalamic infarction is the small vessel disease. Isolated TI and PCA+TI patients differ in terms of etiologic mechanism and infarct topography. Variant territorial involvement and multiple area involvements can be quite common in thalamic infarcts.

Impact of cerebral large-artery disease and blood flow in the posterior cerebral artery territory on cognitive function.

OBJECTIVES: The purpose of this study was to elucidate the association of cerebral large artery disease (CLAD) with cerebral blood flow (CBF) in the posterior cerebral artery (PCA) territory and cognitive performance. METHOD: We prospectively registered patients with CLAD who had internal carotid or middle cerebral artery (MCA) with the degree of stenosis ≥50%. Automated brain segmentation was used to quantify CBF in the thalamus, hippocampus, and PCA and MCA territories. We measured cognitive function of patients using the Wechsler Memory Scale Revised (WMS-R), the Mini-Mental State Examination (MMSE), and the Montreal Cognitive Assessment. Patients were divided into 3 groups according to CBF of the cortical and subcortical PCA territory. RESULTS: There were 60 patients included in this study. The degree of stenosis was significantly correlated with CBF in the PCA territory (Γ = 0.35, P = .006) and hippocampus (Γ = 0.34, P = .008). Verbal memory, general memory, and reproduction on WMS-R and MMSE were significantly reduced areas with low CBF in the PCA territory compared with areas with middle and high CBF. CONCLUSIONS: CBF of the PCA territory was significantly inversely correlated with the degree of stenosis in CLAD patients. Low CBF of the PCA territory was significantly associated with reduced cognitive and memory functions.

Clinical-radiographic correlates of Artery of Percheron infarcts in a case series of 6 patients.

Bilateral thalamic strokes due to Artery of Percheron (AOP) occlusion are rare but have been previously reported in the literature. It is due to a rare anatomic variant where a solitary arterial trunk from the proximal segment of either posterior cerebral artery (PCA) supplies bilateral thalami and midbrain. Despite its description in the literature, these strokes are usually missed and patient's symptoms are not thought to be secondary to a vascular etiology. Through this report we aim to describe the clinical and radiographic features seen in these patients. We describe a series of 6 patients who present with varying levels of somnolence and oculomotor nerve palsies who had an occlusion of the AOP with bilateral thalamic infarcts with midbrain involvement. These clinical presentations, combined with the "V" sign on MRI are important in making the diagnosis.

Artery of Percheron Infarct - a diagnostic and prognostic conundrum!

A 39 year old male was found unconscious at home. On arrival to the hospital the patient was profoundly somnolent but easily rousable, with no focal neurological deficits. Imaging confirmed bilateral thalamic infarcts from the occlusion of Artery of Percheron, a rare anatomic variant which is a single arterial trunk supplying the thalamus and midbrain bilaterally. Anti-platelet therapy was initiated as soon as the diagnosis was established and the patient showed a rapid remarkable recovery over the next 48 hours. He continued to improve subsequently and was at baseline functional status at 6 months. Extensive investigations for etiologies were mostly unrevealing. In such patients presenting with drowsiness/somnolence, a posterior circulation stroke should be considered if no evidence of other more common causes are found. A CT head must be followed by an MRI to confirm the diagnosis and subsequent focus should be on eliciting risk factors and careful evaluation for etiologies.

Hypointensity on Susceptibility-Weighted Images Prior to Signal Change on Diffusion-Weighted Images in a Hyperacute Ischemic Infarction: a Case Study

Susceptibility-weighted imaging (SWI) is well known for detecting the presence of hemorrhagic transformation, microbleeds and the susceptibility of vessel signs in acute ischemic stroke. But in some cases, it can provide the tissue perfusion state as well. We describe a case of a patient with hyperacute ischemic infarction that had a slightly hypodense, patchy lesion at the left thalamus on the initial SWI, with a left proximal posterior cerebral artery occlusion on a magnetic resonance (MR) angiography and delayed time-to-peak on an MR perfusion performed two hours after symptom onset. No obvious abnormal signals at any intensity were found on the initial diffusion-weighted imaging (DWI). On a follow-up MR image (MRI), an acute ischemic infarction was seen on DWI, which is the same location as the lesion on SWI. The hypointensity on the initial SWI reflects the susceptibility artifact caused by an increased deoxyhemoglobin in the affected tissue and vessels, which reflects the hypoperfusion state due to decreasing arterial flow. It precedes the signal change on DWI that reflects a cytotoxic edema. This case highlights that, in some hyperacute stages of ischemic stroke, hypointensity on an SWI may be a finding before the hyperintensity is seen on a DWI.

A case of acute bilateral thalamic infarction presenting in a sleep-like coma after alcohol ingestion

The artery of Percheron is a rare anatomical variant, in which a common trunk arises from one posterior cerebral artery and then branches to supply each of the thalami and the midbrain separately. Occlusion of this artery triggers a bilateral thalamic infarction. The most commonly reported clinical findings are an altered mental status, vertical gaze palsy, and memory impairment. A 51-year-old man was transferred to the emergency department with a sudden loss of consciousness after drinking alcohol. He appeared to be sleeping deeply. His wife insisted that he had not drunk a quantity of alcohol that would render him unconscious. Magnetic resonance imaging of the brain revealed an acute, bilateral, paramedian thalamic infarction. He was admitted and treated with antiplatelet agents. On the following day, four-vessel cerebral angiography revealed stenosis of the left, distal vertebral artery. Three weeks after admission, he was discharged with persistent hypersomnia, memory impairment, and behavioral changes.

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.