OBJECTIVE: We aimed to validate hyperintense vessel sign (HVS) on FLAIR imaging or posterior cerebral artery (PCA) laterality on MR angiography beyond 4.5 hours after stroke onset.
METHODS: Data from acute ischemic stroke patients with internal carotid or middle cerebral artery occlusion who underwent CT perfusion imaging at baseline, follow-up MR perfusion imaging and angiography within 30 hours after stroke, without effective recanalization on follow-up imaging, were analysed retrospectively. Patients were separately classified as high or low HVS (>5 or ≤5 slices of HVS), and PCA laterality positive or negative group. We compared core and penumbra volumes at follow-up imaging and neurological outcomes between high or low HVS group, and between PCA laterality positive or negative group.
RESULTS: Of 49 patients analyzed, four patients with artifacts were excluded and 45 were classified into high (n = 23) or low (n = 22) HVS group. High group had a smaller core volume (median 32 ml versus 109 ml, p = 0.004), larger penumbra volume at follow-up (68 ml versus 0 ml, p = 0.001), and better outcomes (modified Rankin Scale at three months, 3 versus 5, p = 0.03). For PCA laterality analysis, 1 patient with previously occluded PCA was excluded and 48 patients were classified as positive (n = 22) or negative (n = 26). Positive group had larger core volume (116 ml versus 37 ml), and no significant differences in penumbral volumes or outcomes.
CONCLUSIONS: Prominent HVS in later time was associated with small core volume, persistent penumbra volume and favorable outcomes.

OBJECTIVE: Arterial supply of thalamus is complex and highly variable. In particular, the distribution pattern of thalamoperforating arteries received more attention some decades ago than in recent years.
METHODS: We are presenting the case of a 46-year-old patient with wake-up drowsiness, complex oculomotor disorder and dysarthria. He was investigated in the acute phase using non-contrast brain Computed Tomography (NCCT), CT Angiography (CTA), and in the following days Digital Subtraction Angiography (DSA) was performed Results. The NCCT showed a subacute ischemic stroke in the right anterior thalamus and rostral midbrain with normal findings on CTA. DSA imaged a variant of thalamic supply (Percheron type III), constituted by perforating branches arising from an artery bridging the P1 segments of both Posterior Cerebral Arteries (PCAs).
RESULTS: The thalamus has a complex and variable arterial supply, mainly in the pattern of paramedian thalamic-mesencephalic perforating arteries. The most reported variant is Percheron type IIb and supplies the paramedian thalami and the rostral midbrain. Type IIb occlusion usually causes a bilateral paramedian thalamic stroke, but rostral midbrain and anterior thalamus are involved in 57% and 19% cases. The rarer Type III variant probably prevented the bilateral extension of infarction and involved the territory of tuberothalamic and paramedian perforating arteries.
CONCLUSIONS: Currently, DSA allows directly imaging variants in thalamic vascularization and better understanding the stroke mechanisms. In particular, in the presented case, a medium-sized vessel occlusion rather than a small vessel occlusion mechanism might be raised, leading to a different diagnostic pathway.

BACKGROUND: Whereas mechanical thrombectomy (MT) has become standard-of-care treatment for patients with salvageable brain tissue after acute stroke caused by large-vessel occlusions, the results of MT in patients with medium-vessel occlusions (MEVOs), particularly in the posterior cerebral artery (PCA), are not well known.
METHODS: Using data from the international Stroke Thrombectomy and Aneurysm Registry (STAR), we assessed presenting characteristics and clinical outcomes for patients who underwent MT for primary occlusions in the P2 PCA segment. As a subanalysis, we compared the PCA MeVO outcomes with STAR\'s anterior circulation MeVO outcomes, namely middle cerebral artery (MCA) M2 and M3 segments.
RESULTS: Of the 9812 patients in STAR, 43 underwent MT for isolated PCA MeVOs. The patients\' median age was 69 years (interquartile range 61-79), and 48.8% were female. The median NIH Stroke Scale score was 9 (range 6-17). After recanalization, 67.4% of patients achieved successful recanalization (modified treatment in cerebral infarction score [mTICI] ≥ 2b), with a first-pass success rate of 44.2%, and 39.6% achieved a modified Rankin score of 0-2 at 90 days. Nine patients (20.9%) had died by the 90-day follow-up. In comparison with M2 and M3 MeVOs, there were no differences in presenting characteristics among the three groups. Patients with PCA MeVOs were less likely to undergo intra-arterial thrombolysis (4.7% PCA vs. 10.1% M2 vs. 16.2% M3, p = 0.046) or to achieve successful recanalization (mTICI ≥ 2b, 67.4%, 86.7%, 82.3%, respectively, p < 0.001); however, there were no differences in the rates of successful first-pass recanalization (44.2%, 49.8%, 52.3%, respectively, p = 0.65).
CONCLUSIONS: We describe the STAR experience performing MT in patients with PCA MeVOs. Our analysis supports that successful first-pass recanalization can be achieved in PCA MEVOs at a rate similar to that in MCA MeVOs, although further study and possible innovation may be necessary to improve successful PCA MeVO recanalization rates.

Previous studies have reported various anatomical differences in the cerebral artery between healthy subjects and patients with posterior circulation cerebral infarction. In particular, basilar artery angulation has been associated with posterior circulation cerebral infarction. We compared anatomical variations and the degree of anterior and lateral vertebrobasilar artery angulation and deviation to compare the incidence of cerebral infarction of healthy subjects and patients with posterior circulation cerebral infarction. We compared basilar artery anatomy using brain magnetic resonance angiography in 97 patients who underwent brain magnetic resonance angiography during health checkups at our hospital and in 92 patients diagnosed with posterior circulation cerebral infarction between 2012 and 2022. Anatomical variations, including fetal-type posterior cerebral artery, hypoplastic P1 segment, vertebrobasilar dolichoectasia, and dominant vertebral artery, as well as the degree of anterior and lateral deviation and angulation, were evaluated. Correlations between these variations and the occurrence of cerebral infarction were analyzed. The prevalence of hypoplastic P1 was significantly differences in patients with posterior circulation cerebral infarction (odds ratio: 5.655). Furthermore, patients with posterior circulation cerebral infarction exhibited more acute anterior and lateral angulation, as well as lateral deviation. Hypoplastic P1 and more acute anterior or lateral angulation of the vertebrobasilar artery are associated with increased frequency of cerebral infarction.

OBJECTIVE: To describe a case of replaced posterior cerebral artery (PCA) in which all branches of the PCA arose from the anterior choroidal artery (AChA) with an early branching temporal artery.
METHODS: An 83-year-old man with cerebral infarctions underwent cranial magnetic resonance (MR) imaging and MR angiography using a 3-Tesla scanner. MR angiography was performed using a standard 3-dimensional time-of-flight technique.
RESULTS: A large anomalous artery arose from the supraclinoid segment of the right internal carotid artery (ICA) and supplied all branches of the right PCA, mimicking fetal-type PCA. The temporal branch arose from the proximal segment of this artery. In MR angiographic source images, a tiny artery arose from the right ICA proximal to the origin of the anomalous artery, indicating a hypoplastic right posterior communicating artery (PCoA). Thus, we concluded that the anomalous artery was a replaced PCA; all branches of the PCA arose from the AChA.
CONCLUSIONS: We present a case involving a replaced PCA with an early branching temporal artery, as seen on MR angiography. Careful observation of MR angiographic source images is useful for identifying small arteries. To our knowledge, this is the first report of this combined variation in the relevant English-language literature.

OBJECTIVE: Despite the known poor outcomes of patients with hemorrhagic moyamoya disease (MMD), previous studies have not explored the entire population of hemorrhagic MMD, often excluding severely impaired patients due to the lack of imaging studies demonstrating cerebral angioarchitecture. Herein, we investigate the prevalence, location of intracerebral hematoma (ICH), and outcomes in patients with hemorrhagic MMD, including severely impaired individuals who underwent emergency computed tomography (CT) angiography (CTA) to identify secondary ICHs.
METHODS: We conducted a retrospective analysis of 2092 patients admitted to our hospital within 3 days of ICH onset from January 2010 to December 2022. CTA was performed for all patients with ICH, principally.
RESULTS: CTA was performed in 1645 (78.6%) patients. We diagnosed MMD in 40 patients (2.5%), making it the third leading cause of secondary ICH. Twenty patients had anterior-type hematomas, while the remaining twenty had posterior-type hematomas. At 90 days after onset, 19 patients (95%) with anterior-type hematomas had unfavorable outcomes (modified Rankin scale [mRS] scores of 3-6), compared to 11 patients (55%) with posterior-type hematomas. The number of unfavorable outcomes was significantly higher in the anterior-type group compared to the posterior-type group (p = 0.008).
CONCLUSIONS: This comprehensive study highlights that the majority of MMD cases with ICH result in unfavorable outcomes, especially when the ICH is located in the anterior circulation. While recent studies have focused on preventing bleeding from choroidal anastomosis in the posterior circulation, overall outcome improvement of hemorrhagic MMD necessitates a greater emphasis on addressing anterior circulation ICHs.

Artery of Percheron (AOP) is an uncommon anatomical variation in the posterior circulation neurovasculature. It is a single artery arising from P1 segment of posterior cerebral artery (PCA) which supplies bilateral paramedian thalami and the rostral midbrain and as a result, occlusion of it leads to bilateral thalamic and mesencephalic infarction. Due to very low incidence (ranges from 0.1% to 2% of all ischemic strokes) and varied presentation, the diagnosis of AOP infarction requires strong clinical and radiological suspicion and hence, AOP infarction is often missed and patients are rarely thrombolysed. Here we discuss a patient with acute altered sensorium who recovered completely in short time following treatment with intra-venous thrombolysis for bilateral medial thalamic ischemic stroke due to AOP occlusion.

BACKGROUND: The fetal-type posterior cerebral artery (PCA) is defined as a variant anatomy in which the posterior communicating artery (PCOM) is larger than the hypoplastic or aplastic P1 segment of the PCA. The authors present the novel case of a patient with a duplicated right PCA in parallel with fetal-type and conventional PCAs supplying adjacent components of the PCA cerebral territory.
METHODS: A 59-year-old woman presented with a modified Fisher Scale score 4 subarachnoid hemorrhage. A right irregular PCOM aneurysm that measured 9.5 mm × 4.5 mm × 4.5 mm arose from the base of a variant branch supplying a portion of the PCA, rather than a conventional PCOM, and was found on digital subtraction angiography. Following endovascular coil embolization, the patient was discharged home.
CONCLUSIONS: The fetal-type variant has implications for thromboembolic events. If an embolism occludes the anterior circulation in a patient with a fetal-type PCA, it may result in an infarct in the PCA territory. Awareness of cerebral arterial anatomy, including an atypical collateral supply, informs a treating team\'s latitude in tolerance of which sites must be preserved and which can be safely sacrificed. https://thejns.org/doi/10.3171/CASE23735.

OBJECTIVE: Posterior cerebral artery involvement (PCAi) has been identified as an important factor related to poor prognosis in moyamoya disease (MMD). This study summarized the characteristics of children with MMD and PCAi, clarified the clinical course, identified prognostic predictors, and investigated the long-term effect of encephaloduroarteriosynangiosis for posterior circulation (EDAS-p).
METHODS: We retrospectively reviewed all our pediatric MMD cases with follow-up angiograms from November 2003 to December 2016. PCAi was classified as early-onset at initial diagnosis and delayed-onset after anterior circulation revascularization. Multivariable data including clinical features, radiographic findings, and surgical outcomes were analyzed.
RESULTS: Among 570 children with MMD, 246 (43.2%) had PCAi, with 176 (30.9%) classified as early-onset PCAi. During a median follow-up period of 10 years, 17.8% (70/394) of patients without initial PCAi developed delayed-onset PCAi. The median time to detection of a new PCA lesion was 15.5 (range 7-110) months from initial diagnosis, with a median age of 10.5 (3-22). Younger age at onset, familial occurrence, advanced Suzuki stages, and preoperative infarctions were predictors of delayed-onset PCAi. EDAS-p was performed on 294 hemispheres of 195 patients with PCAi. Stroke-free survival was significantly higher in the EDAS-p group than in the non-EDAS-p group (99.0% vs 90.2%; p < 0.001 [Breslow test]; p = 0.001 [log-rank test]; median follow-up: 101 months).
CONCLUSIONS: PCAi is not uncommon in children with MMD, underscoring the need for long-term close clinical monitoring, especially in patients with high-risk factors for PCA progression. EDAS-p may be a safe and effective procedure for preventing subsequent stroke in children with MMD and PCAi.

OBJECTIVE: Cerebral Vasomotor Reactivity (VMR) is a property of cerebral hemodynamics that protects from cerebrovascular disease. We aimed to explore the VMR longitudinal changes in patients with acute non-disabling stroke/Transient Ischemic Attack (TIA) to understand its implication in stroke ethiopatogenesis.
METHODS: VMR by Transcranial Doppler Breath Holding test was performed at 48-72 h from stroke onset (T1) and after 6 months (T2) on MCA of the non-affected hemisphere and PCA of the affected hemisphere.
RESULTS: We consecutively enrolled 124 patients with a median age of 66.0 (IQR 54.75-74.25) years with a median NIHSS 2 (IQR 1-3). Both MCA (1.38 %/s SD 0.58) and PCA (1.35 %/s SD 0.75) BHI at T1 did not differ among different stroke subtypes (p=0.067 and p=0.350; N=124). MCA and PCA BHI decreased from T1 to T2 (respectively 1.39 %/s SD 0.56 vs 1.18%/s SD 0.44 and 1.30 %/s SD 0.69 vs 1.20 %/s SD 0.51; N=109) regardless of ethiopatogenesis (respectively p<0.0001 and p=0.111).
CONCLUSIONS: The VMR is higher in acute phase than at 6 months in patients with non-disabling stroke/TIA, regardless of etiopathogenesis. The higher VMR in acute phase could be sustained by an increased Cerebral Blood Flow due to collateral circulation activation supporting the ischemic zone.