Continuous spike-wave of slow sleep in a patient with KCNB1-related epilepsy responsive to highly purified cannabidiol: a case report and comparison with literature.

KCNB1-associated encephalopathy is characterized by intellectual disability (ID), autism spectrum disorder and epilepsy. Specific treatments are still lacking. We describe a 12-year-old boy with severe ID and treatment-resistant seizures due to a pathogenic KCNB1 variant. His EEG showed a CSWS pattern. Aged 11, he started treatment with highly purified cannabidiol (CBD) and has been seizure free for 18 months, with significant EEG and social skills improvements. This suggests CBD may benefit CSWS, likely due to its anti-inflammatory properties. Some preclinical studies also indicate CBDs interact with voltage-gated channels, leading us to speculate its possible role for treating KCNB1 related encephalopathy.

The Role of Electroencephalography in Children with Acute Altered Mental Status of Unknown Etiology: A Prospective Study.

INTRODUCTION: Acute altered mental status (AAMS) is often a challenge for clinicians, since the underlying etiologies cannot always easily be inferred based on the patient's clinical presentation, medical history, or early examinations. The aim of this study is to evaluate the role of electroencephalogram (EEG) as a diagnostic tool in AAMS of unknown etiology in children. MATERIALS AND METHODS: We conducted a prospective study involving EEG assessments on children presenting with AAMS between May 2017 and October 2019. Inclusion criteria were age 1 month to 18 years and acute (<1 week) and persistent (>5 minutes) altered mental status. Patients with a known etiology of AAMS were excluded. A literature review was also performed. RESULTS: Twenty patients (median age: 7.7 years, range: 0.5-15.4) were enrolled. EEG contributed to the diagnosis in 14/20 cases, and was classified as diagnostic in 9/20 and informative in 5/20. Specifically, EEG was able to identify nonconvulsive status epilepticus (NCSE) in five children and psychogenic events in four. EEG proved to be a poorly informative diagnostic tool at AAMS onset in six children; however, in five of them, it proved useful during follow-up. CONCLUSIONS: Limited data exist regarding the role of EEG in children with AAMS of unknown etiology. In our population, EEG proved to be valuable tool, and was especially useful in the prompt identification of NCSE and psychogenic events.

Ultrastructural and Immunohistochemical Diagnosis of a Neonatal Herpes Simplex Virus Infection Presenting as Fulminant Hepatitis: A Case Report.

TORCH (Toxoplasmosis, Rubella, Cytomegalovirus, Herpes Simplex Virus and Syphilis) infections are a major cause of intrauterine and perinatal infections with associated morbidity and mortality. Neonatal Herpes Simplex Virus infection caused by an enveloped, double-stranded DNA virus of the Herpesviridae family is devastating and fatal. Herpes Viruses are not hepatotropic but may rarely cause hepatitis. Most cases of HSV hepatitis rapidly progress to fulminant hepatic failure and often fatal before the diagnosis or transplantation. Nowadays, despite the availability of antiviral treatment (acyclovir), the outcome remains poor because of late identification of hepatic Herpes Simplex Virus (HSV) infection. We report a male neonate suspected with a metabolic/mitochondrial disease and multi-organ involvement but who developed a fulminant hepatic failure and disseminated coagulopathy secondary to HSV type 1 (HSV-1) infection. The postmortem diagnosis was performed demonstrating HSV-1 in liver tissue by transmission electron microscopy and by retrospective detection of HSV specific antigens by immunohistochemistry.

Further delineation and long-term evolution of electroclinical phenotype in Mowat Wilson Syndrome. A longitudinal study in 40 individuals.

BACKGROUND: Epilepsy is a main feature of Mowat Wilson Syndrome (MWS), a congenital malformation syndrome caused by ZEB2 variants. The aim of this study was to investigate the long-term evolution of the electroclinical phenotype of MWS in a large population. METHODS: Forty-individuals with a genetically confirmed diagnosis were enrolled. Three age groups were identified (t1 = 0-4; t2 = 5-12; t3 = >13 years); clinical data and EEG records were collected, analyzed, and compared for age group. Video-EEG recorded seizures were reviewed. RESULTS: Thirty-six of 40 individuals had epilepsy, of whom 35/35 aged >5 years. Almost all (35/36) presented focal seizures at onset (mean age at onset 3.4 ±â€¯2.3 SD) that persisted, reduced in frequency, in 7/22 individuals after the age of 13. Absences occurred in 22/36 (mean age at onset 7.2 ±â€¯0.9 SD); no one had absences before 6 and over 16 years old. Paroxysmal interictal abnormalities in sleep also followed an age-dependent evolution with a significant increase in frequency at school age (p = 0.002) and a reduction during adolescence (p = 0.008). Electrical Status Epilepticus during Sleep occurred in 14/36 (13/14 aged 5-13 years old at onset). Seven focal seizure ictal video-EEGs were collected: all were long-lasting and more visible clinical signs were often preceded by prolonged electrical and/or subtle (erratic head and eye orientation) seizures. Valproic acid was confirmed as the most widely used and effective drug, followed by levetiracetam. CONCLUSIONS: Epilepsy is a major sign of MWS with a characteristic, age-dependent, electroclinical pattern. Improvement with adolescence/adulthood is usually observed. Our data strengthen the hypothesis of a GABAergic transmission imbalance underlying ZEB2-related epilepsy.

Narcolepsy during Childhood: An Update.

Narcolepsy type 1 (NT1) is a rare central disorder of hypersomnolence characterized by excessive daytime sleepiness, cataplexy, sleep paralysis, hallucinations, and fragmented nocturnal sleep usually arising in adolescence or young adulthood. Recently, the childhood NT1 diagnoses have increased for improved disease awareness and for several cases occurring after the H1N1 pandemic influenza or vaccination. As in adults, the occurrence of NT1 in individuals with a genetic predisposition of the immune system (e.g., human leukocyte antigen, HLA-DQB1*0602) together with the role of environmental triggers (e.g., H1N1 influenza virus, streptococcus ß hemolyticus) further supports the autoimmune pathogenesis. Children with NT1 close to disease onset show a peculiar cataplexy phenotype characterized by persistent hypotonia with prominent facial involvement (cataplectic facies) and by a complex mosaic of hyperkinetic movement abnormalities that increase during emotional stimulation. This phenotype progressively vanishes along the disease course leading to the typical picture of cataplexy (i.e., muscle weakness exclusively evoked by strong emotions). This possibly explains in part the misdiagnoses and diagnostic delay. Childhood NT1 also shows behavioral abnormalities and psychiatric disorders, encompassing depressive feelings, hyperactive/aggressive behavior, up to psychotic features. The association with obesity and precocious puberty strikingly suggests that NT1 arising in prepubertal children may reflect a wide hypothalamic derangement secondary to hypocretin neuronal loss. The complexity of the childhood NT1 phenotype claims a multidisciplinary assessment and management, taking behavioral and endocrinological features into account. NT1 indeed is a lifelong disorder with a devastating impact on quality of life, especially when arising across developmental age, and targeted school programs, medicolegal and psychological supports are essential for patients care. Controlled studies are mandatory to assess safety and efficacy of the current symptomatic off-label medications on which also relies the treatment for children with NT1, and hopefully future pathogenetic evidences will pave the way to better disease prevention and therapies to modify the disease course.

Psychogenic non-epileptic seizures in individuals with intellectual disability/borderline cognitive function: Characterization through a comparison study.

PURPOSE: We set out to characterize psychogenic non-epileptic seizures (PNES) in individuals with either intellectual disability (ID) or borderline intellectual function (BIF) in comparison to those with normal cognitive function. We aimed to identify differences between the two groups to improve clinical management protocols. METHODS: We conducted a retrospective, observational, single-center study. The medical records of individuals (aged ≥ 14 years) diagnosed with PNES, confirmed through video-electroencephalography (vEEG) at a specialized epilepsy center between January 2008 and December 2021, were reviewed. We restricted our study to individuals who underwent comprehensive neuropsychological evaluations. Furthermore, demographic, clinical, and neuropsychological data with potential prognostic indicators, alongside the reevaluation of vEEG recordings were studied. We compared two study groups based on intelligence quotient (IQ): individuals without ID (IQ≥85; n = 25) and those with either mild ID or BIF (n = 25). RESULTS: No statistically significant clinical differences were observed between the two groups. Individuals with mild ID/BIF didn't show a longer diagnostic delay, and the prescription of inappropriate antiseizure medications (ASMs) was comparable in both cohorts. Most individuals with mild ID/BIF were treated with behavioral psychotherapeutic approaches with similar outcomes in both subgroups. CONCLUSIONS: Individuals with mild ID/BIF and PNES don't differ in clinical management. Demographic and clinical data, as well as semiology, were comparable to those of individuals with normal cognitive function. Cognitive behavioral therapy (CBT) appears to be an effective treatment approach for individuals with and without mild ID/BIF. Further studies are needed to validate and ascertain their possible applicability in individuals with moderate/severe ID.

Generation of two iPSC lines from Mowat-Wilson syndrome patients carrying heterozygous ZEB2 mutations.

ZEB2 is a protein-coding gene belonging to a very restricted family of transcription factors. ZEB2 acts mainly as a transcription repressor, is expressed in various tissues and its role is fundamental for the correct development of the nervous system. The best-known clinical picture associated with ZEB2 mutations is Mowat-Wilson syndrome, caused mostly by haploinsufficiency and characterized by possible multi-organ malformations, dysmorphic features, intellectual disability, and epilepsy. In this study we report the generation of IGGi004-A and IGGi005-A, iPSC clones from two patients carrying different heterozygous mutations in ZEB2, which can be used for disease modelling, pathophysiological studies and therapeutics testing.

Structural brain abnormalities in Pallister-Killian syndrome: a neuroimaging study of 31 children.

BACKGROUND: Pallister-Killian syndrome (PKS) is a rare genetic disorder caused by mosaic tetrasomy of 12p with wide neurological involvement. Intellectual disability, developmental delay, behavioral problems, epilepsy, sleep disturbances, and brain malformations have been described in most individuals, with a broad phenotypic spectrum. This observational study, conducted through brain MRI scan analysis on a cohort of patients with genetically confirmed PKS, aims to systematically investigate the neuroradiological features of this syndrome and identify the possible existence of a typical pattern. Moreover, a literature review differentiating the different types of neuroimaging data was conducted for comparison with our population. RESULTS: Thirty-one individuals were enrolled (17 females/14 males; age range 0.1-17.5 years old at first MRI). An experienced pediatric neuroradiologist reviewed brain MRIs, blindly to clinical data. Brain abnormalities were observed in all but one individual (compared to the 34% frequency found in the literature review). Corpus callosum abnormalities were found in 20/30 (67%) patients: 6 had callosal hypoplasia; 8 had global hypoplasia with hypoplastic splenium; 4 had only hypoplastic splenium; and 2 had a thin corpus callosum. Cerebral hypoplasia/atrophy was found in 23/31 (74%) and ventriculomegaly in 20/31 (65%). Other frequent features were the enlargement of the cisterna magna in 15/30 (50%) and polymicrogyria in 14/29 (48%). Conversely, the frequency of the latter was found to be 4% from the literature review. Notably, in our population, polymicrogyria was in the perisylvian area in all 14 cases, and it was bilateral in 10/14. CONCLUSIONS: Brain abnormalities are very common in PKS and occur much more frequently than previously reported. Bilateral perisylvian polymicrogyria was a main aspect of our population. Our findings provide an additional tool for early diagnosis.Further studies to investigate the possible correlations with both genotype and phenotype may help to define the etiopathogenesis of the neurologic phenotype of this syndrome.

Cognitive, Behavioral, and Sensory Profile of Pallister-Killian Syndrome: A Prospective Study of 22 Individuals.

BACKGROUND: Developmental delay and intellectual disability are two pivotal elements of the phenotype of Pallister-Killian Syndrome (PKS). Our study aims to define the cognitive, adaptive, behavioral, and sensory profile of these patients and to evaluate possible correlations between the different aspects investigated and with the main clinical and demographic variables. METHODS: Individuals of any age with genetically confirmed PKS were recruited. Those ≤ 42 months were administered the Bayley Scales of Infant and Toddler Development Third Edition (Bayley-III), and those > 42 months the Vineland Adaptive Behavior Scales-Second Edition (Vineland-II). Stereotyped behaviors (Stereotypy Severity Scale, SSS) and aggressive behaviors (Behavior Problems Inventory-Short Version, BPIs) were assessed in all subjects > 1 year; sensory profile (Child Sensory Profile 2, C-SP2) in all aged 2-18 years. RESULTS: Twenty-two subjects were enrolled (11 F/11 M; age 9 months to 28 years). All subjects ≤ 42 months had psychomotor developmental delay. Of the subjects > 42 months, 15 had low IQ deviation, and 1 in the normal range. Stereotypies were frequent (median SSS-total score 25/68). Lower Vineland-II values corresponded to greater intensity and frequency of stereotypies (p = 0.004 and p = 0.003), and self-injurious behaviors (p = 0.002 and p = 0.002). Patients with severe low vision had greater interference of stereotypies (p = 0.027), and frequency and severity of aggressive behaviors (p = 0.026; p = 0.032). The C-SP2, while not homogeneous across subjects, showed prevalence of low registration and sensory seeking profiles and hypersensitivity to tactile and auditory stimuli. Lower Vineland-II scores correlated with higher Registration scores (p = 0.041), while stereotypies were more frequent and severe in case of high auditory sensitivity (p = 0.019; p = 0.007). Finally, greater sleep impairment correlated with stereotypies and self-injurious behaviors, and lower Vineland-II scores. CONCLUSIONS: The present study provides a further step in the investigation of the etiopathogenesis of the syndrome. Furthermore, these aspects could guide rehabilitation therapy through the identification of targeted protocols.

Neurological Phenotype of Mowat-Wilson Syndrome.

Mowat-Wilson Syndrome (MWS) (OMIM # 235730) is a rare disorder due to ZEB2 gene defects (heterozygous mutation or deletion). The ZEB2 gene is a widely expressed regulatory gene, extremely important for the proper prenatal development. MWS is characterized by a specific facial gestalt and multiple musculoskeletal, cardiac, gastrointestinal, and urogenital anomalies. The nervous system involvement is extensive and constitutes one of the main features in MWS, heavily affecting prognosis and life quality of affected individuals. This review aims to comprehensively organize and discuss the neurological and neurodevelopmental phenotype of MWS. First, we will describe the role of ZEB2 in the formation and development of the nervous system by reviewing the preclinical studies in this regard. ZEB2 regulates the neural crest cell differentiation and migration, as well as in the modulation of GABAergic transmission. This leads to different degrees of structural and functional impairment that have been explored and deepened by various authors over the years. Subsequently, the different neurological aspects of MWS (head and brain malformations, epilepsy, sleep disorders, and enteric and peripheral nervous system involvement, as well as developmental, cognitive, and behavioral features) will be faced one at a time and extensively examined from both a clinical and etiopathogenetic point of view, linking them to the ZEB2 related pathways.

Computed Tomography in Acute Severe Central Nervous System Complications in Children Treated for Cancer: Still a Useful Diagnostic Tool in the Emergency Setting.

We retrospectively checked patients who underwent chemotherapy and/or hematopoietic stem cell transplantation from 2007 to 2016, in order to evaluate whether early computed tomography is useful in children treated for cancer with acute central nervous system complications. Out of a total sample of 443 patients, 52 children (11.7%) presented these complications. In the end, 31 patients were included, with a total of 33 events of central nervous system complications. The computed tomography was abnormal in 22 events (67%) and diagnostic for a specific complication in 20 events (61%), whereas it directly influenced the treatment in 16 events (48%). Computed tomography should be still considered a relevant diagnostic tool in the management of acute central nervous system complications in the emergency setting.

Sleep in Children With Pallister Killian Syndrome: A Prospective Clinical and Videopolysomnographic Study.

Objectives: Pallister-Killian syndrome (PKS) is a rare genetic disorder with multi-organ involvement caused by mosaic tetrasomy of chromosome 12p. Although many caregivers report the presence of impaired sleep in their children, there are no clear data in the literature on this issue and no systematic study has ever been performed. With this study, we aimed to characterize the features of sleep in Pallister-Killian syndrome and identify the possible influence of clinical and demographic features. Moreover, our aim was to verify the effectiveness of conventional screening questionnaires in this particular group of patients. Methods: We prospectively enrolled 14 patients aged 1-17 years in collaboration with PKS Kids Italia ONLUS. The Sleep Disturbance Scale for Children (SDSC) questionnaire was administered to caregivers. Then, video polysomnography (VPSG) of at least 24 h was performed and results were compared with a same-aged control group. Results: A total of 92% of patients had abnormal SDSC scores, extremely high in the "disorder of initiating and maintaining sleep" (DIMS) and "sleep breathing disorders" (SBD) subscales. VPSG showed a significantly impaired macrostructure in PKS patients, with a higher Arousal Index (p < 0.00001) and percentage of time spent in N3 (p < 0.00001), and reduced Sleep Efficiency (p = 0.0006). After dividing both PKS and controls into two groups based on median age, some peculiarities emerged: the younger group had higher Awakenings Index (p = 0.0207) and percentage of time spent in N1 (p = 0.015) while the older group showed higher time in bed (TIB) (p = 0.0485), compared with controls. Due to poor compliance, the Apnea-Hypopnea Index (AHI) was evaluated only for 10 PKS children, being significantly increased (p = 0.0427) compared with controls. SBD subscale scores in SDSC were significantly related to AHI values in VPSG (p = 0.0099). Conclusions: This study constitutes the first attempt to describe the sleep pattern in PKS. Despite small numbers due to the rarity of the syndrome, our VPSG results confirm the high prevalence of sleep disorders (SDs) in these patients. It is therefore essential to investigate and treat them. The SDSC scale is a good screening tool for early detection also in these patients, with particular sensitivity in detecting breathing disorders.

Epilepsy features in ARID1B-related Coffin-Siris syndrome.

Coffin-Siris syndrome (CSS) is a rare congenital malformation syndrome, caused by mutations in the ARID1B gene in over half of the cases. While the clinical characteristics of the syndrome have been increasingly described, a detailed evaluation of the epileptic phenotype in patients with ARID1B alterations and CSS has not been approached yet. We report seven patients with ARID1B-related CSS, focusing on epilepsy and its electroclinical features. The evolution of epilepsy and EEG findings of children with CSS are described and compared with patients previously reported in the literature. The patients described here reveal common features, consistent with those of patients previously described in the literature. The epilepsy phenotype of CSS due to ARID1B pathogenic variants may be described as focal epilepsy with seizures, variable in frequency, arising from motor areas, with onset in the first years of life and susceptibility to fever, and interictal perisylvian (centrotemporal) epileptiform abnormalities that are enhanced during sleep with possible evolution to an EEG pattern of continuous spike and wave during sleep (without documented developmental regression). Additional information emerging from other patients is needed to confirm this definition.

Mowat-Wilson syndrome: growth charts.

BACKGROUND: Mowat-Wilson syndrome (MWS; OMIM #235730) is a genetic condition caused by heterozygous mutations or deletions of the ZEB2 gene. It is characterized by moderate-severe intellectual disability, epilepsy, Hirschsprung disease and multiple organ malformations of which congenital heart defects and urogenital anomalies are the most frequent ones. To date, a clear description of the physical development of MWS patients does not exist. The aim of this study is to provide up-to-date growth charts specific for infants and children with MWS. Charts for males and females aged from 0 to 16 years were generated using a total of 2865 measurements from 99 MWS patients of different ancestries. All data were collected through extensive collaborations with the Italian MWS association (AIMW) and the MWS Foundation. The GAMLSS package for the R statistical computing software was used to model the growth charts. Height, weight, body mass index (BMI) and head circumference were compared to those from standard international growth charts for healthy children. RESULTS: In newborns, weight and length were distributed as in the general population, while head circumference was slightly smaller, with an average below the 30th centile. Up to the age of 7 years, weight and height distribution was shifted to slightly lower values than in the general population; after that, the difference increased further, with 50% of the affected children below the 5th centile of the general population. BMI distribution was similar to that of non-affected children until the age of 7 years, at which point values in MWS children increased with a less steep slope, particularly in males. Microcephaly was sometimes present at birth, but in most cases it developed gradually during infancy; many children had a small head circumference, between the 3rd and the 10th centile, rather than being truly microcephalic (at least 2 SD below the mean). Most patients were of slender build. CONCLUSIONS: These charts contribute to the understanding of the natural history of MWS and should assist pediatricians and other caregivers in providing optimal care to MWS individuals who show problems related to physical growth. This is the first study on growth in patients with MWS.

Myoclonic epilepsy with photosensitivity in infants with Pallister-Killian Syndrome.

INTRODUCTION: Pallister-Killian Syndrome (PKS) (OMIM #601803) is a rare genetic disorder caused by a mosaic tetrasomy of the short arm of chromosome 12. Epilepsy is a frequent concern in PKS patients. METHODS: we report 3 PKS patients, with early-onset myoclonic epilepsy and photosensitivity. In these children, we analysed epileptic history and the EEG phenotype. RESULTS: Epilepsy onset was in the first 2 years of life in all patients and in 2 of them myoclonic seizures were the only seizure type. In all children photosensitivity was observed and myoclonic seizures were mainly related to low-frequency (1-6 Hz) intermittent photic stimulation. Levetiracetam was effective and well tolerated in the 2 treated patients. CONCLUSIONS: early-onset myoclonic epilepsy is a possible clinical manifestation of PKS. Low-frequency photosensitivity is a peculiar bioelectrical marker in these children.

Sleep in Mowat-Wilson Syndrome: a clinical and video-polysomnographic study.

OBJECTIVE: Sleep disturbances are frequently reported in Mowat-Wilson Syndrome (MWS). The current study aimed to evaluate clinical and video-polysomnographic (VPSG) characteristics of the sleep architecture and abnormal electroencephalogram (EEG) patterns during sleep in MWS. METHODS: Sixteen individuals with MWS (range 16 months-25 years), attending the Department of Child Neurology and Psychiatry of the University of Bologna, were included. The "Sleep Disturbances Scale for Children (SDSC)" questionnaire was administered to all parents of MWS patients, and all patients underwent a VPSG recording. RESULTS: The analysis of the SDSC questionnaire revealed disturbances mainly at the sleep-wake transition and in initiating and maintaining sleep. Evaluation of sleep structure in MWS patients showed a significant reduction of total sleep time, an increase of wake after sleep onset and arousal index as compared to normal controls. An EEG pattern characterized by slowing of background activity and poverty of physiological sleep characterisitcs was observed in all patients. Moreover, in patients aged >7 years, anteriorly predominant spike and waves were observed, markedly activated by sleep configuring a sub-continuous or continuous activity. CONCLUSION: Our data (both clinical and VPSG) documented the presence of significant and clinically relevant sleep disturbances in MWS patients. Moreover, we identified a characteristic age-dependent sleep EEG pattern that could provide a new element to assist in the management of MWS.

Central Nervous System Complications in Children Receiving Chemotherapy or Hematopoietic Stem Cell Transplantation.

Therapy-related neurotoxicity greatly affects possibility of survival and quality of life of pediatric patients treated for cancer. Central nervous system (CNS) involvement is heterogeneous, varying from very mild and transient symptoms to extremely severe and debilitating, or even lethal syndromes. In this review, we will discuss the broad scenario of CNS complications and toxicities occurring during the treatment of pediatric patients receiving both chemotherapies and hematopoietic stem cell transplantation. Different types of complications are reviewed ranging from therapy related to cerebrovascular with a specific focus on neuroradiologic and clinical features.

Life-threatening complications of posterior reversible encephalopathy syndrome in children.

BACKGROUND: Although the posterior reversible encephalopathy syndrome (PRES) is considered to have a benign clinical outcome, the presentation of PRES can be associated with life-threatening complications such as severe cerebral hemorrhage, cerebellar herniation and refractory status epilepticus (SE). The aim of this paper is to report incidence, clinical features and outcome of life-threatening complications related to PRES in children. METHODS: Patients who suffered from life-threatening complications were retrospectively identified from a group composed by 27 consecutive children diagnosed with PRES in our hospital between 2000 and 2012. The clinical, radiological and EEG features and the outcome of these patients were evaluated and compared to the characteristics of patients with no complications. RESULTS: Five patients (18%) presented life-threatening complications: 2 cerebral hemorrhages with mass effect and midline shift (1 massive intraparenchymal hemorrhage and 1 subdural hemorrhage and intraparenchymal hemorrhage), 2 transforaminal cerebellar herniations and 1 refractory SE. Two children died because of complications and 2 children required urgent neurosurgical intervention. The infratentorial involvement at onset of PRES and the observation of focal neurological deficits other than visual disturbances were significantly more frequent in children with life-threatening complications (p < 0.01). CONCLUSIONS: PRES is associated with a non-negligible incidence of life-threatening complications. A careful clinical, neuroradiological and EEG monitoring is necessary in order to improve the outcome especially in the case of focal neurological deficits and infratentorial involvement.