The Frequency of Intermediate Alleles in Patients with Cerebellar Phenotypes

Cerebellar syndromes are clinically and etiologically heterogeneous and can be classified as hereditary, neurodegenerative non-hereditary, or acquired. Few data are available on the frequency of each form in the clinical setting. Growing interest is emerging regarding the genetic forms caused by triplet repeat expansions. Alleles with repeat expansion lower than the pathological threshold, termed intermediate alleles (IAs), have been found to be associated with disease manifestation. In order to assess the relevance of IAs as a cause of cerebellar syndromes, we enrolled 66 unrelated Italian ataxic patients and described the distribution of the different etiology of their syndromes and the frequency of IAs. Each patient underwent complete clinical, hematological, and neurophysiological assessments, neuroimaging evaluations, and genetic tests for autosomal dominant cerebellar ataxia (SCA) and fragile X-associated tremor/ataxia syndrome (FXTAS). We identified the following diagnostic categories: 28% sporadic adult-onset ataxia, 18% cerebellar variant of multiple system atrophy, 9% acquired forms, 9% genetic forms with full-range expansion, and 12% cases with intermediate-range expansion. The IAs were six in the FMR1 gene, two in the gene responsible for SCA8, and one in the ATXN2 gene. The clinical phenotype of patients carrying the IAs resembles, in most of the cases, the one associated with full-range expansion. Our study provides an exhaustive description of the causes of cerebellar ataxia, estimating for the first time the frequency of IAs in SCAs- and FXTAS-associated genes. The high percentage of cases with IAs supports further screening among patients with cerebellar syndromes.

Reduced cerebral blood flow and cognitive dysfunction following isolated cerebellar infarction: two case reports

Cognitive impairment in focal cerebellar disorders has been widely recognized and is described as cerebellar cognitive affective syndrome (CCAS). However, the relationship between CCAS and crossed cerebello-cerebral diaschisis (CCD) has rarely been discussed. The present report describes the uncommon phenomenon of CCD in two cases with isolated cerebellar infarction, and discuss its contribution to cognitive impairment. Cognitive performance was examined using the CCAS scale and a battery of neuropsychological assessments. Moreover, the relative distribution of cerebral and cerebellar blood flow was measured using three-dimensional arterial spin labeling imaging. Case 1 showed deficits in general cognition and had impaired language, episodic memory, and executive function. Case 2 showed deficits in general cognition at baseline, and cognitive deterioration of visuospatial abilities, language, episodic memory, and executive function was observed at the 3-month follow-up. Both cases met the diagnosis criteria of CCAS. Reduced cerebral blood flow was observed in the cerebral hemisphere contralateral to the cerebellar infarction at baseline in Case 1, and at the 3-month follow-up in Case 2. The present report describes cognitive decline after isolated cerebellar infarction in combination with contralateral cerebral hypoperfusion, as measured using quantitative arterial spin labeling. One possible mechanism involves the functional depression of cerebello-cerebral pathways.

Cerebellar leptomeningeal enhancement: An imaging finding of rapidly progressive Purkinje cell cytoplasmic autoantibody type 1 paraneoplastic cerebellar syndrome

Purkinje cell cytoplasmic autoantibody type 1 (PCA1), also known as anti-Yo, is a 'high-risk' paraneoplastic antibody, associated with rapidly progressive cerebellar syndrome. In patients with this syndrome, various MRI abnormalities have been documented, including atrophy in the cerebellum and brainstem, T2 hyperintensity in the brainstem and spinal cord, and cranial nerve enhancement. This report introduces an imaging finding, cerebellar leptomeningeal enhancement, which was observed in all three cases at early stages. Despite neurological deterioration, all patients underwent immunotherapy, and subsequent follow-up MRI revealed resolution of the leptomeningeal enhancement, suggesting that this feature is distinct from meningeal carcinomatosis.

Mixed Aphasia Caused by Bilateral Cerebellar Infarcts: a Case Report

Although neuroanatomical and physiological understanding of the cerebellum has evolved over recent decades and continues to develop, there is much that remains to be expounded upon, especially with regard to nonmotor roles. Neurocognitive and language processing is one area where involvement of the cerebellum is no longer in question, but the extent and mechanism of this relationship have yet to be defined. For example, which of the cerebellar hemispheres is involved continues to be debated. We present a case wherein a thrombus in the basilar artery led to bihemispheric cerebellar strokes with profound mixed effects on the patient's language and cognition. To the authors' knowledge, this is the first reported case of bilateral cerebellar strokes resulting in a mixed aphasia reported in scientific literature. This demonstrates the importance of continued research into a model for cerebellar function and the clinical impact of lesions to various cerebellar regions.

A missense variant in EXOSC8 causes exon skipping and expands the phenotypic spectrum of pontocerebellar hypoplasia type 1C

Pontocerebellar hypoplasia (PCH) is a rare heterogeneous neurodegenerative disorder affecting the pons and cerebellum and is currently classified into 17 types (PCH1-PCH17). PCH1 is distinguishable from other types by the association of spinal motor neuron dysfunction. Based on the underlying genetic etiology, PCH1 is further classified into 6 different subtypes (PCH1 A-F). Of them, PCH type 1C is caused by pathogenic variants in EXOSC8 gene and so far, only four families have been described in the literature. In this study, we report a new patient with PCH1 who proved by whole-exome sequencing to harbor a novel homozygous missense variant in the splice region of EXOSC8 gene (c.238 G > A; p.Val80Ile). Studying mRNA of the patient confirmed that this variant results in skipping of exon 5 of the gene and early protein truncation. Our patient presented with the main clinical findings of PCH type 1C including psychomotor retardation, spasticity, spinal muscle atrophy, and respiratory problems. However, unlike most of the reported cases, he did not develop hearing or visual impairment and displayed a longer survival. In addition, our patient had dysmorphic facies, nystagmus, congenital esotropia and contractures which were infrequently described in patients with EXOSC8. Diaphragmatic hernia, dilated lateral ventricles, hypoplastic temporal lobes, and thinning of the brain stem were additional new findings noted in our patient. This study presents the fifth family with this extremely rare type of PCH and expands the associated clinical and brain imaging findings.

Analysis of the Clinical Features and Imaging Findings of Pontocerebellar Hypoplasia Type 2D Caused by Mutations in SEPSECS Gene

Pontocerebellar hypoplasia type 2D (PCH2D) caused by SEPSECS gene mutations is very rare and only described in a few case reports. In this study, we analyzed the clinical features and imaging findings of these individuals, so as to provide references for the clinic. We reported a case of PCH2D caused by a new complex heterozygote mutation in SEPSECS gene, and reviewed the literatures to summarize the clinical features and imaging findings and compare the differences between early-onset patients (EOPs) and late-onset patients (LOPs). Of 23 PCH2D patients, 19 cases were early-onset and 4 cases were late-onset, with average ages of 4.1 ± 4.0 years and 21.8 ± 9.4 years, females were more prevalent (14/19). EOPs mainly distributed in Arab countries (10/14) and Finland (4/14), while LOPs in East Asia (3/3). EOPs develop severe initial symptoms at the average age of 4.1 ± 7.8 months or shortly after birth, while LOPs experienced mild developmental delay in infancy. Microcephaly (10/11), intellectual disability (10/11), decreased motor function (10/11), and spastic or dystonic quadriplegia (8/10) were the common clinical features of EOPs and LOPs. EOPs also presented with visual impairment (5/7), seizures (4/7), neonatal irritability/opisthotonus (3/7), tremors/myoclonus (3/7), dysmorphic features (3/7), and other symptoms. EOPs were characterized by cerebellar symptoms (4/4). Magnetic resonance imaging (MRI) revealed progressive cerebellar atrophy followed by less pronounced cerebral atrophy, and there was no pons atrophy in LOPs. Most patients of PCH2D were severe early-onset, and a few were late-onset with milder symptoms. EOPs and LOPs shared some common clinical features and MRI findings, but also had their own characteristics.

Differentiating Genetic Forms of Pontocerebellar Hypoplasia From Acquired Lesions Resembling Pontocerebellar Hypoplasia: Clinical, Neurodevelopmental, and Imaging Insight From 19 Extremely Premature Patients

It is well established that extreme prematurity can be associated with cerebellar lesions potentially affecting the neurologic prognosis. One of the commonly observed lesions in these cases is pontocerebellar hypoplasia resulting from prematurity, which can pose challenges in distinguishing it from genetically caused pontocerebellar hypoplasia. This confusion leads to unacceptable and prolonged diagnostic ambiguity for families as well as difficulties in genetic counseling. Therefore, it is crucial to identify the clinical and neuroradiologic features allowing to differentiate between acquired and genetic forms of pontocerebellar hypoplasia in order to guide clinical practices and improve patient care. In this regard, we report in the present manuscript the clinical, developmental, and radiologic characteristics of 19 very premature children (gestational age <28 weeks, now aged 3-14 years) with cerebellar lesions and discuss the causal mechanisms. Our findings support the notion that a combination of specific clinical and radiologic criteria is essential in distinguishing between acquired and genetic forms of pontocerebellar hypoplasia.

Cerebellar Abscess Induced by Cochlear Fistula due to Chronic Suppurative Otitis Media

Cochlear fistulas with cholesteatoma as the primary disease have been reported frequently in the relevant literature. However, there are no reports of cochlear fistula without cholesteatoma due to chronic suppurative otitis media with intracranial complications. We report a case of cochlear fistula due to chronic otitis media that was diagnosed after the onset of a cerebellar abscess. The patient was a 25-year-old man with severe autism. He was admitted to our hospital with otorrhea from his left ear, emesis, and impaired consciousness. Computed tomography (CT) of the head showed left suppurative otitis media, left cerebellar abscess, and brainstem compression due to hydrocephalus. Right extra-ventricular drainage and brain abscess drainage were urgently performed. The next day, foramen magnum decompression and abscess drainage with partial resection of the swollen cerebellum were performed for decompression purposes. He was subsequently treated with antimicrobial therapy, but magnetic resonance imaging of the head showed an increase in the size of the cerebellar abscess. Re-examination of the temporal bone CT scans revealed a bony defect in the left cochlear promontory angle. We assumed that the cochlear fistula was responsible for the otogenic brain abscess. Thus, the patient underwent surgical closure of the cochlear fistula. After the operation, the cerebellar abscess lesion gradually shrank, and his general condition stabilized. Cochlear fistula should be considered in the management of patients with inflammatory middle ear disease associated with otogenic intracranial complications in the middle ear.

Cerebellar infarction caused by vertebral artery dissection: A case report

RATIONALE

Vertebral artery dissection is an important cause of posterior circulation ischemic stroke in young and middle-aged people. We reported a young man with cerebellar infarction caused by dissection of the right vertebral artery.

PATIENT CONCERNS

A 34-year-old man presented with intermittent dizziness, blurred vision, nausea, and transient tinnitus 10 days before admission. All these symptoms were gradually aggravated and followed by vomiting and unfavorable movement of the right limbs. All these symptoms gradually aggravated.

DIAGNOSIS

Neurological examination on admission showed ataxia of the right limbs. Magnetic resonance imaging of the head revealed a right cerebellar infarction. High-resolution vessel wall magnetic resonance imaging showed dissection of the right vertebral artery. Whole-brain CT digital subtraction angiography revealed occlusion of the third segment (V3) of the right vertebral artery. This supports the diagnosis of vertebral artery dissection.

INTERVENTIONS

The patient received anticoagulant treatment with warfarin.

OUTCOMES

After 2 weeks of treatment, the patient showed remarkably alleviated dizziness and unfavorable movement of the right limbs. After 3 months of treatment, the modified Rankin Scale score was 0. MRI of the head revealed that the original right cerebellar focus was softened, and there were no newly formed infarct foci.

LESSONS

When young and middle-aged patients without atherosclerotic risk factors encounter sudden dizziness, tinnitus, and unfavorable limb movement, vertebral artery dissection may be considered. Careful inquiry into the medical history may help make a final diagnosis. Further high-resolution vessel wall magnetic resonance imaging is an effective means to find arterial dissection. Early diagnosis and treatment for vertebral artery dissection has a favorable prognosis.

A presurgical voxel-wise predictive model for cerebellar mutism syndrome in children with posterior fossa tumors

BACKGROUND

This study aimed to investigate cerebellar mutism syndrome (CMS)-related voxels and build a voxel-wise predictive model for CMS.

METHODS

From July 2013 to January 2022, 188 pediatric patients diagnosed with posterior fossa tumor were included in this study, including 38 from a prospective cohort recruited between 2020 and January 2022, and the remaining from a retrospective cohort recruited in July 2013-Aug 2020. The retrospective cohort was divided into the training and validation sets; the prospective cohort served as a prospective validation set. Voxel-based lesion symptoms were assessed to identify voxels related to CMS, and a predictive model was constructed and tested in the validation and prospective validation sets.

RESULTS

No significant differences were detected among these three data sets in CMS rate, gender, age, tumor size, tumor consistency, presence of hydrocephalus and paraventricular edema. Voxels related to CMS were mainly located in bilateral superior and inferior cerebellar peduncles and the superior part of the cerebellum. The areas under the curves for the model in the training, validation and prospective validation sets were 0.889, 0.784 and 0.791, respectively.

CONCLUSIONS

Superior and inferior cerebellar peduncles and the superior part of the cerebellum were related to CMS, especially the right side, and voxel-based lesion-symptom analysis could provide valuable predictive information before surgery.

Surgical corridors for congenital aural atresia with otogenic cerebellar abscess and lateral sinus thrombosis

The following is a case report of an adolescent with mental retardation who had congenital aural atresia with contralateral congenital facial palsy. She developed multiple intracranial complications (cerebellar abscess and lateral sinus thrombosis) due to cholesteatoma. We managed her in a multidisciplinary approach. This report discusses case management, emphasising the meticulous intraoperative steps taken in identifying the landmarks and precautions adopted to avoid postoperative facial palsy and other complications.

Comparison of Cerebellar Grey Matter Alterations in Bipolar and Cerebellar Patients: Evidence from Voxel-Based Analysis

The aim of this study was to compare the patterns of cerebellar alterations associated with bipolar disease with those induced by the presence of cerebellar neurodegenerative pathologies to clarify the potential cerebellar contribution to bipolar affective disturbance. Twenty-nine patients affected by bipolar disorder, 32 subjects affected by cerebellar neurodegenerative pathologies, and 37 age-matched healthy subjects underwent a 3T MRI protocol. A voxel-based morphometry analysis was used to show similarities and differences in cerebellar grey matter (GM) loss between the groups. We found a pattern of GM cerebellar alterations in both bipolar and cerebellar groups that involved the anterior and posterior cerebellar regions (p = 0.05). The direct comparison between bipolar and cerebellar patients demonstrated a significant difference in GM loss in cerebellar neurodegenerative patients in the bilateral anterior and posterior motor cerebellar regions, such as lobules I-IV, V, VI, VIIIa, VIIIb, IX, VIIb and vermis VI, while a pattern of overlapping GM loss was evident in right lobule V, right crus I and bilateral crus II. Our findings showed, for the first time, common and different alteration patterns of specific cerebellar lobules in bipolar and neurodegenerative cerebellar patients, which allowed us to hypothesize a cerebellar role in the cognitive and mood dysregulation symptoms that characterize bipolar disorder.

A 53-Year-Old Man Presents to the ED With Shortness of Breath, Cough, and Fever

A 53-year-old man presented to the ED at a time of low severe acute respiratory syndrome coronavirus 2, also known as coronavirus disease 2019 (COVID-19), prevalence and reported 2 weeks of progressive shortness of breath, dry cough, headache, myalgias, diarrhea, and recurrent low-grade fevers to 39°C for 1 week with several days of recorded peripheral capillary oxygen saturation of 80% to 90% (room air) on home pulse oximeter. Five days earlier, he had visited an urgent care center where a routine respiratory viral panel was reportedly negative. A COVID-19 reverse transcriptase polymerase chain reaction test result was pending at the time of ED visit. He reported a past medical history of gastroesophageal reflux disease that was treated with famotidine. Travel history included an out-of-state trip 3 weeks earlier, but no recent international travel.

A First Case of Acute Cerebellitis Associated with Coronavirus Disease (COVID-19): a Case Report and Literature Review

Novel coronavirus (severe acute respiratory syndrome-coronavirus-2: SARS-CoV-2), which originated from Wuhan, China, has spread to the other countries in a short period of time. We report a 47-year-old male who was admitted to our hospital due to suffering from progressive vertigo and ataxia for 7 days prior to the admission. Neurological examination revealed cerebellar dysfunction, and brain magnetic resonance imaging (MRI) depicted edema of the cerebellar hemisphere associated with leptomeningeal enhancement. Cerebrospinal fluid (CSF) analysis showed mild lymphocytic pleocytosis, elevated protein, and lactate dehydrogenase. SARS-CoV-2 RNA was detected in the oropharyngeal/nasopharyngeal and CSF specimens. As a result, treatment with lopinavir/ritonavir was initiated, and patient symptoms and signs improved significantly during the course of hospitalization. To the best of our knowledge, this is the first case of acute cerebellitis associated with COVID-19 disease which is reported in the literature so far.

Endovascular treatment for the flow-related aneurysm originating from an anterior inferior cerebellar artery supplying the cerebellar arteriovenous malformation

BACKGROUND

When a flow-related aneurysm originates from an anterior inferior cerebellar artery (AICA) supplying the cerebellar arteriovenous malformation (AVM), the management becomes very complicated. Endovascular treatment (EVT) was an option, but no consensus has been achieved.Methods and materials: A retrospective investigation was performed for patients with flow-related aneurysm originating from an AICA supplying the cerebellar AVM.

RESULTS

Ten patients, harboring 13 aneurysms, were identified. Of the 5 a1 aneurysms, 2 underwent stent assisted coiling, 2 underwent parent artery occlusion (PAO), and 1 was intact. Of the 8 a2 aneurysms, 3 underwent coiling with preservation of the AICA, 3 underwent PAO with Onyx, 1 underwent PAO with coils, and 1 was intact. Seven patients underwent partial embolization of the cerebellar AVM, 3 were intact. One patient died 6 hours postoperatively for cerebellar AVM rebleeding. During a follow-up from 6 months to 6 years, 9 patients had favorable recovery.

CONCLUSION

For the flow-related aneurysm originating from an AICA supplying the cerebellar AVM, the EVT depends on the specific circumstances. When the aneurysm is located at the a1 segment, coiling of the aneurysm with preservation of the parent AICA should be performed. PAO is the last resort. When the a2 aneurysm is proximal to the internal auditory artery, coiling of the aneurysm with preservation of the AICA is preferred. When the aneurysm is distal to the internal auditory artery, PAO can be safely performed.

Orthostatic Enlargement of a Supracerebellar Arachnoid Cyst With Cerebellar Descent Visualized by Upright Computed Tomography

BACKGROUND

Posterior fossa arachnoid cysts are often asymptomatic, but can rarely cause postural headache, the mechanism of which remains unknown.

CASE DESCRIPTION

We present a 40-year-old woman with an asymptomatic supracerebellar arachnoid cyst. Upright computed tomography (CT) showed enlargement of the arachnoid cyst and caudal descent of the cerebellum compared with supine CT with narrowing of the craniocervical junction cerebrospinal fluid space.

CONCLUSIONS

This finding aids in understanding the association of posterior fossa arachnoid cysts with orthostatic headache. Clinicians should be aware of possible posture-related changes in intracranial structures.

An Uncommon Case of Neuroenteric Cyst Located at the Lateral Cerebellomedullary Cistern

We present the case of a 42-year-old woman with a 5-week history of headache, progressive dysphagia, dysphonia, and hoarseness. A brain magnetic resonance imaging revealed an extra-axial cyst of the left lateral cerebellomedullary cistern. The subsequent histopathologic examination diagnosed a neuroenteric cyst. This case sheds light on the pivotal role of histologic identification of neuroenteric cyst, which could be crucial for further diagnostic investigations, especially in pediatric patients.

De Novo KAT5 Variants Cause a Syndrome with Recognizable Facial Dysmorphisms, Cerebellar Atrophy, Sleep Disturbance, and Epilepsy

KAT5 encodes an essential lysine acetyltransferase, previously called TIP60, which is involved in regulating gene expression, DNA repair, chromatin remodeling, apoptosis, and cell proliferation; but it remains unclear whether variants in this gene cause a genetic disease. Here, we study three individuals with heterozygous de novo missense variants in KAT5 that affect normally invariant residues, with one at the chromodomain (p.Arg53His) and two at or near the acetyl-CoA binding site (p.Cys369Ser and p.Ser413Ala). All three individuals have cerebral malformations, seizures, global developmental delay or intellectual disability, and severe sleep disturbance. Progressive cerebellar atrophy was also noted. Histone acetylation assays with purified variant KAT5 demonstrated that the variants decrease or abolish the ability of the resulting NuA4/TIP60 multi-subunit complexes to acetylate the histone H4 tail in chromatin. Transcriptomic analysis in affected individual fibroblasts showed deregulation of multiple genes that control development. Moreover, there was also upregulated expression of PER1 (a key gene involved in circadian control) in agreement with sleep anomalies in all of the individuals. In conclusion, dominant missense KAT5 variants cause histone acetylation deficiency with transcriptional dysregulation of multiples genes, thereby leading to a neurodevelopmental syndrome with sleep disturbance, cerebellar atrophy, and facial dysmorphisms, and suggesting a recognizable syndrome.

Wernekink Commissure Syndrome: A Rare Cause of Bilateral Cerebellar Syndrome

PURPOSE

Focal signs are a big deal in neurology and are among the most important clues leading to diagnosis and localization. Wernekink commissure syndrome is due to lesions in the caudal paramedian midbrain involving the entire decussation of the superior cerebellar peduncles, resulting in the clinical hallmark of a bilateral cerebellar syndrome.

CASE REPORT

A 79-year-old man presented with sudden, severe unsteadiness associated with slurring of speech, binocular double vision, and bilateral hand tremor. Examination showed right INO, moderately severe dysarthria, bilateral dysmetria and dysdiadochokinesia, with severe truncal ataxia and bilateral upper and lower limb ataxia. Also, bilateral coarse tremor was noted in both hands which was present at rest, action and on reaching for objects. Brain MRI revealed an acute infarction involving the Wernekinck decussation in the right caudal midbrain and mesencephalo-pontine junction.

CONCLUSION

The differential of Wernekink Commissure Syndrome is complex, and localization and lateralization are extremely difficult owing to prominent bilateral cerebellar symptoms. The finding of an associated unilateral INO in some cases makes it possible to confidently narrow the list of differentials and localize the lesion to the paramedian tegmentum ipsilateral to the non-adducting eye.

Case Report: A Case of Severe Cryptococcal Immune Reconstitution Inflammatory Syndrome Presenting with Brain and Intradural Abscesses in an HIV Patient

Clinical worsening or new manifestation of cryptococcal disease following initiation of anti-retroviral therapy (ART) in an HIV patient is a hallmark of cryptococcal immune reconstitution inflammatory syndrome (C-IRIS). However, it can be difficult to distinguish IRIS from worsening or new infection. Here, we present a case of severe C-IRIS involving multiple cerebellar, spinal, and intradural abscesses and spinal arachnoiditis 7 months after ART initiation in an AIDS patient with uncertain prior ART compliance. He had multiple prior episodes of cryptococcal meningitis with complications necessitating ventriculoperitoneal shunt placement and was on suppressive fluconazole when he developed worsening brain manifestations. He received empiric anti-cryptococcal re-induction without improvement. All cerebrospinal fluid cultures remained sterile, with negative Cryptococcus PCR testing, and his condition continued to worsen prior to corticosteroid initiation. Ultimately, C-IRIS was diagnosed by brain biopsy. This case demonstrates an extreme in severity of C-IRIS and in the timeline of presentation after ART initiation.

Radiology of post-operative paediatric cerebellar mutism syndrome

BACKGROUND

Post-operative paediatric cerebellar mutism syndrome is a well-recognized complication following posterior fossa tumour resection in children. Over the past few decades, imaging has played an important role in understanding this disorder.

AIM

This review article aims to focus on the disorder from a radiological perspective, summarizing the salient radiological evidence related to the anatomical structures, pathophysiology, and risk factors related to this disorder.

CONCLUSION

Radiological studies have been integral to the improved understanding of this condition. Future large multicentre studies and quantitative analysis techniques will be vital in further refinement of our understanding of this complex condition.

Pediatric post-operative cerebellar mutism syndrome, cerebellar cognitive affective syndrome, and posterior fossa syndrome: historical review and proposed resolution to guide future study

BACKGROUND

Cerebellar mutism (CM), pseudobulbar palsy, posterior fossa syndrome (PFS), and cerebellar cognitive affective syndrome (CCAS) are terms that have been used, sometimes interchangeably, to refer to the complex neurological constellation that occurs following surgical removal of cerebellar and fourth ventricular tumors, mostly in children, but also sometimes in adults.

METHODS

This paper reviews the origins of what is now regarded as pediatric post-operative cerebellar mutism, the cerebellar cognitive affective syndrome, and the neurological manifestations of injury to or disruption of brainstem and cerebellar structures. It examines the specific components of each of these phenomena in the context of the evolving understanding of the role of the cerebellum in nervous system function.

RESULTS

Children undergoing surgical management of tumors in the posterior cranial fossa are at risk of experiencing cranial neuropathies, corticospinal damage, cerebellar ataxia and related motor disorders, neuropsychiatric and cognitive changes, and in some patients, mutism. These clinical presentations are differentiated from each other and examined in the context of the relevant anatomical structures and distributed neural circuits. The term posterior fossa syndrome is not sufficiently helpful in distinguishing the different elements of the clinical phenomena from each other, and because of this lack of precision and specificity, there is consensus among investigators in the international Posterior Fossa Society that the designation be retired.

CONCLUSIONS

Using contemporary brain imaging methods and guided by careful clinical observation and meticulous definition of clinical phenomenology, it is now feasible to perform detailed structure function correlation analyses to achieve two critical goals in the care of children with tumors in the posterior cranial fossa. The first goal is to identify and understand the neural circuits responsible for the different manifestations-arousal, cranial neuropathies, long tract signs, cerebellar motor syndrome, cerebellar vestibular syndrome, cerebellar cognitive affective syndrome including emotional dyscontrol, and mutism. The second goal is to transform this knowledge into practical clinical intervention, preventing the complications inherent in the necessary surgery whenever possible, and develop new approaches to treatment with methods including brain modulation targeting interconnected nodes of the damaged neural circuits.

The Cerebellar Cognitive Affective/Schmahmann Syndrome: a Task Force Paper

Sporadically advocated over the last two centuries, a cerebellar role in cognition and affect has been rigorously established in the past few decades. In the clinical domain, such progress is epitomized by the "cerebellar cognitive affective syndrome" ("CCAS") or "Schmahmann syndrome." Introduced in the late 1990s, CCAS reflects a constellation of cerebellar-induced sequelae, comprising deficits in executive function, visuospatial cognition, emotion-affect, and language, over and above speech. The CCAS thus offers excellent grounds to investigate the functional topography of the cerebellum, and, ultimately, illustrate the precise mechanisms by which the cerebellum modulates cognition and affect. The primary objective of this task force paper is thus to stimulate further research in this area. After providing an up-to-date overview of the fundamental findings on cerebellar neurocognition, the paper substantiates the concept of CCAS with recent evidence from different scientific angles, promotes awareness of the CCAS as a clinical entity, and examines our current insight into the therapeutic options available. The paper finally identifies topics of divergence and outstanding questions for further research.

Non-linear spelling in writing after a pure cerebellar lesion

The most common deficits in processing written language result from damage to the graphemic buffer system and refer to semantic and lexical problems or difficulties in phoneme-graphene conversion. However, a writing disorder that has not yet been studied in depth is the non-linear spelling phenomenon. Indeed, although some cases have been described, no report has exhaustively explained the cognitive mechanism and the anatomical substrates underlying this process. In the present study, we analyzed the modality of non-linear writing in a patient affected by a focal cerebellar lesion, who presented with an alteration of the normal trend to write the order of the letters. Based on this evidence, we analyzed the functional connectivity between the cerebellum and the brain network that subtends handwriting and demonstrated how the cerebellar lesion of the patient affected the connections between the cerebellum and cortical areas that support the anatomical system of writing. This is the first report of non-linear spelling in a patient with a lesion outside the fronto-parietal network, specifically with a focal cerebellar lesion. We propose that non-linear writing can be interpreted in view of the role of the cerebellum in timing and sequential processing. Thus, considering the current functional connectivity data, we hypothesize that the cerebellum might be relevant in the mechanism that allows the correct activation timing of letters within a string and placement of the letters in a specific sequential writing order.

Fourth ventricle index: sonographic marker for severe fetal vermian dysgenesis/agenesis

OBJECTIVE

Prenatal diagnosis of midbrain-hindbrain (MB-HB) malformations relies primarily on abnormal size and shape of the cerebellum and retrocerebellar space, particularly 'open fourth ventricle' (4V), the most common indicator of MB-HB malformations. The aim of this study was to present the fourth ventricle index (4VI), and to evaluate its role as a marker for severe vermian dysgenesis/agenesis in cases without open 4V.

METHODS

This was a prospective cross-sectional study of patients with singleton low-risk pregnancy at 14 + 1 to 36 + 6 gestational weeks presenting between May 2016 and November 2017 for routine ultrasound examination. Axial images of the fetal 4V were obtained and the 4VI was calculated as the ratio between the laterolateral and the anteroposterior diameters. Reference ranges were constructed and retrospectively collected values from 44 fetuses with confirmed anomalies involving severe vermian dysgenesis/agenesis (Joubert syndrome and related disorders, rhombencephalosynapsis, cobblestone malformations and cerebellar hypoplasia) but without open 4V were compared with the normal values.

RESULTS

In total, 384 healthy fetuses were enrolled into the study, from which reference ranges were produced, and 44 cases were collected retrospectively. The 4VI in the normal fetuses was always > 1. In affected fetuses, it was always below mean -2 SD and < 1.

CONCLUSIONS

The 4VI is a sonographic marker for severe fetal vermian dysgenesis/agenesis in the absence of an open 4V. It may be incorporated easily into the routine brain scan; 4VI < 1 indicates a need for dedicated fetal neuroimaging for diagnosis and prenatal counseling. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Multiple aneurysms on the subarcuate artery arising from the anterior inferior cerebellar artery in a patient with a Borden type I transverse-sigmoid dural arteriovenous fistula manifesting as subarachnoid hemorrhage: A case report

BACKGROUND

Peripheral anterior inferior cerebellar artery (AICA) aneurysms are rare and commonly associated with vascular malformations, such as cerebellar arteriovenous malformations (AVMs). We present a case wherein multiple AICA feeding aneurysms on the subarcuate artery as a feeding artery of a Borden type I transverse-sigmoid dural arteriovenous fistula (dAVF) manifested as subarachnoid hemorrhage.

CASE DESCRIPTION

A 67-year-old woman presented with acute severe headache. Brain computed tomography (CT) demonstrated subarachnoid hemorrhage mainly in the posterior fossa. A transverse-sigmoid dAVF was detected on magnetic resonance angiography (MRA) and three-dimensional-CT angiography (3D-CTA), with no cortical venous reflex. The patient underwent conventional angiography, which showed multiple aneurysms on a small branch of the AICA, feeding a transverse-sigmoid dAVF (Borden type I). The AICA aneurysms seemed flow dependent and ruptured owing to high-flow arteriovenous shunts through the dAVF. Based on the source images of the MRA, the small artery arising from the AICA was considered the subarcuate artery, and it was confirmed on 3D-CTA after the artery was successfully embolized with Onyx without any complications. Multiple aneurysms on the subarcuate artery are extremely rare, and the artery has not been identified as a feeding artery of the transverse-sigmoid dAVF.

CONCLUSION

A rare case of multiple ruptured aneurysms on the subarcuate artery was reported in a patient with a Borden type I dAVF at the transverse-sigmoid sinuses manifesting as subarachnoid hemorrhage. Onyx embolization of the parent artery occlusion was feasible and useful in treating this type of feeding artery aneurysm of the AICA with a dAVF.

Cerebral small vessel disease in patients with spontaneous cerebellar hemorrhage

BACKGROUND

Spontaneous cerebellar-intracerebral hemorrhage (ICH) can be associated with both cerebral amyloid angiopathy (CAA) and hypertensive small vessel disease (HTN-SVD, i.e. arteriolosclerosis). To better understand the underlying microangiopathy of cerebellar-ICH, we aimed to evaluate the spatial distribution of supratentorial cerebral microbleeds (CMBs) and neuropathologic profiles in these patients.

METHODS

We enrolled consecutive cerebellar-ICH patients. Clinical variables and MRI markers specific for CAA and HTN-SVD were assessed. Patients were classified into categories according to the topography (strictly-lobar, strictly-deep, and mixed) of supratentorial CMBs and comparisons were performed. Available neuropathological material was reviewed to evaluate the presence and severity of arteriolosclerosis and CAA.

RESULTS

Ninety-eight cerebellar-ICH patients were enrolled. Fifty patients (51%) had at least one supratentorial CMB. Twelve patients (12%) had strictly lobar-CMBs, 12 patients (12%) showed strictly deep-CMBs and mixed-CMBs (lobar and deep CMBs) were present in 26 cerebellar-ICH patients (27%). In multivariable analysis, cerebellar-ICH patients with mixed-CMBs were associated with higher prevalence of hypertension (OR 4.9, 95% confidence interval [CI] 1.2-20, p = 0.017) but with lower prevalence of severe centrum-semiovale enlarged perivascular spaces (OR 0.2, CI 0.05-0.8, p = 0.024) when compared to cerebellar-ICH patients with strictly lobar-CMBs. Vascular risk factors and neuroimaging characteristics were similar between strictly deep-CMBs and mixed-CMBs. Six patients had available neuropathological material for analyses and they all showed some degree of arteriolosclerosis.

CONCLUSIONS

Cerebellar-ICH patients frequently show supratentorial CMBs. The mixed-CMBs pattern appears to be the most common. Our radiological and pathological results suggest that the majority of cerebellar-ICH patients harbor HTN-SVD as dominant microangiopathy.

A computational framework for the detection of subcortical brain dysmaturation in neonatal MRI using 3D Convolutional Neural Networks

Deep neural networks are increasingly being used in both supervised learning for classification tasks and unsupervised learning to derive complex patterns from the input data. However, the successful implementation of deep neural networks using neuroimaging datasets requires adequate sample size for training and well-defined signal intensity based structural differentiation. There is a lack of effective automated diagnostic tools for the reliable detection of brain dysmaturation in the neonatal period, related to small sample size and complex undifferentiated brain structures, despite both translational research and clinical importance. Volumetric information alone is insufficient for diagnosis. In this study, we developed a computational framework for the automated classification of brain dysmaturation from neonatal MRI, by combining a specific deep neural network implementation with neonatal structural brain segmentation as a method for both clinical pattern recognition and data-driven inference into the underlying structural morphology. We implemented three-dimensional convolution neural networks (3D-CNNs) to specifically classify dysplastic cerebelli, a subset of surface-based subcortical brain dysmaturation, in term infants born with congenital heart disease. We obtained a 0.985 ± 0. 0241-classification accuracy of subtle cerebellar dysplasia in CHD using 10-fold cross-validation. Furthermore, the hidden layer activations and class activation maps depicted regional vulnerability of the superior surface of the cerebellum, (composed of mostly the posterior lobe and the midline vermis), in regards to differentiating the dysplastic process from normal tissue. The posterior lobe and the midline vermis provide regional differentiation that is relevant to not only to the clinical diagnosis of cerebellar dysplasia, but also genetic mechanisms and neurodevelopmental outcome correlates. These findings not only contribute to the detection and classification of a subset of neonatal brain dysmaturation, but also provide insight to the pathogenesis of cerebellar dysplasia in CHD. In addition, this is one of the first examples of the application of deep learning to a neuroimaging dataset, in which the hidden layer activation revealed diagnostically and biologically relevant features about the clinical pathogenesis. The code developed for this project is open source, published under the BSD License, and designed to be generalizable to applications both within and beyond neonatal brain imaging.

Mitochondrial POLG related disorder presenting prenatally with fetal cerebellar growth arrest

We report the prenatal findings of severe cerebellar growth arrest in two siblings with POLG1 mutations. The first presented with seizures and lactic acidosis immediately after premature birth and was diagnosed with mitochondrial disease on muscle biopsy. Molecular DNA analysis confirmed homozygous missense mutation in the POLG1 gene. The pregnancy of the second sibling was monitored closely by repeat fetal ultrasounds since the parents declined invasive testing. A detailed fetal ultrasound at 19 weeks gestation showed a small cerebellum with transcerebellar diameter (TCD) on axial cranial imaging, measuring below the 5th centile for gestational age. Molecular analysis confirmed the same homozygous familial mutation in the POLG1gene. This report further delineates the phenotypic features of the POLG related disorders and expands it to the prenatal era. Subsequent pregnancies were monitored by molecular analysis, using chorionic villus sampling (CVS).

Cerebellar involvement in autism and ADHD

The cerebellum has long been known for its importance in motor learning and coordination. However, increasing evidence supports a role for the cerebellum in cognition and emotion. Consistent with a role in cognitive functions, the cerebellum has emerged as one of the key brain regions affected in nonmotor disorders, including autism spectrum disorder and attention deficit-hyperactivity disorder. Here, we discuss behavioral, postmortem, genetic, and neuroimaging studies in humans in order to understand the cerebellar contributions to the pathogenesis of both disorders. We also review relevant animal model findings.

Prediction of a multiple sclerosis diagnosis in patients with clinically isolated syndrome using the 2016 MAGNIMS and 2010 McDonald criteria: a retrospective study

BACKGROUND

In 2016, the Magnetic Resonance Imaging in Multiple Sclerosis (MAGNIMS) network proposed modifications to the MRI criteria to define dissemination in space (DIS) and time (DIT) for the diagnosis of multiple sclerosis in patients with clinically isolated syndrome (CIS). Changes to the DIS definition included removal of the distinction between symptomatic and asymptomatic lesions, increasing the number of lesions needed to define periventricular involvement to three, combining cortical and juxtacortical lesions, and inclusion of optic nerve evaluation. For DIT, removal of the distinction between symptomatic and asymptomatic lesions was suggested. We compared the performance of the 2010 McDonald and 2016 MAGNIMS criteria for multiple sclerosis diagnosis in a large multicentre cohort of patients with CIS to provide evidence to guide revisions of multiple sclerosis diagnostic criteria.

METHODS

Brain and spinal cord MRI and optic nerve assessments from patients with typical CIS suggestive of multiple sclerosis done less than 3 months from clinical onset in eight European multiple sclerosis centres were included in this retrospective study. Eligible patients were 16-60 years, and had a first CIS suggestive of CNS demyelination and typical of relapsing-remitting multiple sclerosis, a complete neurological examination, a baseline brain and spinal cord MRI scan obtained less than 3 months from clinical onset, and a follow-up brain scan obtained less than 12 months from CIS onset. We recorded occurrence of a second clinical attack (clinically definite multiple sclerosis) at months 36 and 60. We evaluated MRI criteria performance for DIS, DIT, and DIS plus DIT with a time-dependent receiver operating characteristic curve analysis.

FINDINGS

Between June 16, 1995, and Jan 27, 2017, 571 patients with CIS were screened, of whom 368 met all study inclusion criteria. At the last evaluation (median 50·0 months [IQR 27·0-78·4]), 189 (51%) of 368 patients developed clinically definite multiple sclerosis. At 36 months, the two DIS criteria showed high sensitivity (2010 McDonald 0·91 [95% CI 0·85-0·94] and 2016 MAGNIMS 0·93 [0·88-0·96]), similar specificity (0·33 [0·25-0·42] and 0·32 [0·24-0·41]), and similar area under the curve values (AUC; 0·62 [0·57-0·67] and 0·63 [0·58-0·67]). Performance was not affected by inclusion of symptomatic lesions (sensitivity 0·92 [0·87-0·96], specificity 0·31 [0·23-0·40], AUC 0·62 [0·57-0·66]) or cortical lesions (sensitivity 0·92 [0·87-0·95], specificity 0·32 [0·24-0·41], AUC 0·62 [0·57-0·67]). Requirement of three periventricular lesions resulted in slightly lower sensitivity (0·85 [0·78-0·90], slightly higher specificity (0·40 [0·32-0·50], and similar AUC (0·63 [0·57-0·68]). Inclusion of optic nerve evaluation resulted in similar sensitivity (0·92 [0·87-0·96]), and slightly lower specificity (0·26 [0·18-0·34]) and AUC (0·59 [0·55-0·64]). AUC values were also similar for DIT (2010 McDonald 0·61 [0·55-0·67] and 2016 MAGNIMS 0·61 [0·55-0·66]) and DIS plus DIT (0·62 [0·56-0·67] and 0·64 [0·58-0·69]).

INTERPRETATION

The 2016 MAGNIMS criteria showed similar accuracy to the 2010 McDonald criteria in predicting the development of clinically definite multiple sclerosis. Inclusion of symptomatic lesions is expected to simplify the clinical use of MRI criteria without reducing accuracy, and our findings suggest that needing three lesions to define periventricular involvement might slightly increase specificity, suggesting that these two factors could be considered during further revisions of multiple sclerosis diagnostic criteria.

FUNDING

UK MS Society, National Institute for Health Research University College London Hospitals Biomedical Research Centre, Dutch MS Research Foundation.

Rapid, label-free identification of cerebellar structures using multiphoton microscopy

The cerebellum is the prominent laminar structure of the mammalian brain that has been implicated in various psychiatric and neurological diseases. Although clinical brain imaging techniques have provided precise anatomic images of cerebellar structures, a definitive diagnosis still requires adequate resolution to identify individual layers in cerebellar cortex, the extent of tumor, even requires the histological tissue examination during surgical procedures. In this study, multiphoton microscopy (MPM), based on second harmonic generation (SHG) and two-photon excited fluorescence (TPEF), was perform on the rat cerebellar structures and pathology with the combination of image analysis methods. Results show that MPM can reveal the cerebellar vermis, hemispheres, medulla, and ventricle, as well as axon bundles, Purkinje cells, capillaries, and the pia mater of the cerebellum. Together with custom-developed image processing algorithms, MPM could further differentiate between the gray and white matter, as well as evaluate the Purkinje cell layer, identify the cerebellar tumor boundary, and distinguish between the tumor core and peritumor regions. Our results establish a direct visualization and rapid assessment approach for the cerebellar structures, as well as suggest the feasibility of in vivo multiphoton microendoscopes and fiberscopes as clinical tools for neuropathological diagnoses.

Rapid, label-free identification of cerebellar structures using multiphoton microscopy

The cerebellum is the prominent laminar structure of the mammalian brain that has been implicated in various psychiatric and neurological diseases. Although clinical brain imaging techniques have provided precise anatomic images of cerebellar structures, a definitive diagnosis still requires adequate resolution to identify individual layers in cerebellar cortex, the extent of tumor, even requires the histological tissue examination during surgical procedures. In this study, multiphoton microscopy (MPM), based on second harmonic generation (SHG) and two-photon excited fluorescence (TPEF), was perform on the rat cerebellar structures and pathology with the combination of image analysis methods. Results show that MPM can reveal the cerebellar vermis, hemispheres, medulla, and ventricle, as well as axon bundles, Purkinje cells, capillaries, and the pia mater of the cerebellum. Together with custom-developed image processing algorithms, MPM could further differentiate between the gray and white matter, as well as evaluate the Purkinje cell layer, identify the cerebellar tumor boundary, and distinguish between the tumor core and peritumor regions. Our results establish a direct visualization and rapid assessment approach for the cerebellar structures, as well as suggest the feasibility of in vivo multiphoton microendoscopes and fiberscopes as clinical tools for neuropathological diagnoses.

[Degenerative cerebellar diseases and differential diagnoses]

CLINICAL/METHODICAL ISSUE

Cerebellar syndromes result in distinct clinical symptoms, such as ataxia, dysarthria, dysmetria, intention tremor and eye movement disorders.

STANDARD RADIOLOGICAL METHODS

In addition to the medical history and clinical examination, imaging is particularly important to differentiate other diseases, such as hydrocephalus and multi-infarct dementia from degenerative cerebellar diseases. Degenerative diseases with cerebellar involvement include Parkinson's disease, multiple system atrophy as well as other diseases including spinocerebellar ataxia.

ACHIEVEMENTS

In addition to magnetic resonance imaging (MRI), nuclear medicine imaging investigations are also helpful for the differentiation.

PRACTICAL RECOMMENDATIONS

Axial fluid-attenuated inversion recovery (FLAIR) and T2-weighted sequences can sometimes show a signal increase in the pons as a sign of degeneration of pontine neurons and transverse fibers in the basilar part of the pons. The imaging is particularly necessary to exclude other diseases, such as normal pressure hydrocephalus (NPH), multi-infarct dementia and cerebellar lesions.

Cerebellar Infarction Presenting with Acute Vestibular Syndrome in Two U.S. Air Force Pilots

BACKGROUND

Cerebellar infarction is an uncommon but serious cause of isolated acute vestibular symptoms, particularly in young, healthy individuals, and can easily be overlooked. We present two cases of cerebellar infarction in U.S. Air Force pilots, one of which occurred during flight.

CASE REPORTS

A 41-yr-old man developed acute vertigo, disequilibrium, nausea, and headache, with progressive slow symptomatic improvement, and presented to medical attention 4 d after symptom onset. Brain magnetic resonance imaging showed right inferomedial cerebellar infarction. Echocardiography discovered patent foramen ovale and atrial septal aneurysm. A 40-yr-old man developed severe vertigo, nausea, and vomiting during initial aircraft descent. Head computed tomography scan was performed acutely and was normal. Initial assessment was benign paroxysmal positional vertigo. Brain magnetic resonance imaging 1 mo after symptom onset showed a small right inferior cerebellar infarction. Patent foramen ovale and bilateral atrial enlargement were seen on echocardiography. Both pilots made full neurological recoveries and were eventually returned to flight status.

DISCUSSION

Central causes of isolated acute vestibular symptoms are uncommon and are often not considered in otherwise healthy individuals. Cerebellar infarction is one of these uncommon but increasingly recognized causes of acute vestibular symptoms. As evaluation and management of central causes are much different from peripheral conditions, prompt localization confirmation is paramount. Accurate evidence-based bedside screening methods are available for rapid localization. Awareness of the possibility of central etiologies and careful clinical evaluation with application of bedside screening methods in patients with acute vestibular symptoms will reduce the number of inaccurate diagnoses.Hesselbrock RR. Cerebellar infarction presenting with acute vestibular syndrome in two U.S. Air Force pilots. Aerosp Med Hum Perform. 2017; 88(9):880-883.

Arterial Thoracic Outlet Syndrome and Cerebellar Infarction Following a Stress Fracture of the First Rib and Extensive Callus Formation: A Case Report

CASE

Stress fractures of the first rib rarely have been reported in association with sports activities. We report a case of a cerebellar infarction that possibly was associated with arterial thoracic outlet syndrome (aTOS) that developed as a result of extensive callus formation in a young baseball player with a stress fracture of the first rib.

CONCLUSION

According to the literature, almost all cases of stress fracture in the first rib have a relatively good prognosis, and there are only a few reports of TOS occurring as a rare late complication. To our knowledge, there have been no prior reports of cerebellar infarction associated with aTOS following a stress fracture of the first rib.

Purple patches in an immunocompromised patient: a report of secondary disseminated cutaneous mucormycosis in a man with chronic lymphocytic leukemia

A 60-year-old man with chronic lymphocytic leukemiadeveloped a deeply violaceous annular patchwith a halo of erythema on the right thigh duringhospitalization for neutropenic fever. Associatedsymptoms included chronic cough and fatigue.Bilateral lung opacities with hilar lymphadenopathywere noted on chest computed tomographyscan. Punch biopsy and tissue culture confirmeda diagnosis of secondary disseminated cutaneousmucormycosis. Although rare, physicians shouldinclude mucormycosis in the differential diagnosisof purpuric patches in immunosuppressed patients.Prompt skin biopsy and tissue culture may optimizethe success of treatment.

[Language disorders in acute cerebellitis: beyond dysarthria]

INTRODUCTION

Acute cerebellitis is one of the main causes of cerebellar syndrome in infancy. Among the wide range of manifestations, headache and ataxia being the most predominant, we can find other less frequent, although nonetheless interesting, ones, such as language disorders, which go beyond the well-known cerebellar dysarthria. The different combinations in which the symptoms can appear, especially when not accompanied by ataxia, make the condition a real challenge for the clinician.

CASE REPORTS

Two patients, aged 2 and 4 years, with clinical features, lab tests and neuroimaging results consistent with parainfectious acute cerebellitis. Both of them also presented a striking language disorder, one in the form of cerebellar mutism and the other in the form of hypofluency and agrammatism, the latter also developing in the absence of ataxia. Both cases progressed favourably, and mild speech alterations persisted in the follow-up visits.

CONCLUSIONS

Cases such as these expand the range of clinical manifestations of acute cerebellitis. The involvement of the cerebellum in neurocognitive processes like language is becoming increasingly more important and, although many aspects are still only speculations, managing to define its true role will have important repercussions on the diagnosis, treatment and long-term prognosis of these patients.

Cerebellar disruptions and neurodevelopmental disabilities

The vulnerability of the cerebellum during prenatal life to disruptive events such as hemorrhage and infection leads to a wide variety of morphological abnormalities. This review discusses various prenatal cerebellar disruptions including cerebellar agenesis, unilateral cerebellar hypoplasia, cerebellar cleft, global cerebellar hypoplasia, and vanishing cerebellum in Chiari type II malformation. For each entity, we discuss the definition, potential pathomechanism, clinical findings including neurocognitive and behavioral problems, neuroimaging features, and management. Accurate recognition of cerebellar disruptions and their differentiation from malformations is important in terms of diagnosis, prognosis, and genetic counselling.