Structure-function coupling in macroscale human brain networks.

Precisely how the anatomical structure of the brain gives rise to a repertoire of complex functions remains incompletely understood. A promising manifestation of this mapping from structure to function is the dependency of the functional activity of a brain region on the underlying white matter architecture. Here, we review the literature examining the macroscale coupling between structural and functional connectivity, and we establish how this structure-function coupling (SFC) can provide more information about the underlying workings of the brain than either feature alone. We begin by defining SFC and describing the computational methods used to quantify it. We then review empirical studies that examine the heterogeneous expression of SFC across different brain regions, among individuals, in the context of the cognitive task being performed, and over time, as well as its role in fostering flexible cognition. Last, we investigate how the coupling between structure and function is affected in neurological and psychiatric conditions, and we report how aberrant SFC is associated with disease duration and disease-specific cognitive impairment. By elucidating how the dynamic relationship between the structure and function of the brain is altered in the presence of neurological and psychiatric conditions, we aim to not only further our understanding of their aetiology but also establish SFC as a new and sensitive marker of disease symptomatology and cognitive performance. Overall, this Review collates the current knowledge regarding the regional interdependency between the macroscale structure and function of the human brain in both neurotypical and neuroatypical individuals.

QSIPrep: an integrative platform for preprocessing and reconstructing diffusion MRI data.

Diffusion-weighted magnetic resonance imaging (dMRI) is the primary method for noninvasively studying the organization of white matter in the human brain. Here we introduce QSIPrep, an integrative software platform for the processing of diffusion images that is compatible with nearly all dMRI sampling schemes. Drawing on a diverse set of software suites to capitalize on their complementary strengths, QSIPrep facilitates the implementation of best practices for processing of diffusion images.

The expanding horizons of network neuroscience: From description to prediction and control.

The field of network neuroscience has emerged as a natural framework for the study of the brain and has been increasingly applied across divergent problems in neuroscience. From a disciplinary perspective, network neuroscience originally emerged as a formal integration of graph theory (from mathematics) and neuroscience (from biology). This early integration afforded marked utility in describing the interconnected nature of neural units, both structurally and functionally, and underscored the relevance of that interconnection for cognition and behavior. But since its inception, the field has not remained static in its methodological composition. Instead, it has grown to use increasingly advanced graph-theoretic tools and to bring in several other disciplinary perspectives-including machine learning and systems engineering-that have proven complementary. In doing so, the problem space amenable to the discipline has expanded markedly. In this review, we discuss three distinct flavors of investigation in state-of-the-art network neuroscience: (i) descriptive network neuroscience, (ii) predictive network neuroscience, and (iii) a perturbative network neuroscience that draws on recent advances in network control theory. In considering each area, we provide a brief summary of the approaches, discuss the nature of the insights obtained, and highlight future directions.

[Ischemic stroke in coronavirus disease 2019]. / Ischämische Hirninfarkte bei Coronavirus-19-Erkrankung.

This article reports two cases of patients with coronavirus disease 2019 (COVID-19) in which occlusion of large cerebral arteries occurred. These occurred in a female patient in the early stage of COVID-19 and in the second case in the late stage. One female patient could be successfully treated with i.v. thrombolysis and mechanical thrombectomy. Coagulopathy in the course of COVID-19 can result in severe stroke with poor outcome even in younger patients. With respect to the etiology of arterial occlusions (COVID-19-induced hypercoagulopathy, cardiomyopathy, vasculitis) there is a necessity for further research.

Cerebral Cortical Microinfarcts on Magnetic Resonance Imaging and Their Association With Cognition in Cerebral Amyloid Angiopathy.

Background and Purpose- We aimed to explore the association between presence of cerebral cortical microinfarcts (CMIs) on magnetic resonance imaging and other small-vessel disease neuroimaging biomarkers in cerebral amyloid angiopathy (CAA) and to analyze the role of CMIs on individual cognitive domains and dementia conversion. Methods- Participants were recruited from an ongoing longitudinal research cohort of eligible CAA patients between March 2006 and October 2016. A total of 102 cases were included in the analysis that assessed the relationship of cortical CMIs to CAA neuroimaging markers. Ninety-five subjects had neuropsychological tests conducted within 1 month of magnetic resonance imaging scanning. Seventy-five nondemented CAA patients had cognitive evaluation data available during follow-up. Results- Among 102 patients enrolled, 40 patients had CMIs (39%) on magnetic resonance imaging. CMIs were uniformly distributed throughout the cortex without regional predilection ( P=0.971). The presence of CMIs was associated with lower total brain volume (odds ratio, 0.85; 95% CI, 0.74-0.98; P=0.025) and presence of cortical superficial siderosis (odds ratio, 2.66; 95% CI, 1.10-6.39; P=0.029). In 95 subjects with neuropsychological tests, presence of CMIs was associated with impaired executive function (ß, -0.23; 95% CI, -0.44 to -0.02; P=0.036) and processing speed (ß, -0.24; 95% CI, -0.45 to -0.04; P=0.020). Patients with CMIs had a higher cumulative dementia incidence compared with patients without CMIs ( P=0.043), whereas only baseline total brain volume (hazard ratio, 0.76; 95% CI, 0.62-0.92; P=0.006) independently predicted dementia conversion. Conclusions- Magnetic resonance imaging-detected CMIs in CAA correlated with greater overall disease burden. The presence of CMIs was associated with worse cognitive performance, whereas only total brain atrophy independently predicted dementia conversion.

Distribution of Lacunar Infarcts in Asians With Intracerebral Hemorrhage: A Magnetic Resonance Imaging and Amyloid Positron Emission Tomography Study.

BACKGROUND AND PURPOSE: We evaluated whether lacunes in centrum semiovale (lobar lacunes) were associated with cerebral amyloid angiopathy (CAA) markers in an Asian intracerebral hemorrhage (ICH) population. METHODS: One hundred ten patients with primary ICH were classified as CAA-ICH (n=24; mean age, 70.9±13.9) or hypertensive ICH (n=86; mean age, 59.3±13.0) according to the presence of strictly lobar (per modified Boston criteria) or strictly deep bleeds (both ICH and cerebral microbleeds), respectively. Lacunes were evaluated in the supratentorial area and classified as lobar or classical deep based on the location. A subgroup of 36 patients also underwent Pittsburgh Compound B positron emission tomography to measure cerebral amyloid deposition and global standardized uptake value ratio were calculated. RESULTS: Lobar lacunes were more frequent in CAA-ICH than hypertensive ICH (29.2 versus 11.6%; P=0.036). In multivariable models, lobar lacunes were associated with lobar cerebral microbleed (odds ratio, 6.8; 95% confidence interval, 1.6-29.9; P=0.011) after adjustment for age, sex, hypertension, and white matter hyperintensity. In 15 CAA-ICH and 21 hypertensive ICH patients with Pittsburgh Compound B positron emission tomography, correlation analyses between lobar lacune counts and global standardized uptake value ratio showed positive association (ρ=0.40; P=0.02) and remained significant after adjustment for age (r=0.34; P=0.04). CONCLUSIONS: Our findings expand on recent work showing that lobar lacunes are more frequent in CAA-ICH than hypertensive ICH. Their independent association with lobar cerebral microbleeds and brain amyloid deposition suggests a relationship with CAA even in an Asian cohort with overall higher hypertensive load.

Acute convexity subarachnoid haemorrhage and cortical superficial siderosis in probable cerebral amyloid angiopathy without lobar haemorrhage.

INTRODUCTION: Acute non-traumatic convexity subarachnoid haemorrhage (cSAH) is increasingly recognised in cerebral amyloid angiopathy (CAA). We investigated: (a) the overlap between acute cSAH and cortical superficial siderosis-a new CAA haemorrhagic imaging signature and (b) whether acute cSAH presents with particular clinical symptoms in patients with probable CAA without lobar intracerebral haemorrhage. METHODS: MRI scans of 130 consecutive patients meeting modified Boston criteria for probable CAA were analysed for cortical superficial siderosis (focal, ≤3 sulci; disseminated, ≥4 sulci), and key small vessel disease markers. We compared clinical, imaging and cortical superficial siderosis topographical mapping data between subjects with versus without acute cSAH, using multivariable logistic regression. RESULTS: We included 33 patients with probable CAA presenting with acute cSAH and 97 without cSAH at presentation. Patients with acute cSAH were more commonly presenting with transient focal neurological episodes (76% vs 34%; p<0.0001) compared with patients with CAA without cSAH. Patients with acute cSAH were also more often clinically presenting with transient focal neurological episodes compared with cortical superficial siderosis-positive, but cSAH-negative subjects with CAA (76% vs 30%; p<0.0001). Cortical superficial siderosis prevalence (but no other CAA severity markers) was higher among patients with cSAH versus those without, especially disseminated cortical superficial siderosis (49% vs 19%; p<0.0001). In multivariable logistic regression, cortical superficial siderosis burden (OR 5.53; 95% CI 2.82 to 10.8, p<0.0001) and transient focal neurological episodes (OR 11.7; 95% CI 2.70 to 50.6, p=0.001) were independently associated with acute cSAH. CONCLUSIONS: This probable CAA cohort provides additional evidence for distinct disease phenotypes, determined by the presence of cSAH and cortical superficial siderosis.

Relationship between white matter connectivity loss and cortical thinning in cerebral amyloid angiopathy.

Patients with cerebral amyloid angiopathy (CAA) show loss of white matter connectivity and cortical thinning on MRI, primarily in posterior brain regions. Here we examined whether a potential causal relationship exists between these markers of subcortical and cortical brain injury by examining whether changes in cortical thickness progress in tandem with changes in their underlying connections. Thirty-one patients with probable CAA with brain MRI at two time points were included (follow-up time: 1.3 ± 0.4 years). Brain networks were reconstructed using diffusion MRI-based fiber tractography. Of each network node, we calculated the change in fractional anisotropy-weighted connectivity strength over time and the change in cortical thickness. The association between change in connectivity strength and cortical thickness was assessed with (hierarchical) linear regression models. Our results showed that decline in posterior network connectivity over time was strongly related to thinning of the occipital cortex (ß = 0.65 (0.35-0.94), P < 0.001), but not to thinning of the other posterior or frontal cortices. However, at the level of individual network nodes, we found no association between connectivity strength and cortical thinning of the corresponding node (ß = 0.009 ± 0.04, P = 0.80). Associations were independent of age, sex, and other brain MRI markers of CAA. To conclude, CAA patients with greater progressive loss of posterior white matter connectivity also have greater progression of occipital cortical thinning, but our results do not support a direct causal relationship between them. The association can be better explained by a shared underlying mechanism, which may form a potential target for future treatments. Hum Brain Mapp 38:3723-3731, 2017. © 2017 Wiley Periodicals, Inc.

Progression of Brain Network Alterations in Cerebral Amyloid Angiopathy.

BACKGROUND AND PURPOSE: We recently showed that cerebral amyloid angiopathy (CAA) is associated with functionally relevant brain network impairments, in particular affecting posterior white matter connections. Here we examined how these brain network impairments progress over time. METHODS: Thirty-three patients with probable CAA underwent multimodal brain magnetic resonance imaging at 2 time points (mean follow-up time: 1.3±0.4 years). Brain networks of the hemisphere free of intracerebral hemorrhages were reconstructed using fiber tractography and graph theory. The global efficiency of the network and mean fractional anisotropies of posterior-posterior, frontal-frontal, and posterior-frontal network connections were calculated. Patients with moderate versus severe CAA were defined based on microbleed count, dichotomized at the median (median=35). RESULTS: Global efficiency of the intracerebral hemorrhage-free hemispheric network declined from baseline to follow-up (-0.008±0.003; P=0.029). The decline in global efficiency was most pronounced for patients with severe CAA (group×time interaction P=0.03). The decline in global network efficiency was associated with worse executive functioning (ß=0.46; P=0.03). Examination of subgroups of network connections revealed a decline in fractional anisotropies of posterior-posterior connections at both levels of CAA severity (-0.006±0.002; P=0.017; group×time interaction P=0.16). The fractional anisotropies of posterior-frontal and frontal-frontal connections declined in patients with severe but not moderate CAA (group×time interaction P=0.007 and P=0.005). Associations were independent of change in white matter hyperintensity volume. CONCLUSIONS: Brain network impairment in patients with CAA worsens measurably over just 1.3-year follow-up and seem to progress from posterior to frontal connections with increasing disease severity.

Small vessel disease and cognitive impairment: The relevance of central network connections.

Central brain network connections greatly contribute to overall network efficiency. Here we examined whether small vessel disease (SVD) related white matter alterations in central brain network connections have a greater impact on executive functioning than alterations in non-central brain network connections. Brain networks were reconstructed from diffusion-weighted MRI scans in 72 individuals (75 ± 8 years) with cognitive impairment and SVD on MRI. The centrality of white matter connections in the network was defined using graph theory. The association between the fractional anisotropy (FA) of central versus non-central connections, executive functioning, and markers of SVD was evaluated with linear regression and mediation analysis. Lower FA in central network connections was more strongly associated with impairment in executive functioning than FA in non-central network connections (r = 0.41 vs. r = 0.27; P < 0.05). Results were consistent across varying thresholds to define the central subnetwork (>50%-10% connections). Higher SVD burden was associated with lower FA in central as well as non-central network connections. However, only central network FA mediated the relationship between white matter hyperintensity volume and executive functioning [change in regression coefficient after mediation (95% CI): -0.15 (-0.35 to -0.02)]. The mediation effect was not observed for FA alterations in non-central network connections [-0.03 (-0.19 to 0.04)]. These findings suggest that the centrality of network connections, and thus their contribution to global network efficiency, appears to be relevant for understanding the relationship between SVD and cognitive impairment. Hum Brain Mapp 37:2446-2454, 2016. © 2016 Wiley Periodicals, Inc.

Structural network alterations and neurological dysfunction in cerebral amyloid angiopathy.

Cerebral amyloid angiopathy is a common form of small-vessel disease and an important risk factor for cognitive impairment. The mechanisms linking small-vessel disease to cognitive impairment are not well understood. We hypothesized that in patients with cerebral amyloid angiopathy, multiple small spatially distributed lesions affect cognition through disruption of brain connectivity. We therefore compared the structural brain network in patients with cerebral amyloid angiopathy to healthy control subjects and examined the relationship between markers of cerebral amyloid angiopathy-related brain injury, network efficiency, and potential clinical consequences. Structural brain networks were reconstructed from diffusion-weighted magnetic resonance imaging in 38 non-demented patients with probable cerebral amyloid angiopathy (69 ± 10 years) and 29 similar aged control participants. The efficiency of the brain network was characterized using graph theory and brain amyloid deposition was quantified by Pittsburgh compound B retention on positron emission tomography imaging. Global efficiency of the brain network was reduced in patients compared to controls (0.187 ± 0.018 and 0.201 ± 0.015, respectively, P < 0.001). Network disturbances were most pronounced in the occipital, parietal, and posterior temporal lobes. Among patients, lower global network efficiency was related to higher cortical amyloid load (r = -0.52; P = 0.004), and to magnetic resonance imaging markers of small-vessel disease including increased white matter hyperintensity volume (P < 0.001), lower total brain volume (P = 0.02), and number of microbleeds (trend P = 0.06). Lower global network efficiency was also related to worse performance on tests of processing speed (r = 0.58, P < 0.001), executive functioning (r = 0.54, P = 0.001), gait velocity (r = 0.41, P = 0.02), but not memory. Correlations with cognition were independent of age, sex, education level, and other magnetic resonance imaging markers of small-vessel disease. These findings suggest that reduced structural brain network efficiency might mediate the relationship between advanced cerebral amyloid angiopathy and neurologic dysfunction and that such large-scale brain network measures may represent useful outcome markers for tracking disease progression.

Estimating Total Cerebral Microinfarct Burden From Diffusion-Weighted Imaging.

BACKGROUND AND PURPOSE: Cerebral microinfarcts (CMI) are important contributors to vascular cognitive impairment. Magnetic resonance imaging diffusion-weighted imaging (DWI) hyperintensities have been suggested to represent acute CMI. We aim to describe a mathematical method for estimating total number of CMI based on the presence of incidental DWI lesions. METHODS: We reviewed magnetic resonance imaging scans of subjects with cognitive decline, cognitively normal subjects and previously reported subjects with past intracerebral hemorrhage (ICH). Based on temporal and spatial characteristics of DWI lesions, we estimated the annual rate of CMI needed to explain the observed rate of DWI lesion detection in each group. To confirm our estimates, we performed extensive sampling for CMI in the brain of a deceased subject with past lobar ICH who found to have a DWI lesion during life. RESULTS: Clinically silent DWI lesions were present in 13 of 343 (3.8%) cognitively impaired and 10 of 199 (5%) cognitively intact normal non-ICH patients, both lower than the incidence in the past ICH patients (23 of 178; 12.9%; P<0.0006). The predicted annual incidence of CMI ranges from 16 to 1566 for non-ICH and 50 to 5041 for ICH individuals. Histological sampling revealed a total of 60 lesions in 32 sections. Based on previously reported methods, this density of CMI yields an estimated total brain burden maximum likelihood estimate of 9321 CMIs (95% confidence interval, 7255-11 990). CONCLUSIONS: Detecting even a single DWI lesion suggests an annual incidence of hundreds of new CMI. The cumulative effects of these lesions may directly contribute to small-vessel-related vascular cognitive impairment.

Anatomic pattern of intracerebral hemorrhage expansion: relation to CT angiography spot sign and hematoma center.

BACKGROUND AND PURPOSE: We sought to identify baseline determinants of the anatomic pattern of hematoma expansion in patients with intracerebral hemorrhage and spot sign. METHODS: We coregistered baseline and follow-up CT scans from 15 intracerebral hemorrhage patients and measured growth at each surface node from baseline to follow-up hematoma. We analyzed the effects of proximity to the spot sign or hematoma center on distance of expansion, controlling for covariates. RESULTS: There was substantial node-to-node variation in the extent of expansion around each hematoma surface (mean coefficient of variation for expansion distance, 0.43; 95% confidence interval, 0.39-0.48), indicating nonuniform expansion. Closer proximity to the hematoma center was independently associated with increased expansion (0.185 mm greater expansion for each 1 mm closer to the center; P<0.0001). Closer proximity to the spot sign was not independently associated with increased expansion in models including both terms. CONCLUSIONS: Hemorrhages expand nonuniformly around their surface with a tendency for greater expansion closer to their center. These findings provide a novel framework for analyzing mechanisms underlying hemorrhage growth and response to treatment.

The Coexistence of Occult (Latent) Thyroid Cancer and Multinodular Goiter After Total Thyroidectomy: A Retrospective Study.

Introduction Multinodular goiter (MNG) is a common thyroid disorder characterized by the presence of multiple nodules within the thyroid gland. While most cases of MNG are benign, there is a risk of malignancy, particularly in nodules with certain features. The coexistence of occult (latent) thyroid cancer within MNG presents diagnostic and management challenges, underscoring the need for comprehensive investigation and treatment strategies. Objective The objective of this retrospective study is to investigate the prevalence of occult thyroid carcinoma in non-toxic MNG following total thyroidectomy. Materials and methods The study population consisted of 412 patients who underwent total thyroidectomy between 2004 and 2022 at the Second Surgical Department of the 424 General Military Hospital of Education in Thessaloniki. Data collection included patients' demographic characteristics, surgical indications for thyroidectomy, and histopathological examination findings. Initial data were available for all 412 patients, while sufficient information was present for 319 individuals, with a subset of 271 undergoing total thyroidectomy due to non-toxic MNG. Out of the aforementioned group, 253 cases were histologically confirmed as MNG. Subsequently, a statistical analysis was conducted concerning age, gender, the association of MNG with malignancy, and other thyroid disorders. Results Out of the total 412 thyroidectomies performed, 271 patients remained for statistical analysis and study. Among them, 253 patients had histologically confirmed MNG. Among the histological findings, 38 cases (14.02%) were identified with occult carcinoma within MNG. The predominant histological type was papillary thyroid carcinoma (PTC), comprising 93.3% of cases. Additionally, 18 patients (6.64%) were diagnosed with MNG, Hashimoto's thyroiditis (HT), and malignancy concurrently. Conclusions The coexistence of occult thyroid carcinoma within MNG underscores the importance of vigilant evaluation and management strategies in patients undergoing total thyroidectomy. These findings emphasize the need for comprehensive preoperative assessment and postoperative surveillance to detect and address occult thyroid cancer, thereby optimizing patient care and outcomes.

Internal Herniation Causing Double Obstruction of the Small Bowel and Urinary Tract: A Rare Case Presentation.

Small bowel obstruction is one of the most common urgent surgical conditions, caused by a variety of factors, with adhesions, malignancies, and hernias, internal and external, being the most common. Many types of internal hernias have been described in the literature; however, internal hernia caused by the ureter as a secondary complication of ureteroplasty is rare and only a few cases have been reported worldwide. This presentation discusses an interesting case of small bowel obstruction accompanied by obstruction of the urinary tract due to an internal hernia caused by the ureter. A 58-year-old female presented to the emergency department (ED) with acute pain in the abdominal and right lumbar region. Her surgical history includes hysterectomy, right ureter injury, and ureteroplasty performed 10 years ago. Clinical examination showed tenderness in the lower abdomen, positive Giordano's sign on the right, and metallic bowel sounds. A computer tomography scan revealed right-sided hydronephrosis, absence of excretion in the right urinary tract, and dilated loops of the small intestine. An exploratory laparoscopy revealed a small bowel loop strangulated by the ureter, followed by laparotomy, resection of a segment of the ileum, oblique anastomosis, and reimplantation of the right ureter. The patient was discharged eight days postoperatively without any complications. This case underscores the significance of surgical history in order to recognize even rarer causes of small bowel obstruction.

Acute Abdomen Accompanied by Torsion of a Segment of the Jejunum Due to Meckel's Diverticulum: A Rare and Interesting Case.

Meckel's diverticulum is a common congenital anomaly of the gastrointestinal tract and is often asymptomatic. This case report details the diagnosis and treatment of small bowel obstruction particularly in a segment of the jejunum in a 41-year-old woman due to Meckel's diverticulum. The patient presented with diffuse abdominal pain and bloating. Imaging and clinical evaluation revealed signs of ileus, leading to an exploratory laparotomy. Intraoperative findings included a mass consistent with Meckel's diverticulum causing adhesion and torsion of the jejunum. The surgical intervention involved adhesiolysis and segmental enterectomy with side-to-side anastomosis. Histopathological analysis confirmed Meckel's diverticulum with ectopic gastric mucosa. The patient had an uneventful postoperative recovery and was discharged on the seventh postoperative day.

Thalamic Roles in Conscious Perception Revealed by Low-Intensity Focused Ultrasound Neuromodulation.

The neural basis of conscious perception remains incompletely understood. While cortical mechanisms of conscious content have been extensively investigated, the role of subcortical structures, including the thalamus, remains less explored. We aim to elucidate the causal contributions of different thalamic regions to conscious perception using transcranial low-intensity focused ultrasound (LIFU) neuromodulation. We hypothesize that modulating different thalamic regions would result in distinct perceptual outcomes. We apply LIFU in human volunteers to investigate region-specific and sonication parameter-dependent effects. We target anterior (transmodal-dominant) and posterior (unimodal-dominant) thalamic regions, further divided into ventral and dorsal regions, while participants perform a near-threshold visual perception task. Task performance is evaluated using Signal Detection Theory metrics. We find that the high duty cycle stimulation of the ventral anterior thalamus enhanced object recognition sensitivity. We also observe a general (i.e., region-independent) effect of LIFU on decision bias (i.e., a tendency toward a particular response) and object categorization accuracy. Specifically, high duty cycle stimulation decreases categorization accuracy, whereas low duty cycle shifts decision bias towards a more conservative stance. In conclusion, our results provide causal insight into the functional organization of the thalamus in shaping human visual experience and highlight the unique role of the transmodal-dominant ventral anterior thalamus.

Changes in brain connectivity and neurovascular dynamics during dexmedetomidine-induced loss of consciousness.

Understanding the neurophysiological changes that occur during loss and recovery of consciousness is a fundamental aim in neuroscience and has marked clinical relevance. Here, we utilize multimodal magnetic resonance neuroimaging to investigate changes in regional network connectivity and neurovascular dynamics as the brain transitions from wakefulness to dexmedetomidine-induced unconsciousness, and finally into early-stage recovery of consciousness. We observed widespread decreases in functional connectivity strength across the whole brain, and targeted increases in structure-function coupling (SFC) across select networks-especially the cerebellum-as individuals transitioned from wakefulness to hypnosis. We also observed robust decreases in cerebral blood flow (CBF) across the whole brain-especially within the brainstem, thalamus, and cerebellum. Moreover, hypnosis was characterized by significant increases in the amplitude of low-frequency fluctuations (ALFF) of the resting-state blood oxygen level-dependent signal, localized within visual and somatomotor regions. Critically, when transitioning from hypnosis to the early stages of recovery, functional connectivity strength and SFC-but not CBF-started reverting towards their awake levels, even before behavioral arousal. By further testing for a relationship between connectivity and neurovascular alterations, we observed that during wakefulness, brain regions with higher ALFF displayed lower functional connectivity with the rest of the brain. During hypnosis, brain regions with higher ALFF displayed weaker coupling between structural and functional connectivity. Correspondingly, brain regions with stronger functional connectivity strength during wakefulness showed greater reductions in CBF with the onset of hypnosis. Earlier recovery of consciousness was associated with higher baseline (awake) levels of functional connectivity strength, CBF, and ALFF, as well as female sex. Across our findings, we also highlight the role of the cerebellum as a recurrent marker of connectivity and neurovascular changes between states of consciousness. Collectively, these results demonstrate that induction of, and emergence from dexmedetomidine-induced unconsciousness are characterized by widespread changes in connectivity and neurovascular dynamics.

Appendicitis Caused by a Giant Appendicolith.

The coproliths of the appendix are accumulations of fecal remnants within its lumen. They are categorized based on their size into coproliths < 1cm, which are the most common, and giant coproliths, with a diameter > 2cm. It's important to note that the pathophysiology of acute appendicitis is characterized by the obstruction of the appendix lumen. This leads to distension due to the inability to expel secretions, ischemia, and ultimately rupture of its wall. This presentation discusses an interesting case of acute appendicitis caused by a giant coprolith. It also covers the clinical approach and information according to international literature. A 38-year-old man presented with sudden-onset right lower quadrant pain. Clinical examination revealed tenderness, a positive McBurney's point, elevated inflammation markers, and a radiopaque finding on an X-ray. A CT scan revealed a 2.5cm coprolith in the appendix. An exploratory laparoscopy revealed appendix wall rupture, followed by subumbilical incision appendicectomy and cleansing of purulent collection. The patient was discharged from the hospital on the fourth postoperative day without any complications, demonstrating a smooth recovery process. The presence of a coprolith predisposes the development of acute appendicitis. This condition is associated with a worse prognosis, as it increases the likelihood of perforation and the formation of intraperitoneal abscesses. This case underscores the clinical significance of giant coproliths as a potential etiology for acute appendicitis. Early recognition and timely surgical intervention are pivotal in achieving favorable patient outcomes.

Descending Colon Perforation Due to Ingestion of Foreign Body.

Foreign body ingestion is a common reason for emergency department (ED) visits, with rare complications necessitating immediate surgical intervention. This case report discusses diagnosis and treatment, emphasizing the importance of prompt intervention. A 45-year-old male with dentures presented with acute left abdominal pain. Diagnostic tests identified a foreign body in the descending colon, leading to laparoscopic surgery. Early laparoscopy offers a safe and reliable alternative to exploratory laparotomy. This case underscores the significance of swift diagnosis, preventing severe complications like peritonitis, obstruction, and hemorrhage. In conclusion, while foreign body ingestion is common, intestinal perforation remains extremely rare. Physicians should consider it in their differential diagnosis, with computed tomography (CT) and rapid surgical intervention as crucial components of proper management.