Middle Cerebellar Peduncle Research Articles

Structural connectivity at term equivalent age and language in preterm children at 2 years corrected

Abstract We previously reported interhemispheric structural hyperconnectivity bypassing the corpus callosum in children born extremely preterm (EPT, <28 weeks) versus term children. This increased connectivity was positively associated with language performance at 4 to 6 years of age in our prior work. In the present study, we aim to investigate whether this extracallosal connectivity develops in EPT at term-equivalent age (TEA) by leveraging a prospective cohort study of 350 very and extremely preterm infants followed longitudinally in the Cincinnati Infant Neurodevelopment Early Prediction Study. For this secondary analysis, we included only children born EPT and without significant brain injury (n=95). We use higher-order diffusion modeling to assess the degree to which extracallosal pathways are present in EPT infants and predictive of later language scores at 22-26 months corrected age. We compare results obtained from two higher-order diffusion models: generalized q-sampling imaging (GQI) and constrained spherical deconvolution (CSD). Advanced magnetic resonance imaging was obtained at TEA (39-44 weeks post-menstrual age, PMA). For structural connectometry analysis, we assessed the level of correlation between white matter connectivity at the whole brain level at TEA and language scores at 2 years corrected age, controlling for PMA, sex, brain abnormality score, and social risk. For our CSD analyses, we performed connectivity-based fixel enhancement (CBFE), using probabilistic tractography to inform statistical testing of the hypothesis that fiber metrics at TEA relate to language scores at 2 years corrected age after adjusting for covariates. 95 infants were EPT with no significant brain injury. Of these, 53 had complete neurodevelopmental and imaging datasets that passed quality control. In the connectometry analyses adjusted for covariates and multiple comparisons (p<0.05), the following tracks were inversely correlated with language: bilateral cerebellar white matter and middle cerebellar peduncles, bilateral corticospinal tracks, posterior commissure, and the posterior inferior fronto-occipital fasciculus (IFOF). No tracks from the CSD/CBFE analyses remained significant after correction for multiple comparisons. Our findings provide critical information about the ontogeny of structural brain networks supporting language in EPT. Greater connectivity in more posterior tracks that include the cerebellum and connections to the regions of the temporal lobes at TEA appears to be disadvantageous for language development.

Microstructural Properties of the Cerebellar Peduncles in Children with Developmental Language Disorder

Abstract Children with developmental language disorder (DLD) struggle to learn their native language for no apparent reason. While research on the neurobiological underpinnings of the disorder has focused on the role of cortico-striatal systems, little is known about the role of the cerebellum in DLD. Cortico-cerebellar circuits might be involved in the disorder as they contribute to complex sensorimotor skill learning, including the acquisition of spoken language. Here, we used diffusion-weighted imaging data from 77 typically developing and 54 children with DLD and performed probabilistic tractography to identify the cerebellum’s white matter tracts: the inferior, middle, and superior cerebellar peduncles. Children with DLD showed lower fractional anisotropy (FA) in the inferior cerebellar peduncles (ICP), fiber tracts that carry motor and sensory input via the inferior olive to the cerebellum. Lower FA in DLD was driven by lower axial diffusivity. Probing this further with more sophisticated modeling of diffusion data, we found higher orientation dispersion but no difference in neurite density in the ICP of DLD. Reduced FA is therefore unlikely to be reflecting microstructural differences in myelination, rather the organization of axons in these pathways is disrupted. ICP microstructure was not associated with language or motor coordination performance in our sample. We also found no differences in the middle and superior peduncles, the main pathways connecting the cerebellum with the cortex. To conclude, it is not cortico-cerebellar but atypical olivocerebellar white matter connections that characterize DLD and suggest the involvement of the olivocerebellar system in speech and language acquisition and development.

Deep Learning-based Approach for Brainstem and Ventricular MR Planimetry: Application in Patients with Progressive Supranuclear Palsy.

"Just Accepted" papers have undergone full peer review and have been accepted for publication in Radiology: Artificial Intelligence. This article will undergo copyediting, layout, and proof review before it is published in its final version. Please note that during production of the final copyedited article, errors may be discovered which could affect the content. Purpose To develop a fast and fully automated deep learning (DL)-based method for the MRI planimetric segmentation and measurement of the brainstem and ventricular structures most affected in patients with progressive supranuclear palsy (PSP). Materials and Methods In this retrospective study, T1-weighted MR images from healthy controls (n=84) were used to train DL models for segmenting the midbrain, pons, middle cerebellar peduncles (MCP), superior cerebellar peduncle (SCP), third ventricle (3rd V) and frontal horns (FHs). Internal, external and clinical test datasets (n=305) were used to assess segmentation model reliability. DL masks from test datasets were used to automatically extract midbrain and pons areas and the width of MCP, SCP, 3rd V and FHs. Automated measurements were compared with those manually performed by an expert radiologist. Finally, these measures were combined to calculate the midbrain-to-pons area ratio, magnetic resonance parkinsonism index (MRPI) and MRPI 2.0, which were used to differentiate patients with PSP (n=71) from those with Parkinson's disease (PD, n=129). Results Dice coefficients above 0.85 were found for all brain regions when comparing manual and DL-based segmentations. A strong correlation was observed between automated and manual measurements (Spearman's Rho>0.80, p<0.001). DL-based measurements showed excellent performance in differentiating patients with PSP from those with PD, with an area under the receiver operating characteristic curve above 0.92. Conclusion Automated approach successfully segmented and measured the brainstem and ventricular structures. DL-based models may represent a useful approach to support the diagnosis of PSP and potentially other conditions associated with brainstem and ventricular alterations. ©RSNA, 2024.

18F-FDG Brain PET/MRI in Chronic Lymphocytic Inflammation With Pontine Perivascular Enhancement Responsive to Steroids.

An 89-year-old man presented with progressive gait disturbance, diplopia, and ataxia. Initial brain MRI demonstrated T2/FLAIR hyperintense signal abnormality in the pons extending along the middle cerebellar peduncles into the cerebellum, with associated punctate, patchy, and linear enhancement on postcontrast imaging. Initially, this was attributed to brainstem encephalitis; however, sarcoidosis, histiocytosis, and paraneoplastic/autoimmune encephalitis remained on the differential. One month after initial MRI, 18F-FDG brain PET/MRI was performed and showed marked pontine hypermetabolism corresponding to the signal abnormality and enhancement on structural imaging. Collectively, these findings are characteristic of chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids.

Dominant CST3 variants cause adult onset leukodystrophy without amyloid angiopathy.

Leukodystrophies are rare genetic white matter disorders that have been regarded as mainly occurring in childhood. Recent years altered this perception, as a growing number of leukodystrophies was described to have an onset at adult ages. Still, many adult patients presenting with white matter changes remain without a specific molecular diagnosis. We describe a novel adult onset leukodystrophy in 16 patients from eight families carrying one of four different stop-gain or frameshift dominant variants in the CST3 gene. Clinical and radiological features differ markedly from the previously described Icelandic Cerebral Amyloid Angiopathy that was found in patients carrying p.Leu68Asn substitution in CST3. The clinical phenotype consists of recurrent episodes of hemiplegic migraine associated with transient unilateral focal deficits and slowly progressing motor symptoms and cognitive decline in mid-old adult ages. In addition, in some cases acute onset clinical deterioration led to a prolonged episode with reduced consciousness and even early death. Radiologically, pathognomonic changes are found at typical predilection sites involving the deep cerebral white matter sparing a periventricular and directly subcortical rim, the middle blade of corpus callosum, posterior limb of the internal capsule, middle cerebellar peduncles, cerebral peduncles, and specifically the globus pallidus. Histopathologic characterization in two autopsy cases did not reveal angiopathy, but instead micro- to macrocystic degeneration of the white matter. Astrocytes were activated at early stages and later on displayed severe degeneration and loss. In addition, despite loss of myelin, elevated numbers of partly apoptotic oligodendrocytes were observed. A structural comparison of the variants in CST3 suggests that specific truncations of Cystatin C result in an abnormal function, possibly by rendering the protein more prone to aggregation. Future studies are required to confirm the assumed effect on the protein and to determine pathophysiologic downstream events at the cellular level.

Amyloid pathology and vascular risk are associated with distinct patterns of cerebral white matter hyperintensities: A multicenter study in 3132 memory clinic patients.

White matter hyperintensities (WMH) are associated with key dementia etiologies, in particular arteriolosclerosis and amyloid pathology. We aimed to identify WMH locations associated with vascular risk or cerebral amyloid-β1-42 (Aβ42)-positive status. Individual patient data (n=3,132; mean age 71.5±9 years; 49.3% female) from 11 memory clinic cohorts were harmonized. WMH volumes in 28 regions were related to a vascular risk compound score (VRCS) and Aß42 status (based on cerebrospinal fluid or amyloid positron emission tomography), correcting for age, sex, study site, and total WMH volume. VRCS was associated with WMH in anterior/superior corona radiata (B = 0.034/0.038, p<0.001), external capsule (B = 0.052, p<0.001), and middle cerebellar peduncle (B = 0.067, p<0.001), and Aß42-positive status with WMH in posterior thalamic radiation (B = 0.097, p<0.001) and splenium (B = 0.103, p<0.001). Vascular risk factors and Aß42 pathology have distinct signature WMH patterns. This regional vulnerability may incite future studies into how arteriolosclerosis and Aß42 pathology affect the brain's white matter. Key dementia etiologies may be associated with specific patterns of white matter hyperintensities (WMH). We related WMH locations to vascular risk and cerebral Aβ42 status in 11 memory clinic cohorts. Aβ42 positive status was associated with posterior WMH in splenium and posterior thalamic radiation. Vascular risk was associated with anterior and infratentorial WMH. Amyloid pathology and vascular risk have distinct signature WMH patterns.

Neglected tracts of the brainstem: transverse peduncular tract of Gudden and taenia pontis.

The anatomy and function of the brainstem have fascinated scientists for centuries; however, the brainstem remains one of the least studied regions of the human brain. As the authors delved into studying this structure, they observed a growing tendency to forget or neglect previously identified structures. The aim of this study was to describe two such structures: the transverse peduncular tract, also known as the Gudden tract, and the taenia pontis. The authors analyzed the potential effects of neglecting these structures during brainstem surgery and the implications for clinical practice. After removal of the arachnoid and vascular structures, 20 human brainstem specimens were frozen and stored at -16°C for 2 weeks, according to the method described by Klingler. The specimens were then thawed and dissected with microsurgical techniques. The results of microsurgical fiber dissection at each step were photographed. This study revealed two previously neglected or forgotten structures within the brainstem. The first is the transverse peduncular tract of Gudden, which arises from the brachium of the superior colliculus. This tract follows an arcuate course along the lateral and ventral surfaces of the midbrain, perpendicular to the cerebral peduncle, and terminates in the nuclei of the transverse peduncular tract within the interpeduncular fossa. The second structure is the taenia pontis, which originates contralaterally in the interpeduncular fossa. It becomes visible at the level of the pontomesencephalic sulcus and extends to the base of the lateral mesencephalic sulcus, where it divides into several thin bundles. Along the interpeduncular sulcus, between the superior and middle cerebellar peduncles, it reaches the parabrachial recess and enters the cerebellum. Recently, with increasing understanding and expertise in brainstem research, surgical approaches to this area have become more common, emphasizing the importance of a detailed knowledge of the brainstem. The two structures mentioned in this paper are described in history books and were widely studied in the 19th century but have not been mentioned in modern literature. The authors propose that a deeper understanding of these structures may prove valuable in neurosurgical practice and help reduce patient comorbidity.

Case report: Cystic vestibular schwannoma

Background: Cerebellopontine angle tumors are a severe condition because of their life-threatening and functional loss potential, explained by the narrowness of the posterior fossa. The vestibular schwannoma, or acoustic neuroma, is a benign, well-circumscribed extraaxial tumor that arises from Schwann cells of the vestibulocochlear cranial nerve. The tumor is usually mainly solid, but can sometimes develop small cystic areas, due to degenerative modifications, causing microcyst formation. The coalescent of small cysts leading to forming a larger one, and responsible of a predominant cystic contingent, is rare, which makes interesting the case we are about to present. Case report: We are about to report the case of a 64-year-old male patient, with no particular medical history, which clinical interview has noted only tinnitus as a present symptom. He had experienced one year ago several disequilibrium and dizziness episodes, who have subsequently stopped over time, without any particular treatment. He also felt a little loss of hearing, especially in the left ear, but thought it was probably age related. No clinical abnormality including the facial nerve palsy was found. The MRI showed a stage 4 (Koos classification) left cystic vestibular schwannoma. This lesion was compressing the left vertebral and basilar arteries, the brain stream, the left cerebellar hemisphere, the left middle cerebellar peduncle, and the fourth ventricle, causing a triventricular hydrocephalus. After reviewing all potential therapeutic options, the patient declined surgery and decided to postpone the treatment. Conclusion: MRI is definitely the best way to explore the posterior fossa, especially the cerebellopontine angle, and helps us differentiate between all numerous tumors than can develop in this space.

Retrosigmoid Transmiddle Cerebellar Peduncle Approach for Resection of a Giant Pontine Cavernous Malformation: 2-Dimensional Operative Video.

Pioneering work in defining brainstem safe entry zones and development of surgical techniques has made microsurgical removal of brainstem cavernous malformation possible.1,2 The middle cerebellar peduncle (MCP) is a robust route for access to deep-seated lesions within the pons. The peduncle can be accessed by splitting the petrosal fissure of the cerebellum to obtain a more direct view to the MCP through a retrosigmoid approach. The author presents a case of a female with a history of 3 bleeds attributable to a giant pontine cavernous malformation. The patient consented to the procedure. Given the aggressive natural history of deep cavernous malformations, especially in the year following a bleed, surgical removal was recommended. Step-by-step description of access to the MCP through splitting the petrosal fissure, and key steps for removal of a pontine cavernous malformation are described.

Cerebellar symptoms after dengue fever with bright middle cerebellar peduncle sign

Dengue fever is a seasonal epidemic that effects population all across Pakistan every monsoon season and leads to thousands of cases every year. Dengue fever can be associated with neurological complications both during the acute stage and after recovery. These include encephalitis and hemorrhagic complications as well as late immune-related conditions such as Guillain-Barre syndrome and acute disseminated encephalomyelitis. Here we present case of a patient who developed new onset cerebellar symptoms two weeks after recovery from dengue fever, with a middle cerebellar peduncle sign on MRI Brain.

Unusual PSMA uptake in seronegative paraneoplastic brainstem encephalitis: A case report

Paraneoplastic encephalitis, especially seronegative, is a heterogeneous group of disorders with varied symptoms at presentation. We present the case of a 63-year-old male who presented with motor weakness and altered sensorium. Magnetic resonance imaging of the brain showed altered signal intensity in the midbrain, pons, anterior part of the medulla, and bilateral middle cerebellar peduncle. T2 hyperintensity was also seen in the bilateral basal ganglia and internal capsule region. 18 fluoro-deoxyglucose positron emission tomography/computed tomography (18 FDG PET/CT) showed increased FDG uptake in the brain stem, left thalamus, and periventricular location. 68Ga-prostate-specific membrane antigen (PSMA) PET/CT done in view of elevated serum Prostate-specific antigen levels show a focal PSMA-avid lesion in the prostate gland and increased PSMA uptake in the brain stem, which is an atypical site of PSMA uptake. Our study highlights the importance of paraneoplastic syndromes with varied clinical presentation and low specificity to antibodies. These spectra of diseases are fatal but treatable and therefore should be evaluated diligently to reduce morbidity

Hot cross bun in pediatric age multi-system atrophy an unusual presentation

A 10-year-old female was brought to emergency department with complaint fever, cold, and cough for 5 days followed by weakness of upper limb weakness more than Lower limb associated with inability to walk/stand, brought to emergency with altered sensorium. Nervous system: Confused and altered, tone is normal, power: 3/3 in upper limbs 2/2 in lower limbs and reflexes in bilateral knee brisk, bilateral plantar-extensor; On general examination revealed hypomimia, dysarthria and bilateral bradykinesia along with ataxic gait and pyramidal signs. Blood investigation were normal and diagnosis made by neuroimaging s/o: Bilaterally symmetrical abnormal signal in both postero-medial thalami, bilateral insular cortices, pons and bilateral middle cerebellar peduncles. It is extending into pons involving transverse pontocerebellar tracts and median pontine raphe nuclei giving 'Hot cross bun sign' (HCBS). During course of treatment child had autonomic disturbances. Child was treated with supportive medication and methyl-presdnisolone followed by oral steroid. Child had responded to treatment given and child has been discharged with no neurological deficit on oral medications. We concluded autonomic dysfunction in any patient presenting with acute onset of weakness with short duration must evaluate for MSA and institute appropriate treatment.

Differentiation between Parkinson's Disease and the Parkinsonian Subtype of Multiple System Atrophy Using the Magnetic Resonance T1w/T2w Ratio in the Middle Cerebellar Peduncle.

Multiple system atrophy with predominant parkinsonism (MSA-P) can hardly be distinguished from Parkinson's disease (PD) clinically in the early stages. This study investigated whether a standardized T1-weighted/T2-weighted ratio (sT1w/T2w ratio) can effectively detect degenerative changes in the middle cerebellar peduncle (MCP) associated with MSA-P and PD and evaluated its potential to distinguish between these two diseases. We included 35 patients with MSA-P, 32 patients with PD, and 17 controls. T1w and T2w scans were acquired using a 1.5-T MR system. The MCP sT1w/T2w ratio was analyzed via SPM12 using a region-of-interest approach in a normalized space. The diagnostic performance of the MCP sT1w/T2w ratio was compared between the MSA-P, PD, and controls. Patients with MSA-P had significantly lower MCP sT1w/T2w ratios than patients with PD and controls. Furthermore, MCP sT1w/T2w ratios were lower in patients with PD than in the controls. The MCP sT1w/T2w ratio showed excellent or good accuracy for differentiating MSA-P or PD from the control (area under the curve (AUC) = 0.919 and 0.814, respectively) and substantial power for differentiating MSA-P from PD (AUC = 0.724). Therefore, the MCP sT1w/T2w ratio is sensitive in detecting degenerative changes in the MCP associated with MSA-P and PD and is useful in distinguishing MSA-P from PD.

Significant tumor compression of the middle cerebellar peduncle is associated with worse facial nerve outcomes and lower extent of resection in surgery for medium-sized vestibular schwannomas – A radiographic analysis of a case series

Background and ObjectiveOptimizing the extent of resection (EOR) and facial nerve outcomes (FNO) remain a challenge in medium to large vestibular schwannomas (VS). Currently, tumor size has been the only consistently reported factor predicting FNO and EOR. Here, we sought to evaluate whether the degree of the tumor’s compression on the middle cerebellar peduncle (PC) influences FNO and EOR in medium to large VS. MethodsThis retrospective case series included 99 patients who underwent surgical resection of their VSs from 2014 to 2022. Preoperative MR imaging was used to measure the degree of PC. Patient medical records were queried to determine the EOR and FNO. ResultsPatients with unfavorable FNO (HB 3 +) immediately post-op had significantly greater PC than those with favorable FNO (19.9 vs. 15.4 mm, P = .047). This significance was not observed at the last follow-up but there was a trend. When medium-sized tumors (15–30 mm) were analyzed separately, patients with unfavorable FNO immediate post-op and at last follow-up had significantly greater PC than their favorable counterparts (14.1 vs 8.7 mm). Significantly greater PC was also observed in patients who underwent subtotal resection (20.7 mm) compared to near (14.3 mm) and gross total resection (10.8 mm). Multivariate analyses confirmed these findings in medium-sized tumors, but not large-sized tumors. ConclusionThe degree of PC as measured on preoperative imaging can predict FNO and EOR in medium-sized vestibular schwannomas. Medium-sized tumors with > 15 mm of PC likely will have worse FNO and lower EOR.

Advanced Cognitive Patterns in Multiple System Atrophy Compared to Parkinson’s Disease: An Individual Diffusion Tensor Imaging Study

Although both Multiple system atrophy (MSA) and Parkinson's disease (PD) belong to alpha-synucleinopathy, they have divergent clinical courses and prognoses. The degeneration of white matter has a considerable impact on cognitive performance, yet it is uncertain how PD and MSA affect its functioning in a similar or different manner. In this study, a total of 116 individuals (37 PD with mild cognitive impairment (PD-MCI), 37 MSA (parkinsonian variant) with mild cognitive impairment (MSA-MCI), and 42 healthy controls) underwent diffusion tensor imaging (DTI) and cognitive assessment. Utilizing probabilistic fiber tracking, association fibers, projection fibers, and thalamic fibers were reconstructed. Subsequently, regression, support vector machine, and SHAP (Shapley Addictive exPlanations) analyzes were conducted to evaluate the association between microstructural diffusion metrics and multiple cognitive domains, thus determining the white matter predictors of MCI. MSA-MCI patients exhibited distinct white matter impairment extending to the middle cerebellar peduncle, corticospinal tract, and cingulum bundle. Furthermore, the fractional anisotropy (FA) and mean diffusivity (MD)values of the right anterior thalamic radiation were significantly associated with global efficiency (FA: B=0.69, P<0.001, VIF=1.31; MD: B=-0.53, P=0.02, VIF=2.50). The diffusion metrics of white matter between PD-MCI and MSA-MCI proved to be an effective predictor of the MCI, with an accuracy of 0.73 (P<0.01), and the most predictive factor being the MD of the anterior thalamic radiation. Our results demonstrated that MSA-MCI had a more noticeable deterioration in white matter, which potentially linked to various cognitive domain connections. Diffusion MRI could be a useful tool in comprehending the neurological basis of cognitive impairment in Parkinsonian disorders.

Rates of change of pons and middle cerebellar peduncle diameters are diagnostic of multiple system atrophy of the cerebellar type.

Definitive diagnosis of multiple system atrophy of the cerebellar type (MSA-C) is challenging. We hypothesized that rates of change of pons and middle cerebellar peduncle diameters on MRI would be unique to MSA-C and serve as diagnostic biomarkers. We defined the normative data for anterior-posterior pons and transverse middle cerebellar peduncle diameters on brain MRI in healthy controls, performed diameter-volume correlations and measured intra- and inter-rater reliability. We studied an Exploratory cohort (2002-2014) of 88 MSA-C and 78 other cerebellar ataxia patients, and a Validation cohort (2015-2021) of 49 MSA-C, 13 multiple system atrophy of the parkinsonian type (MSA-P), 99 other cerebellar ataxia patients and 314 non-ataxia patients. We measured anterior-posterior pons and middle cerebellar peduncle diameters on baseline and subsequent MRIs, and correlated results with Brief Ataxia Rating Scale scores. We assessed midbrain:pons and middle cerebellar peduncle:pons ratios over time. The normative anterior-posterior pons diameter was 23.6 ± 1.6 mm, and middle cerebellar peduncle diameter 16.4 ± 1.4 mm. Pons diameter correlated with volume, r = 0.94, P < 0.0001. The anterior-posterior pons and middle cerebellar peduncle measures were smaller at first scan in MSA-C compared to all other ataxias; anterior-posterior pons diameter: Exploratory, 19.3 ± 2.6 mm versus 20.7 ± 2.6 mm, Validation, 19.9 ± 2.1 mm versus 21.1 ± 2.1 mm; middle cerebellar peduncle transverse diameter, Exploratory, 12.0 ± 2.6 mm versus 14.3 ±2.1 mm, Validation, 13.6 ± 2.1 mm versus 15.1 ± 1.8 mm, all P < 0.001. The anterior-posterior pons and middle cerebellar peduncle rates of change were faster in MSA-C than in all other ataxias; anterior-posterior pons diameter rates of change: Exploratory, -0.87 ± 0.04 mm/year versus -0.09 ± 0.02 mm/year, Validation, -0.89 ± 0.48 mm/year versus -0.10 ± 0.21 mm/year; middle cerebellar peduncle transverse diameter rates of change: Exploratory, -0.84 ± 0.05 mm/year versus -0.08 ± 0.02 mm/year, Validation, -0.94 ± 0.64 mm/year versus -0.11 ± 0.27 mm/year, all values P < 0.0001. Anterior-posterior pons and middle cerebellar peduncle diameters were indistinguishable between Possible, Probable and Definite MSA-C. The rate of anterior-posterior pons atrophy was linear, correlating with ataxia severity. Using a lower threshold anterior-posterior pons diameter decrease of -0.4 mm/year to balance sensitivity and specificity, area under the curve analysis discriminating MSA-C from other ataxias was 0.94, yielding sensitivity 0.92 and specificity 0.87. For the middle cerebellar peduncle, with threshold decline -0.5 mm/year, area under the curve was 0.90 yielding sensitivity 0.85 and specificity 0.79. The midbrain:pons ratio increased progressively in MSA-C, whereas the middle cerebellar peduncle:pons ratio was almost unchanged. Anterior-posterior pons and middle cerebellar peduncle diameters were smaller in MSA-C than in MSA-P, P < 0.001. We conclude from this 20-year longitudinal clinical and imaging study that anterior-posterior pons and middle cerebellar peduncle diameters are phenotypic imaging biomarkers of MSA-C. In the correct clinical context, an anterior-posterior pons and transverse middle cerebellar peduncle diameter decline of ∼0.8 mm/year is sufficient for and diagnostic of MSA-C.

Features of trigeminal nerve exit on the base of the brain: neurovascular conflict

The trigeminal nerve is a complex anatomical formation that performs very important tasks in terms of functionality. This article focuses on the study of the exit of the trigeminal nerve and its syntopy with arteries. It is the study of the location of nearby vessels relative to the nerve and their neurovascular conflict that determines the relevance of this work. The prevalence of trigeminal neuralgia (TN) is quite high and amounts to 40–60 patients per 100,000 population, and the incidence according to the World Health Organization is within 2–4 people per 10,000 population. The maximum risk of neurovascular conflict is observed in the age group of people from 45 to 60 years. It is also known that women suffer from neuralgia significantly more often than men. Not only the exact diagnosis, but also the selection of the most appropriate treatment tactics will depend on the result of studies of the individual anatomical features of the pons area. The authors of the article studied 17 preparations of the base of the brain of middle-aged individuals, fixed in a 7 % formalin solution. Of the 17 preparations studied, neurovascular relationships were noted in 14, which is 82.4 % of the total. As a result of morphometric measurements, the data on the length and width of the pons, the thickness of the trigeminal nerve roots, and the middle cerebellar peduncles were obtained. Statistical data processing and photographic documentation were carried out. The clinical manifestations of the disease, diagnostic options, and various methods of treatment were considered. The most effective method of treating neurovascular conflict is surgery, the first mention of which dates back to 1934.

The Contributions of the Cerebellar Peduncles and the Frontal Aslant Tract in Mediating Speech Fluency

Abstract Fluent speech production is a complex task that spans multiple processes, from conceptual framing and lexical access, through phonological encoding, to articulatory control. For the most part, imaging studies portraying the neural correlates of speech fluency tend to examine clinical populations sustaining speech impairments and focus on either lexical access or articulatory control, but not both. Here, we evaluated the contribution of the cerebellar peduncles to speech fluency by measuring the different components of the process in a sample of 45 neurotypical adults. Participants underwent an unstructured interview to assess their natural speaking rate and articulation rate, and completed timed semantic and phonemic fluency tasks to assess their verbal fluency. Diffusion magnetic resonance imaging with probabilistic tractography was used to segment the bilateral cerebellar peduncles (CPs) and frontal aslant tract (FAT), previously associated with speech production in clinical populations. Our results demonstrate distinct patterns of white matter associations with different fluency components. Specifically, verbal fluency is associated with the right superior CP, whereas speaking rate is associated with the right middle CP and bilateral FAT. No association is found with articulation rate in these pathways, in contrast to previous findings in persons who stutter. Our findings support the contribution of the cerebellum to aspects of speech production that go beyond articulatory control, such as lexical access, pragmatic or syntactic generation. Further, we demonstrate that distinct cerebellar pathways dissociate different components of speech fluency in neurotypical speakers.

Progressive white matter degeneration in patients with spinocerebellar ataxia type 2.

Spinocerebellar ataxia type 2 (SCA2) is a progressive neurodegenerative disorder characterized by cerebellar atrophy. However, studies to elucidate the longitudinal progression of the neuropathology are limited. We sought to identify brain macrostructural and microstructural alterations in patients with SCA2 using fixel-based analysis (FBA) to better understand its distribution patterns and progression. We enrolled 9 patients with SCA2 and 16 age- and gender-matched controls. Longitudinal clinical and imaging data were collected at baseline, and 3.5 years later. Fiber density (FD), fiber-bundle cross-section (FC), and a combination of FD and FC (FDC) were calculated. The paired t-test was used to examine longitudinal differences. The associations between fixel-based metrics and clinical variables were explored in SCA2 patients. At baseline, patients with SCA2 displayed multiple white matter tracts with significantly decreased FD, FC, and FDC in the corticospinal tract, cerebellar peduncles, brainstem, corpus callosum, thalamus, striatum, and prefrontal cortex, compared to controls. Over time, many of these macrostructural and microstructural alterations progressed, manifesting lower FD, FC, and FDC in corticospinal tract, middle cerebellar peduncle, brainstem, striatum, fornix, and cingulum. No significant brain white matter alterations were found in the healthy controls over time. There was no association between the FBA-derived metrics and clinical variables in SCA2. This study provides evidence of brain macrostructural and microstructural alterations and of progression over time in SCA2. The FBA-derived metrics may serve as potential biomarkers of SCA2 progression.

Body Mass Index, but not Visceral Abdominal Obesity and Insulin Resistance, Negatively Impacts White Matter Microstructure in Midlife

AbstractBackgroundMidlife obesity, as evidenced by high body mass index (BMI), is increasingly understood as a risk factor for development of Alzheimer’s disease. Importantly, visceral fat, by producing adipokines, contributes to inflammation as well as insulin resistance, mechanisms involved in development of Alzheimer’s disease. Herein, we aimed to assess association of white matter microstructure, measured by Diffusion tensor imaging (DTI), with obesity and abdominal adipose tissue composition at midlife.MethodA total of 34 middle‐aged (age: 51.27 ± 6.12 years, BMI: 32.28 ± 6.39 kg/m2), cognitively normal participants, underwent bloodwork, brain and abdominal MRI. Insulin resistance status was assessed using Homeostatic Model Assessment for Insulin Resistance. Abdominal visceral and subcutaneous adipose tissue (VAT, SAT) were automatically segmented using VOXel Analysis Suite (Voxa) and VAT/SAT ratio was calculated. A diffusion spectrum imaging scheme with a total of 98 diffusion samplings and a voxel size of 2 mm was acquired. Using DSI studio (https://dsi‐studio.labsolver.org/), the diffusion data were reconstructed using generalized q‐sampling imaging and the tensor metrics were calculated. Fractional anisotropy (FA), mean, axial, and radial diffusivity (MD, AD, RD, respectively) for white matter tracts were compared across study groups using one‐way ANOVA. Multiple regression models with sex, age, and education as covariates were used to assess the association of BMI, VAT/SAT ratio, and HOMA‐IR with DTI metrics.ResultOur data showed that BMI was negatively associated with AD values in right inferior fronto‐occipital fasciculus, tapetum and forceps major of Corpus Callosum (CC), superior and middle cerebellar peduncle, and bilateral reticular tract. The negative association of BMI with AD values in tapetum of CC was significant only in women. Right reticular tract MD and superior cerebellar peduncle MD and RD values were also significantly associated with BMI. There were no significant associations between neither of diffusion metrics and VAT/SAT ratio or HOMA‐IR.ConclusionAssociation of midlife obesity with lower axonal diffusivity, reflective of lower white matter integrity, with differential patterns in men and women especially in CC, is in line with previous findings in healthy individuals. Reduced axonal diffusivity in reticular and brain stem pathways could be indicative of early dysregulations observed in Alzheimer’s disease.