Origin Of Middle Cerebral Artery Research Articles

Striatal Blood Flow Changes by Middle Cerebral Artery Occlusion and Its Effect on Neurological Deficits in Mice.

We attempted to record the regional cerebral blood flow (CBF) simultaneously at various regions of the cerebral cortex and the striatum during middle cerebral artery (MCA) occlusion and to evaluate neurological deficits and infarct formation. In male C57BL/6J mice, CBF was recorded in three regions including the ipsilateral cerebral cortex and the striatum with laser Doppler flowmeters, and the origin of MCA was occluded with a monofilament suture for 15-90 min. After 48 h, neurological deficits were evaluated, and infarct was examined by triphenyltetrazolium chloride (TTC) staining. CBF decrease in the striatum was approximately two-thirds of the MCA-dominant region of the cortex during MCA occlusion. The characteristic CBF fluctuation because of spontaneously occurred spreading depolarization observed throughout the cortex was not found in the striatum. Ischemic foci with slight lower staining to TTC were found in the ipsilateral striatum in MCA-occluded mice for longer than 30 min (n = 54). Twenty-nine among 64 MCA-occluded mice exhibited neurological deficits even in the absence of apparent infarct with minimum staining to TTC in the cortex, and the severity of neurological deficits was not correlated with the size of the cortical infarct. Neurological deficits might be associated with the ischemic striatum rather than with cortical infarction.

Anomalous origin of a middle cerebral artery from anterior cerebral artery with no association to an accessory or duplicated middle cerebral artery

The middle cerebral artery (MCA) is one of the major paired intracranial arteries involved in the formation of the circle of Willis. MCA is the most complex of the intracranial arteries mainly because it supplies the cerebral neocortex, which has been significantly developed in humans. The MCA is a recent phylogenetic acquisition and can be considered as a collateral branch of the anterior cerebral artery (ACA). Anomalies of the middle cerebral artery are less commonly reported than other intracranial arteries. Previously, described anomalies include accessory MCA, duplicated MCA, fenestration of MCA and variations of the branching patterns. Recently, several reports have been published describing unfused or twig-like MCA, in which the single MCA trunk is substituted by a collateral plexiform arterial network. This manuscript would like to report our unique case of an anomalous MCA origin from the anterior cerebral artery unassociated with duplication or accessory MCA.

Cerebral Arterial Asymmetries in the Neonate: Insight into the Pathogenesis of Stroke

Neonatal and adult strokes are more common in the left than in the right cerebral hemisphere in the middle cerebral arterial territory, and adult extracranial and intracranial vessels are systematically left-dominant. The aim of the research reported here was to determine whether the asymmetric vascular ground plan found in adults was present in healthy term neonates (n = 97). A new transcranial Doppler ultrasonography dual-view scanning protocol, with concurrent B-flow and pulsed wave imaging, acquired multivariate data on the neonatal middle cerebral arterial structure and function. This study documents for the first-time systematic asymmetries in the middle cerebral artery origin and distal trunk of healthy term neonates and identifies commensurately asymmetric hemodynamic vulnerabilities. A systematic leftward arterial dominance was found in the arterial caliber and cortically directed blood flow. The endothelial wall shear stress was also asymmetric across the midline and varied according to vessels’ geometry. We conclude that the arterial structure and blood supply in the brain are laterally asymmetric in newborns. Unfavorable shearing forces, which are a by-product of the arterial asymmetries described here, might contribute to a greater risk of cerebrovascular pathology in the left hemisphere.

Microsurgical Anatomy of Middle Cerebral Artery in Northwest Indian Population: A Cadaveric Brain Dissection Study.

Background:Microsurgical anatomy of the Middle Cerebral Artery (MCA) of the Northwest Indian population has not been described to date. A study of cadaveric brains will add to the existing knowledge of brain vessels.Objective:To study and compare the microsurgical anatomy of MCA in Northwest Indian Population with that of the available literature.Methods and Material:15 Formalin Fixed Cadaveric brains, that is 30 vessels from its origin from Internal Cerebral Artery to M5 segment with respect to diameter, length and branching pattern were studied under high magnification (operating microscope) and the data compared with literature.Results:The main trunk of MCA was 16±3 mm long with no significant differences between both sides. Its outer diameter was 3±0.1 mm. Among the early branches 58% were destined to the temporal lobe. Distance between the origin of the early branch from MCA origin was 4±2mm on the right side and 4.5±2.5 mm on the left side. The most consistent perforating branch group was the intermediate group. The pattern of branching of the main trunk was bifurcation (73%), single trunk (10%) and trifurcation (10%). Within the bifurcation group, inferior trunk dominance was seen in 50%. Amongst the cortical branches diameter of the angular artery was largest and the temporo-polar was smallest. No significant difference in the data as compared to literature.Conclusions:The knowledge of anatomy of MCA and its variations are important for neurosurgical residents' training and neurosurgeons dealing with MCA aneurysm management or bypass surgeries.

Selection Strategy for Optimal Keyhole Approaches for Middle Cerebral Artery Aneurysms: Lateral Supraorbital Versus Minipterional Craniotomy

The lateral supraorbital (LS) and minipterional (MP) approaches have been reported for treating intracranial aneurysms as alternative to the pterional approach. We describe our decision making for selecting the minicraniotomy, LS versus MP, for managing noncomplex aneurysms of the middle cerebral artery (MCA), based on the depth of the aneurysm within the Sylvian fissure. We report on a consecutive case series of 50 patients who underwent clipping of 54 ruptured/unruptured MCA aneurysms by means of LS or MP craniotomies. The distance between the MCA (M1) origin and the aneurysmal neck is key to selection of the approach: LS was used for MCA aneurysms <15 mm from the M1 origin and MP for MCA aneurysms ≥15 mm from the M1 origin. 11 of 50 patients presented with subarachnoid hemorrhage (10 ruptured MCA aneurysms). Overall, 59 aneurysms were successfully clipped (54 of the MCA). The mean distance between the M1 origin and the aneurysmal neck was 10.1 mm (range, 4-17 mm) for patients treated by LS and 20 mm (range, 15-30 mm) for those treated by MP. All but 1 MCA aneurysms were successfully treated. At last follow-up (mean, 14 months), no reperfusion of the clipped aneurysms was observed. Our strategy for selecting the keyhole approach based on the depth of the aneurysm within the Sylvian fissure is efficient and safe. We suggest the use of the LS approach when the aneurysm is <15 mm from the M1 origin and the MP approach when the aneurysm is ≥15 mm from the M1 origin.

Duplicated middle cerebral artery origin with an aneurysm

Rationale:Middle cerebral artery (MCA) anomalies are relatively rare and often related to aneurysms. Familiarity with these anomalies is important in resolving problems that arise in the complex angioarchitecture. Reports often describe that aneurysms that are related to accessory or duplicated MCA are often located at its origin.Patient concerns:A 59-year-old man presented with a headache for 10 days, without nausea and vomiting. The physical examination was negative.Diagnosis:A computed tomography (CT) scan revealed an intracerebral hematoma in the deep right frontal lobe, near the caudate nucleus. Digital subtraction angiography (DSA) revealed an anomalous duplicated origin of the right MCA, with occlusion of the main MCA trunk as well as twisting and dilation of the accessory MCA trunk. A wide-necked aneurysm was located at a sharp curve of the tortuous accessory MCA trunk. A ruptured aneurysm related to a duplicated MCA origin was diagnosed.Interventions:Open surgery was rejected by the patient; hence, palliative endovascular coil embolization of the larger daughter sac was performed.Outcomes:The postoperative course was uneventful. There was no rebleeding at 8-months follow-up.Lessons:MCA anomalies are relatively rare and often related to aneurysms. It is important to be familiar with these anomalies as related lesions often manifest within a complex angioarchitecture. Aneurysms at the trunk of an anomalous MCA are a rare entity and open surgery may be recommended.

Contralateral Approach to Middle Cerebral Artery Aneurysms: An Anatomical-Clinical Analysis to Improve Patient Selection

A contralateral approach to aneurysm clipping in cases of bilateral middle cerebral artery (MCA) aneurysms reduces surgical time and cost. However, there is a lack of evidence for objective patient selection. In this study, we assessed the change in surgical freedom along the contralateral MCA to provide objective evidence for patient selection. Sixteen cadaveric specimens were studied. Through a pterional approach, the surgical freedom was calculated moving distally along the contralateral MCA in 5-mm increments. In addition, in a series of 19 MCA aneurysms clipped contralaterally by the senior author, the average length of the MCA from its origin to the aneurysm neck was measured on angiography. In these patients treated via a contralateral approach, the average length of the MCA segment from its origin to the aneurysm neck was 12.4 mm. Starting at the MCA origin, surgical freedom decreased significantly between all adjacent target points except at 5-10 mm from the MCA origin. After the proximal 5 mm, there is no significant decrease in surgical maneuverability within the proximal 10 mm of MCA when approached contralaterally. When compared to the average length of the MCA from its origin to the aneurysm neck in the clinical series, it can be concluded that the first 10 mm (average, 12.4 mm) of the contralateral MCA may be considered a surgical comfort zone for a contralateral approach. This criterion may be useful for patient selection for a contralateral approach in cases of multiple bilateral intracranial aneurysms.

Annals for Educators - 20 June 2017

Annals for Educators - 20 June 2017

Anomalies of the Middle Cerebral Artery

There are several anomalies of the middle cerebral artery (MCA) in humans, such as accessory MCA, duplicated MCA, fenestration of MCA, and duplicated origin of MCA. Recently, unfused or twig-like MCA, which indicates MCA trunk occlusion with collateral plexiform arterial network, have been reported. During the embryonic stage, MCA is thought to generate from plexiform arterial twigs arising from the anterior cerebral artery, and these twigs form the definitive MCA by fusion and regression at the end of the development stage. Any interruption during the fusion of the arterial twigs may result in MCA anomalies, and the unfused or twig-like MCA, especially, is hypothesized to be the persistent primitive arterial twigs. Clinically, it is challenging to differentiate the unfused or twig-like MCA from unilateral moyamoya disease, in which stenotic change begins at the MCA. The knowledge of the anomalies of the MCA is important to perform a safe surgical or endovascular intervention.

Factors Affect on development and clinical course of ischemic stroke in children

Child strokes cause persistent neurologic impairment affecting on quality of life. Prophylaxis cerebral infarction in children promoted by Identification of factors influencing on development of ischemic stroke. 47 children with arterial ischemic stroke confirmed by MRI or CT was enrolled in cohort study. All children has focal neurological symptomatic which was assessed by pedNIHSS, PSOM, British muscular strength scale. General cerebral symptoms precede focal neurologic impairments in 67% cases. Fact of head trauma was documented in 55% observed children. Seizures occurs in 24% cases in acute period ischemic stroke. As major part of children had lacunar infarction in middle cerebral artery origin, so motor dysfunctions was admitted in clinical curse of general cases. By neuroimaging data we defined lacunar infarctions mainly in basal ganglia, thalamus and internal capsule. In the rest 5 cases - in cortex, white matter, frontal, parietal and occipital lobes, cerebellum and brain stem. In 10 children during observation over time the secondary haemorrhage at ischaemic site was detected. Besides post-ischemic alterations additional structural features was assessed in neuroimaging study. Calcification in white mater of brain was reviled in one third children with ischemic stroke (33,4%). Overwhelming majority calcifications in white mater of brain was diagnosed in lenticular-striatal arteries infarctions. Latent factors structure influenced on severity neurologic outcomes was received by partial least square method (PLS). Acquired data emphasize importance of mind depression, vertigo, dysphagia as poor outcome predictors.

Anastomotic aneurysm formation after superficial temporal artery – middle cerebral artery bypass surgery in 5 months

Summary Direct revascularization is beneficial in patients with moyamoya disease under selective conditions. Here, we report the case of a patient with moyamoya disease who developed a complication following revascularization through cerebrovascular bypass surgery. A 42-year-old man experienced an acute onset of weakness in the right limbs with slurred speech. He was initially treated for a suspected transient ischemic attack. Further workup revealed luminal narrowing in the left M1 segment (from the origin of middle cerebral artery to its bifurcation) and total luminal occlusion of the right M1 segment of the middle cerebral artery. Direct revascularization using a superficial temporal artery to the middle cerebral artery bypass procedure was performed. Postoperative follow-up brain computed tomography in the outpatient clinic revealed aneurysm formation at the anastomotic site of the right superficial temporal artery to the middle cerebral artery. Various theories have been postulated to explain this rare complication. Here, we discuss possible etiologies for the formation and management of aneurysms at anastomotic sites with a review of similar cases in the literature.

Long-term survival in permanent middle cerebral artery occlusion: a model of malignant stroke in rats.

Occlusion of the middle cerebral artery (MCA) by an intraluminal filament is widely used to study focal brain ischemia in male Sprague-Dawley rats. However, permanent occlusion goes along with a high fatality. To overcome this drawback we designed a new filament carrying a bowling pin-shaped tip (BP-tip) and compared this with three conventionally tipped filaments. Follow-up periods were 24 h (all groups) and 72 and 120 h in BP-tip group. Ischemic damage and swelling were quantified using silver nitrate staining. Collateral flow via the posterior cerebral artery (PCA) was assessed using selective dye perfusion of the internal carotid artery. Despite a comparable decrease of brain perfusion in all groups, ischemic damage was significantly smaller in BP-tips (p < 0.05). Moreover, BP-tip significantly reduced mortality from 60% to 12.5% and widely spared the occipital region and hypothalamus from ischemic damage. Conventional but not BP-tip filaments induced vascular distortion, measured as gross displacement of the MCA origin, which correlated with occipital infarction size. Accordingly, BP-tip occluded rats showed a significantly better collateral filling of the PCA territory. Ischemic volume significantly increased in BP-tip occlusion at 72 h follow-up. BP-tip filaments offer superior survival in permanent MCA occlusion, while mimicking the course of a malignant stroke in patients.

Results of re-exploration because of compromised distal blood flow after clipping unruptured intracranial aneurysms.

One of the major causes for performing unplanned re-exploration of a craniotomy after microsurgery for unruptured intracranial aneurysms (UIAs) is compromised distal blood flow after clipping. Therefore, it is important to identify the causes of compromised distal blood flow after clipping and the factors that influence the prognosis for re-exploration in order to decrease ischemic complications related to clipping UIAs. Between January 2007 and December 2013, 1954 patients underwent microsurgery for UIAs. In this cohort, 20 patients (1.0%) required unplanned re-exploration of the craniotomy for several reasons, and 11 patients (0.6%) underwent unplanned re-exploration with clip repositioning or changing of the previous clip because of compromised distal blood flow after clipping. Patient characteristics, aneurysm properties, intraoperative findings, annual incidence and prognosis were analyzed in these 11 patients. The annual incidence of re-exploration has gradually decreased since the introduction of several intraoperative monitoring techniques. In total, 3.0% of UIAs in the M1 trunk, 0.8% of UIAs at the origin of the anterior choroidal artery (AchA) and 0.5% of UIAs at the bifurcation of the middle cerebral artery (MCA) required re-exploration. Here, all 11 UIAs had broad necks, and atherosclerosis was identified around 10 UIAs. Six patients with compromised MCA flow demonstrated relatively better outcomes following re-exploration than five patients with a compromised lenticulostriate artery (LSA) or AchA flow. Four patients with delayed ischemic symptoms demonstrated relatively better outcomes than the seven patients who developed ischemic symptoms immediately postoperatively. Clinicians need to be more careful not to compromise distal blood flow when clipping UIAs at the MCA and AchA origin. Various intraoperative monitoring techniques can help reduce the incidence of compromised distal blood flow after clipping.

Platelet rich clots are resistant to lysis by thrombolytic therapy in a rat model of embolic stroke.

BackgroundEarly recanalization of occluded vessels in stroke is closely associated with improved clinical outcome. Microbubble-enhanced sonothrombolysis is a promising therapy to improve recanalization rates and reduce the time to recanalization. Testing any thrombolytic therapy requires a model of thromboembolic stroke, but to date these models have been highly variable with regards to clot stability. Here, we developed a model of thromboembolic stroke in rats with site-specific delivery of platelet-rich clots (PRC) to the main stem of the middle cerebral artery (MCA). This model was used in a subsequent study to test microbubble-enhanced sonothrombolysis.MethodsIn Study 1 we investigated spontaneous recanalization rates of PRC in vivo over 4 hours and measured infarct volumes at 24 hours. In Study 2 we investigated tPA-mediated thrombolysis and microbubble-enhanced sonothrombolysis in this model.ResultsStudy 1 demonstrated stable occlusion out to 4 hours in 5 of 7 rats. Two rats spontaneously recanalized at 40 and 70 minutes post-embolism. Infarct volumes were not significantly different in recanalized rats, 43.93 ± 15.44% of the ischemic hemisphere, compared to 48.93 ± 3.9% in non-recanalized animals (p = 0.7). In Study 2, recanalization was not observed in any of the groups post-treatment.ConclusionsSite specific delivery of platelet rich clots to the MCA origin resulted in high rates of MCA occlusion, low rates of spontaneous clot lysis and large infarction. These platelet rich clots were highly resistant to tPA with or without microbubble-enhanced sonothrombolysis. This resistance of platelet rich clots to enhanced thrombolysis may explain recanalization failures clinically and should be an impetus to better clot-type identification and alternative recanalization methods.Electronic supplementary materialThe online version of this article (doi:10.1186/s13231-014-0014-y) contains supplementary material, which is available to authorized users.

Abstract 310: Do Biologic Variations in Plasminogen Levels Affect Endogenous Fibrinolysis and Outcomes in Acute Thrombotic Disease Such as Ischemic Stroke?

Introduction: After activation of plasminogen (Pg), plasmin is the key enzyme that acutely dissolves thrombi. Yet, despite significant biologic variation in Pg levels between humans, there is no clear link between Pg levels (or Pg deficiency) and the development or resolution of acute thrombotic vascular diseases such as stroke. Hypothesis: We tested the hypothesis that plasma levels of Pg affect endogenous fibrinolysis, brain injury, hemorrhage and swelling after thromboembolic stroke. Methods and results: We examined male and female Pg +/+ ([Pg] =84±4.8 μg/ml), Pg +/- ([Pg] =37±5.2 μg/ml) and Pg -/- ([Pg] =1.3±3 μg/ml) mice, n= 10-13 per group. Ischemic stroke was induced by endovascular placement of an autologous 125 I-fibrin plasma clot at the origin of middle cerebral artery (MCA) that reduced hemispheric blood flow by ≥80%. After 6 hours of stroke, the dissolution of the culprit MCA thrombus was determined and the effects on brain injury were assessed. Data was analyzed by a two-way ANOVA with Neumann-Keul’s correction. There was a dose-dependent relationship between Pg levels and endogenous dissolution of the MCA thrombus (p=0.0019) with Pg +/+ mice showing greater lysis (20.7±6.6%) than Pg +/- mice (19.0±3.8%) and Pg -/- mice (12.6±6.4%). There was a significant, inverse dose-response effect on brain infarction with higher Pg levels associated with less severe infarction: Pg +/+ (24.8±4.3%) &lt;Pg +/- (27.3±9.4%) &lt;Pg -/- (37.4±8.9%) mice. No significant sex based differences were found in fibrinolysis and brain injury. Brain swelling showed a significant, but non-linear dose-dependence on Pg levels (p&lt;0.01) which was affected by sex (p&lt;0.01). There was no significant association between brain hemorrhage and Pg levels. Conclusions: In vivo, Pg levels have concentration-dependent effects on endogenous fibrinolysis, brain infarction and swelling after thromboembolic stroke. Further studies should be done to assess how Pg levels may affect outcomes in human thrombotic diseases.

Real-time imaging of mouse lenticulostriate artery following brain ischemia

Detection of microvascular changes in experimental stroke models is limited by current technologies. Using state-of-the-art synchrotron radiation (SR), we explored the feasibility of detecting the normal morphological variations of lenticulostriate arteries (LSAs) and the changes to LSAs following middle cerebral artery occlusion (MCAO). Cerebral microvessels of ICR mice were imaged with synchrotron radiation microangiography using nonionic iodine and barium sulfate as contrast agents. Using SR we reproducibly observed the detailed cerebral microvasculature of LSAs arising from the origin of middle cerebral artery (MCA) with a resolution of approximately 5 micrometers, at least a 20-fold greater resolution compared to CT or MRI imaging. Notably, SR microangiography was able to reveal ischemia/reperfusion induced leakage in the lenticulostriate artery territory. To our knowledge this is the first time that the three-dimensional morphology of LSAs and real time visualization of LSA hemorrhage have been characterized in live mice. This work demonstrates that SR microangiography can provide a unique tool for furthering experimental stroke research to examine the efficacy of neuroprotective therapies on parameters such as angiogenesis and vascular integrity.

Regional variations in brain oxygenation during temporary clipping in aneurysm surgery

Objectives: Brain tissue oxygen concentration (PbtO2) monitoring has been used in aneurysm surgery to detect decreased brain oxygenation during temporary clipping. The effects of circulatory interruption according to different aneurysm locations have not been established. In this work, variations in PbtO2 during temporary clipping were studied in anterior communicating (AcomA), posterior communicating (PcomA) origin, and middle cerebral artery (MCA) aneurysm surgery.Methods: PbtO2 was monitored during surgery of 41 patients; aneurysms were located in the AcomA (10 cases), origin of PcomA (8 cases), and MCA bifurcation (23 cases). Temporary clips were used in all cases. Variations in PbtO2 values obtained during application of temporary clips were evaluated and studied according to the duration and type of circulatory interruption for each aneurysm location.Results: In AcomA aneurysm surgery, a significant decrease in PbtO2 values was found in 31% of the periods of temporary clipping, whereas in PcomA and MCA aneurysm surgery, significant decreases were found in all temporary clip applications (100%). In MCA aneurysms, the amplitude of decrease in PbtO2 was higher when the circulatory interruption lasted for 2 or more minutes, compared with shorter periods of temporary clipping.Discussion: During temporary clipping, different variations in PbtO2 values were obtained when comparing frontal and temporal regions of monitoring: in MCA and PcomA origin aneurysms, significant variations were registered in all periods of temporary regional circulatory interruption, but the same results were not found in frontal monitoring for AcomA aneurym surgery.

Cerebrovascular geometry in the anterior circulation: an analysis of diameter, length and the vessel taper

BackgroundA study was undertaken to determine the typical length, diameter and taper of vessels in the anterior cerebral circulation.MethodsThe sample size was calculated at 100 patients based on similar measurements...

Neurobehavioural deficits correlate with the cerebral infarction volume of stroke animals: A comparative study on ischaemia-reperfusion and photothrombosis models

The study investigated the correlation between infarction areas and behavioural deficits in middle cerebral artery occlusion (MCAO) and photothrombosis stroke models. In the MCAO model, a 0.38 mm-diameter silicone-coated thread was introduced through the left external carotid artery and advanced 18 mm via the internal carotid artery to the origin of middle cerebral artery of male Sprague–Dawley rats weighing 300–350 g. The thread was removed for reperfusion after occlusion for 0.5, 1 or 2 h. In the photothrombosis model, after a midline incision on the scalp, a focused light (10,000 lux, 6 mm-diameter) was delivered 1 mm anterior to the bregma and 3 mm left of the midline for 5, 10 or 20 min. During the first 2 min of irradiation, Rose Bengal dye (30 mg/kg) was injected intravenously. Twenty four hours post-surgery, the animals were subjected to neurological scoring and behavioural performances, and were sacrificed for macroscopic and microscopic examinations of brain injury. Total infarction volumes in the MCAO model rats increased in an occlusion time-dependent manner, while the infarction volumes in photothrombosis model rats plateaued relatively quickly with no time-dependent increase. The MCAO model displayed neurological scores and behavioural deficits that correlated well with infarction volumes, while relatively poor correlation between infarction volume and neurobehavioural abnormalities was evident in the photothrombosis model. The results indicate the suitability of the MCAO model for studies on preventive or therapeutic compounds related to functional recovery, although the photothrombosis model might be useful to generate focused lesions leading to the location-related behavioural changes.

Focal Cerebral Ischemia Model by Endovascular Suture Occlusion of the Middle Cerebral Artery in the Rat

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable clinical state; in the development of animal models of focal ischemia, however, achieving reproducibility of experimentally induced infarct volume is essential. The rat is a widely used animal model for stroke due to its relatively low animal husbandry costs and to the similarity of its cranial circulation to that of humans2,3. In humans, the middle cerebral artery (MCA) is most commonly affected in stroke syndromes and multiple methods of MCA occlusion (MCAO) have been described to mimic this clinical syndrome in animal models. Because recanalization commonly occurs following an acute stroke in the human, reperfusion after a period of occlusion has been included in many of these models. In this video, we demonstrate the transient endovascular suture MCAO model in the spontaneously hypertensive rat (SHR). A filament with a silicon tip coating is placed intraluminally at the MCA origin for 60 minutes, followed by reperfusion. Note that the optimal occlusion period may vary in other rat strains, such as Wistar or Sprague-Dawley. Several behavioral indicators of stroke in the rat are shown. Focal ischemia is confirmed using T2-weighted magnetic resonance images and by staining brain sections with 2,3,5-triphenyltetrazolium chloride (TTC) 24 hours after MCAO.