Parieto-occipital Regions Research Articles

Rapidly growing diffuse neurofibroma of the scalp with calvarial defect in a young woman: A rare entity

Background: A diffuse neurofibroma, a variant of neurofibroma, most commonly occurs in young adults and involves the head and neck. In the absence of neurofibromatosis, associated calvarial defect with these swellings is rarely seen.Case Description: An 18-year-old woman presented with a history of rapidly progressive painless large swelling over the bilateral parieto-occipital region of scalp. It was soft and boggy with brownish discoloration of overlying skin. Imaging study showed brilliantly enhancing diffuse lesion involving the bilateral parieto-occipital region of scalp and extending into the extradural region. She underwent excision of lesion. Postoperatively, she developed flap necrosis and it was allowed to heal with the secondary intention. The biopsy findings were consistent with neurofibroma. The patient is on regular follow-up, without any evidence of recurrence at 1 year.Conclusion: Rapidly growing solitary diffuse neurofibroma is rare in children and adolescents. Preoperative diagnosis may be difficult and surgical treatment needs to be individualized. These patients need regular follow-up for early detection of recurrence.

Frequency-specific task modulation of human brain functional networks: A fast fMRI study

How coherent neural oscillations are involved in task execution is a fundamental question in neuroscience. Although several electrophysiological studies have tackled this issue, the brain-wide task modulation of neural coherence remains uncharacterized. Here, with a fast fMRI technique, we studied shifts of brain-wide neural coherence across different task states in the ultraslow frequency range (0.01–0.7 Hz). First, we examined whether the shifts of the brain-wide neural coherence occur in a frequency-dependent manner. We quantified the shift of a region's average neural coherence by the inter-state variance of the mean coherence between the region and the rest of the brain. A clustering analysis based on the variance's spatial correlation between frequency components revealed four frequency bands (0.01–0.15 Hz, 0.15–0.37 Hz, 0.37–0.53 Hz, and 0.53–0.7 Hz) showing band-specific shifts of the brain-wide neural coherence. Next, we investigated the similarity of the inter-state variance's spectra between all pairs of regions. We found that regions showing similar spectra correspond to those forming functional modules of the brain network. Then, we investigated the relationship between identified frequency bands and modules’ inter-state variances. We found that modules showing the highest variance are those made up of parieto-occipital regions at 0.01–0.15 Hz, while it is replaced with another consisting of frontal regions above 0.15 Hz. Furthermore, these modules showed specific shifting patterns of the mean coherence across states at 0.01–0.15 Hz and above 0.15 Hz, suggesting that identified frequency bands differentially contribute to neural interactions during task execution. Our results highlight that usage of the fast fMRI enables brain-wide investigation of neural coherence up to 0.7 Hz, which opens a promising track for assessment of the large-scale neural interactions in the ultraslow frequency range.

Transient Amplitude Modulation of Alpha-Band Oscillations by Short-Time Intermittent Closed-Loop tACS.

Non-invasive brain stimulation (NIBS) techniques such as transcranial alternating current stimulation (tACS) have recently become extensively utilized due to their potential to modulate ongoing neuronal oscillatory activity and consequently to induce cortical plasticity relevant for various cognitive functions. However, the neurophysiological basis for stimulation effects as well as their inter-individual differences is not yet understood. In the present study, we used a closed-loop electroencephalography-tACS(EEG-tACS) protocol to examine the modulation of alpha oscillations generated in occipito-parietal areas. In particular, we investigated the effects of a repeated short-time intermittent stimulation protocol (1 s in every trial) applied over the visual cortex (Cz and Oz) and adjusted according to the phase and frequency of visual alpha oscillations on the amplitude of these oscillations. Based on previous findings, we expected higher increases in alpha amplitudes for tACS applied in-phase with ongoing oscillations as compared to an application in anti-phase and this modulation to be present in low-alpha amplitude states of the visual system (eyes opened, EO) but not high (eyes closed, EC). Contrary to our expectations, we found a transient suppression of alpha power in inter-individually derived spatially specific parieto-occipital components obtained via the estimation of spatial filters by using the common spatial patterns approach. The amplitude modulation was independent of the phase relationship between the tACS signal and alpha oscillations, and the state of the visual system manipulated via closed- and open-eye conditions. It was also absent in conventionally analyzed single-channel and multi-channel data from an average parieto-occipital region. The fact that the tACS modulation of oscillations was phase-independent suggests that mechanisms driving the effects of tACS may not be explained by entrainment alone, but rather require neuroplastic changes or transient disruption of neural oscillations. Our study also supports the notion that the response to tACS is subject-specific, where the modulatory effects are shaped by the interplay between the stimulation and different alpha generators. This favors stimulation protocols as well as analysis regimes exploiting inter-individual differences, such as spatial filters to reveal otherwise hidden stimulation effects and, thereby, comprehensively induce and study the effects and underlying mechanisms of tACS.

Alpha oscillations do not implement gain control in early visual cortex but rather gating in parieto-occipital regions.

Spatial attention provides a mechanism for, respectively, enhancing relevant and suppressing irrelevant information. While it is well established that attention modulates oscillations in the alpha band, it remains unclear if alpha oscillations are involved in directly modulating the neuronal excitability associated with the allocation of spatial attention. In this study, in humans, we utilized a novel broadband frequency (60–70 Hz) tagging paradigm to quantify neuronal excitability in relation to alpha oscillations in a spatial attention paradigm. We used magnetoencephalography to characterize ongoing brain activity as it allows for localizing the sources of both the alpha and frequency tagging responses. We found that attentional modulation of alpha power and the frequency tagging response are uncorrelated over trials. Importantly, the neuronal sources of the tagging response were localized in early visual cortex (V1) whereas the sources of the alpha activity were identified around parieto‐occipital sulcus. Moreover, we found that attention did not modulate the latency of the frequency tagged responses. Our findings point to alpha band oscillations serving a downstream gating role rather than implementing gain control of excitability in early visual regions.

Neurophysiological indicators of internal attention: An electroencephalography–eye‐tracking coregistration study

IntroductionMany goal‐directed and spontaneous everyday activities (e.g., planning, mind wandering) rely on an internal focus of attention. Internally directed cognition (IDC) was shown to differ from externally directed cognition in a range of neurophysiological indicators such as electroencephalogram (EEG) alpha activity and eye behavior.MethodsIn this EEG–eye‐tracking coregistration study, we investigated effects of attention direction on EEG alpha activity and various relevant eye parameters. We used an established paradigm to manipulate internal attention demands in the visual domain within tasks by means of conditional stimulus masking.ResultsConsistent with previous research, IDC involved relatively higher EEG alpha activity (lower alpha desynchronization) at posterior cortical sites. Moreover, IDC was characterized by greater pupil diameter (PD), fewer microsaccades, fixations, and saccades. These findings show that internal versus external cognition is associated with robust differences in several indicators at the neural and perceptual level. In a second line of analysis, we explored the intrinsic temporal covariation between EEG alpha activity and eye parameters during rest. This analysis revealed a positive correlation of EEG alpha power with PD especially in bilateral parieto‐occipital regions.ConclusionTogether, these findings suggest that EEG alpha activity and PD represent time‐sensitive indicators of internal attention demands, which may be involved in a neurophysiological gating mechanism serving to shield internal cognition from irrelevant sensory information.

Decoding Analysis of Alpha Oscillation Networks on Maintaining Driver Alertness.

The countermeasure of driver fatigue is valuable for reducing the risk of accidents caused by vigilance failure during prolonged driving. Listening to the radio (RADIO) has been proven to be a relatively effective “in-car” countermeasure. However, the connectivity analysis, which can be used to investigate its alerting effect, is subject to the issue of signal mixing. In this study, we propose a novel framework based on clustering and entropy to improve the performance of the connectivity analysis to reveal the effect of RADIO to maintain driver alertness. Regardless of reducing signal mixing, we introduce clustering algorithm to classify the functional connections with their nodes into different categories to mine the effective information of the alerting effect. Differential entropy (DE) is employed to measure the information content in different brain regions after clustering. Compared with the Louvain-based community detection method, the proposed method shows more superior ability to present RADIO effectin confused functional connection matrices. Our experimental results reveal that the active connection clusters distinguished by the proposed method gradually move from frontal region to parieto-occipital regionwith the progress of fatigue, consistent with the alpha energy changes in these two brain areas. The active class of the clusters in parieto-occipital region significantly decreases and the most active clusters remain in the frontal region when RADIO is taken. The estimation results of DE confirm the significant change (p < 0.05) of information content due to the cluster movements. Hence, preventing the movement of the active clusters from frontal region to parieto-occipital region may correlate with maintaining driver alertness. The revelation of alerting effect is helpful for the targeted upgrade of fatigue countermeasures.

Dissociation between Temporal and Spatial Anticipation in the Neural Dynamics of Goal-directed Movement Preparation.

It is well documented that providing advanced information regarding the spatial location of a target stimulus (i.e., spatial anticipation) or its timing of occurrence (i.e., temporal anticipation) influences reach preparation, reducing RTs. Yet, it remains unknown whether the RT gains attributable to temporal and spatial anticipation are subtended by similar preparatory dynamics. Here, this issue is addressed in humans by investigating EEG beta-band activity during reach preparation. Participants performed a reach RT task in which they initiated a movement as fast as possible toward visual targets following their appearance. Temporal anticipation was manipulated by having the target appear after a constant or variable delay period, whereas spatial anticipation was manipulated by precueing participants about the upcoming target location in advance or not. Results revealed that temporal and spatial anticipation both reduced reach RTs, with no interaction. Interestingly, temporal and spatial anticipation were associated with fundamentally different patterns of beta-band modulations. Temporal anticipation was associated with beta-band desynchronization over contralateral sensorimotor regions specifically around the expected moment of target onset, the magnitude of which was correlated with RT modulations across participants. In contrast, spatial anticipation did not influence sensorimotor activity but rather led to increased beta-band power over bilateral parieto-occipital regions during the entire delay period. These results argue for distinct states of preparation incurred by temporal and spatial anticipation. In particular, sensorimotor beta-band desynchronization may reflect the timely disinhibition of movement-related neuronal ensembles at the expected time of movement initiation, without reflecting its spatial parameters per se.

Thalamic pulvinar metabolism, sleep disturbances, and hallucinations in dementia with Lewy bodies: Positron emission tomography and actigraphy study.

Although sleep disturbances are prevalent among patients with dementia with Lewy bodies (DLB), their neural substrates remain unclear. We aimed to clarify the neural substrates of sleep disturbances in patients with DLB. We evaluated sleep disturbances, neuropsychiatric symptoms, and brain glucose metabolism in 22 patients with probable DLB using actigraphy, the Neuropsychiatric Inventory (NPI), and 18 F-fluorodeoxyglucose (FDG) positron emission tomography, respectively. Total sleep time (TST) and average activity count per minute (AAC) during sleep were calculated for seven consecutive days via actigraphy. We investigated associations between FDG uptake and the actigraphy parameters using Statistical Parametric Mapping version 12b. Spearman's rank correlation coefficients were used to investigate associations among TST, AAC, and clinical symptoms. The level of statistical significance was set at P < .05. P values were adjusted using the Benjamini-Hochberg method for multiple comparisons. This study was registered with ClinicalTrials.gov (NCT00776347). TST exhibited a significant positive association with FDG uptake in the bilateral orbitofrontal cortex and left thalamus, while AAC exhibited a significant negative association with FDG uptake in the left thalamus and the left parieto-occipital region. FDG uptake in the left pulvinar was associated with both TST and AAC. In addition, TST exhibited a significant negative association with the NPI hallucinations score (r = -0.66, P = .001), while AAC exhibited significant positive associations with the NPI delusions (r = 0.70, P < .001) and hallucinations (r = 0.63, P = .002) scores. TST and bodily activity during sleep are associated with dysfunction of the left pulvinar and the severity of hallucinations in patients with DLB.

A new species of Neosclerocalyptus Paula Couto, 1957 (Xenarthra, Glyptodontidae, Hoplophorinae) from the middle Pleistocene of the Pampean region, Argentina

A new species of the genus Neosclerocalyptus Paula Couto, 1957 (= Sclerocalyptus Ameghino, 1891), N. gouldi n. sp.(Cingulata, Glyptodontidae, Hoplophorini) is described. Th is new taxon, comes from the Bonaerian Stage (middle Pleistocene; c. 0.4-0.13 Ma) of San Andres de Giles, Buenos Aires province, Argentina. Th e type consists mainly of an associated skull, mandible and cephalic shield in an excellent state of preservation. Morphological characters that distinguish the species include: a) lesser pneumatization and lateral expansion of fronto-nasal sinuses compared to N. paskoensis; b) descending processes of maxillaries and zygomatic arches very robust and with marked ridges; c) lower third of descending processes markedly inclined toward the sagittal plane; d) inclination of the parieto-occipital skull region intermediate between those of Ensenadan and Lujanian forms; e) infraorbital fora mina larger than in N. paskoensis, similar in size to those of N. ornatus; and f) occipital area less expanded laterally than in N. paskoensis. Th is new taxon completes the chronological distribution of genus Neosclerocalyptus which, until now, included two well-characterized species for the Ensenadan (early Pleistocene: N. pseudornatus and N. ornatus) and one Lujanian (late Pleistocene-early Holocene: N. paskoensis). The Bonaerian species, N. migoyanus, recognized by Ameghino, should be considered as a nomen dubium, due to the lack of diagnostic characters.

Dream Recall upon Awakening from Non-Rapid Eye Movement Sleep in Older Adults: Electrophysiological Pattern and Qualitative Features

Several findings support the activation hypothesis, positing that cortical arousal promotes dream recall (DR). However, most studies have been carried out on young participants, while the electrophysiological (EEG) correlates of DR in older people are still mostly unknown. We aimed to test the activation hypothesis on 20 elders, focusing on the Non-Rapid Eye Movement (NREM) sleep stage. All the subjects underwent polysomnography, and a dream report was collected upon their awakening from NREM sleep. Nine subjects were recallers (RECs) and 11 were non-RECs (NRECs). The delta and beta EEG activity of the last 5 min and the total NREM sleep was calculated by Fast Fourier Transform. Statistical comparisons (RECs vs. NRECs) revealed no differences in the last 5 min of sleep. Significant differences were found in the total NREM sleep: the RECs showed lower delta power over the parietal areas than the NRECs. Consistently, statistical comparisons on the activation index (delta/beta power) revealed that RECs showed a higher level of arousal in the fronto-temporal and parieto-occipital regions than NRECs. Both visual vividness and dream length are positively related to the level of activation. Overall, our results are consistent with the view that dreaming and the storage of oneiric contents depend on the level of arousal during sleep, highlighting a crucial role of the temporo-parietal-occipital zone.

The Neurocognitive Correlates of Human Reasoning: A Meta-analysis of Conditional and Syllogistic Inferences.

Inferring knowledge is a core aspect of human cognition. We can form complex sentences connecting different pieces of information, such as in conditional statements like "if someone drinks alcohol, then they must be older than 18." These are relevant for causal reasoning about our environment and allow us to think about hypothetical scenarios. Another central aspect to forming complex statements is to quantify about sets, such as in "some apples are green." Reasoning in terms of the ability to form these statements is not yet fully understood, despite being an active field of interdisciplinary research. On a theoretical level, several conceptual frameworks have been proposed, predicting diverging brain activation patterns during the reasoning process. We present a meta-analysis comprising the results of 32 neuroimaging experiments about reasoning, which we subdivided by their structure, content, and requirement for world knowledge. In conditional tasks, we identified activation in the left middle and rostrolateral pFC and parietal regions, whereas syllogistic tasks elicit activation in Broca's complex, including the BG. Concerning the content differentiation, abstract tasks exhibit activation in the left inferior and rostrolateral pFC and inferior parietal regions, whereas content tasks are in the left superior pFC and parieto-occipital regions. The findings clarify the neurocognitive mechanisms of reasoning and exhibit clear distinctions between the task's type and content. Overall, we found that the activation differences clarify inconsistent results from accumulated data and serve as useful scaffolding differentiations for theory-driven interpretations of the neuroscientific correlates of human reasoning.

Simultaneous acute Marchiafava-Bignami disease and posterior reversible encephalopathy syndrome: a case almost misdiagnosed.

Marchiafava-Bignami disease (MBD) is a rare neurological disease, and is characterized by callosal lesions consisting of necrosis and demyelination. Posterior reversible encephalopathy syndrome (PRES) is a clinical syndrome, and refers to a disorder with reversible subcortical vasogenic brain edema, predominantly involving the bilateral parieto-occipital regions. Never before had articles reported that the two diseases occurred simultaneously. We report a 49-year-old male alcoholic with both MBD and PRES who had a good prognosis after correct diagnosis and timely treatment.

Predicting unconsciousness after propofol administration: qCON, BIS, and ALPHA band frequency power.

During anesthesia induction with propofol the level of arousal progressively decreases until reaching loss of consciousness (LOC). In addition, there is a shift of alpha activity from parieto-occipital to frontal zones, defined as anteriorization. Whilst monitoring LOC and anteriorization would be useful to improve propofol dosage and patient safety, the current devices for anesthetic depthmonitoring are unable to detect these events. The aim of this study was to observe LOC and anteriorization during anesthesia induction with propofol by applying electrodes placed in the frontal and parietal areas. Bispectral index (BIS) and quantium consciousness index (qCON) monitors were simultaneously employed. BIS™ and qCON sensors were placed in the frontal and parieto-occipital regions of 10 alopecic patients who underwent anesthesia with propofol, alfentanil, and remifentanil. The initial biophase target of propofol was 2.5 mcg/mL which was gradually increased until reaching LOC. Wilcoxon signed-rank test was used to study differences in alpha power and qCON/BIS indices along the study; and Pk value to evaluate predictive capability of anteriorization of BIS, qCON, and alpha waves. Parietal BIS and qCON values became significantly higher than frontal values 15min after loss of eye reflex. Anteriorization was observed with both monitors. Pk values for BIS and qCON were strongly predictive of frontal alpha absolute power. During anesthesia induction with propofol it is possible to identify anteriorization with BIS and qCON in the frontal and parieto-occipital regions. Both indices showed different patterns which need to be further studied.

Squamous Cell Carcinoma of Scalp: Our Experience in a Single Tertiary Care Centre.

Cutaneous cancer is a rare entity accounting for less than 1% of all diagnosed cancers in India. In contrast to the West, squamous cell carcinoma is the commonest skin cancer in India, often affecting the scalp. However, due to their rarity, not much is known regarding their biological behavior and prognosis. The present study is a retrospective cohort study undertaken in a tertiary cancer centre on 19 consecutive cases of squamous cell carcinoma of the scalp over a period of 5years. Patients with non-sqamous histology and those associated with xeroderma pigmentosum were excluded. Nineteen patients were evaluated with a mean age of 52.7years. Majority presented with a swelling (11 patients; 57.9%) in the parieto-occipital region (13 patients; 68.4%). All patients underwent wide excision with or without excision of underlying bone or dura, depending on involvement. Only 4 (21%) required major reconstruction. On histopathology, 8 (42.1%) were poorly differentiated, while 3 (15.8%) had presence of perineural invasion (PNI). The mean duration of follow-up was 38.14months. Three of the 4 (75%) and 2 of 3 (66.67%) patients with poorly differentiated histology and PNI respectively developed recurrence, while only 1 of the 6 (16.67%) with close or positive base margin developed recurrence. Hence, to conclude, poorly differentiated histology and PNI are poor prognostic indicators, while in the event the mucoperiosteum is clinically uninvolved, the underlying bone may be preserved in select cases, even if the base margin is close.

Higher hypnotic suggestibility is associated with the lower EEG signal variability in theta, alpha, and beta frequency bands.

Variation of information in the firing rate of neural population, as reflected in different frequency bands of electroencephalographic (EEG) time series, provides direct evidence for change in neural responses of the brain to hypnotic suggestibility. However, realization of an effective biomarker for spiking behaviour of neural population proves to be an elusive subject matter with its impact evident in highly contrasting results in the literature. In this article, we took an information-theoretic stance on analysis of the EEG time series of the brain activity during hypnotic suggestions, thereby capturing the variability in pattern of brain neural activity in terms of its information content. For this purpose, we utilized differential entropy (DE, i.e., the average information content in a continuous time series) of theta, alpha, and beta frequency bands of fourteen-channel EEG time series recordings that pertain to the brain neural responses of twelve carefully selected high and low hypnotically suggestible individuals. Our results show that the higher hypnotic suggestibility is associated with a significantly lower variability in information content of theta, alpha, and beta frequencies. Moreover, they indicate that such a lower variability is accompanied by a significantly higher functional connectivity (FC, a measure of spatiotemporal synchronization) in the parietal and the parieto-occipital regions in the case of theta and alpha frequency bands and a non-significantly lower FC in the central region's beta frequency band. Our results contribute to the field in two ways. First, they identify the applicability of DE as a unifying measure to reproduce the similar observations that are separately reported through adaptation of different hypnotic biomarkers in the literature. Second, they extend these previous findings that were based on neutral hypnosis (i.e., a hypnotic procedure that involves no specific suggestions other than those for becoming hypnotized) to the case of hypnotic suggestions, thereby identifying their presence as a potential signature of hypnotic experience.

Brain Tuberculoma as a Differential Diagnosis of Single Intracranial Lesion: Case Report

AbstractTuberculosis (TB) of the central nervous system (CNS) is considered one of the most severe forms of presentation of the disease. Although only 1% of TB cases involve the CNS, these cases represent around between 5 and 15% of extrapulmonary forms.1 2 Tuberculous meningitis (TBM) is the most frequent form of CNS TB. The granulomas formed in the cerebral tuberculoma may cause hydrocephalus and other symptoms indicative of a CNS mass lesion. In the absence of active TB or TBM, the symptoms may be interpreted as indicative of tumors.3 4 The prognosis is directly related to the early diagnosis and proper treatment installation.5 We report the case of a patient with intracranial hypertension syndrome, expansive mass in the parieto-occipital region, accompanied by a lesion in the rib, initially thought to be a metastatic lesion, although posteriorly diagnosed as a cerebral tuberculoma.

Left Parietal Craniotomy for Resection of Grade IV Arteriovenous Malformation: 2-Dimensional Operative Video.

Parieto-occipital arteriovenous malformations (AVMs) are the second most common site for cranial AVMs. These lesions are defined as eloquent when the nidus involves either the postcentral gyrus or the occipital pole. If located on the dominant hemisphere, these lesions can also involve the arcuate fasciculus ventrally. This patient had a large unruptured Spetzler-Martin grade IV AVM within the parieto-occipital region extending deeply to the ventricle, following presentation with a seizure. The digital subtraction angiography demonstrated feeding vessels from both the middle cerebral artery and posterior cerebral artery distributions. Despite the high Spetzler-Martin grade, the lesion demonstrated favorable features such as a compact nidus, convexity presence, and lack of involvement of the precentral and postcentral gyrus. Preoperative embolization was utilized. The AVM was successfully resected both superficially and deeply to the level of the atrium of the lateral ventricle. Postoperative angiography demonstrated complete removal of the AVM, and the patient made a complete recovery from the procedure. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Clinical, ocular motor, and imaging profile of Niemann-Pick type C heterozygosity.

To characterize subclinical abnormalities in asymptomatic heterozygote NPC1 mutation carriers as markers of neurodegeneration. Motor function, cognition, mood, sleep, and smell function were assessed in 20 first-degree heterozygous relatives of patients with Niemann-Pick disease type C (NPC) (13 male, age 52.7 ± 9.9 years). Video-oculography and abdominal ultrasound with volumetry were performed to assess oculomotor function and size of liver and spleen. NPC biomarkers in blood were analyzed. 18F-fluorodesoxyglucose PET was performed (n = 16) to detect patterns of brain hypometabolism. NPC heterozygotes recapitulated characteristic features of symptomatic NPC disease and demonstrated the oculomotor abnormalities typical of NPC. Hepatosplenomegaly (71%) and increased cholestantriol (33%) and plasma chitotriosidase (17%) levels were present. The patients also showed signs seen in other neurodegenerative diseases, including hyposmia (20%) or pathologic screening for REM sleep behavior disorder (24%). Cognitive function was frequently impaired, especially affecting visuoconstructive function, verbal fluency, and executive function. PET imaging revealed significantly decreased glucose metabolic rates in 50% of participants, affecting cerebellar, anterior cingulate, parieto-occipital, and temporal regions, including 1 with bilateral abnormalities. NPC heterozygosity, which has a carrier frequency of 1:200 in the general population, is associated with abnormal brain metabolism and functional consequences. Clinically silent heterozygous gene variations in NPC1 may be a risk factor for late-onset neurodegeneration, similar to the concept of heterozygous GBA mutations underlying Parkinson disease.

White Matter Hyperintensities and Cognitive Impairment in Healthy and Pathological Aging: A Quantified Brain MRI Study

Background: Brain changes involving the white matter (WM), often an indication of cerebrovascular pathology, are frequently seen in patients with mild cognitive impairment (MCI) and Alzheimer disease (AD). Few studies have examined possible cognitive domain- or group-specific cognitive effects of WM pathology in old age, MCI, and AD. Objective: Our purpose was to examine the relationship between WM hyperintensities (WMH), a typical marker for WM pathology, and cognitive functioning in healthy old age and pathological aging using quantified MRI data. Methods: We utilized multidomain neuropsychological data and quantified MRI data from a sample of 42 cognitively healthy older adults and 44 patients with MCI/AD (total n = 86). Results: After controlling for age and education, WMH in the temporal and parieto-occipital lobes was associated with impairments in processing speed and parieto-occipital pathology with verbal memory impairment in the whole sample. Additionally, temporal WMH was associated with impaired processing speed in the patient group specifically. Conclusions: WM pathology is strongly associated with impaired processing speed, and our results indicate that these impairments arise from WMH in the temporal and parieto-occipital regions. In MCI and AD patients with temporal WMH, processing speed impairments are especially prominent. The results of this study increase our knowledge of cognitive repercussions stemming from temporal and/or parieto-occipital WM pathology in healthy and pathological aging.

Brain Atrophy and the Risk of Futile Endovascular Reperfusion in Acute Ischemic Stroke

Background and Purpose- We aimed to evaluate the impact of brain atrophy on long-term clinical outcome in patients with acute ischemic stroke treated with endovascular therapy, and more specifically, to test whether there are interactions between the degree of atrophy and infarct volume, and between atrophy and age, in determining the risk of futile reperfusion. Methods- We studied consecutive patients with acute ischemic stroke with proximal anterior circulation intracranial arterial occlusions treated with endovascular therapy achieving successful arterial recanalization. Brain atrophy was evaluated on baseline computed tomography with the global cortical atrophy scale, and Evans index was calculated to assess subcortical atrophy. Infarct volume was assessed on control computed tomography at 24 hours using the formula for irregular volumes (A×B×C/2). Main outcome variable was futile recanalization, defined by functional dependence (modified Rankin Scale score >2) at 3 months. The predefined interactions of atrophy with age and infarct volume were studied in regression models. Results- From 361 consecutive patients with anterior circulation acute ischemic stroke treated with endovascular therapy, 295 met all inclusion criteria. Futile reperfusion was observed in 144 out of 295 (48.8%) patients. Cortical atrophy affecting parieto-occipital and temporal regions was associated with futile recanalization. Total global cortical atrophy score and Evans index were independently associated with futile recanalization in an adjusted logistic regression. Multivariable adjusted regression models disclosed significant interactions between global cortical atrophy score and infarct volume (odds ratio, 1.003 [95%CI, 1.002-1.004], P<0.001) and between global cortical atrophy score and age (odds ratio, 1.001 [95% CI, 1.001-1.002], P<0.001) in determining the risk of futile reperfusion. Conclusions- A higher degree of cortical and subcortical brain atrophy is associated with futile endovascular reperfusion in anterior circulation acute ischemic stroke. The impact of brain atrophy on insufficient clinical recovery after endovascular reperfusion appears to be independently amplified by age and by infarct volume.