Middle cerebellar peduncles: Magnetic resonance imaging and pathophysiologic correlate

Microstructural alterations of cerebellar peduncles in multiple sclerosis: a diffusion tensor imaging study

BACKGROUND AND PURPOSE

Ataxia, tremors, dysarthria, and sometimes impaired cognition are the signs of cerebellum involvement in multiple sclerosis (MS). These symptoms affect up to 80% of patients and are usually hard to treat. To find the underlying involvement of the cerebellum in MS, we assessed the microstructural alterations with DTI in the cerebellar peduncles of the affected subjects.

MATERIALS AND METHODS

We included 58 relapsing-remitting MS patients and 27 healthy controls. Patients were divided into 18 patients of relapsing-remitting MS with cerebellar impairment (RRMSc) and 40 without cerebellar impairment (RRMSnc). Using Diffusion Tensor Imaging (DTI), we calculated fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) metrics in all subjects. We also checked if there were associations between DTI metrics and clinical cerebellar measures (i.e., tremor severity and the scale for the assessment and rating of ataxia).

RESULTS

ANOVA and post-hoc results showed significant differences in DTI metrics between RRMSc and HC and between RRMSnc and HC subjects. Inferior peduncle RD remained the only metric with a significant difference across all pairwise comparisons. The general linear model assessing the effects of the three study groups on the association between DTI metrics and clinical cerebellar measures yielded no significant result.

CONCLUSIONS

Our study showed that DTI can mainly reveal significant differences between different MS groups and HCs. Our results imply the role of cerebellar peduncles in the pathophysiology of MS and that this role does not necessarily reflect the severity of cerebellar signs of the patients.

Alterations of White Matter Functional Networks in Pediatric Drug-Resistant Temporal Lobe Epilepsy: A Graph Theory Analysis Study

Neurological disorder can cause functional network changes in white matter (WM). However, changes in the WM functional network in children with drug-resistant temporal lobe epilepsy (DRTLE) require further clarification. Therefore, we combine graph theory with resting-state functional magnetic resonance imaging (rs-fMRI) and T1-weighted imaging (T1WI) to investigate the topological features of the WM network in children with DRTLE, discover potential biomarkers, and understand the underlying neurological mechanisms. We included 91 children (43 with DRTLE and 48 healthy controls), acquiring structural and functional MRI data to construct WM functional networks. Graph theory was applied to evaluate topological differences and their correlation with onset age, disease duration and cognitive measures. A Support Vector Machine model classified individuals with DRTLE based on WM connectivity, with accuracy validated through leave-one-out cross-validation. The global topological properties of the WM network in children with DRTLE were altered, manifesting as an imbalance between global integration and segregation Local nodal efficiency changes in the association fibers exhibited reduced information transfer and centrality at several nodes. Conversely, commissural and projection fibers displayed increased network properties. Cognitive metrics correlated with nodal disturbances. The classification model achieved 73.6% accuracy and an area under the curve (AUC) of 0.744. This indicates that the WM functional network in DRTLE presents with anomalies in the topological attributes, which are associated with cognitive impairments. The WM functional connectivity may serve as valuable indicators for clinical classification of the condition. The insights provided have augmented our understanding of the complex neurological mechanisms involved in epilepsy.

Infratentorial white matter integrity as a potential biomarker for post-stroke aphasia

Traditionally, neuroimaging studies of post-stroke aphasia focus on supratentorial brain regions related to language function and recovery. However, stroke-induced lesions often distort these areas, posing a challenge for neuroimaging analyses aimed at identifying reliable biomarkers. This study seeks to explore alternative biomarkers in regions less affected by direct stroke damage, such as white matter regions below the tentorium, to overcome these methodological limitations. Diffusion tensor imaging was accomplished on 55 participants with chronic post-stroke aphasia. Focusing on regions below the tentorium, correlations were analysed between Western Aphasia Battery-Revised scores and average fractional anisotropy values. The volume of intersection between each participant's lesion and their left arcuate fasciculus was also analysed for correlations with Western Aphasia Battery-Revised scores as well. Linear regression analyses were then conducted using regions showing significant correlations as univariate predictors. After applying multiple comparisons corrections, we found that average fractional anisotropy in the middle cerebellar peduncle was positively correlated with aphasia quotient (P = 0.004), spontaneous speech (P = 0.005), auditory verbal comprehension (P = 0.004), naming and word finding (P = 0.005) and repetition (P = 0.013). Average fractional anisotropy in the left inferior cerebellar peduncle positively correlated with spontaneous speech (P = 0.018) and auditory verbal comprehension (P = 0.018). Average fractional anisotropy in the left corticospinal tract positively correlated with aphasia quotient (P = 0.019) and spontaneous speech (P = 0.005). The volume of intersection between the left arcuate fasciculus and participant lesion was negatively correlated with aphasia quotient (P = 0.014) and repetition (P = 0.002). Through linear regression analyses, average fractional anisotropy of the middle cerebellar peduncle significantly predicted aphasia quotient and all subscores. Average fractional anisotropy of the left inferior cerebellar peduncle significantly predicted all scores except repetition. Average fractional anisotropy of the left corticospinal tract significantly predicted all scores except for auditory verbal comprehension. The volume of intersection between the left arcuate fasciculus and lesions significantly predicted all scores except for auditory verbal comprehension. These findings underscore the potential of infratentorial white matter regions as biomarkers of aphasia severity, encompassing overall and specific subdomain impairment. By shifting the focus to below the tentorium, it becomes possible to find more robust targets for further research and therapeutic interventions. This approach is not only able to sidestep analytical complications posed by cortical lesions, it also opens new doors for understanding complex cerebellar mechanisms that underlie language function and recovery post-stroke.

Involvement of the Cerebellar Peduncles in FMR1 Premutation Carriers: A Pictorial Review of Their Anatomy, Imaging, and Pathology

The cerebellar peduncles (CPs) contain essential pathways connecting the cerebellum and other regions of the central nervous system, yet their role is often overlooked in daily medical practice. Individuals with the FMR1 premutation are at risk of developing fragile X-associated tremor/ataxia syndrome (FXTAS), a late-onset neurodegenerative disorder. The major clinical and radiological signs of FXTAS are cerebellar gait ataxia, intention tremor, and T2-weighted MRI hyperintensity of the middle cerebellar peduncle (MCP sign). Over the years, metabolic and structural abnormalities have also been described in the CPs of FMR1 premutation carriers, with some being associated with CGG repeat length and FMR1 mRNA levels. Evidence seems to associate the clinical disfunction observed in FXTAS with MCP abnormalities. However, other tracts within the different CPs may also contribute to the symptoms observed in FXTAS. By integrating imaging and pathological data, this review looks to enhance the understanding of the functional anatomy of the CPs and their involvement in different pathological entities, with special interest in premutation carriers and FXTAS. This review, therefore, aims to provide accessible knowledge on the subject of the CPs and their functional anatomy through detailed diagrams, offering a clearer understanding of their role in FMR1 premutation.

Microstructural Alterations of Cerebellar Peduncles in Relapsing Remitting Multiple Sclerosis: a Systematic Review and Meta-Analysis of Diffusion Tensor Imaging Studies

Damage to cerebellar peduncles is common in patients with relapsing-remitting multiple sclerosis (RRMS). This can lead to a diverse range of motor and cognitive disabilities. Here, we aimed to evaluate the quantitative alterations of cerebellar peduncles using diffusion tensor imaging (DTI). After a comprehensive search in Web of Science, PubMed, Embase, and Scopus and a rigorous screening, eligible studies underwent data extraction and risk of bias assessment. Standardized Mean Difference (SMD) with a 95% CI was used as effect size. We compared DTI metrics in the cerebellar peduncle regions (SCP, MCP, ICP) between RRMS patients and healthy controls (HC). Sensitivity analysis employed the leave-one-out method. Contour-enhanced funnel plots and Pustejovsky test were used to evaluate the publication bias. Additionally, subgroup analysis was performed using available variables. In eleven included studies encompassing 623 RRMS patients and 416 HC, RRMS patients exhibited significantly decreased fractional anisotropy (FA) values in the SCP (SMD - 0.26) and MCP (SMD - 1.03), increased mean diffusivity (MD) values in the SCP (SMD 1.46), MCP (SMD 0.48) and ICP (SMD 0.70), elevated radial diffusivity (RD) values in the MCP (SMD 0.85) and ICP (SMD 1.20) compared to HC. The subgroup analysis revealed that individuals with elevated EDSS scores exhibited reduced FA and increased MD in the SCP region. No considerable publication bias was detected. No outliers were detected in the sensitivity analysis. DTI proves promising for identifying microstructural abnormalities in cerebellar peduncles of RRMS patients, with decreased FA and increased RD, and MD values observed.

Elucidating Microstructural Alterations in Neurodevelopmental Disorders: Application of Advanced Diffusion-Weighted Imaging in Children With Rasopathies

Neurodevelopmental disorders (NDDs) can severely impact functioning yet effective treatments are limited. Greater insight into the neurobiology underlying NDDs is critical to the development of successful treatments. Using a genetics-first approach, we investigated the potential of advanced diffusion-weighted imaging (DWI) techniques to characterize the neural microstructure unique to neurofibromatosis type 1 (NF1) and Noonan syndrome (NS). In this prospective study, children with NF1, NS, and typical developing (TD) were scanned using a multi-shell DWI sequence optimized for neurite orientation density and dispersion imaging (NODDI) and diffusion kurtosis imaging (DKI). Region-of-interest and tract-based analysis were conducted on subcortical regions and white matter tracts. Analysis of covariance, principal components, and linear discriminant analysis compared between three groups. 88 participants (Mage = 9.36, SDage = 2.61; 44 male) were included: 31 NS, 25 NF1, and 32 TD. Subcortical regions differed between NF1 and NS, particularly in the thalamus where the neurite density index (NDI; estimated difference 0.044 [95% CI: -0.034, 0.053], d = 2.36), orientation dispersion index (ODI; estimate 0.018 [95% CI: 0.010, 0.026], d = 1.39), and mean kurtosis (MK; estimate 0.049 [95% CI: 0.025, 0.072], d = 1.39) were lower in NF1 compared with NS (all p < 0.0001). Reduced NDI was found in NF1 and NS compared with TD in all 39 white matter tracts investigated (p < 0.0001). Reduced MK was found in a majority of the tracts in NF1 and NS relative to TD, while fewer differences in ODI were observed. The middle cerebellar peduncle showed lower NDI (estimate 0.038 [95% CI: 0.021, 0.056], p < 0.0001) and MK (estimate 0.057 [95% CI: 0.026, 0.089], p < 0.0001) in NF1 compared to NS. Multivariate analyses distinguished between groups using NDI, ODI, and MK measures. Principal components analysis confirmed that the clinical groups differ most from TD in white matter tract-based NDI and MK, whereas ODI values appear similar across the groups. The subcortical regions showed several differences between NF1 and NS, to the extent that a linear discriminant analysis could classify participants with NF1 with an accuracy rate of 97%. Differences in neural microstructure were detected between NF1 and NS, particularly in subcortical regions and the middle cerebellar peduncle, in line with pre-clinical evidence. Advanced DWI techniques detected subtle alterations not found in prior work using conventional diffusion tensor imaging.

Sensitivity of Advanced Magnetic Resonance Imaging to Progression over Six Months in Early Spinocerebellar Ataxia

BACKGROUND

Clinical trials for upcoming disease-modifying therapies of spinocerebellar ataxias (SCA), a group of rare movement disorders, lack endpoints sensitive to early disease progression, when therapeutics will be most effective. In addition, regulatory agencies emphasize the importance of biological outcomes.

OBJECTIVES

READISCA, a transatlantic clinical trial readiness consortium, investigated whether advanced multimodal magnetic resonance imaging (MRI) detects pathology progression over 6 months in preataxic and early ataxic carriers of SCA mutations.

METHODS

A total of 44 participants (10 SCA1, 25 SCA3, and 9 controls) prospectively underwent 3-T MR scanning at baseline and a median [interquartile range] follow-up of 6.2 [5.9-6.7] months; 44% of SCA participants were preataxic. Blinded analyses of annual changes in structural, diffusion MRI, MR spectroscopy, and the Scale for Assessment and Rating of Ataxia (SARA) were compared between groups using nonparametric testing. Sample sizes were estimated for 6-month interventional trials with 50% to 100% treatment effect size, leveraging existing large cohort data (186 SCA1, 272 SCA3) for the SARA estimate.

RESULTS

Rate of change in microstructural integrity (decrease in fractional anisotropy, increase in diffusivities) in the middle cerebellar peduncle, corona radiata, and superior longitudinal fasciculus significantly differed in SCAs from controls (P < 0.005), with high effect sizes (Cohen's d = 1-2) and moderate-to-high responsiveness (|standardized response mean| = 0.6-0.9) in SCAs. SARA scores did not change, and their rate of change did not differ between groups.

CONCLUSIONS

Diffusion MRI is sensitive to disease progression at very early-stage SCA1 and SCA3 and may provide a >5-fold reduction in sample sizes relative to SARA as endpoint for 6-month-long trials. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

fMRI signals in white matter rewire gray matter community organization

Human brain gray matter (GM) has usually been clustered into multiple functional networks. The white matter (WM) fiber bundles are known to interconnect these networks simultaneously, engaging in numerous cognitive functions. However, the exact interconnections between GM and WM are still unclear, whether functional signals in WM rewires GM community organization remains to be explored. In this study, we divided brain functional connections into three types by using edge-centric method, including intra-GM, intra-WM and GM-WM connections, and calculated the edge community evaluation indexes for quantifying GM community engagement. The results showed that the involvement of WM significantly enhanced community entropy in the heteromodal system, while the sensory-attention system remained barely changed. In addition, delta community entropy showed a significant correlation with clinical cognitive scale. Our results suggested that WM rewired GM community organization, enhancing the community engagement of brain regions in the heteromodal system. This involvement was observed to be disrupted in disease groups. Our study revealed that considering the functional signals of GM and WM simultaneously could better understand the brain's functional organization.

Infarct of the Middle Cerebellar Peduncle Mimicking Bell's Palsy: A Case Report

The anterior inferior cerebellar artery (AICA) supplies the middle cerebellar peduncle, lower pons, upper medulla, and anterior inferior cerebellum. Ischemia in the AICA can cause the lateral inferior pontine syndrome. AICA syndrome is characterized by facial sensory loss and weakness, Horner syndrome, prolonged vertigo, audio-vestibular loss, and cerebellar signs. Many studies on AICA territory infarcts have demonstrated the rarity of complete AICA syndrome. In all cases of AICA territory infarcts, involvement of the middle cerebellar peduncle was observed, with the seventh cranial nerve (facial nerve) being the most frequently involved cranial nerve, vertigo was the most common presenting symptom, and atherosclerosis was the most common etiology. This case report aims to investigate the occurrence of middle cerebellar peduncle infarcts that mimic Bell's palsy, highlighting the importance of accurate diagnosis and appropriate management in such cases. Recognizing the unique characteristics and clinical presentation of middle cerebellar peduncle (MCP) infarcts is essential for distinguishing them from more common conditions like Bell's palsy, thereby ensuring timely and effective treatment.

Effects of Adapted Physical Activity on White Matter Integrity in Patients with Schizophrenia

Schizophrenia is associated with changes in white matter (WM) integrity and with reduced life expectancy, in part because of the cardiometabolic side effects of antipsychotics. Physical activity (PA) has emerged as a candidate lifestyle intervention that is safe and effective. The study aimed to assess how an adapted PA program delivered remotely by web (e-APA) improved WM integrity in patients with schizophrenia (SZPs) and healthy controls (HCs) and to evaluate associations among WM integrity, cardiorespiratory fitness, and symptom severity. This longitudinal study was conducted over 16 weeks with 31 participants (18 SZPs and 13 HCs). Diffusion tensor imaging and tract-based spatial statistics were employed to assess WM integrity. Cardiorespiratory fitness was measured by maximal oxygen uptake (VO2max), and assessments for clinical symptoms included the Positive and Negative Syndrome Scale, Self-evaluation of Negative Symptoms and the Brief Negative Syndrome Scale (BNSS). Only the SZPs had significantly increased WM integrity after the e-APA program, with increased fractional anisotropy and decreased radial diffusivity in fasciculi involved in motor functions and language process. Furthermore, decreased negative symptoms assessed with BNSS were associated with greater WM integrity following the program. These findings suggest that e-APA may improve WM integrity abnormalities and support e-APA as a promising therapeutic strategy.

Functional alterations in bipartite network of white and grey matters during aging

The effects of normal aging on functional connectivity (FC) within various brain networks of gray matter (GM) have been well-documented. However, the age effects on the networks of FC between white matter (WM) and GM, namely WM-GM FC, remains unclear. Evaluating crucial properties, such as global efficiency (GE), for a WM-GM FC network poses a challenge due to the absence of closed triangle paths which are essential for assessing network properties in traditional graph models. In this study, we propose a bipartite graph model to characterize the WM-GM FC network and quantify these challenging network properties. Leveraging this model, we assessed the WM-GM FC network properties at multiple scales across 1,462 cognitively normal subjects aged 22-96 years from three repositories (ADNI, BLSA and OASIS-3) and investigated the age effects on these properties throughout adulthood and during late adulthood (age ≥70 years). Our findings reveal that (1) heterogeneous alterations occurred in region-specific WM-GM FC over the adulthood and decline predominated during late adulthood; (2) the FC density of WM bundles engaged in memory, executive function and processing speed declined with age over adulthood, particularly in later years; and (3) the GE of attention, default, somatomotor, frontoparietal and limbic networks reduced with age over adulthood, and GE of visual network declined during late adulthood. These findings provide unpresented insights into multi-scale alterations in networks of WM-GM functional synchronizations during normal aging. Furthermore, our bipartite graph model offers an extendable framework for quantifying WM-engaged networks, which may contribute to a wide range of neuroscience research.

Voxel-based meta-analysis of gray matter and white matter changes in patients with spinocerebellar ataxia type 3

Purpose

Increasing neuroimaging studies have revealed gray matter (GM) and white matter (WM) anomalies of several brain regions by voxel-based morphometry (VBM) studies on patients with spinocerebellar ataxia type 3 (SCA3); however, the findings of previous studies on SCA3 patients by VBM studies remain inconsistent. The study aimed to identify consistent findings of gray matter (GM) and white matter (WM) changes in SCA3 patients by voxel-wise meta-analysis of whole-brain VBM studies.

Methods

VBM studies comparing GM or WM changes in SCA3 patients and healthy controls (HCs) were retrieved from PubMed, Embase, Web of Science, and Medline databases from January 1990 to February 2023. Manual searches were also conducted, and authors of studies were contacted for additional data. The coordinates with significant differences in GM and WM between SCA3 patients and HCs were extracted from each cluster. A meta-analysis was performed using anisotropic effect size-based signed differential mapping (AES-SDM) software.

Results

A total of seven studies comprising 160 SCA3 patients and 165 HCs were included in the GM volume meta-analysis. Three studies comprising 57 SCA3 patients and 63 HCs were included for WM volume meta-analysis. Compared with HC subjects, the reduced GM volume in SCA3 patients was found in the bilateral cerebellar hemispheres, cerebellar vermis, pons, right lingual gyrus, and right fusiform gyrus. The decreased WM volume was mainly concentrated in the bilateral cerebellar hemispheres, right corticospinal tract, middle cerebellar peduncles, cerebellar vermis, and left lingual gyrus. No increased density or volume of any brain structures was found. In the jackknife sensitivity analysis, the results remained largely robust.

Conclusion

Our meta-analysis clearly found the shrinkage of GM and WM volume in patients with SCA3. These lesions are involved in ataxia symptoms, abnormal eye movements, visual impairment, cognitive impairment, and affective disorders. The findings can explain the clinical manifestations and provide a morphological basis for SCA3.

Clinical and cognitive correlates tractography analysis in patients with white matter hyperintensity of vascular origin

Purpose

White matter hyperintensity lesions (WMHL) in the brain are a consequence of cerebral small vessel disease and microstructural damage. Patients with WMHL have diverse clinical features, and hypertension, advanced age, obesity, and cognitive decline are often observed. However, whether these clinical features are linked to interrupted structural connectivity in the brain requires further investigation. This study therefore explores the white matter pathways associated with WMHL, with the objective of identifying neural correlates for clinical features in patients with WMHL.

Methods

Diffusion magnetic resonance imaging (MRI) and several clinical features (MoCA scores, hypertension scores, body mass index (BMI), duration of hypertension, total white matter lesion loads, and education.) highly related to WMHL were obtained in 16 patients with WMHL and 20 health controls. We used diffusion MRI connectometry to explore the relationship between clinical features and specific white matter tracts using DSI software.

Results

The results showed that the anterior splenium of the corpus callosum, the inferior longitudinal fasciculus, the anterior corpus callosum and the middle cerebellar peduncle were significantly correlated with hypertension scores (false discovery rate (FDR) = 0.044). The anterior splenium of the corpus callosum, the left thalamoparietal tract, the inferior longitudinal fasciculus, and the left cerebellar were significantly correlated with MoCA scores (FDR = 0.016). The anterior splenium of corpus callosum, inferior fronto-occipital fasciculus, cingulum fasciculus, and fornix/fimbria were significantly correlated with body mass index (FDR = 0.001).

Conclusion

Our findings show that hypertension score, MoCA score, and BMI are important clinical features in patients with WMHL, hypertension degree and higher BMI are associated with whiter matter local disconnection in patients with WMHL, and may contribute to understanding the cognitive impairments observed in patients with WMHL.

Artificial neural network applied to fragile X-associated tremor/ataxia syndrome stage diagnosis based on peripheral mitochondrial bioenergetics and brain imaging outcomes

No proven prognosis is available for the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS). Artificial neural network analyses (ANN) were used to predict FXTAS progression using data from 127 adults (noncarriers and FMR1 premutation carriers with and without FXTAS) with five outcomes from brain MRI imaging and 22 peripheral bioenergetic outcomes from two cell types. Diagnosis accuracy by ANN predictions ranged from 41.7 to 86.3% (depending on the algorithm used), and those misclassified usually presented a higher FXTAS stage. ANN prediction of FXTAS stages was based on a combination of two imaging findings (white matter hyperintensity and whole-brain volumes adjusted for intracranial volume) and four bioenergetic outcomes. Those at Stage 3 vs. 0-2 showed lower mitochondrial mass, higher oxidative stress, and an altered electron transfer consistent with mitochondrial unfolded protein response activation. Those at Stages 4-5 vs. 3 had higher oxidative stress and glycerol-3-phosphate-linked ATP production, suggesting that targeting mGPDH activity may prevent a worse prognosis. This was confirmed by the bioenergetic improvement of inhibiting mGPDH with metformin in affected fibroblasts. ANN supports the prospect of an unbiased molecular definition in diagnosing FXTAS stages while identifying potential targets for personalized medicine.

Clinically Isolated Brainstem Progressive Multifocal Leukoencephalopathy: Diagnostic Challenges

Patient: Female, 47-year-old

Final Diagnosis: Brainstem progressive multifocal leukoencephalopathy

Symptoms: Dizziness • intermittent slurred speech • right-sided facial droop and numbness

Medication: —

Clinical Procedure: Lumbar puncture

Specialty: Neurology

DTI Connectometry Analysis Reveals White Matter Changes in Cognitively Impaired World Trade Center Responders at Midlife

BACKGROUND

More than 8% of responders who participated in the search and rescue efforts at the World Trade Center (WTC) following 9/11 developed early-onset cognitive impairment (CI). Approximately 23% were also diagnosed with chronic post-traumatic stress disorder (PTSD).

OBJECTIVE

To shed light on the pathophysiology of these WTC-related conditions, we examined diffusion connectometry to identify altered white matter tracts in WTC responders with CI and/or PTSD compared to unaffected responders.

METHODS

99 WTC responders (mean age 56 years) consisting of CI-/PTSD- (n = 27), CI+/PTSD- (n = 25), CI-/PTSD+ (n = 24), and CI+/PTSD+ (n = 23) were matched on age, sex, occupation, race, and education. Cognitive status was determined using the Montreal Cognitive Assessment and PTSD status was determined using the DSM-IV SCID. Diffusion tensor imaging was acquired on a 3T Siemens Biograph mMR scanner. Connectometry analysis was used to examine whole-brain tract-level differences in white matter integrity as reflected by fractional anisotropy (FA) values after adjusting for confounders.

RESULTS

Analyses identified that FA was negatively correlated with CI and PTSD status in the fornix, cingulum, forceps minor of the corpus callosum and the right uncinate fasciculus. Furthermore, FA was negatively correlated with PTSD status, regardless of CI status in the superior thalamic radiation and the cerebellum.

CONCLUSION

This is the first connectometry study to examine altered white matter tracts in a sample of WTC responders with CI and/or PTSD. Results from this study suggest that WTC responders with early-onset CI may be experiencing an early neurodegenerative process characterized by decreased FA in white matter tracts.

Molecular Pathogenesis and Peripheral Monitoring of Adult Fragile X-Associated Syndromes

Abnormal trinucleotide expansions cause rare disorders that compromise quality of life and, in some cases, lifespan. In particular, the expansions of the CGG-repeats stretch at the 5’-UTR of the Fragile X Mental Retardation 1 (FMR1) gene have pleiotropic effects that lead to a variety of Fragile X-associated syndromes: the neurodevelopmental Fragile X syndrome (FXS) in children, the late-onset neurodegenerative disorder Fragile X-associated tremor-ataxia syndrome (FXTAS) that mainly affects adult men, the Fragile X-associated primary ovarian insufficiency (FXPOI) in adult women, and a variety of psychiatric and affective disorders that are under the term of Fragile X-associated neuropsychiatric disorders (FXAND). In this review, we will describe the pathological mechanisms of the adult “gain-of-function” syndromes that are mainly caused by the toxic actions of CGG RNA and FMRpolyG peptide. There have been intensive attempts to identify reliable peripheral biomarkers to assess disease progression and onset of specific pathological traits. Mitochondrial dysfunction, altered miRNA expression, endocrine system failure, and impairment of the GABAergic transmission are some of the affectations that are susceptible to be tracked using peripheral blood for monitoring of the motor, cognitive, psychiatric and reproductive impairment of the CGG-expansion carriers. We provided some illustrative examples from our own cohort. Understanding the association between molecular pathogenesis and biomarkers dynamics will improve effective prognosis and clinical management of CGG-expansion carriers.

Diffusion-Weighted Imaging is Key to Diagnosing Specific Diseases

This article reviews diseases for which persistent signal abnormalities on diffusion-weighted imaging are the key to their diagnosis. Specifically, updated knowledge regarding the neuroimaging patterns of the following diseases is summarized: sporadic Creutzfeldt-Jakob disease, neuronal intranuclear inclusion disease, and hereditary diffuse leukoencephalopathy with axonal spheroids-colony-stimulating factor receptors/adult-onset leukoencephalopathy with axonal spheroids and pigmented glia. In addition, their differential diagnoses; clinical manifestations; and pathologic, genetic, and imaging correlates are discussed.

Suspecting unwitnessed hypoglycaemia

Hypoglycaemic coma can present with acute neurological dysfunction mimicking stroke. It may be masked by normoglycaemia due to physiological compensatory mechanisms (Somogyi phenomenon). Specific MR brain scan changes should alert the clinician to consider this alternative to stroke in the acute setting in patients with a history of recurrent hypoglycaemia, even when the blood glucose is not low at presentation. Rapid identification and treatment of hypoglycaemia may confer a good prognosis with radiological resolution.

Bilateral middle cerebellar peduncle lesions: Neuroimaging features and differential diagnoses

OBJECTIVES

Lesions limited to the bilateral middle cerebellar peduncles (MCPs) are uncommon. This retrospective study investigated diseases with a proclivity for the bilateral MCPs and explored the associations between their neuroimaging features and clinical findings for the differential diagnosis of such lesions.

METHODS

We enrolled 26 patients who were admitted to our department between January 2016 and March 2019 with bilateral MCP abnormalities on magnetic resonance imaging (MRI). The demographic, clinical, and neuroimaging characteristics, and the biomarkers and diagnoses were evaluated.

RESULTS

Although all patients exhibited symmetrical bilateral MCP hypointensities on T1-weighted imaging and hyperintensities on T2-weighted and fluid-attenuated inversion recovery imaging, they were diagnosed with different conditions. Diagnoses included acute cerebral infarction (ACI) (n = 9, 34.62%), Wallerian degeneration (WD) (n = 8, 30.77%), multiple system atrophy (MSA) (n = 6, 23.08%), neuromyelitis optica (NMO) (n = 1, 3.85%), heroin-induced leukoencephalopathy (n = 1, 3.85%), and primary central nervous system lymphoma (PCNSL) (n = 1, 3.85%). Patients with ACI exhibited bilateral MCP-restricted diffusion hyperintensities on diffusion-weighted imaging and corresponding stenosis or occlusion of the vertebrobasilar system. The initial MRI of patients with WD depicted pontine infarctions, while symmetrical MCP lesions were observed on follow-up MRI. Symmetrical MCP lesions, cruciform hyperintensity, and marked atrophy in the posterior fossa were characteristic manifestations of MSA. Longitudinally extensive myelitis affecting more than three vertebral segments on cervical MRI and positive serum AQP4-IgG may be indicative of NMO. Heroin-induced leukoencephalopathy was characterized by extra-symmetrical lesions in the posterior limbs of the internal capsules, while the anterior limbs were spared. PCNSL was indicated by a significant and characteristic "fist" sign on contrast-enhanced MRI.

CONCLUSIONS

Bilateral MCP lesions were most frequently observed in cerebrovascular diseases, followed by neurodegenerative diseases, inflammatory diseases, toxic encephalopathies, and lymphomas. Our findings demonstrate that bilateral MCP signal abnormalities are more common in patients with ACI and WD, with fewer degenerative processes than previously believed. The high frequency of WD may be attributed to the specific awareness of this pathology. WD can also present with stage-related restricted diffusion and should not be mistaken for a new infarction. The symmetrical bilateral MCP hypointensities on T1-weighted imaging and hyperintensities on T2-weighted imaging often raise concern regarding a demyelinating process. Our findings emphasize that neurologists should consider the aforementioned conditions and correlate the specific neuroimaging characteristics and medical history before arriving at the final diagnosis.

A unique presentation of 5-fluorouracil (5-FU) induced cerebral encephalopathy

5-Fluorouracil (5-FU), a commonly used antimetabolite and antineoplastic agent, has been approved for the treatment of various cancers. It is associated with systemic side-effects such as gastrointestinal problems, neutropenia. 5-FU-related encephalopathy is very rarely reported. Imaging with computed tomography (CT) and magnetic resonance imaging (MRI) plays a key role in diagnosing and monitoring the changes. Since the prognosis of cerebral involvement is usually good if recognized and treated in time, the reporting radiologist and treating physician should be familiar with them. We present a rare case of 5-FU-induced encephalopathy that was diagnosed based on her clinical and MRI findings and managed successfully.

Differential value of brain magnetic resonance imaging in multiple system atrophy cerebellar phenotype and spinocerebellar ataxias

Clinically differentiating multiple system atrophy cerebellar (MSA-C) phenotype and spinocerebellar ataxias (SCAs) is challenging especially in the early stage. We assessed diagnostic value of brain magnetic resonance imaging (MRI) in differentiating MSA-C and SCAs based at different disease stages (<3, 3–7, and >7 years of disease duration). Overall, 186 patients with probable MSA-C and 117 with genetically confirmed SCAs were included. Hot cross bun (HCB) signs and middle cerebellar peduncle (MCP) hyperintensities were exclusively prevalent in MSA-C compared to SCAs at <3 years (HCB, 44.6% versus 0.9%; MCP hyperintensities, 38.3% versus 0.9%, respectively). Sensitivity, specificity, and positive predictive value (PPV) for HCB signs to differentiate MSA-C from SCAs were 45%, 99%, and 99% and those for MCP hyperintensities were 68%, 99%, and 99%, respectively; considering both HCB signs and MCP hyperintensities, specificity and PPV were 100%. However, the differential value of MRI signs decreased over time. MCP widths were smaller and showed more significant decrease in MSA-C than in SCAs. In conclusion, pontine and MCP changes were exclusively prominent in early stage MSA-C rather than in SCAs. Therefore, we should consider disease duration when interpreting pontine and MCP changes in brain MRIs, which will help better differentiate MSA-C and SCAs.

Successful treatment of non-HIV progressive multifocal leukoencephalopathy: case report and literature review

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a subacute onset demyelinating disease caused by JC virus and characterized by multifocal involvement of the subcortical white matter and cerebellar hemispheres or peduncles on magnetic resonance imaging (MRI). However, non-HIV PML patients with brain lesions limited to the cerebellum and brainstem have not been well characterized.

METHODS

We report a 68-year-old man with systemic lupus erythematosus under treatment with immunosuppressants who developed non-HIV PML with brain lesions limited to the cerebellum and brainstem and successfully treated with a combination of mefloquine and mirtazapine. We performed a literature review to characterize patients with non-HIV PML with brain lesions limited to the cerebellum and brainstem.

RESULTS

Eight cases with non-HIV brainstem/cerebellar form PML were identified including our case. All cases had compromised status related underlying diseases. Four (50%) had a good prognosis. Five cases were treated, including 3 with favourable outcomes. Between the good prognosis group (n = 4) and the poor prognosis group (n = 4), treatment status for PML and the interval between the initial manifestation and diagnosis did not differ. Among those who performed contrast-enhanced brain imaging, lesion enhancement was related to good prognosis (good prognosis group vs. poor prognosis group; 100% vs. 0%).

CONCLUSION

PML should be considered in the differential diagnosis of brain lesions limited to the cerebellum and brainstem in immunocompromised patients. The presence of immune response against JC virus and inflammatory reactions may indicate good prognosis in non-HIV brainstem/cerebellar form PML.

Lack of Correlation Between Intracranial Carotid Artery Modified Woodcock Calcification Score and Prognosis of Patients With Acute Ischemic Stroke After Intravenous Thrombolysis

There have been few studies about the association between intracranial carotid artery calcification (ICAC) and acute ischemic stroke (AIS) prognosis after intravenous thrombolysis (IVT). We aimed to analyze the association between ICAC and prognosis (including symptomatic intracranial hemorrhage (sICH), functional outcome and death) of AIS patients treated with IVT. In this retrospective study, we consecutively included 232 AIS patients treated with IVT between April 2012 and December 2018. ICAC was evaluated using the modified Woodcock calcification visual score on non-enhanced cranial computed tomography scans. Poor functional outcome was defined as a modified Rankin Scale score > 2 at 3 months. We found that the modified Woodcock calcification score was associated with ICH, poor outcome, and death in univariable analyses on the symptomatic side and/or bilaterally. However, after adjustment for other different covariates, the results showed no significant difference. We documented that the presence and severity of ICAC did not significantly modify the beneficial effects of rtPA treatment in AIS.

Atrophy of cerebellar peduncles in essential tremor: a machine learning-based volumetric analysis

BACKGROUND

Subtle cerebellar signs are frequently observed in essential tremor (ET) and may be associated with cerebellar dysfunction. This study aims to evaluate the macrostructural integrity of the superior, middle, and inferior cerebellar peduncles (SCP, MCP, ICP) and cerebellar gray and white matter (GM, WM) volumes in patients with ET, and compare these volumes between patients with and without cerebellar signs (ETc and ETnc).

METHODS

Forty patients with ET and 37 age- and gender-matched healthy controls were recruited. Atlas-based region-of-interest analysis of the SCP, MCP, and ICP and automated analysis of cerebellar GM and WM volumes were performed. Peduncular volumes were employed in a multi-variate classification framework to attempt discrimination of ET from controls.

RESULTS

Significant atrophy of bilateral MCP and ICP and bilateral cerebellar GM was observed in ET. Cerebellar signs were present in 20% of subjects with ET. Comparison of peduncular and cerebellar volumes between ETnc and ETc revealed atrophy of right SCP, bilateral MCP and ICP, and left cerebellar WM in ETc. The multi-variate classifier could discriminate between ET and controls with a test accuracy of 86.66%.

CONCLUSIONS

Patients with ET have significant atrophy of cerebellar peduncles, particularly the MCP and ICP. Additional atrophy of the SCP is observed in the ETc group. These abnormalities may contribute to the pathogenesis of cerebellar signs in ET.

KEY POINTS

• Patients with ET have significant atrophy of bilateral middle and inferior cerebellar peduncles and cerebellar gray matter in comparison with healthy controls. • Patients of ET with cerebellar signs have significant atrophy of right superior cerebellar peduncle, bilateral middle and inferior cerebellar peduncle, and left cerebellar white matter in comparison with ET without cerebellar signs. • A multi-variate classifier employing peduncular volumes could discriminate between ET and controls with a test accuracy of 86.66%.

The cerebellar peduncle as localization of a recurrent atypical plexus papilloma: A case report

Background:

Choroid plexus papillomas (CPPs) are infrequently encountered brain tumors with the majority originating in the ventricular system. Rarely, CPP occurs outside of the ventricles.

Case Description:

We report the case of a recurrent CPP that initially originated within the fourth ventricle, though years later it recurred in the left middle cerebellar peduncle.

Conclusion:

Patients with cerebellar plexus papilloma need long-term follow-up comprising regular magnetic resonance imagings since, in patients with a history of CPP, any new mild symptomatology, even years after the initial presentation, may be an early sign of tumor recurrence.

Primary infratentorial diffuse large b-cell lymphoma: a challenging diagnosis in an immunocompetent patient

We describe the case of a female patient, 52 years old, with dizziness and left motor incoordination for 2 weeks. Brain MRI magnetic resonance imaging) revealed a hyperintense lesion on T2-weighted images, without restricted diffusion, in the left middle cerebellar peduncle. Spectroscopy demonstrated peak of lipids and perfusion did not show any elevation in relative cerebral blood volume (rCBV). The patient underwent an open biopsy and resection, and the diagnosis of diffuse large B-cell lymphoma (DLBCL) was established. The patient received intravenous dexamethasone with symptoms remission, followed by four cycles of methotrexate plus cytarabine. After 3 months, the patient returned with decreased consciences level and a new MRI revealed a right superior frontal gyrus lesion with features suggesting a lymphomatous lesion. The patient died five days after her relapse.

Voxel-based meta-analysis of gray and white matter volume abnormalities in spinocerebellar ataxia type 2

OBJECTIVE

To identify the consistent findings from the whole-brain voxel-based morphometry (VBM) studies on spinocerebellar ataxia type 2 (SCA2).

METHODS

The whole-brain VBM studies comparing SCA2 patients and healthy controls (HCs) were systematically searched in PubMed, Embase databases from January 2000 to June 2017. The coordinates with significant differences in gray matter (GM) and white matter (WM) between SCA2 patients and HCs were extracted separately from each cluster. A meta-analysis was performed using anisotropic effect size-based signed differential mapping (AES-SDM) software.

RESULTS

A total of five studies with 65 SCA2 patients and 124 HCs were included in the GM meta-analysis. Four of the five studies with 50 SCA2 patients and 109 HCs were included in the WM meta-analysis. Significant and consistent GM volume reductions were detected in bilateral cerebellar hemispheres, cerebellar vermis, the right fusiform gyrus, the right parahippocampal gyrus, and the right lingual gyrus. The WM volume reductions were observed in bilateral cerebellar hemispheres, cerebellar vermis, middle cerebellar peduncles, pons, and bilateral cortico-spinal projections. The findings of the study remained largely unchanged in jackknife sensitivity analysis.

CONCLUSIONS

The consistent findings from our meta-analysis showed that GM volume reductions in SCA2 patients were not limited in cerebellum while significant WM volume reductions widely existed in cerebellum and pyramidal system. The findings provide morphological basis for further studies on SCA2.

Main inherited neurodegenerative cerebellar ataxias, how to recognize them using magnetic resonance imaging?

Ataxia is a neurodegenerative disease resulting from brainstem, cerebellar, and/or spinocerebellar tracts impairments. Symptoms onset could vary widely from childhood to late-adulthood. Autosomal cerebellar ataxias are considered as one of the most complex group in neurogenetics. In addition to their genetic heterogeneity, there is an important phenotypic variability in the expression of cerebellar impairment, complicating the genetic mutation research. A pattern recognition approach using brain MRI measures of atrophy, hyperintensities and iron-induced hypointensity of the dentate nuclei, could be therefore helpful in guiding genetic research. This review will discuss a pattern recognition approach that, associated with the age at disease onset, and clinical manifestations, may help neuroradiologists differentiate the most frequent profiles of ataxia.

Stroke Mimics: The Quest for Leptomeningeal Anastomoses and Isolated Diffusion-Weigthed MR Signal

Stroke is caused by occlusion of a medium- or large-sized vessel in the brain. The treatment with either intravenous or intra-arterial thrombolysis is based on an accurate and time-sensitive diagnosis. On clinical and imaging grounds a number of entities-seizures, toxic-metabolic, infectious, or demyelinating diseases-can mimic stroke. Identifying them is paramount as the treatment differs significantly. Prior imaging reviews have focused on the nonterritorial distribution of these mimics. However, some important questions arise here. Are the vascular territories and their boundaries invariable in the human brain? Where should we draw the lines separating arterial territories? van der Zwan and colleagues addressed these questions decades ago. For him and others, the leptomeningeal anastomoses-a contentious concept for some but increasingly linked to collateral flow in stroke-is an important anatomic structure with significant variations in their distribution and pathophysiology. Variations in blood supply appear larger that traditionally taught. We revisit this concept and entertained their implications in cases of stroke mimics. For instance, the distribution of abnormalities in some toxic-metabolic processes appear to correlate with areas where rich leptomeningeal anastomoses are expected. We will also explore the concept of hyperintense signal on diffusion weighted-imaging with no correlated changes on apparent diffusion coefficient maps. We name this finding as "isolated DWI signal" and lay-out its importance in the recognition of many entities mimicking stroke. Taking together, the discussed anatomic and imaging concepts will help radiologists and clinicians to recognize not only the common but the unusual entities imitating stroke in the emergency room.

A novel homozygous MFN2 mutation associated with severe and atypical CMT2 phenotype

BACKGROUND

Charcot-Marie-Tooth (CMT) neuropathies represent the most common forms of inherited polyneuropathies. CMT2A, the axonal form, accounts for about one third of all CMT cases. Variants in the MFN2 gene have been recognized to be a major cause of CMT2A. To date, more than 100 pathogenetic mutations in MFN2 have been identified, leading to different neurological clinical spectrum, varying from hereditary neuropathies to more severe clinical phenotypes. Pathogenic variants in MFN2 mainly act in a dominant manner, although in a few sporadic or familial cases, homozygous or compound heterozygous mutations have been reported.

RESULTS

We describe a child carrying a novel homozygous MFN2 mutation leading to an early-onset sensorimotor axonal neuropathy with an atypical and severe phenotype.

CONCLUSION

The case highlights a very rare mechanism of inheritance for MFN2 mutations and expands the clinical and allelic variance of severe CMT2A phenotype. Moreover, it proposes the involvement of cerebellar peduncles observed at neuroimaging as a novel clue to suspect the diagnosis and address genetic testing.

Subacute Sclerosing Panencephalitis of the Brainstem as a Clinical Entity

Subacute sclerosing panencephalitis (SSPE) is a rare progressive neurological disorder of early adolescence caused by persistent infection of the measles virus, which remains prevalent worldwide despite an effective vaccine. SSPE is a devastating disease with a characteristic clinical course in subcortical white matter; however, atypical presentations of brainstem involvement may be seen in rare cases. This review summarizes reports to date on brainstem involvement in SSPE, including the clinical course of disease, neuroimaging presentations, and guidelines for treatment. A comprehensive literature search was performed for English-language publications with keywords “subacute sclerosing panencephalitis” and “brainstem” using the National Library of Medicine PubMed database (March 1981–September 2017). Eleven articles focusing on SSPE of the brainstem were included. Predominant brainstem involvement remains uncharacteristic of SSPE, which may lead to misdiagnosis and poor outcome. A number of case reports have demonstrated brainstem involvement associated with other intracranial lesions commonly presenting in later SSPE stages (III and IV). However, brainstem lesions can appear in all stages, independent of higher cortical structures. The varied clinical presentations complicate diagnosis from a neuroimaging perspective. SSPE of the brainstem is a rare but important clinical entity. It may present like canonical SSPE or with unique clinical features such as absence seizures and pronounced ataxia. While SSPE generally progresses to the brainstem, it can also begin with a primary focus of infection in the brainstem. Awareness of varied SSPE presentations can aid in early diagnosis as well as guide management and treatment.

The Pediatric Cerebellum in Inherited Neurodegenerative Disorders: A Pattern-recognition Approach

Evaluation of imaging studies of the cerebellum in inherited neurodegenerative disorders is aided by attention to neuroimaging patterns based on anatomic determinants, including biometric analysis, hyperintense signal of structures, including the cerebellar cortex, white matter, dentate nuclei, brainstem tracts, and nuclei, the presence of cysts, brain iron, or calcifications, change over time, the use of diffusion-weighted/diffusion tensor imaging and T2*-weighted sequences, magnetic resonance spectroscopy; and, in rare occurrences, the administration of contrast material.

Extensive Microhemorrhages of the Cerebellar Peduncles After High-Altitude Cerebral Edema

Pichler Hefti, Jacqueline, Philipp Hoigné-Perret, and Raimund Kottke. Extensive microhemorrhages of the cerebellar peduncles after high-altitude cerebral edema. High Alt Med Biol. 18:182-184, 2017.-Neuromagnetic resonance imaging (MRI) of subjects who suffered from high-altitude cerebral edema (HACE) typically shows cerebral microhemorrhages (MH) of the corpus callosum, in particular the splenium, and supratentorial white matter. This is a case report of a 43-year-old male, who suffered from unusually prolonged severe ataxia and amnesia after having been rescued during the ascent to Mount Everest at 6400 m. MRI of the brain 63 days after the incident showed the typical MH in the corpus callosum, but, in addition, extensive MH were found in the middle cerebellar peduncles. These infratentorial MH might reflect the pronounced atactic gait disorder. This case describes the first HACE-associated MH in the cerebellar peduncles in a high-altitude mountaineer indicating a potential vulnerability of infratentorial brain areas to hypobaric hypoxia.