Diffusion Tensor Imaging in Joubert Syndrome

BACKGROUND AND PURPOSE: Neuropathologic findings and preliminary imaging studies demonstrated the absence of pyramidal tract and superior cerebellar peduncular decussation in individual patients with Joubert syndrome (JS). We hypothesized that functional-structural neuroimaging findings do not differ between the genetic forms of JS. MATERIALS AND METHODS: MR imaging was performed with a 3T MR imaging-unit. Multiplanar T2- and T1-weighted imaging was followed by diffusion tensor imaging (DTI). Isotropic diffusion-weighted images, apparent diffusion coefficient maps, and color-coded fractional anisotropy maps, including tractography, were subsequently calculated. RESULTS: In all 6 patients studied, DTI showed that the fibers of the superior cerebellar peduncles did not decussate in the mesencephalon and the corticospinal tract failed to cross in the caudal medulla. The patients represented various genetic forms of JS. CONCLUSION: In JS, the fibers of the pyramidal tract and the superior cerebellar peduncles do not cross, irrespective of the underlying mutation

Joubert syndrome and related disorders: spectrum of neuroimaging findings in 75 patients

VH and MTS are the neuroimaging hallmarks of JSRD. We aimed to look at the full spectrum of neuroimaging findings in JSRD and reviewed the MR imaging of 75 patients with JSRD, including 13 siblings and 4 patients with OFD VI. All patients had VH and enlargement of the fourth ventricle. The degree of VH and the form of the MTS were variable. In most patients, the cerebellar hemispheres were normal and the PF was enlarged. Brain stem morphology was abnormal in 30% of the patients. Supratentorial findings included hippocampal malrotation, callosal dysgenesis, migration disorders, cephaloceles, and ventriculomegaly. All patients with OFD VI had a similar pattern, including HH in 2 patients. No neuroimaging-genotype correlation could be found. The wide neuroimaging spectrum in our patients supports the heterogeneity of JSRD. Neuroimaging differences in siblings represent intrafamilial heterogeneity. Due to the absence of a correlation with genotype, neuroimaging findings are of limited value in classifying patients with JSRD

Brain MRI Findings in Pediatric-Onset Neuromyelitis Optica Spectrum Disorder

BACKGROUND AND PURPOSE: Differentiating pediatric-onset neuromyelitis optica spectrum disorder from acute disseminated encephalomyelitis could be challenging, especially in cases presenting with only brain manifestations. Our purpose was to investigate brain MR imaging features that may help distinguish these 2 entities. MATERIALS AND METHODS: We retrospectively examined initial brain MR imaging studies of 10 patients with pediatric-onset neuromyelitis optica spectrum disorder (female/male ratio, 7:3) and 10 patients with acute disseminated encephalomyelitis (female/male ratio, 2:8). The mean age of the patients was 10.3 ± 5.6 and 8.7 ± 5.3 years, respectively. Brain lesions were evaluated with respect to location, extent, expansion, T1 hypointensity, contrast enhancement/pattern, and diffusion characteristics. The χ2 test (Yates or Fisher exact χ2tests) was used to compare differences between groups. RESULTS: Cerebral subcortical ± juxtacortical and pons ± middle cerebellar peduncle were the most frequent locations involved in both neuromyelitis optica spectrum disorder (n = 5 and 4, respectively) and acute disseminated encephalomyelitis (n = 9 and 7, respectively). Thalamic lesions were more frequent in acute disseminated encephalomyelitis (P = .020) and were detected only in 1 patient with neuromyelitis optica spectrum disorder. None of the patients with neuromyelitis optica spectrum disorder had hypothalamic, internal capsule, or cortical lesions. The internal capsule involvement was found to be significantly different between groups (P = .033). There was no significant difference in terms of extent, expansion, T1 hypointensity, contrast enhancement/pattern, and diffusion characteristics. CONCLUSIONS: Although there is a considerable overlap in brain MR imaging findings, thalamic and internal capsule involvement could be used to differentiate pediatric-onset neuromyelitis optica spectrum disorder from acute disseminated encephalomyelitis.PubMedWo

Compound Heterozygous Variants in ROBO1 Cause a Neurodevelopmental Disorder With Absence of Transverse Pontine Fibers and Thinning of the Anterior Commissure and Corpus Callosum

Background Axonal guidance disorders are characterized by white matter tracts with an anomalous course, failure to cross the midline, or presence of anomalous white matter tracts. Diffusion tensor imaging (DTI) is a suitable noninvasive, in vivo neuroimaging tool to study axonal guidance disorders. We describe a novel disorder in a boy with compound heterozygous variants in the ROBO1 gene. Patient Description The child was referred at age 13\uc2\ua0months because of developmental delay. At age nine years, he had severe intellectual disability and hyperactivity. He was nonverbal and wheelchair dependent because of spastic diplegia and ataxia. Brain magnetic resonance imaging with DTI revealed marked pontine hypoplasia, thinning of the anterior commissure and corpus callosum, and absence of the transverse pontine fibers. In addition, at the level of the pons the corticospinal tracts and medial lemnisci were not clearly separated from each other. Whole exome sequencing revealed compound heterozygous variants in the ROBO1 gene. Conclusion This child's neuroimaging phenotype (absence of the transverse pontine fibers and thinning of the anterior commissure and corpus callosum as shown by DTI) is suggestive of an axonal guidance disorder and supports a pathogenic role of the compound heterozygous variants in the ROBO1 gene

Neuroimaging characteristics of nasopharyngeal carcinoma in children

BACKGROUND AND PURPOSE Pediatric nasopharyngeal carcinoma (NPC) is a rare epithelial origin tumor associated with undifferentiated histology, Epstein–Barr virus (EBV) infection, and genetic risk factors. Childhood NPC is usually clinically silent, often presenting with advanced locoregional compromise, including skull base invasion and cervical lymphadenopathy, and has a better prognosis than adult NPC. This article describes computed tomography (CT) and magnetic resonance imaging (MRI) features in a cohort of 28 pediatric NPC patients. METHODS A retrospective review was performed among children with histopathology proven NPC diagnoses between 1996 and 2019 for this study. The electronic medical records were reviewed to determine demographics, EBV serology, and World Health Organization (WHO) type. Nasopharyngeal CT and/or MRI at presentation for tumor spread as well as density and/or intensity, lymphadenopathy, postcontrast enhancement and diffusion characteristics before treatment were evaluated. RESULTS Twenty-eight patients (21 males, 7 females) were included. The mean patient age at diagnosis was 13.3 (range 7 to 17) years. EBV was positive in 71.4% of patients. The majority of patients (78.6%) had a WHO type III tumor, unilateral fossa of Rosenmuller involvement (71.4%). Neuroimaging features were CT isodensity, T1-isointensity, T2-hyperintensity, and heterogeneous postcontrast enhancement for all patients (100%) and restricted diffusion (90%). CONCLUSIONS Although uncommon in pediatric patients, NPC should be in the differential diagnosis of adolescents presenting with a nasopharyngeal mass. Recognizing key imaging characteristics is helpful in the diagnosis of NPC