Clinical and Neuroimaging Findings in Thalamic Territory Infarctions: A Review

Type III Percheron's variant in thalamic-mesencephalic infarction: the unexpected anastomosis

PURPOSE

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.

Stroke Mimicking Symptoms and Consequences of Alcohol Intoxication: A Case Report

A 41-year-old Black male with a history of hypertension was involved in a car accident, after which he exhibited symptoms such as slow and incoherent speech, unstable gait, dizziness, drowsiness, slow thinking, and loss of strength in his limbs. Despite multiple negative alcohol tests, his symptoms mimicked those of acute alcohol intoxication. Upon presentation to the emergency room, physical examination and brain imaging revealed a right anterior thalamic ischemic infarction. He was discharged completely recovered after two days without sequelae. This case underscores the importance of considering stroke as a differential diagnosis in patients presenting with symptoms similar to alcohol intoxication, particularly in hypertensive individuals.

The effects of P2 segment of posterior cerebral artery to thalamus blood supply pattern on gait in cerebral small vessel disease: A 7 T MRI based study

Gait disturbance is a manifestation of cerebral small vessel disease (CSVD). The posterolateral thalamus (PL), whose blood is mainly supplied by the P2 segment of posterior cerebral artery (P2-PCA), plays pivotal roles in gait regulation. We investigated the influence of the distance between P2-PCA and PL on gait with varying CSVD burden. 71 participants were divided into low and high CSVD burden groups. The distance from P2-PCA to PL was measured using 7 T TOF-MRA and categorized into an immediate or distant PCA-to-thalamus pattern. Functional connectivity (FC) and voxel-based morphometry were assessed to evaluate functional and structural alterations. In the low CSVD burden group, immediate PCA-to-thalamus supply strongly correlates with longer step length and higher wave phase time percent, and exhibited enhanced FCs in left supplementary motor area, right precentral cortex (PreCG.R). While in the high CSVD burden group, no association between PCA-to-thalamus pattern and gait was found, and we observed reduced FC in PreCG.R with immediate PCA-to-thalamus pattern. Higher CSVD burden was associated with decreased gray matter density in bilateral thalamus. However, no significant structural thalamic change was observed between the two types of PCA-to-thalamus patterns in all patients. Our study demonstrated patients with immediate PCA-to-thalamus supply exhibited better gait performance in low CSVD burden populations, which also correlated with enhanced FCs in motor-related cortex, indicating the beneficial effects of the immediate PCA-to-thalamus supply pattern. In the higher burden CSVD populations, the effects of PCA-to-thalamus pattern on gait are void, attributable to the CSVD-related thalamic destruction and impairment of thalamus-related FC.

Diagnostic and prognostic implications of non-high-density lipoprotein cholesterol and homocysteine levels for cognitive impairment in thalamic infarction

BACKGROUND

Patients with thalamic infarction experience abnormal blockages of multinucleated vessels, affecting the body and thereby the thalamus. Most patients with thalamic infarction have an adverse prognosis, which seriously affects their safety. Therefore, it is essential to analyze the independent risk factors that influence the prognosis of patients with thalamic infarction and develop corresponding preventive measures.

AIM

To explore the effect of non-high-density lipoprotein cholesterol (non-HDL-C) and Homocysteine (Hcy) levels in cognitive impairment in thalamic infarction.

METHODS

From March 2019 to March 2022, 80 patients with thalamic infarction were divided into a group with cognitive impairment [Montreal Cognitive Assessment (MoCA) score < 26; 35 patients] and a group with normal cognitive function (MoCA score of 26-30; 45 patients) according to the MoCA score. In addition, 50 healthy people in the same period were selected as the control group. A correlation between the non-HDL-C and Hcy levels and the MoCA score and receiver operating characteristic curve was observed, and the serum non-HDL-C and Hcy levels were analyzed for the diagnosis of cognitive impairment in patients with thalamic infarction. According to the Modified Rankin Scale (MRS) score, 80 patients with thalamic infarction were divided into a good prognosis group (MRS score ≤ 2) and a poor prognosis group (MRS score >2).

RESULTS

The non-HDL-C and Hcy levels were significantly higher in the group with cognitive impairment than in the group with normal cognitive function (P < 0.05). There was no significant difference in the non-HDL-C level between the control group and the group with normal cognitive function (P > 0.05). The MoCA scores of the group with cognitive impairment were significantly lower than those of the group with normal cognitive function and the control group (P < 0.05). There was a significant difference between the control group and the group with normal cognitive function (P < 0.05). The non-HDL-C and Hcy levels were correlated with the MoCA score (P < 0.05), cognitive impairment [areas under the curve (AUC) = 0.709, 95% confidence interval (95%CI): 0.599-0.816], the non-HDL-C level, and could predict cognitive impairment in patients with thalamic infarction (AUC = 0.738, 95%CI: 0.618-0.859). Hcy combined with non-HDL-C levels can predict cognitive impairment in patients with thalamic infarction (AUC = 0.769, 95%CI: 0.721-0.895).There were 50 patients in the good prognosis group and 30 patients in the poor prognosis group. Compared with the good prognosis group, in the poor prognosis group, the National Institutes of Health Stroke Scale (NIHSS) score, non-HDL-C level, Hcy level, large-area cerebral infarction, atrial fibrillation, and activated partial prothrombin time were statistically significant (P < 0.05). The non-HDL-C level, the Hcy level, the NIHSS score, extensive cerebral serum, and atrial fibrillation may all be independent risk factors for poor prognosis in patients with thalamic infarction (P < 0.05).

CONCLUSION

Non-HDL-C and Hcy levels are positively correlated with cognitive impairment in patients with thalamic infarction. Non-HDL-C and Hcy levels can be used in the diagnosis of cognitive impairment in patients with thalamic infarction, and the combined detection effect is better. The main factors affecting the prognosis of patients with thalamic infarction are the non-HDL-C level, the Hcy level, the NIHSS score, large-area cerebral infarction, and atrial fibrillation. Clinically, corresponding preventive measures can be formulated based on the above factors to prevent poor prognosis and reduce mortality.

In humans, striato-pallido-thalamic projections are largely segregated by their origin in either the striosome-like or matrix-like compartments

Cortico-striato-thalamo-cortical (CSTC) loops are fundamental organizing units in mammalian brains. CSTCs process limbic, associative, and sensorimotor information in largely separated but interacting networks. CTSC loops pass through paired striatal compartments, striosome (aka patch) and matrix, segregated pools of medium spiny projection neurons with distinct embryologic origins, cortical/subcortical structural connectivity, susceptibility to injury, and roles in behaviors and diseases. Similarly, striatal dopamine modulates activity in striosome and matrix in opposite directions. Routing CSTCs through one compartment may be an anatomical basis for regulating discrete functions. We used differential structural connectivity, identified through probabilistic diffusion tractography, to distinguish the striatal compartments (striosome-like and matrix-like voxels) in living humans. We then mapped compartment-specific projections and quantified structural connectivity between each striatal compartment, the globus pallidus interna (GPi), and 20 thalamic nuclei in 221 healthy adults. We found that striosome-originating and matrix-originating streamlines were segregated within the GPi: striosome-like connectivity was significantly more rostral, ventral, and medial. Striato-pallido-thalamic streamline bundles that were seeded from striosome-like and matrix-like voxels transited spatially distinct portions of the white matter. Matrix-like streamlines were 5.7-fold more likely to reach the GPi, replicating animal tract-tracing studies. Striosome-like connectivity dominated in six thalamic nuclei (anteroventral, central lateral, laterodorsal, lateral posterior, mediodorsal-medial, and medial geniculate). Matrix-like connectivity dominated in seven thalamic nuclei (centromedian, parafascicular, pulvinar-anterior, pulvinar-lateral, ventral lateral-anterior, ventral lateral-posterior, ventral posterolateral). Though we mapped all thalamic nuclei independently, functionally-related nuclei were matched for compartment-level bias. We validated these results with prior thalamostriate tract tracing studies in non-human primates and other species; where reliable data was available, all agreed with our measures of structural connectivity. Matrix-like connectivity was lateralized (left > right hemisphere) in 18 thalamic nuclei, independent of handedness, diffusion protocol, sex, or whether the nucleus was striosome-dominated or matrix-dominated. Compartment-specific biases in striato-pallido-thalamic structural connectivity suggest that routing CSTC loops through striosome-like or matrix-like voxels is a fundamental mechanism for organizing and regulating brain networks. Our MRI-based assessments of striato-thalamic connectivity in humans match and extend the results of prior tract tracing studies in animals. Compartment-level characterization may improve localization of human neuropathologies and improve neurosurgical targeting in the GPi and thalamus.

Mapping the primate thalamus: systematic approach to analyze the distribution of subcortical neuromodulatory afferents

Neuromodulatory afferents to thalamic nuclei are key for information transmission and thus play critical roles in sensory, motor, and limbic processes. Over the course of the last decades, diverse attempts have been made to map and describe subcortical neuromodulatory afferents to the primate thalamus, including axons using acetylcholine, serotonin, dopamine, noradrenaline, adrenaline, and histamine. Our group has been actively involved in this endeavor. The published descriptions on neuromodulatory afferents to the primate thalamus have been made in different laboratories and are not fully comparable due to methodological divergences (for example, fixation procedures, planes of cutting, techniques used to detect the afferents, different criteria for identification of thalamic nuclei…). Such variation affects the results obtained. Therefore, systematic methodological and analytical approaches are much needed. The present article proposes reproducible methodological and terminological frameworks for primate thalamic mapping. We suggest the use of standard stereotaxic planes to produce and present maps of the primate thalamus, as well as the use of the Anglo-American school terminology (vs. the German school terminology) for identification of thalamic nuclei. Finally, a public repository of the data collected under agreed-on frameworks would be a useful tool for looking up and comparing data on the structure and connections of primate thalamic nuclei. Important and agreed-on efforts are required to create, manage, and fund a unified and homogeneous resource of data on the primate thalamus. Likewise, a firm commitment of the institutions to preserve experimental brain material is much needed because neuroscience work with non-human primates is becoming increasingly rare, making earlier material still more valuable.

Alterations of optic tract and retinal structure in patients after thalamic stroke

Objectives

To investigate the association between degeneration of retinal structure and shrinkage of the optic tract in patients after thalamic stroke.

Materials and methods

Patients with unilateral thalamic stroke were included. Structural magnetic resonance imaging (MRI) and optical coherence tomography (OCT) were performed to obtain parameters of optic tract shrinkage (lateral index) and retina structural thickness (retinal nerve fiber layer, RNFL; peripapillary retinal nerve fiber layer, pRNFL; ganglion cell-inner plexiform layer, GCIP), respectively. Visual acuity (VA) examination under illumination was conducted using Snellen charts and then converted to the logarithm of the minimum angle of resolution (LogMAR). We investigated the association between LI and OCT parameters and their relationships with VA.

Results

A total of 33 patients and 23 age-sex matched stroke-free healthy controls were enrolled. Patients with thalamic stroke showed altered LI compared with control participants (P = 0.011) and a significantly increased value of LI in the subgroup of disease duration more than 6 months (P = 0.004). In these patients, LI were significantly associated with pRNFL thickness (β = 0.349, 95% confidence interval [CI]: 0.134–0.564, P = 0.002) after adjusting for confounders (age, sex, hypertension, diabetes, dyslipidemia, and lesion volume). LI and pRNFL were both significantly associated with VA in all patients (LI: β = −0.275, 95% CI: −0.539 to −0.011, P = 0.041; pRNFL: β = −0.023, 95% CI: −0.046 to −0.001, P = 0.040) and in subgroup of disease duration more than 6 months (LI: β = −0.290, 95% CI: −0.469 to −0.111, P = 0.002; pRNFL: β = −0.041, 95% CI: −0.065 to −0.017, P = 0.003).

Conclusion

Shrinkage of the optic tract can be detected in patients with thalamic stroke, especially after 6 months of stroke onset. In these patients, the extent of optic tract atrophy is associated with pRNFL thickness, and they are both related to visual acuity changes.

The Amnestic Syndrome of Posterior Cerebral Artery Infarction

OBJECTIVE

Little is known about the character and underlying lesions of ischemic amnesia. We therefore studied episodic memory functions and brain lesions in 84 patients with acute ischemic infarcts in the supply territory of the posterior cerebral artery (PCA). We also aimed to learn how the neural memory systems are organized.

METHODS

Standard neuropsychological tests were used to assess verbal and figural memory. Patients were split in memory-impaired and memory-intact. Lesions were demarcated, normalized and anatomically labeled, using standard mapping procedures.

RESULTS

Of the 84 patients more than 80% had an amnestic syndrome, mostly with combined, less often with figural or verbal memory impairment. Amnesia in subjects with left hemispheric lesions was more frequent and more severe, with significantly lower scores on the verbal memory test. Normal performance or figural amnesia were prevalent after right hemispheric lesions. However, no amnesia subtype was strictly tied to left- or right-sided brain damage. Hippocampal and thalamic lesions were common, but 30% of lesions were extrahippocampal located in the ventral occipito-temporal cortex and long occipital white matter tracts. Most amnestic-patients lacked awareness for their memory impairment.

CONCLUSIONS

Memory impairment is a key clinical manifestation of acute PCA stroke. Amnesia is more frequent and more severe after left stroke, suggesting a left hemisphere dominance of the two memory systems. Domain specific memory appears not strictly lateralized, since deficits in verbal and figural memory were found after lesions of both sides. Extrahippocampal lesions may also cause memory impairment.

Acute percheron infarction: a precision learning

Background

So far, the diagnosis of acute artery of percheron (AOP) infarction is uncommon. In this study, patients with acute AOP infarction were studied to explore the relationship of imaging findings, clinical manifestations and prognosis of acute AOP infarction.

Materials

A total of 23 patients with acute AOP infarction in our institution from 2014 to 2019 were reviewed retrospectively. All cases were evaluated by computed tomography (CT) and magnetic resonance imaging (MRI). The modified Rankin scale (MRS), blood examination, electrocardiogram and transthoracic echocardiography were used for detailed clinical and prognostic evaluation. All standard risk factors for these patients were recorded. The MRS scores were performed 90 days after discharge.

Results

Four different types of acute AOP infarction were identified: (a) bilateral paramedian thalamic infarction (BPTI, 52%); (b) bilateral paramedian thalamic with rostral midbrain infarction (BPTRMI, 30%), (c) bilateral paramedian and anterior thalamic infarction (BPATI, 13%), and (d) bilateral paramedian thalamic with red nuclei infarction (BPTRNI, 4%). These patients had consciousness disorder, memory dysfunctions, vertical gaze paresis and mesencephalothalamic syndrome. The 65% of patients with BPTI and BPATI experienced relatively good functional recovery and could carry out daily life activities (MRS score ≤ 2). However, patients with BPTRMI may have an unfavorable outcome.

Conclusions

Although the clinical features are variable, DWI or ADC map can improve the diagnosis of acute AOP infarction patterns. Acute AOP occlusion requires immediate diagnosis and treatment to obtain more favorable outcome and avoid additional unnecessary procedures.

White matter volume loss drives cortical reshaping after thalamic infarcts

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White matter volume loss after unilateral thalamic infarcts shows the trajectories of sensory and ocular motor input from the brainstem to the thalamus and their thalamocortical connections.

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The extensive volume loss drives reshaping of the cortex more than grey matter atrophy. Associated ocular motor and vestibular symptoms are compensated over time due to their redundant and intermingled connectivity and an early integration with other sensory modalities.

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Associated ocular motor and vestibular symptoms are compensated over time due to their redundant and intermingled connectivity and an early integration with other sensory modalities.

Objective

The integration of somatosensory, ocular motor and vestibular signals is necessary for self-location in space and goal-directed action. We aimed to detect remote changes in the cerebral cortex after thalamic infarcts to reveal the thalamo-cortical connections necessary for multisensory processing and ocular motor control.

Methods

Thirteen patients with unilateral ischemic thalamic infarcts presenting with vestibular, somatosensory, and ocular motor symptoms were examined longitudinally in the acute phase and after six months. Voxel- and surface-based morphometry were used to detect changes in vestibular and multisensory cortical areas and known hubs of central ocular motor processing. The results were compared with functional connectivity data in 50 healthy volunteers.

Results

Patients with paramedian infarcts showed impaired saccades and vestibular perception, i.e., tilts of the subjective visual vertical (SVV). The most common complaint in these patients was double vision or vertigo / dizziness. Posterolateral thalamic infarcts led to tilts of the SVV and somatosensory deficits without vertigo. Tilts of the SVV were higher in paramedian compared to posterolateral infarcts (median 11.2° vs 3.8°). Vestibular and ocular motor symptoms recovered within six months. Somatosensory deficits persisted. Structural longitudinal imaging showed significant volume reduction in subcortical structures connected to the infarcted thalamic nuclei (vestibular nuclei region, dentate nucleus region, trigeminal root entry zone, medial lemniscus, superior colliculi). Volume loss was evident in connections to the frontal, parietal and cingulate lobes. Changes were larger in the ipsilesional hemisphere but were also detected in homotopical regions contralesionally. The white matter volume reduction led to deformation of the cortical projection zones of the infarcted nuclei.

Conclusions

White matter volume loss after thalamic infarcts reflects sensory input from the brainstem as well the cortical projections of the main affected nuclei for sensory and ocular motor processing. Changes in the cortical geometry seem not to reflect gray matter atrophy but rather reshaping of the cortical surface due to the underlying white matter atrophy.

Surgical Approach to Thalamic Tumors

Thalamic tumors are deep-seated lesions. Recent improvements in therapeutic approaches and surgical techniques have allowed a more accurate approach to these lesions and a reduction in morbidity and mortality. In this article, the various surgical approaches for the resection of thalamic tumors are described. Each of these approaches has its own indications and risk of complications. Resection of thalamic tumors needs specific anatomical knowledge, especially the vascular anatomy of the region and the thalamic peduncles.

Evaluation of neuroimaging findings in thalamic lesions: what can we think?

The diseases that affect the thalamus are heterogeneous in their etiologies, including infectious, inflammatory, vascular, toxic-metabolic, and neoplastic causes. It is often difficult to make the clinical differentiation between different entities. Within this context, computed tomography and magnetic resonance imaging have come to be of fundamental importance for defining the etiology and planning the treatment. In this pictorial essay, we will illustrate the main causes of diseases affecting the thalamus, discussing the possible differential diagnoses, as well as the most relevant imaging aspects.

Pure Thalamic Infarct: 8-Year Follow-Up Study in a Hospital in China

Pure thalamic infarct is a rare lacunar stroke type, with little known about long-term outcomes. This 8-year, single-center, retrospective study evaluated the clinical background, etiology, Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification, and 8-year follow-up results in 27 patients with pure thalamic infarcts identified by MR diffusion-weighted imaging in Dalian, China. All patients presented chief complaints of limb weakness or sensory disturbances. Hypertension (24/27, 88.9%), diabetes (12/27, 44.4%), atrial fibrillation (1/27, 3.7%), hyperlipidemia (10/27, 37%), hyperhomocysteinemia (6/27, 22.2%), smoking history (10/27, 37%; 9/15, 60% for men; 1/12, 8.3% for women), and excessive alcohol consumption history (7/27, 25.9%; 7/15, 46.7% for men; 0 for women) were observed in our patient population. Based on TOAST classification, 1 patient had large artery atherosclerosis (7.14%), 23 had small vessel occlusion (SVO; 85.2%), and 3 patients were unidentified due to lack of cerebral angiography. The thalamic blood supply classification were as follows: 23 (85.2%), inferolateral territory; 1 (3.7%), tuberothalamic territory; 2 (7.4%), combination of tuberothalamic and paramedian arteries; 1 (3.7%), combination of inferolateral and paramedian arteries; 0, posterior choroidal arteries. During the 8-year follow-up, 3 patients died of colon cancer, multi-organ failure, and kidney failure, respectively; 7 presented with a recurrent stroke; while 10 recovered well with their risk factors under control. In conclusion, our cohort of pure thalamic infarcts were mainly due to SVO (TOAST), with hypertension as the main risk factor, and the inferolateral artery as the most implicated arterial territory. Less severe outcome or stroke recurrence are identified in long-term follow-up of pure thalamic infarcts. Other comorbidities would be cause of death in aged patients.

Isolated thalamic stroke - analysis of clinical characteristics and asymmetry of lesion distribution in a retrospective cohort study

Background

More patients with left-hemispheric than right-hemispheric strokes are admitted to hospitals. This is due to the easier recognition of cortical symptoms of the dominant-hemisphere. The thalamus constitutes a “micro-model” of the brain cortex with structure-function relationships known to be asymmetric, especially for language, memory, and visuo-spatial neurocognitive functions. The goal of this study was to characterize clinical symptoms and lesion distribution patterns of patients with acute isolated thalamic stroke (ITS) and to evaluate whether left-sided lesions are overrepresented in the hospital.

Methods

We performed a radiological database search including all brain scans performed in the Center of Neurology and Neurosurgery of the University Hospital Frankfurt between 2010 and 2019. A total of 5733 patients presenting with acute ischemic stroke were screened for ITS. Based on the MRI data, a lesion-overlap map was then generated to visualize the ITS lesion distribution.

Results

Fifty-eight patients with unilateral ITS were identified. A majority of 38 patients (65.5%) showed left-sided ITS, whereas only 20 patients (34.5%) had right-sided ITS (p = 0.012). A particular difference was found for ITS lesions in the anterior thalamus of the anterolateral (n = 10) and anteromedian (n = 3) vascular territory, which were located in the left thalamus in 85% of patients (p = 0.011). No distribution difference was found for ITS lesions in the inferomedial (n = 7), central (n = 8), inferolateral (n = 23) and posterior (n = 7) vascular territories. The neuropsychological symptoms of thalamic aphasia (n = 8), neurocognitive impairment (n = 6), behavioral changes (n = 2), neglect (n = 2) and memory deficits (n = 3) were described predominantly in patients with left-sided ITS (p < 0.01). In contrast, other stroke symptoms (e.g., sensorimotor hemi-syndromes) did not reveal a side preponderance.

Conclusions

The better recognizability of left anterior compared to right anterior thalamic stroke symptoms may have an impact on the frequency in which ITS patients are admitted to the hospital. Clinical characteristics of right anterior thalamic stroke should therefore be further investigated, and diagnostic instruments towards their detection be identified.

Lesion topography of posterior cerebral artery infarcts

This study analyzed the topography of acute ischemic stroke in the posterior cerebral artery (PCA) territory. We studied 84 patients with unilateral ischemic PCA stroke. Patients were classified according to lesion levels as cortico-subcortical (superficial), combined (cortical and mesodiencephalic) or isolated thalamic. To receive a lesion map, data from acute MR and CT imaging were normalized and labelled automatically by mapping to stereotaxic anatomical atlases. Cortical lesions accounted for 41.7%, combined for 36.9%, and isolated thalamic lesions for 21.4%. The maximum overlay of ischemia and, thus, highest occurrence of PCA ischemic stroke was found in the ventral and medial occipito-temporal cortex and adjacent white matter association tracts. Dorsal and peripheral segments of the occipito-temporo-parietal region were only rarely lesioned. This configuration was similar in both hemispheres. Consistent with this lesion pattern, visual field defects (VFD) were the most frequent signs, followed by sensorimotor signs, dizziness and sopor, cognitive and oculomotor deficits, and ataxia. The three vascular subgroups differed not only by their anatomical lesion profile and lesion load, but also by their clinical manifestation; although patients with combined and thalamic lesions were sigificantly younger, they were more disabled than participants with cortical lesions. VFD were only found in cortical and combined, and oculomotor deficits only in mesodiencephalic lesions. White matter lesions were common in the cortico-subcortical and the combined group. Basal occipito-temporal and calcarine regions, and neighbouring white matter tracts have the highest risk of ischemia in acute PCA stroke.

Topographic evaluation of bithalamic infarcts: Are these due to occlusion of the artery of Percheron?

Occlusion of the artery of Percheron (AoP) causes bithalamic paramedian infarct (BTPI). Although it can be diagnosed easily in its pure form, it can be underdiagnosed in cases with concomitant extrathalamic acute infarcts (plus-BTPI) as it may be difficult to determine whether BTPI is due to occlusion of AoP or two different paramedian arteries even with conventional angiography. This study was performed to highlight plus-BTPI that could result from occlusion of AoP rather than of two distinct paramedian arteries using topographic evaluation of bithalamic infarcts. We retrospectively reviewed imaging and clinical databases for patients admitted to radiology department between 2013 and 2019. Two radiologists independently evaluated the results of imaging studies, and findings reached by consensus were used in the analysis. This retrospective review yielded 34 patients with bithalamic infarct. Each affected thalamic vascular region was investigated separately. Any patient could have more than 2 different vascular zone infarct. The affected thalamic vascular territories were paramedian (n = 24), inferolateral (n = 13), anterior (n = 10), and posterior (n = 7). When we evaluated bithalamic infarcts in terms of symmetrically affected territories, the distribution of symmetric affected territories was as: paramedian (n = 18), inferolateral (n = 2), anterior (n = 1), and posterior (n = 1). BTPI had a 4.5-fold higher frequency than the sum of symmetric involvement of other territories (p = 0.0552, OR = 4.5,95%CI 0.93-21.5). In addition, mesencephalic involvement was only observed in BTPI, and not in other patterns (p < 0.001). The fact that in bilateral thalamic infarcts the symmetric involvement of paramedic territory is significantly higher and mesencephalic involvement is seen only in BTPI can suggest that plus-BPTI may develop due to AoP occlusion rather than occlusion of two distinct paramedian arteries.

Altered Thalamocortical Connectivity in 6-Week-Old Infants at High Familial Risk for Autism Spectrum Disorder

Converging evidence from neuroimaging studies has revealed altered connectivity in cortical-subcortical networks in youth and adults with autism spectrum disorder (ASD). Comparatively little is known about the development of cortical-subcortical connectivity in infancy, before the emergence of overt ASD symptomatology. Here, we examined early functional and structural connectivity of thalamocortical networks in infants at high familial risk for ASD (HR) and low-risk controls (LR). Resting-state functional connectivity and diffusion tensor imaging data were acquired in 52 6-week-old infants. Functional connectivity was examined between 6 cortical seeds-prefrontal, motor, somatosensory, temporal, parietal, and occipital regions-and bilateral thalamus. We found significant thalamic-prefrontal underconnectivity, as well as thalamic-occipital and thalamic-motor overconnectivity in HR infants, relative to LR infants. Subsequent structural connectivity analyses also revealed atypical white matter integrity in thalamic-occipital tracts in HR infants, compared with LR infants. Notably, aberrant connectivity indices at 6 weeks predicted atypical social development between 9 and 36 months of age, as assessed with eye-tracking and diagnostic measures. These findings indicate that thalamocortical connectivity is disrupted at both the functional and structural level in HR infants as early as 6 weeks of age, providing a possible early marker of risk for ASD.

Alteration of Resting-state Functional Connectivity in the Sensorimotor Network in Patients with Thalamic Infarction

PURPOSE

To explore changes in functional connectivity (FC) within the sensorimotor network (SMN) and the relationship between the SMN and bilateral thalamus in patients with thalamic infarction (TI) using resting state functional magnetic resonance imaging (rs-fMRI). Also determined was whether those measures are useful for monitoring the functional recovery of somatosensory deficits.

METHODS

The study included 31 patients with TI presenting somatosensory dysfunction and 31 controls who underwent clinical assessments and MRI scanning at 6 months after a stroke. An independent component analysis was used to identify the SMN. The mean time courses of SMN activity were extracted for each subject, and FC with the bilateral thalamus was assessed. Differences in connectivity strength were compared between groups. Finally, we correlated the altered FC values with clinical data from patients with TI.

RESULTS

Compared to controls, patients with TI showed decreases in FC within SMN in the ipsilesional posterior central gyrus (PCG) (Z-score = -4.581, cluster size = 171), but presented increased FC within the SMN in the ipsilesional supplementary motor area (SMA) (Z-score = 4.648, cluster size = 46). The FC values of the ipsilesional SMA correlated with the somatosensory function score of patients with TI (r = 0.426, P = 0.027). Increased FC was observed between the SMN and bilateral thalamus in patients with TI. The region exhibiting increased FC was adjacent to the lesion in the affected thalamus, while the area with increased FC overlapped the location of the lesion when the lesion was mirrored onto the unaffected thalamus.

CONCLUSION

The increased FC in the ipsilesional SMA and between the SMN and perilesional thalamus might reflect functional reorganization in patients with TI presenting somatosensory deficits.

Four patients with infarction in key areas of the Papez circuit, with anterograde amnesia as the main manifestation

The Papez circuit is an important brain structure that is closely associated with learning and memory. In this report, we present four patients with anterograde amnesia as the main manifestation induced by Papez circuit infarction. In addition, we review the distribution of the responsible arteries in key and rare regions to investigate the pathogenesis of these infarctions.

Bilateral thalamic stroke after tonsillectomy in a patient with collateral extracranial anastomosis - case report

Haemorrhage remains the most frequent and serious complication of tonsillectomy. When bleeding is recurrent, gushing, and ceases spontaneously, pseudoaneurysm of the injured artery in the proximity of the tonsillar bed should be suspected. Haemorrhage related to pseudoaneurysm occurs most commonly in the first 30 days after surgery. It can sometimes be excessive and requires a revision procedure such as external carotid artery (ECA) ligation or embolisation. During those procedures, ECA should be checked for possible anastomoses, otherwise the bleeding may persist despite the intervention. We report an unusual case of a patient with recurrent post-tonsillectomy haemorrhage due to pseudoaneurysm of the facial artery, which persisted after ECA ligation because of the presence of collateral occipital-vertebral anastomosis. Due to the recurrence of bleeding episodes, endovascular treatment was implemented. However, the embolisation was complicated by bilateral thalamic stroke with unclear mechanism. This case highlights the importance of anastomosis between ECA and the vertebrobasilar system, both in recurrence of significant post-tonsillectomy bleeding and in potential thromboembolic complications. Therefore, ECA ligation should always be accompanied by exclusion of possible anastomoses. In cases of non-life-threatening bleeding, embolisation seems to be the proper and more selective therapy.