Contralateral Posterior Cerebral Artery Research Articles

Abstract TP199: Prominent Laterality of the Posterior Cerebral Artery on MR Angiography Before Mechanical Thrombectomy in Patients With the Middle Cerebral Artery Occlusion Predicts Long-Term Functional Outcome

Background and Purpose: Well-developed collateral flow is reported to be associated with a reduction of infarct volume, successful reperfusion, and better functional outcome in acute ischemic stroke (AIS). Relatively increased visualization of posterior cerebral artery (PCA) ipsilateral to the ischemic lesion on MR angiography (MRA), a sign of prominent PCA laterality (PCAL), represents the development of collateral flow from PCA to middle cerebral artery (MCA) territory. However, the prognostic value of PCAL on functional outcome in AIS patients having MCA occlusion and undergoing mechanical thrombectomy, is not well known. Methods: We retrospectively reviewed initial MRA scans of pre-morbidly independent patients treated with mechanical thrombectomy for M1-segment occlusion from September 2017 to May 2022. PCAL was defined as better visualization of ipsilateral PCA, compared to contralateral PCA, by one or more segments on MRA. We divided patients into two groups, those presenting PCAL and not, and compared the background characteristics, in-hospital management, and functional outcome between the two groups. Factors associated with favorable outcome (mRS score 0-2) at 3 months after onset were assessed using multivariate logistic regression analysis. Results: In total, 172 patients (76 female [44%], median age 77 [IQR 74.5-78.0] years, median NIHSS score 16 [15-18]) were included. Of these, 86 patients (50%) presented PCAL on initial MRA. There is no significant difference between the two groups in age, sex, major vascular risk factors, NIHSS on admission, DWI-ASPECTS, onset-to-recanalization time (OTR), and preclinical modified Rankin scale. Multivariate logistic regression analysis showed an adjusted odds ratio of 2.11 for a favorable outcome in patients with PCAL (95% CI: 0.986 to 4.53, P=0.054). When focused on the cases with OTR >6 hours (n=53), PCAL was independently associated with favorable outcome (OR 5.77, 95% CI: 1.28 to 26.0, P=0.022). Conclusion: PCAL on initial MRA in patients with M1-segment occlusion predicts favorable long-term functional outcome after mechanical thrombectomy, especially in the case taking longer time from onset to recanalization.

Effect of the addition of 123I-iomazenil single-photon emission computed tomography to brain perfusion single-photon emission computed tomography on the detection accuracy of misery perfusion in adult patients with ischemic moyamoya disease.

The present prospective study aimed to determine whether the addition of 123I-iomazenil (IMZ) single-photon emission computed tomography (SPECT) to brain perfusion SPECT could improve the detection accuracy of misery perfusion on positron emission tomography (PET) in adult patients with ischemic moyamoya disease (MMD). Oxygen extraction fraction (OEF) and brain perfusion were assessed using 15O gas PET and N-isopropyl-p-[123I]-iodoamphetamine (IMP) SPECT, respectively, in 137 patients. IMZ SPECT was also performed. Regions of interest (ROIs) were automatically placed in the five middle cerebral artery (MCA) territories ipsilateral to the symptomatic cerebral hemisphere and in the contralateral posterior cerebral artery territory using a three-dimensional stereotaxic ROI template. The radioactive count of the MCA ROI to the contralateral posterior cerebral artery ROI was calculated on IMP SPECT (relative SPECT-IMP uptake) and IMZ SPECT (relative SPECT-IMZ uptake). The relative SPECT-IMZ uptake to the relative SPECT-IMP uptake was also calculated (relative SPECT-IMZ/IMP uptake). Of the five MCA ROIs in the symptomatic cerebral hemisphere in each patient, the ROI with the highest PET-OEF value (one ROI per patient) was selected for analysis. Significant correlations were observed between the PET-OEF and relative SPECT-IMP uptake (correlation coefficient, -0.683) and relative SPECT-IMZ/IMP uptake (correlation coefficient, 0.875). The area under the receiver operating characteristic curve for detecting misery perfusion (PET-OEF > 51.3%) was significantly greater for the relative SPECT-IMZ/IMP uptake than for the relative SPECT-IMP uptake (difference between areas, 0.080; p = 0.0004). The sensitivity, specificity, and positive- and negative-predictive values for the relative SPECT-IMZ/IMP uptake for detecting misery perfusion were 100%, 92%, 81%, and 100%, respectively. The specificity and positive-predictive value were significantly greater for the relative SPECT-IMZ/IMP uptake than for the relative SPECT-IMP uptake. The addition of IMZ SPECT to brain perfusion SPECT improves the detection accuracy of misery perfusion on PET in adult patients with ischemic MMD.

A Case of Occlusion of the Contralateral Posterior Cerebral Artery Caused by the Migration of Onyx during Embolization of Cerebral Arteriovenous Malformation and Successful Recanalization Therapy Using a Stent Retriever

A Case of Occlusion of the Contralateral Posterior Cerebral Artery Caused by the Migration of Onyx during Embolization of Cerebral Arteriovenous Malformation and Successful Recanalization Therapy Using a Stent Retriever

Anatomical Assessment of the Endoscopic Assisted Lateral Supraorbital Approach and Endoscopic Endonasal Transclival Approach to Basilar Apex Aneurysms.

To assess the feasibility of using an endoscopic-assisted lateral supraorbital (LSO) approach and an endoscopic endonasal transclival approach (EETA) for basilar apex (BAX) aneurysms. Ten cases with LSO approaches, with or without posterior clinoidectomy and endoscopic assistance, and 10 cases with EETA, with or without drilling of the dorsum sellae, were performed on 20 cadaveric heads. Anatomical exposure and surgical freedom at the BAX were evaluated. Anatomical exposure provided by the LSO approach was limited to the BAX and ipsilateral posterior cerebral artery (PCA) and increased with a mean value of 5.0 mm after posterior clinoidectomy; the basilar artery, contralateral PCA, and superior cerebellar arteries (SCAs) were visualized in all cases. Accordingly, surgical freedom was larger. Endoscopic assistance provided a significant increase in basilar artery exposure; however, surgical freedom did not increase markedly. The main advantage of EETA was the greatest exposure of the basilar artery. With drilling of the dorsum sellae, anatomical exposure increased by a mean value of 3.4 mm, and provided the greatest amount of surgical freedom and visualization of the basilar artery terminal bifurcation and of the SCAs in all cases. The endoscopic-assisted LSO approach and the EETA may represent a feasible approach for treatment of BAX aneurysms lying within 5.0 mm below and within 3.4 mm above the dorsum sellae.

Ipsilateral and Contralateral Posterior Cerebral Artery Blood Velocities During Handgrip Exercise

Ipsilateral and Contralateral Posterior Cerebral Artery Blood Velocities During Handgrip Exercise

Fluid-attenuated inversion recovery vascular hyperintensities in predicting cerebral hyperperfusion after intracranial arterial stenting.

No reliable imaging sign predicting cerebral hyperperfusion after intracranial arterial stenting (IAS) had been described in the literature. This study evaluated the effect of fluid-attenuated inversion recovery vascular hyperintensities (FVHs), also called hyperintense vessel sign on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) MR images, in predicting significant increase in cerebral blood flow (CBF) defined by arterial spin labeling (ASL) after IAS. We reviewed ASL CBF images and T2-FLAIR MR images before (D0), 1day after (D1), and 3days after (D3) IAS of 16 patients. T1-weighted MR images were used as cerebral maps for calculating CBF. The changes in CBF values after IAS were calculated in and compared among stenting and nonstenting vascular territories. An increase more than 50% of CBF was considered as hyperperfusion. The effect of FVHs in predicting hyperperfusion was calculated. The D1 CBF value was significantly higher than the D0 CBF value in stenting vascular, contralateral anterior cerebral artery, contralateral middle cerebral artery, and contralateral posterior cerebral artery (PCA) territories (all P<.05). The D1 and D3 CBF values were significantly higher than the D0 CBF value in overall vascular (P<.001), overall nonstenting vascular (P<.001), and ipsilateral PCA (P<.05) territories. The rate of more than 50% increases in CBF was significantly higher in patients who exhibited asymmetric FVHs than in those who did not exhibit these findings. FVHs could be a critical predictor of a significant increase in CBF after IAS.

Ultrasound and Clinical Predictors of Recurrent Ischemia in Symptomatic Internal Carotid Artery Occlusion.

Occlusion of the internal carotid artery puts patients at risk of recurrent ischemic events because of hemodynamic compromise. Our goal was to characterize clinical and duplex parameters indicating patients at risk of recurrent ischemia. We retrospectively identified patients with symptomatic internal carotid artery occlusion. Clinical characteristics and ultrasound parameters, including collateral networks, were analyzed. Predictors for recurrent ipsilateral ischemia were investigated by Cox regression analysis. Of 68 patients, at least 1 recurrent ischemic event within the same vascular territory was observed in 14 patients (20.6%) within 2 to 92 days (median, 29.5 days). The median follow-up period was 6 months. Diabetes mellitus and previous transient ischemic attack were associated with recurrence, as was activation of the maximum number of collateral pathways on transcranial ultrasound (28.6% versus 5.6%; P=0.03). Furthermore, flow in the posterior cerebral arteries was higher in patients with recurrence in ipsilateral and contralateral posterior cerebral artery P2 segments (76 IQR 37.5 versus 59, IQR 22.5 cm/s and 68, IQR 35.6 versus 52, IQR 21 cm/s; P<0.01 and 0.02). Flow increases in both posterior cerebral artery P2 segments suggest intensified compensatory efforts when other collaterals are insufficient. Together with the presence of diabetes mellitus and a history of transient ischemic attack, this duplex parameter indicates that patients with internal carotid artery are at particular risk of recurrent ischemia.

Thalamic arteriovenous malformation fed by the artery of Percheron originating from the contralateral posterior cerebral artery in a child

Artery of Percheron (AOP) is a rare variant of thalamoperforating artery with a single common trunk feeding both thalami and with or without contribution to the rostral midbrain. We report the first case of thalamic arteriovenous malformation (AVM) fed by AOP with hemorrhagic onset. A 12-month-old girl suddenly weakened and developed coma. Left thalamic hemorrhage was detected with the third and both lateral ventricles' hematoma. Thalamic AVM was discovered to be fed by an AOP originating from the contralateral posterior cerebral artery. Endovascular embolization of AVM was impossible due to a risk of bilateral thalamic infarction and anatomical inaccessibility. Thalamic AVM was removed by high superior parietal approach without new neurological symptoms. The first case of thalamic AVM fed by AOP originating from the contralateral posterior cerebral artery is reported. Surgical removal of AVM would be at the heart of treatment in order to avoid bilateral thalamic infarction.

Reduced Cerebrovascular Reactivity in Posterior Cerebral Arteries in Patients with Primary Open-Angle Glaucoma

To evaluate the hemodynamics and vasoreactivity in the posterior cerebral artery (PCA) in patients with primary open-angle glaucoma (POAG). Case-control study. Thirteen POAG patients (age range, 40-60 years) with marked visual field loss (mean deviation [MD], <-6 dB); a preserved, mostly normal, central visual field of at least 5°; and best-corrected visual acuity of at least 20/40 formed the study group. Exclusion criterion was presence or history of any systemic disorder including cardiovascular diseases. The control group consisted of 12 healthy subjects matched for age and sex with the study group. Applying transcranial Doppler sonography, we measured hemodynamic parameters in both PCAs at baseline, under monocular reversing checkerboard stimulation, and under hyperventilation. The eye with more marked visual field loss was selected in glaucoma patients, whereas in controls, the tested eye was chosen randomly. Ipsilateral and contralateral PCA were defined according to the tested eye. Peak systolic velocity (PSV), end-diastolic velocity, mean velocity (MV), MV change percentage (MV%), resistivity index (RI), pulsatility index (PI). At baseline, RI (0.55 ± 0.04 vs. 0.52 ± 0.03; P = 0.04) and PI (0.88 ± 0.11 vs. 0.80 ± 0.07; P = 0.04) in the ipsilateral PCA were significantly higher in glaucoma patients than in controls. During checkerboard stimulation, MV% in both PCAs were significantly smaller in the glaucoma group than in controls (19.7 ± 7.2% and 19.0 ± 8.3% vs. 30.7 ± 7.9% and 27.5±9.0%, respectively; P = 0.001 and 0.02, respectively). During hyperventilation, glaucoma patients showed significantly lower MV% in the contralateral PCA than control subjects (-39.8 ± 9.6% versus -47.4 ± 7.0%; P = 0.03). Perimetric pattern standard deviation (PSD) in the tested eye was correlated significantly with RI and PI of the ipsilateral PCA during checkerboard stimulation (P = 0.003, r = -0.76; and P = 0.002, r = -0.76). The MV% of contralateral PCA was correlated inversely with PSD in the fellow eye (P = 0.02, r = -0.64). The difference in MV% between both PCAs was correlated positively with the difference in MD between 2 eyes (P = 0.003, r = 0.75). Under hyperventilation, PSV in the contralateral PCA was correlated negatively with the PSD in the fellow eye (P = 0.03, r = -0.60). Vascular insufficiency in the PCAs may be associated with POAG. Changes in the vasoreactivity of PCAs to central visual stimulation may precede marked central visual field loss.

An anatomical analysis of the mini-modified orbitozygomatic and supra-orbital approaches

Seven sides of cadaver heads were used to compare the surgical exposures provided by the mini-modified orbitozygomatic (MOz) and supra-orbital (SO) approaches. The Optotrak 3020 computerized tracking system (Northern Digital, Waterloo, ON, Canada) was utilized to evaluate the area of anatomical exposure defined by six points: (1) ipsilateral sphenoid ridge; (2) most distal point of the ipsilateral middle cerebral artery (MCA); (3) most distal point of the ipsilateral posterior cerebral artery (PCA); (4) most distal point of the contralateral PCA; (5) most distal point of the contralateral MCA; and (6) contralateral sphenoid ridge. Additionally, angles of approach for the ipsilateral MCA bifurcation, ipsilateral ICA bifurcation, basilar artery tip, contralateral MCA and ICA bifurcation and anterior communicating artery (AcomA) were evaluated, first for SO and then for MOz. An image guidance system was used to evaluate the limits of surgical exposure. No differences in the area of surgical exposure were noted (p>0.05). Vertical angles were significantly wider for the ipsilateral and contralateral ICA bifurcation, AcomA, contralateral MCA and basilar tip (p<0.05) for MOz. No differences in horizontal angles were observed between the approaches for the six targets (p>0.05). There were no differences in the limits of exposure. MOz affords no additional surgical working space. However, our results demonstrate systematically that vertical exposure is improved. The MOz should be performed while planning an approach to these regions and a wider exposure in the vertical axis is needed.

Leptomeningeal Collateral Volume Flow Assessed by Quantitative Magnetic Resonance Angiography in Large‐Vessel Cerebrovascular Disease

Leptomeningeal collateral volume flow has not been previously quantified. Quantitative magnetic resonance angiography (QMRA) can determine flow in the large vessels of the intracranial circulation. We reviewed consecutive QMRA studies performed between December 1, 2004 and August 30, 2005, for cases showing asymmetrically higher flow in a posterior cerebral artery (PCA) just distal to the origin of the posterior communicating artery ipsilateral to a hemodynamic middle cerebral artery (MCA) or internal carotid artery lesion. The mean, range, and standard deviation (SD) of the flow rate in the PCAs, MCAs, and PCA ipsilateral-contralateral difference were calculated. Ipsilateral and contralateral PCA flow rates were compared using the Student's t-test. Sixteen studies met selection criteria. Mean age was 52 years (range 21-79) and 9 were female. MCA flow was below QMRA detection limits in 6 studies. Mean measurable ipsilateral MCA flow reduction was 84 mL/min (range 9-147, SD 51.4). Mean ipsilateral PCA flow was 118 mL/min (range 72-206, SD 38.5) and mean contralateral PCA flow was 68 mL/min (range 35-144, SD 30.5, P < .001); mean difference was 50 mL/min (range 10-93, SD 24.3). Leptomeningeal collateral flow can be assessed with QMRA and may be substantial.

Dominant Ipsilateral Posterior Cerebral Artery on Magnetic Resonance Angiography in Acute Ischemic Stroke

Background: In acute infarction involving the anterior circulation, the ipsilateral posterior cerebral artery (PCA) often appears to be longer than the contralateral PCA on magnetic resonance angiography. We described this finding as dominant ipsilateral PCA (DIPCA). We sought to find the frequency of DIPCA and its predictors. Methods: We recruited 164 consecutive individuals with acute infarct involving the anterior circulation, and analyzed their radiological and clinical features. Results: DIPCA was noted in 27 patients (16.5%). It was more frequent in patients with than in patients without steno-occlusive disease of the ipsilateral anterior circulation (30.5 vs. 2.4%, p < 0.001). Multivariate analysis revealed a significant relationship between the severity of arterial lesions in the ipsilateral anterior circulation and DIPCA (p = 0.039). Conclusions: DIPCA may reflect increased leptomeningeal collateral flow via the ipsilateral PCA, and its development may be dependent on the stenotic anterior circulation.

Contralateral EEG slowing and amobarbital distribution in Wada test: an intracarotid SPECT study.

To relate the occurrence of contralateral electroencephalogram slowing (CES) to amobarbital distribution, we performed electroencephalogram (EEG) monitoring and intracarotid single photon emission computed tomography (SPECT) during an intracarotid amobarbital procedure (IAP). IAP was performed on 22 patients with temporal lobe epilepsy. CES was defined as the occurrence of significant EEG slowing on the contralateral hemisphere (>50% of the ipsilateral hemisphere slowing) after amobarbital injection. To map the distribution of the amobarbital, we injected a mixture of amobarbital and (99m)technetium-ethylcysteinate dimer (99mTc-ECD) into the internal carotid artery and performed a brain SPECT 2 h later. In the SPECT images, regions of interest were determined by ipsilateral and contralateral anterior cerebral artery territories (iACA, cACA), ipsilateral and contralateral middle cerebral artery territories (iMCA, cMCA), and ipsilateral and contralateral posterior cerebral artery territories (iPCA, cPCA), as well as ipsilateral and contralateral anterior and posterior mesial temporal regions (iAMT, cAMT, iPMT, cPMT). The perfusion of amobarbital was interpreted visually in each region. Amobarbital was distributed in the iMCA in all the patients; in the iACA in 20 (90.9%) patients; in the iAMT in 14 (63.5%); and in the iPCA and iPMT in only two (9.1%). CES was observed in 13 (59.1%) patients. Cross-perfusion of amobarbital in limited areas of the cACA were observed in only four of 13 patients. Wada retention memory scores (WRMS) showed no significant difference between the CES- (n = 9) and CES+ (n = 13) groups. Amobarbital rarely perfused the iPCA territory and the iPMT region and was rarely delivered to the contralateral hemisphere. The occurrence of CES was not related to the cross-perfusion of amobarbital. CES appears to be produced by a transient functional disconnection from the ipsilateral hemisphere.

Increase of posterior cerebral artery blood flow velocity during threshold repetitive magnetic stimulation of the human visual cortex: hints for neuronal activation without cortical phosphenes

To analyze the effects of low intensity repetitive transcranial magnetic stimulation over the occipital cortex on regional cerebral perfusion, bilateral simultaneous monitoring of posterior cerebral artery blood flow velocity was performed using transcranial Doopler ultrasonography in 14 healthy subjects. During 20 s of unilateral magnetic stimulation with 3 Hz and 6 Hz a significant increase of ipsilateral flow velocity was observed during both stimulus conditions (3 Hz, 10.2 ± 3.7%; 6 Hz, 12.8 ± 4.7%). A significantly smaller flow velocity increase occurred also in the contralateral posterior cerebral artery (3 Hz, 8.6 ± 4.0%; 6 Hz, 10.6 ± 4.1%). Flow velocity increases were similar to values reported in the literature for physiological activation paradigms so that excessive excitation of the visual cortex does not seem to occur during repetitive magnetic stimulation. The largest increase of flow velocity was observed in the ipsilateral posterior cerebral artery of 5 subjects who experienced phosphenes in the contralateral visual half-field during stimulation (14.3 ± 4.1%; mean of 3 and 6 Hz stimulation). In the other 9 subjects significant velocity increases indicated cortex activation in the absence of cortical phosphenes. The occurrence of maximum velocity responses within 2–3 heart beats following the first cortex stimulus points to a fast adjustment of cerebral perfusion in response to transcranial brain stimulation.

Regional cerebral blood flow, diaschisis, and steal after stroke.

Regional CBF was measured by 133Xe inhalation in unilateral cerebral infarction, carotid TIAs, and normal volunteers. Regional CBF values were bilaterally and symmetrically reduced in patients measured within 3 weeks after stroke. Later, rCBF values returned toward normal in the contralateral hemisphere of patients with infarction and in both hemispheres with carotid TIAs. In cases with carotid occlusive disease, flow reduction was seen in the contralateral posterior cerebral artery distribution, with hyperemia in ipsilateral occipital lobe caused by interhemispheric steal. Brainstem-cerebellar flow values were increased following acute cerebral infarction if patients were alert but reduced if consciousness was impaired.