Lateral Thalamic Infarction and the Vascular Geometry of the Posterior Cerebral Artery.

BACKGROUND: The geometric properties of the parental artery affect the development of local atherosclerosis and perforator infarction. In this study, we aimed at investigating the association between vascular geometry of the posterior cerebral artery (PCA) and the development of isolated lateral thalamic infarction (LTI), the most frequent type of thalamic infarction. METHODS: The geometric properties of the corresponding PCA in LTI patients were assessed and they include the diameters of the distal basilar artery (BA) and proximal PCA, distal BA - PCA angle, first PCA angle (angle between P1 and P2), and the presence of the posterior communicating artery (Pcom). These parameters obtained from the ipsilesional PCA were compared with the contralesional PCA and the corresponding PCA in age- and sex-matched controls. RESULTS: Forty-five LTI patients were enrolled. The ipsilesional PCA in LTI patients demonstrated a greater ipsilesional P1 - P2 angle (81.4 ± 22.6 vs. 71.3 ± 23.2°, respectively; p = 0.04) and a higher prevalence of Pcom (42.2 vs. 13.3%; p = 0.002) when compared to control subjects. In comparison with the contralesional PCA, ipsilesional PCA demonstrated a smaller diameter, larger angle between P1 and P2 segment, and a higher prevalence of Pcom. The presence of hyperlipidemia (OR 3.548 (1.283-9.811); p = 0.02) and Pcom (OR 3.507 (1.104-11.135); p = 0.03) was a factor that was independently associated with LTI. CONCLUSIONS: Local hemodynamics in the PCA may be influenced by the P1 - P2 angle and the presence of Pcom, which are associated with the development of LTI.

Characteristics of dynamic cerebral autoregulation in cerebral small vessel disease: Diffuse and sustained.

Cerebral small vessel disease is a major cause of stroke and vascular dementia; however, the pathogenesis is largely unclear. In this study, we investigated the characteristics of the impairment of dynamic cerebral autoregulation (dCA) in lacunar infarction patients. Seventy-one lacunar infarction patients were enrolled in the study, including 46 unilateral middle cerebral artery (MCA) territory stroke patients and 25 unilateral posterior cerebral artery (PCA) territory stroke patients. Each group of patients was randomly divided into two subgroups. Group 1 underwent dCA assessments in the bilateral MCAs, and Group 2 underwent dCA assessments in the bilateral PCAs. All patients were followed up for 6 months. Transfer function analysis was applied to derive the autoregulatory parameters of gain and phase difference. In the unilateral MCA territory stroke patients, impairments of dCA were observed in both the MCAs and PCAs, and the same results were observed in the unilateral PCA territory stroke patients. These impairments remained unchanged during the 6-month follow-up. In lacunar infarction, which is most prevalent type of cerebral small vessel disease, though patients with unilateral MCA territory/PCA territory stroke, the impairments of dCA were global and sustained. This finding suggests that the physiological changes associated with lacunar infarction were diffuse.

[Posterior cerebral artery infarctions with possible interaction between hypoperfusion and embolism]. / Infarctus cérébraux multiples : éléments en faveur de la coexistence de mécanismes emboliques et hémodynamiques dans le territoire postérieur.

Although embolism and hypoperfusion may well occur concurrently in a non-negligible proportion of cerebral infarction patients, there is currently lack of proof, especially in the posterior circulation. Here, we are reporting on a case of multiple cerebral infarctions in a patient with neurofibromatosis type 1, multiple vascular abnormalities of the posterior cerebral circulation and intracranial artery occlusion. We hypothesize that cerebral blood flow impairment may have affected the clearance and destination of embolic particles.

Progression of stenosis into occlusion of the distal posterior cerebral artery supplying an occipital arteriovenous malformation manifesting as multiple ischemic attacks: case report.

A 31-year-old healthy male presented with a rare case of cerebral arteriovenous malformation (AVM) manifesting as repeated ischemic attacks and cerebral infarction causing left sensori-motor disturbance. Neuroimaging revealed cerebral infarction in the right thalamus as well as right occipital AVM without bleeding. The AVM was mainly fed by the right angular artery, and the right posterior cerebral artery (PCA) showed mild stenosis and segmental dilation at the P(2)-P(3) portion. After referral to our hospital, transient ischemic attacks causing left homonymous hemianopsia, and left arm and leg numbness were frequently recognized. Additional imaging revealed a new ischemic lesion in the occipital lobe, and repeated cerebral angiography showed right PCA occlusion at the P(2)-P(3) segment. Cerebral AVM presenting with cerebral infarction due to occlusion of feeding arteries is rare. In our case, intimal injury due to increased blood flow or spontaneous dissection of the artery were possible causes. We should monitor any changes in the architecture and rheology of the feeding vessels during the clinical course to prevent ischemic complications.

Bilateral paramedian thalamic infarction with hypothalamic dysfunction.

Unilateral thalamic lesions cause transient or permanent behavioral, sensory and oculomotor disturbances; bilateral lesions of thalamus result in more severe and longer lasting symptoms. We present an atypical case of bilateral paramedian thalamic infarct with concomitant hypothalamic dysfunction. The only risk factor of ischaemic stroke found in the patient was a short lasting episode of atrial fibrillation. Bilateral paramedian thalamic infarcts may result from occlusion of one paramedian thalamic artery, which arises from the posterior cerebral artery, either with separated or with a common trunk, thus supplying the thalamus bilaterally. Independently of anatomical variants of thalamus blood supply, the most probable cause of infarct in our patient was unilateral or bilateral occlusion of the posterior cerebral artery by cardioembolism, probably in the course of basilar artery occlusion. Hypothalamic dysfunction may accompany thalamic infarcts; thus hypothalamo-pituitary function should be routinely assessed in bithalamic infarcts.

Topographic patterns of thalamic infarcts in association with stroke syndromes and aetiologies.

OBJECTIVE: To characterise the topographic patterns of thalamic infarcts associated with various stroke syndromes and aetiologies. METHODS: In this study, 168 consecutive patients with acute infarcts involving the thalamus were investigated by use of diffusion weighted MR imaging. Involved thalamic territories were classified into four vascular territories: anterior (polar artery), posteromedial (thalamoperforating artery), ventrolateral (thalamogeniculate artery) and posterolateral (posterior choroidal artery) territory. The distribution of thalamic infarcts involving specific vascular territories in association with various stroke syndromes and aetiologies were analysed. RESULTS: There was a significant association between involvement of the ventrolateral thalamus and isolated thalamic infarcts (49 patients (73%), p<0.01) or posterior cerebral artery infarcts (29 patients (76%), p=0.02), and between involvement of the posteromedial thalamus and top of the basilar artery syndrome (17 patients (77%), p<0.001) or extended posterior circulation infarcts (29 patients (71%), p<0.001). The ventrolateral territory was most commonly affected in association with small vessel disease (43 patients (72%), p=0.03) and the posteromedial territory in association with large artery disease (19 patients (63%), p<0.01). In cardioembolic stroke, the ventrolateral, posteromedial and posterolateral territories were equally affected. CONCLUSIONS: The results of the present study indicate a specific association between the topographic patterns of thalamic infarcts and the stroke syndromes and aetiologies.

Alien hand syndrome in left posterior stroke.

Alien hand syndrome is a rare neurological disorder characterized by involuntary and uncontrollable motor behaviour, usually of an arm or hand. The patient perceives the affected limb as alien, and may personify it. The case of a 61-year-old right-handed woman who developed right posterior AHS after ischaemic stroke in the left posterior cerebral artery territory is reported. Neuroimaging studies disclosed no frontal or parietal involvement, while a posterior thalamic lesion was detected. A possible role of the thalamus in the genesis of AHS is discussed.

Bilateral occipital infarcts associated with carotid atherosclerosis and a persistent hypoglossal artery.

The persistent hypoglossal artery (PHA) is the second most common persistent embryological carotid-basilar connection and usually represents an incidental finding in cerebral arteriograms. The hypoglossal artery connects the primordial carotid artery with the longitudinal neural arteries, which later form the basilar artery. The PHA leaves the internal carotid artery as an extracranial branch, enters the skull through the anterior condyloid foramen, the hypoglossal canal and joins the caudal portion of the basilar artery. We report magnetic resonance and digital subtraction angiography findings in the first case of bilateral occipital infarctions associated with PHA and carotid atherosclerosis. The probable mechanism underlying bilateral occipital infarcts was embolism from the carotid territory to the posterior cerebral arteries. PHA may present a challenge in diagnosis and management of patients with carotid atherosclerosis and vertebrobasilar ischemia.

[A case of alien hand syndrome after right posterior cerebral artery territory infarction].

We report a 63-year-old right-handed man who presented an alien hand syndrome (AHS). He complained of clumsiness of his left hand and admitted to our hospital. On the first examination, he presented left homonymous hemianopia, left spatial neglect and left limb ataxia, but neither paralysis nor sensory impairment. A few days after, he complained that his left hand was controlled by someone else, and we considered this phenomenon as AHS. At that time, he lost sensation of almost all modalities including deep sensation on his left upper and lower limb. Magnetic resonance image examination was performed, and it showed acute cerebral infarction at right posterior cerebral artery territory including right thalamus (ventral posterior lateral nucleus). Generally, AHS is caused by left mediofrontal and callosal lesion (frontal type AHS), or by callosal with bilateral frontal or without frontal lesion (callosal type AHS). However, some cases were reported that they presented AHS after damage of the basal ganglia, right thalamus, right occipital or inferior parietal lobe. Some authors described this phenomenon as "sensory" or "posterior" type AHS. In such cases, included our case, we speculate that sensory impairment causes AHS. Especially in our case, AHS might be caused by not only the sensory impairment but also by left homonymous hemianopia and left spatial neglect. So, because of these symptoms, our patient could not recognize the motion of the left hand, and presented AHS. We think that this "sensory" or "posterior" type AHS should be distinguished from frontal and callosal type AHS.

Posterior cerebral artery occlusion associated with Mycoplasma pneumoniae infection.

Cerebral infarction is a rare complication of Mycoplasma pneumoniae infection. In all cases previously reported in the literature, vascular occlusion occurred in the anterior brain circulation, either the internal carotid or the middle cerebral artery. We report a case of a child with posterior cerebral artery occlusion and resultant hemiparesis associated with M. pneumoniae infection.