Posterior Cerebral Artery Lesions Research Articles

Encephalo-Duro-Pericranio-Synangiosis for the Treatment of Moyamoya Disease with Posterior Cerebral Artery Lesions

We describe our experience performing encephalo-duro-pericranio synangiosis for the parieto-occipital region (EDPS-p) as a treatment for moyamoya disease (MMD) with hemodynamic disturbances caused by lesions of the posterior cerebral artery. From 2004 to 2020, 60 hemispheres of 50 patients with MMD (38/50 females, age 1-55 years) underwent EDPS-p as a treatment for hemodynamic disturbances in the parieto-occipital region. A skin incision was made on the parieto-occipital area to avoid the major skin arteries, and the pedicle flap was created by attaching the pericranium to the dura mater under the craniotomy with multiple small incisions. The surgical outcome was assessed on the basis of the following points: perioperative complications, postoperative improvement of clinical symptoms, subsequent novel ischemic events, qualitative assessment of the development of collateral vessels by magnetic resonance arteriography, quantitative assessment of postoperative perfusion improvement based on the mean transit time, and cerebral blood volume on dynamic susceptibility contrast imaging. Perioperative infarction occurred in 7/60 hemispheres (11.7%). The transient ischemic symptoms observed preoperatively disappeared in 39/41 hemispheres (95.1%) during the follow-up period (12-187 months), and none of the patients experienced novel ischemic events. Collateral vessels supplied from the occipital arteries, middle meningeal arteries, and posterior auricular arteries developed postoperatively in 56/60 hemispheres (93.3%). Postoperative mean transit time and cerebral blood volume showed significant improvement in the occipital, parietal, and temporal areas (P < 0.001), as well as the frontal area (P= 0.01). EDPS-p seems to be an effective surgical treatment for patients with MMD who suffer hemodynamic disturbances caused by posterior cerebral artery lesions.

Three-dimensional simulations of embolic stroke and an equation for sizing emboli from imaging

Stroke simulations are needed to run in-silico trials, develop hypotheses for clinical studies and to interpret ultrasound monitoring and radiological imaging. We describe proof-of-concept three-dimensional stroke simulations, carrying out in silico trials to relate lesion volume to embolus diameter and calculate probabilistic lesion overlap maps, building on our previous Monte Carlo method. Simulated emboli were released into an in silico vasculature to simulate 1000 s of strokes. Infarct volume distributions and probabilistic lesion overlap maps were determined. Computer-generated lesions were assessed by clinicians and compared with radiological images. The key result of this study is development of a three-dimensional simulation for embolic stroke and its application to an in silico clinical trial. Probabilistic lesion overlap maps showed that the lesions from small emboli are homogeneously distributed throughout the cerebral vasculature. Mid-sized emboli were preferentially found in posterior cerebral artery (PCA) and posterior region of the middle cerebral artery (MCA) territories. For large emboli, MCA, PCA and anterior cerebral artery (ACA) lesions were comparable to clinical observations, with MCA, PCA then ACA territories identified as the most to least probable regions for lesions to occur. A power law relationship between lesion volume and embolus diameter was found. In conclusion, this article showed proof-of-concept for large in silico trials of embolic stroke including 3D information, identifying that embolus diameter could be determined from infarct volume and that embolus size is critically important to the resting place of emboli. We anticipate this work will form the basis of clinical applications including intraoperative monitoring, determining stroke origins, and in silico trials for complex situations such as multiple embolisation.

Machine Learning-Based Prediction of Subsequent Vascular Events After 6 Months in Chinese Patients with Minor Ischemic Stroke.

BackgroundTo develop and validate a machine learning model for predicting subsequent vascular events (SVE) 6 months after mild ischemic stroke (MIS) in Chinese patients.MethodsA retrospective analysis was performed on 495 newly diagnosed MIS patients by collecting their basic information, past medical history, initial NIHSS score, symptoms, obstruction sites of MIS, and MRI results. According to the ratio of 7:3, the dataset was divided into a training set (n=346) and a testing set (n=149) through stratified random sampling. In the training set, the recursive feature elimination (RFE) was used to select the optimal combination of features, and two machine learning algorithms, including the logistic regression (LR) and support vector machines (SVM), were used to build the prediction model, which was further validated by using 5-fold cross-validation. The receiver operating characteristic (ROC) curve was used on the testing set to evaluate the model’s performance, and the area under the curve (AUC), sensitivity, specificity, and accuracy were calculated. The calibration curve and decision curve of the two models were further compared.ResultsSVE occurred in 56 cases (11.3%) of 495 patients with MIS during the 6-month follow-up. Finally, the best 15 predictive features were selected, and the top three predictive features were diabetes, posterior cerebral artery lesion, and fasting blood glucose in order. In the testing set, the AUC of the LR model was 0.929 (95% CI: 0.875–0.964), and its accuracy, sensitivity, and specificity were 0.832, 0.765, and 0.841, respectively. The AUC of the SVM model was 0.992 (95% CI: 0.962–1.000), and its accuracy, sensitivity, and specificity were 0.966, 0.824, and 0.985, respectively. The SVM model’s discrimination, calibration, and clinical validity are better than those of the LR model.ConclusionThe predictive models developed using machine learning methods can predict the risk of SVE after 6 months following MIS in Chinese patients.

Specific clinical features and one-stage revascularization surgery for moyamoya disease with severe cerebral ischemia in the territory of posterior cerebral artery.

There are no reports describing the surgical procedure for moyamoya disease (MMD) patients with severe cerebral ischemia in the territory of the posterior cerebral artery (PCA) at initial presentation. In this study, therefore, we describe their clinical and radiological features and clinical results of one-stage revascularization surgery for both anterior and posterior circulation. This study included 6 MMD patients who had severe cerebral ischemia in the PCA territory and underwent one-stage revascularization surgery for both anterior and posterior circulation. Of these, one patient underwent it on both sides. Their clinical and radiological data were precisely analyzed. Compared with usual procedure, craniotomy was extended towards the temporo-parietal area more widely. The parietal branch of superficial temporal artery (STA) was anastomosed to the angular or posterior temporal artery, while the frontal branch was anastomosed to the frontal branch of MCA. Ultimate indirect bypass was added. Their clinical and radiological outcomes were evaluated. Their neurological symptoms included visual and speech disturbance as well as numbness of the extremities. Cerebral infarct was distributed in the posterior temporal, parietal, and/or occipital lobe. Cerebral hemodynamics and metabolism were also impaired in the same regions. These findings were completely different from those in MMD patients without PCA lesion. Postoperative course was uneventful, and none of them recurred stroke during a mean follow-up period of 10.5 years. Surgical collaterals widely provided blood flow to the entire hemispheres, including the occipital lobe. Cerebral hemodynamics and metabolism markedly improved after surgery. One-stage revascularization surgery for both anterior and posterior circulation is feasible and effective to prevent future stroke in MMD patients with severe cerebral ischemia in the PCA territory at initial presentation.

Posterior circulation involvement in pediatric and adult patients with moyamoya disease: a single center experience in 574 patients.

The importance of the posterior cerebral artery (PCA) involvement in moyamoya disease has been highlighted in recent years. However, few studies compared the impact of PCA lesions in moyamoya disease between pediatric and adult patients. We conducted this study to summarize the clinical features of moyamoya patients with PCA lesions and describe the difference between pediatric and adult patients. We reviewed the records of 696 consecutive moyamoya vasculopathy patients from 2009 to 2015. The Suzuki and the Miyamoto stages were used to evaluate the steno-occlusive lesions of the anterior and posterior arteries. Clinical and radiographic features were compared between those with and without PCA involvement, also between pediatric and adult patients. A total of 574 angiograms (140 pediatrics and 434 adults) were reviewed. The prevalence of PCA steno-occlusion did not differ significantly between pediatric patients and adult patients (35.0% vs. 30.4%, P=0.347). Pediatric patients had more advanced PCA stages compared to adult patients (P=0.045). There was a significant correlation of the PCA angiographic stages with the ipsilateral internal carotid artery (ICA) stages, both in pediatrics and in adults (both P<0.001). The frequency of ipsilateral cerebral infarction positively correlated with the advancement of PCA stages in adult patients (P<0.001), but not significant in pediatric patients (P=0.106). Pediatric patients tend to have more advanced PCA lesions than adult patients. The degree of PCA steno-occlusion positively correlates with the ipsilateral ICA stage, both in pediatrics and in adults.

Macular Ganglion Cell Layer and Peripapillary Retinal Nerve Fibre Layer Thickness in Patients with Unilateral Posterior Cerebral Artery Ischaemic Lesion: An Optical Coherence Tomography Study

ABSTRACTThe purpose of this study is to evaluate the macular ganglion cell layer (GCL) and peripapillary retinal nerve fibre layer (RNFL) thickness in patients with unilateral posterior cerebral artery (PCA) ischaemic lesions using spectral-domain optical coherence tomography (SD-OCT). A prospective, case-control study of patients with unilateral PCA lesion was conducted in the neuro-ophthalmology clinic of Centro Hospitalar Lisboa Central. Macular and peripapillary SD-OCT scans were performed in both eyes of each patient. Twelve patients with PCA lesions (stroke group) and 12 healthy normal controls were included in this study. Peripapillary RNFL comparison between both eyes of the same subject in the stroke group found a thinning in the superior-temporal (p = 0.008) and inferior-temporal (p = 0.023) sectors of the ipsilateral eye and nasal sector (p = 0.003) of the contralateral eye. Macular GCL thickness comparison showed a reduction temporally in the ipsilateral eye (p = 0.004) and nasally in the contralateral eye (p = 0.002). Peripapillary RNFL thickness was significantly reduced in both eyes of patients with PCA compared with controls, affecting all sectors in the contralateral eye and predominantly temporal sectors in the ipsilateral eye. A statistically significant decrease in macular GCL thickness was found in both hemiretinas of both eyes of stroke patients when compared with controls (p < 0.05). This study shows that TRD may play a role in the physiopathology of lesions of the posterior visual pathway.

Audiological profile in cases with cerebrovascular accidents

Background: Over the past decades there has been increase demand of audiological complaints coinciding with neurological impairments due to cerebrovascular accidents (CVAs). Most of the cases represent inconsistent responses to acoustic stimuli or total lack of response to sound, documented as auditory agnosia. Aim: The present investigation aims at understanding of potential anatomical co-relates to the involvement of the cortical structure and the processing of auditory stimuli. Materials and Methods: A case series with convenient sampling method included eight cases (six male and two female) with age range 45-55 years with CVA, were taken for this study. Of them two cases were found with lesion in right middle cerebral artery, four cases with left middle cerebral artery and two cases with left posterior cerebral artery lesion confirmed from magnetic resonance imaging scan. Audiological test battery including otoscopy, tuning fork test, pure tone audiometry, speech audiometry, immittance audiometry, dichotic-diotic listening test, auditory brainstem responses, otoacoustic emissions and gap detection tests were carried out including routine ENT evaluation. Results and Conclusion: Result suggests; there is a significant difference in hearing threshold and speech perception in all the eight subjects. The findings and compromised vascular anatomy in all these cases were discussed in this article.

Assessment of the difference in posterior circulation involvement between pediatric and adult patients with moyamoya disease

There is no description of the change in the posterior cerebral artery (PCA) in the diagnostic criteria of moyamoya disease (MMD). However, PCAs are often involved in the clinical setting, and an understanding of the significance of PCA lesions is therefore of great importance when evaluating the disease progression and predicting prognosis. The aim of this study was to assess the difference in posterior circulation involvement in pediatric and adult patients with MMD. The records of 120 consecutive patients with MMD were reviewed. The clinical manifestations at diagnosis were evaluated on the basis of symptoms and CT and MRI findings. The degree of steno-occlusive internal carotid artery (ICA) lesions and the existence of steno-occlusive PCA lesions were evaluated by observing a total of 240 ICAs and PCAs on angiography. Angiographic correlation between anterior and posterior circulation was assessed in pediatric and adult patients with MMD. Seventeen (26%) of 66 pediatric patients and 18 (33%) of 54 adult patients exhibited steno-occlusive PCA lesions. There was no significant difference in the prevalence of PCA lesions between pediatric and adult patients with MMD (p = 0.36). The prevalence of infarction in pediatric and adult patients with PCA involvement was significantly higher than that in pediatric and adult patients without PCA involvement (p = 0.0003 and p = 0.003, respectively). There was no significant difference in the distribution of infarction areas between pediatric and adult patients with PCA involvement (p = 0.62). On the basis of the staging system used, steno-occlusive lesions in ICAs ipsilateral to PCAs with lesions were in significantly advanced stages compared with lesions in ICAs ipsilateral to PCAs without lesions in both pediatric and adult cases (p < 0.0001 and p = 0.0008, respectively). Pediatric patients had less advanced steno-occlusive lesions in ICAs ipsilateral to PCAs with lesions compared with adults (p < 0.05). The clinical significance of posterior circulation involvement in MMD was similar between pediatric and adult patients. The only significant difference was that less advanced ICA lesions could complicate posterior circulation involvement in pediatric patients.

Clinical and radiographic features of moyamoya disease in patients with both cerebral ischaemia and haemorrhage

Objectives. Patients with moyamoya disease (MMD) very rarely develop both cerebral ischaemia and haemorrhage. The aim of this study was to clarify the clinical and radiographic features of MMD in patients who presented with both ischaemia and haemorrhage, compared with MMD patients who presented with one or the other. Materials and methods. The records of 92 consecutive patients with MMD were reviewed. These patients were divided into three groups, according to the type of presentation: ischaemic presentation (Group I); haemorrhagic presentation (Group H); and haemorrhagic-ischaemic presentation (Group H-I). The patient characteristics, areas of infarction, and angiographic findings were evaluated. Results. Seventy-six (82%) of the 92 patients were categorised as Group I, 7 (8%) as Group H, and 9 (10%) as Group H-I. Median follow-up periods for Group H-I was 55 months (IQR, 36–116 months). There were eight females in Group H-I, in which the median age was 30 years. Of the nine cases in Group H-I, six presented with cerebral haemorrhage as the precedent event and three had complications during the acute phase. In Group H-I, the prevalence of posterior cerebral artery (PCA) lesions was high (42%) and infarctions were most frequently found in PCA-related areas. Conclusions. The presence of steno-occlusive PCA lesions may be of pathogenic importance in MMD patients who develop both cerebral ischaemia and haemorrhage. The prevalence of this type of stroke in MMD patients is higher than expected, and further investigation in clinical settings is thus warranted.

Selective visual neglect in right brain damaged patients with splenial interhemispheric disconnection

Left unilateral neglect is frequently reported after right hemispheric lesions of the middle cerebral artery (MCA) damaging the parietal-frontal cortical-subcortical network subserving space representation and awareness. However, accumulating evidence shows that neglect can also follow lesions of the posterior cerebral artery (PCA) that do not directly affect this parietal-frontal network. Surgical studies in the monkeys have demonstrated that complete callosal resection combined with lesion of the right optic tract entirely deprives the right hemisphere of visual inputs from the left hemispace provoking severe left unilateral neglect. Here, through the detailed study of two patients we show, for the first time, that PCA lesions selectively affecting the splenium of the corpus callosum and the adjacent right primary visual cortex provoke severe neglect selectively restricted to the visual domain. No trace of personal, motor or representational-imagery neglect was found. Also at variance with previous case studies in which neglect followed lesion of the trunk or the genu of the corpus callosum, no restriction of neglect to tasks performed with the right hand, no left hemispatial limb akinesia, no tactile extinction for the left hand and no tactile anomia for stimuli explored with the left hand were observed. These findings demonstrate that brain lesions depriving intact parietal and frontal attentional areas from specific sensory inputs can yield spatial neglect limited to specific sensory modalities or sectors of space.

Posterior cerebral artery infarcts and semantic category dissociations: a study of 28 patients

In this study we analysed the relationship between damage in the territory of the posterior cerebral artery and semantic knowledge, with special reference to category dissociations. Twenty-eight posterior cerebral artery stroke patients (18 left, 8 right and 2 bilateral posterior cerebral artery infarctions) completed a neuropsychological battery aimed at assessing semantic knowledge. The battery included picture naming, word-picture matching, a verbal semantic questionnaire and a picture reality decision task. For each participant, the lesion was reconstructed on the basis of MRI images, and was classified according to the involvement of the areas supplied by posterior cerebral artery. Defective naming scores were observed in 12 of 18 left posterior cerebral artery cases (67%), four of eight right posterior cerebral artery cases (50%), and one of two bilateral posterior cerebral artery cases (50%). Only in the bilateral posterior cerebral artery lesion case did we observe the pattern expected in pure visual agnosia, i.e. poor picture naming, poor picture reality decision, and normal verbal semantic questionnaire. Nine left posterior cerebral artery cases and two right posterior cerebral artery cases presented with poor performance on both the picture naming task and the verbal semantic questionnaire, thus suggesting semantic impairment. For 5 of the 12 left posterior cerebral artery patients who fared poorly on the naming task, biological stimuli (overall) were significantly more impaired than artifacts. In three of these five subjects, performance on plant-life stimuli was significantly less accurate than that on animals. A further left posterior cerebral artery patient presented a disproportionate impairment on plant-life stimuli only on the word-picture matching and on the questionnaire. The patterns of performance in these subjects suggest that the observed dissociations originated at the semantic level. Among left posterior cerebral artery patients, a naming deficit only occurred when damage to the fusiform gyrus extended anterior to Talairach's y-coordinate -50, and a disproportionate impairment of biological categories only when the lesion extended anterior to y = -32.5. Results show that the semantic deficit for the category of plant life is a genuine cognitive pattern, and does not depend on loss of colour knowledge. The contrast of left posterior cerebral artery strokes and herpes simplex encephalitis cases shows that the neural substrates for the semantic representation of plant life and animals are, at least in part, distinct. Middle and posterior portions of the left fusiform are crucial for the representation of plant-life knowledge, whereas left anterior temporal areas are more crucial than left posterior and basal temporal areas for the representation of knowledge about animals.

ADDITIONAL SURGERY FOR POSTOPERATIVE ISCHEMIC SYMPTOMS IN PATIENTS WITH MOYAMOYA DISEASE

In patients with moyamoya disease, surgery to revascularize the ischemic brain is a recommended treatment. However, there are a few patients who require additional revascularization surgery because of progression of the disease. Even patients who show no postoperative ischemic symptoms at first may experience late deterioration. We performed additional surgery for such lesions using occipital artery (OA)-posterior cerebral artery (PCA) bypass with indirect revascularization. The efficacy of the procedure is reported. We treated 3 patients with moyamoya disease who showed a transient ischemic attack after revascularization surgery. Three female patients, ranging in age from 6.0 to 35.2 years (mean age, 23.8 years) at the time of surgery, with ischemic symptoms (leg monoparesis in 2, visual impairment in 1) underwent the additional revascularization procedure. Preoperatively, all patients underwent indirect and/or direct revascularization surgery for initial treatment. All patients showed progression of the disease, especially in the PCA. OA-PCA bypass with encephalogaleodurosynangiosis and burr hole surgery were performed for postoperative ischemic symptoms. All patients showed clinical and radiological improvement. The transient ischemic attack was improved in all 3 patients. They did not complain of transient ischemic attack in the recent follow-up period. Follow-up magnetic resonance imaging showed no additional cerebral infarction. Magnetic resonance angiography showed widening of the OA and development of peripheral collateral vessels. Postoperative single-photon emission computed tomographic studies showed marked increase of uptake in both anterior cerebral artery and PCA territories. Cerebral vasodilatory capacity evaluated by an acetazolamide test also showed marked improvement. One patient showed postoperative cerebral edema as a result of focal cerebral hyperperfusion. OA-PCA anastomosis with indirect revascularization was effective for postoperative ischemia that showed symptoms in the anterior cerebral artery and PCA territories as a result of progression of a PCA lesion.

Microsurgical Anatomy and Quantitative Analysis of the Transtemporal-Transchoroidal Fissure Approach to the Ambient Cistern

Surgical approaches to ambient cistern lesions are complex. We investigated the microanatomy of the transtemporal-transchoroidal fissure approach to the ambient cistern with emphasis on exposure of the posterior cerebral artery. Dissections were performed bilaterally in five silicone-injected cadaveric heads. Critical anatomic distances, specifically with reference to the P2 segment of posterior cerebral artery in relation to the inferior choroidal point and P2-P3 junction, were measured with digital calipers. Other landmarks (temporal lobe tip, points from the temporal base to the choroidal fissure) were included for quantitative analysis. The transtemporal-transchoroidal fissure approach provided adequate exposure of the ambient cistern, minimized temporal lobe retraction, and allowed assessment of regional microanatomy. The mean distance from the temporal base to the choroidal fissure measured 18.09 mm (range, 16.9-21.9 mm). The distances from the choroidal fissure to P2 varied at the coronal plane of the inferior choroidal point (mean, 6.96 mm; range, 3.6-12.0 mm) and the P2-P3 junction (mean, 6.02 mm; range, 4.3-6.9 mm), respectively. The transtemporal-transchoroidal fissure approach provides a corridor to the ambient cistern and P2-P3 junction while minimizing temporal lobe retraction and avoiding interruption of temporal lobe venous drainage. Because of widely variable vascular anatomy, access to posterior cerebral artery lesions using this approach requires preoperative imaging to identify the specific location of the P2-P3 junction.

Treatment and outcome in 30 patients with posterior cerebral artery aneurysms.

The records of 30 patients with posterior cerebral artery (PCA) aneurysms treated during a 12-year period were reviewed to determine outcome and the risk of visual field deficit associated with PCA sacrifice. Clinical data and treatment summaries for all patients were maintained in an electronic database. The Glasgow Outcome Scale (GOS) and modified Rankin Scale (mRS) scores were determined by an independent registrar. Visual field changes were determined by review of medical records. Twenty-eight patients were treated with open surgery, one of them after an attempt at detachable coil embolization failed. Two patients underwent successful endovascular PCA sacrifice. The mean GOS and mRS scores in 18 patients with unruptured aneurysms were 4 and 2, respectively, at discharge. Subarachnoid hemorrhage (SAH) from other aneurysms and neurological deficits caused by the PCA lesion or underlying disease contributed to poor outcomes in this group. The mean GOS and mRS scores in 12 patients with ruptured aneurysms were 4 and 4, respectively, at discharge. One patient died of severe vasospasm. Neurological deficits secondary to SAH and, in one patient, treatment of a concomitant arteriovenous malformation contributed to poor outcomes in the patients with ruptured aneurysms. Seven patients with normal visual function preoperatively underwent PCA occlusion. One patient (14%) developed a new visual field deficit. Optimal treatment of PCA aneurysms is performed via one of several surgical approaches or by endovascular therapy. The approach is determined, in part, by the anatomical location and size of the aneurysm and the presence of underlying disease and neurological deficits.

The Relationship between Cerebral Infarction on MR and Angiographic Findings in Moyamoya Disease: Significance of the Posterior Circulation

Purpose: To investigate the relationship between changes in the posterior and anterior circulation, as seen at angiography, and the frequency and extent of cerebral infarction revealed by MR imaging in moyamoya disease. Materials and Methods: This study involved 34 patients (22 females and 12 males, aged 2-52years) in whom cerebral angiography revealed the presence of moyamoya disease (bilateral: unilateral=24:10; total hemispheres= 58) and who also underwent brain MR imaging. To evaluate the angiographic findings, we applied each ngiographic staging system to the anterior and posterior circulation. Leptomeningeal collateral circulation from the cortical branches of the posterior cerebral artery (PCA) was also assigned one of four grades. At MR imaging, areas of cerebral cortical or subcortical infarction in the hemisphere were divided into six zones. White matter and basal ganglionic infarction, ventricular dilatation, cortical atrophy, and hemorrhagic lesions were also evaluated. To demonstrate the statistical significance of the relationship between the angiographic and the MR findings, both the Mantel-Haenszel chi-square test for trend and the chi-square test were used. Results: The degree of steno-occlusive PCA change correlated significantly with the internal carotid artery (ICA) stage (p0.05). The prevalence of infarction showed significant correlation with the degree of steno-occlusive change in both the ICA and PCA. The degree of cerebral ischemia in moyamoya patients increased proportionally with the severity of PCA stenosis rather than with that of steno-occlusive lesions of the anterior circulation. Infarctions tended to be distributed in the anterior part of the hemisphere at PCA stage I or II , while in more advanced PCA lesions, they were also found posteriorly, especially in the territories of the posterior middle cerebral artery (MCA), the posterior border zone, and the PCA (p0.05). Conclusion: The degree of steno-occlusive lesions of the PCA correlated with the ICA stage. Progressive changes in steno-occlusive lesions of the ICA and PCA are associated with the extent and distribution of cerebral infarction. The degree of cerebral ischemia in moyamoya patients increased proportionally with the severity of PCA stenosis rather than with that of steno-occlusive lesions of the anterior circulation. In these patients, the presence of stenotic or occlusive PCA lesions appears to be significantly related to the occurrence of cerebral infarction.

Natural history of stenosis from intracranial atherosclerosis by serial angiography.

Knowledge of the natural history of stenoses due to intracranial atherosclerosis may be useful for evaluating possible treatments such as angioplasty. We retrospectively reviewed records over a 7-year period to identify patients with intracranial atherosclerotic stenoses and serial angiograms. Quantitative measurements of stenoses were made in a blinded manner, and clinical outcomes were reviewed. We identified 21 patients with 45 intracranial stenoses who underwent repeat angiography at an average interval of 26.7 months. The average stenosis for all intracranial lesions was 43.9% initially and 51.8% on follow-up (P=.032). The average stenosis in the intracranial internal carotid artery (ICA) was stable (51.2% versus 52.6%). The average stenosis in the anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA) progressed from 32.4% to 49.7% (P=.037). Based on a minimum 10% change, 20% of intracranial ICA lesions progressed compared with 61% of ACA, MCA, and PCA lesions. Regression occurred in 14% of the intracranial ICA group and 28% of the ACA-MCA-PCA group. Cerebrovascular events were infrequent during this period, with 4 transient ischemic attacks and 1 intracerebral hemorrhage. Intracranial atherosclerotic stenoses are dynamic lesions demonstrating both progression and regression.

Visual imagery and knowledge about the visual appearance of objects in patients with posterior cerebral artery lesions

The purpose of this study was to explore whether patients with left posterior cerebral artery (PCA) lesions have defective mental visual imagery and to differentiate whether such a deficit stems from a loss of knowledge about the visual appearance of objects or from an inability to create mental visual images out of preserved visual knowledge. Normal controls and patients with either left or right PCA lesions were asked to verify low- and high-imagery sentences and then to verify pictorial representations of the predicates of high-imagery sentences. High-imagery questions concerned either the shape or the color of objects. In addition, perceptual discrimination of shape and color was assessed. Patients with right PCA lesions were impaired on the perceptual discrimination tasks. Left PCA patients did not significantly differ from controls on low-imagery sentences but scored significantly lower on shape and color questions. Their impairment was distinctly more severe with the pictorial than with the verbal versions of shape and color questions. In comparison to patients with occipital left PCA lesions, patients with temporo-occipital left PCA lesions were selectively impaired on verbal and visual color questions. It is concluded that patients with left PCA lesions lack knowledge about shape and color of objects, but that their ability to convert visual knowledge into mental images is preserved.

Analysis of the angiographic findings in cases of childhood moyamoya disease.

Cerebral angiograms of 34 patients with childhood moyamoya disease have been analysed, this analysis having revealed the following findings. The blood flow to abnormal net-like vessels (ANV) in the base of the brain is mainly supplied from the internal carotid artery (ICA) in the early stage of this disease. In a later stage, however, the blood supply is mainly from the posterior cerebral artery (PCA). Though, no remarkable change was found in the volumes of ANV from the early to later stages of the disease, the leptomeningeal collaterals, the most prominent anastomoses in moyamoya disease, had a tendency to decrease during the later stage with the development of PCA stenosis. Eighteen occlusive PCA lesions were found in the proximal portion of the PCA in eight cases (44%), and in the distal in nine cases (50%). The incidence of aneurysm (1.5%) and intracranial bleeding was low as compared to cases of adult moyamoya disease.