Subtle Malformation of the Cochlear Apex and Genetic Abnormalities: Beyond the "Thorny" Cochlea.

With the routine use of high-resolution heavily T2-weighted sequences to evaluate patients with hearing deficits, new, subtle phenotypes of cochlear malformations are being discovered and an increasing number of genotype-phenotype correlations are being found through a reverse phenotype approach, which can help guide geneticists. In this brief report, we present subtle malformations of the apical turn of the cochlea related to 3 genetic mutations, emphasizing the importance of a careful assessment of the cochlear apex.

The Cochlea in Branchio-Oto-Renal Syndrome: An Objective Method for the Diagnosis of Offset Cochlear Turns.

BACKGROUND AND PURPOSE: An "unwound" or "offset" cochlea has been described as a characteristic imaging feature in patients with branchio-oto-renal syndrome, and recently recognized to be associated in particular to those with EYA1 gene mutations. Determination of this feature has traditionally relied on subjective visual assessment. Our aim was to establish an objective assessment method for cochlear offset (the cochlear turn alignment ratio) and determine an optimal cutoff turn alignment ratio value that separates individuals with EYA1-branchio-oto-renal syndrome from those with SIX1-branchio-oto-renal syndrome and healthy controls. MATERIALS AND METHODS: Temporal bone CT or MR imaging from 40 individuals with branchio-oto-renal syndrome and 40 controls was retrospectively reviewed. Cochlear offset was determined visually by 2 independent blinded readers and then quantitatively via a standardized technique yielding the cochlear turn alignment ratio. The turn alignment ratio values were compared between cochleae qualitatively assessed as "not offset" and "offset." Receiver operating characteristic analysis was used to determine the ability of the turn alignment ratio to differentiate between these populations and an optimal cutoff turn alignment ratio value. Cochlear offset and turn alignment ratio values were analyzed for each branchio-oto-renal syndrome genotype subpopulation and for controls. RESULTS: The turn alignment ratio can accurately differentiate between cochleae with and without an offset (P < .001). The optimal cutoff value separating these populations was 0.476 (sensitivity = 1, specificity = 0.986, J = 0.986). All except 1 cochlea among the EYA1-branchio-oto-renal syndrome subset and all with unknown genotype branchio-oto-renal syndrome had a cochlear offset and a turn alignment ratio of <0.476. All except 1 cochlea among the SIX1-branchio-oto-renal syndrome subset and all controls had no offset and a turn alignment ratio of >0.476. CONCLUSIONS: There is a statistically significant difference in turn alignment ratios between offset and nonoffset cochleae, with an optimal cutoff of 0.476. This cutoff value allows excellent separation of EYA1-branchio-oto-renal syndrome from SIX1-branchio-oto-renal syndrome and from individuals without branchio-oto-renal syndrome or sensorineural hearing loss. The turn alignment ratio is a reliable and objective metric that can aid in the imaging evaluation of branchio-oto-renal syndrome.

Brain Abnormalities in Patients with Germline Variants in H3F3: Novel Imaging Findings and Neurologic Symptoms Beyond Somatic Variants and Brain Tumors.

BACKGROUND AND PURPOSE: Pathogenic somatic variants affecting the genes Histone 3 Family 3A and 3B (H3F3) are extensively linked to the process of oncogenesis, in particular related to central nervous system tumors in children. Recently, H3F3 germline missense variants were described as the cause of a novel pediatric neurodevelopmental disorder. We aimed to investigate patterns of brain MR imaging of individuals carrying H3F3 germline variants. MATERIALS AND METHODS: In this retrospective study, we included individuals with proved H3F3 causative genetic variants and available brain MR imaging scans. Clinical and demographic data were retrieved from available medical records. Molecular genetic testing results were classified using the American College of Medical Genetics criteria for variant curation. Brain MR imaging abnormalities were analyzed according to their location, signal intensity, and associated clinical symptoms. Numeric variables were described according to their distribution, with median and interquartile range. RESULTS: Eighteen individuals (10 males, 56%) with H3F3 germline variants were included. Thirteen of 18 individuals (72%) presented with a small posterior fossa. Six individuals (33%) presented with reduced size and an internal rotational appearance of the heads of the caudate nuclei along with an enlarged and squared appearance of the frontal horns of the lateral ventricles. Five individuals (28%) presented with dysgenesis of the splenium of the corpus callosum. Cortical developmental abnormalities were noted in 8 individuals (44%), with dysgyria and hypoplastic temporal poles being the most frequent presentation. CONCLUSIONS: Imaging phenotypes in germline H3F3-affected individuals are related to brain features, including a small posterior fossa as well as dysgenesis of the corpus callosum, cortical developmental abnormalities, and deformity of lateral ventricles.

Re-Examining the Cochlea in Branchio-Oto-Renal Syndrome: Genotype-Phenotype Correlation.

BACKGROUND AND PURPOSE: Temporal bone imaging plays an important role in the work-up of branchio-oto-renal syndrome. Previous reports have suggested that the unwound or offset cochlea is a highly characteristic marker for branchio-oto-renal syndrome. Our goals were to examine the prevalence of this finding in a branchio-oto-renal syndrome cohort and analyze genetic-phenotypic associations not previously established. MATERIALS AND METHODS: This multicenter retrospective study included 38 ears in 19 unrelated individuals with clinically diagnosed branchio-oto-renal syndrome and confirmed mutations in the EYA1 or SIX1 genes. Two blinded neuroradiologists independently reviewed and documented temporal bone imaging findings in 13 categories for each ear. Imaging phenotypes were correlated with genotypes. RESULTS: There was excellent interrater agreement for all 13 phenotypic categories (κ ≥ 0.80). Of these, 9 categories showed statistically significant differences between patients with EYA1-branchio-oto-renal syndrome and SIX1-branchio-oto-renal syndrome. Cochlear offset was present in 100% of patients with EYA1-branchio-oto-renal syndrome, but in only 1 ear (12.5%) among patients with SIX1-branchio-oto-renal syndrome. A short thorny appearance of the cochlear apical turn was observed in most patients with SIX1-branchio-oto-renal syndrome. CONCLUSIONS: An offset cochlea is associated with the EYA1-branchio-oto-renal syndrome genotype. The SIX1-branchio-oto-renal syndrome genotype is associated with a different cochlear phenotype that almost always is without offset and has a short thorny tip as the apical turn. Therefore, cochlear offset is not a characteristic marker for all patients with branchio-oto-renal syndrome. The lack of a cochlear offset in a patient with clinically suspected branchio-oto-renal syndrome does not exclude the diagnosis and, in fact, may be predictive of the SIX1 genotype.

Paediatric spinal cord low-grade gliomas-evaluation and management of post-surgical residual disease.

PURPOSE: To assess the evaluation and management of post-surgical residual disease for low-grade intramedullary spinal cord tumours (IMSCT) in childhood. METHODS: A single-centre retrospective review of low-grade IMSCTs treated between 2000 and 2019. All surgeries were performed with intent of safe maximal resection guided by intra-operative neurophysiological monitoring (IONM). Pre- and post-operative MRIs were reviewed to assess the extent of resection (EOR), recorded as follows: gross total resection (GTR), near total resection (NTR), sub-total resection (STR) and partial resection (PR). Outcome measures were time to recurrence, need for and modality of additional therapy and ambulatory status at last follow-up. RESULTS: Thirty patients underwent surgery for IMSCT (median age 6.9 years). EOR was GTR = 8, NTR = 4, STR = 9, PR = 9. All patients were alive at last follow-up (median follow-up 73 months [IQR 93 months]). Eighteen patients (60%) remained radiologically stable. Twelve patients (40%) developed recurrence during surveillance. Progression free survival was significantly better in cases with GTR + NTR in comparison to either STR or PR (p = 0.039). 10/30 (33%) patients were treated with additional therapy. At last follow-up, 26/30 patients were independently mobile. CONCLUSION: Survival rates for low-grade IMSCT are excellent. Radical micro-surgical resection, guided by IONM provides effective means of balancing the objectives of maximal safe resection, functional outcome and tumour control. Whilst evidence of 'residual disease' was identified in over 2/3 of immediate post-operative MRI scans, additional treatment was required in only 1/3 of cases. Critical appraisal of post-operative imaging findings is required to better define 'residual disease'. Small volume residual disease (< 5%) does not compromise progression-free survival.

Spectrum of Neuroradiologic Findings Associated with Monogenic Interferonopathies.

The genetic interferonopathies are a heterogeneous group of disorders thought to be caused by the dysregulated expression of interferons and are now commonly considered in the differential diagnosis of children presenting with recurrent or persistent inflammatory phenotypes. With emerging therapeutic options, recognition of these disorders is increasingly important, and neuroimaging plays a vital role. In this article, we discuss the wide spectrum of neuroradiologic features associated with monogenic interferonopathies by reviewing the literature and illustrate these with cases from our institutions. These cases include intracerebral calcifications, white matter T2 hyperintensities, deep WM cysts, cerebral atrophy, large cerebral artery disease, bilateral striatal necrosis, and masslike lesions. A better understanding of the breadth of the neuroimaging phenotypes in conjunction with clinical and laboratory findings will enable earlier diagnosis and direct therapeutic strategies.

A Diagnostic Algorithm for Posterior Fossa Tumors in Children: A Validation Study.

BACKGROUND AND PURPOSE: Primary posterior fossa tumors comprise a large group of neoplasias with variable aggressiveness and short and long-term outcomes. This study aimed to validate the clinical usefulness of a radiologic decision flow chart based on previously published neuroradiologic knowledge for the diagnosis of posterior fossa tumors in children. MATERIALS AND METHODS: A retrospective study was conducted (from January 2013 to October 2019) at 2 pediatric referral centers, Children's Hospital of Philadelphia, United States, and Great Ormond Street Hospital, United Kingdom. Inclusion criteria were younger than 18 years of age and histologically and molecularly confirmed posterior fossa tumors. Subjects with no available preoperative MR imaging and tumors located primarily in the brain stem were excluded. Imaging characteristics of the tumors were evaluated following a predesigned, step-by-step flow chart. Agreement between readers was tested with the Cohen κ, and each diagnosis was analyzed for accuracy. RESULTS: A total of 148 cases were included, with a median age of 3.4 years (interquartile range, 2.1-6.1 years), and a male/female ratio of 1.24. The predesigned flow chart facilitated identification of pilocytic astrocytoma, ependymoma, and medulloblastoma sonic hedgehog tumors with high sensitivity and specificity. On the basis of the results, the flow chart was adjusted so that it would also be able to better discriminate atypical teratoid/rhabdoid tumors and medulloblastoma groups 3 or 4 (sensitivity = 75%-79%; specificity = 92%-99%). Moreover, our adjusted flow chart was useful in ruling out ependymoma, pilocytic astrocytomas, and medulloblastoma sonic hedgehog tumors. CONCLUSIONS: The modified flow chart offers a structured tool to aid in the adjunct diagnosis of pediatric posterior fossa tumors. Our results also establish a useful starting point for prospective clinical studies and for the development of automated algorithms, which may provide precise and adequate diagnostic tools for these tumors in clinical practice.

Characteristic Cochlear Hypoplasia in Patients with Walker-Warburg Syndrome: A Radiologic Study of the Inner Ear in α-Dystroglycan-Related Muscular Disorders.

BACKGROUND AND PURPOSE: Walker-Warburg syndrome, muscle-eye-brain disease, and Fukuyama congenital muscular dystrophy are α-dystroglycan-related muscular disorders associated with brain malformations and eye abnormalities in which no structural inner ear abnormality has been described radiologically. We collected patients from 6 tertiary pediatric hospitals and reported the radiologic features and frequency of inner ear dysplasias. MATERIALS AND METHODS: Patients previously diagnosed clinicoradiologically with Walker-Warburg syndrome, muscle-eye-brain disease, or Fukuyama congenital muscular dystrophy were included. We recorded the pathogenic variant, when available. Brain MR imaging and/or CT findings were reviewed in consensus, and inner ear anomalies were classified according to previous description in the literature. We then correlated the clinicoradiologic phenotype with the inner ear phenotype. RESULTS: Thirteen patients fulfilled the criteria for the Walker-Warburg syndrome phenotype, 8 for muscle-eye-brain disease, and 3 for Fukuyama congenital muscular dystrophy. A dysplastic cochlea was demonstrated in 17/24. The most frequent finding was a pronounced cochlear hypoplasia type 4 with a very small anteriorly offset turn beyond the normal-appearing basal turn (12/13 patients with Walker-Warburg syndrome and 1/11 with muscle-eye-brain disease or Fukuyama congenital muscular dystophy). Two of 8 patients with muscle-eye-brain disease, 1/3 with Fukuyama congenital muscular dystrophy, and 1/13 with Walker-Warburg syndrome showed a less severe cochlear hypoplasia type 4. The remaining patients without Walker-Warburg syndrome were healthy. The vestibule and lateral semicircular canals of all patients were normal. Cranial nerve VIII was present in all patients with diagnostic MR imaging. CONCLUSIONS: Most patients with the severe α-dystroglycanopathy Walker-Warburg syndrome phenotype have a highly characteristic cochlear hypoplasia type 4. Patients with the milder variants, muscle-eye-brain disease and Fukuyama congenital muscular dystrophy, more frequently have a normal cochlea or milder forms of hypoplasia.

A review of the safety of MRI in cochlear implant patients with retained magnets.

The number of patients with cochlear implants (CIs) is increasing due to expanding indications, and improving CI services. Furthermore, as the use of imaging increases in clinical medicine, it is increasingly likely that patients with CIs will require a magnetic resonance imaging (MRI) examination during their lifetime. Therefore it is important that clinicians are aware of the safety aspects and manufacturer recommendations for CI patients with retained magnets. This article summarises guidelines from all major CI manufacturers and reviews the published literature on the safety of MRI in CI patients with magnets in situ. The most commonly reported complication of MRI in CI patients was pain. Other significant complications included magnet displacement, depolarisation, and polarity reversal. Artefacts caused by the CI remain an issue, but may be reduced by the use of specific sequences. Manufacturer recommendations should be followed to reduce the risk of complications, although complications may occur even when guidelines are followed. For this reason, the indication for imaging these patients should be reviewed, and patients should be appropriately counselled and consented.

Monogenic mimics of Behçet's disease in the young.

OBJECTIVES: Monogenic autoinflammatory disorders (AID) and primary immunodeficiencies can present early in life with features that may be mistaken for Behçet's disease (BD). We aimed to retrospectively describe the clinical and laboratory features of 11 paediatric cases referred for suspected BD who turned out to have an alternative, monogenic disease mimicking BD. METHODS: Retrospective, paediatric BD specialist multicentre case series. Next generation sequencing (NGS) or conventional candidate gene screening approaches were utilized, facilitated in some cases by functional assays. RESULTS: Eleven children referred with suspected BD underwent genetic screening because of atypical BD features, and/or presentation before age 5 years. Eight patients (73%) were Caucasian, two were Pakistani and one was Turkish; 55% were female. A positive family history of BD was reported in 54% cases. The median age of disease onset was 0.6 (range 0.2-2.3) years. All had systemic inflammation and oral ulceration; 5/11 had genital ulceration; 3/11 had ocular involvement; and 9/11 had cutaneous manifestations. Nine/11 had known disease-causing genetic mutations in: TNFAIP3 (n = 2), WDR1 (n = 2), NCF1, AP1S3, LYN, MEFV and GLA. The remaining two cases each had novel variants in STAT1 and TNFRSF1A. CONCLUSION: Rare monogenic diseases can mimic BD, particularly when presenting early in life. These observations are now informing a strategy to explore screening for genetic mimics of BD in a UK cohort of children and adults to better understand the proportion of UK BD patients who may in fact have an underlying monogenetic diagnosis.

Expanding the Distinctive Neuroimaging Phenotype of ACTA2 Mutations.

BACKGROUND AND PURPOSE: Arg179His mutations in ACTA2 are associated with a distinctive neurovascular phenotype characterized by a straight course of intracranial arteries, absent basal Moyamoya collaterals, dilation of the proximal internal carotid arteries, and occlusive disease of the terminal internal carotid arteries. We now add to the distinctive neuroimaging features in these patients by describing their unique constellation of brain malformative findings that could flag the diagnosis in cases in which targeted cerebrovascular imaging has not been performed. MATERIALS AND METHODS: Neuroimaging studies from 13 patients with heterozygous Arg179His mutations in ACTA2 and 1 patient with pathognomonic clinicoradiologic findings for ACTA2 mutation were retrospectively reviewed. The presence and localization of brain malformations and other abnormal brain MR imaging findings are reported. RESULTS: Characteristics bending and hypoplasia of the anterior corpus callosum, apparent absence of the anterior gyrus cinguli, and radial frontal gyration were present in 100% of the patients; flattening of the pons on the midline and multiple indentations in the lateral surface of the pons were demonstrated in 93% of the patients; and apparent "squeezing" of the cerebral peduncles in 85% of the patients. CONCLUSIONS: Because α-actin is not expressed in the brain parenchyma, only in vascular tissue, we speculate that rather than a true malformative process, these findings represent a deformation of the brain during development related to the mechanical interaction with rigid arteries during the embryogenesis.

Computed tomography versus magnetic resonance imaging in paediatric cochlear implant assessment: a pilot study and our experience at Great Ormond Street Hospital.

BACKGROUND: To date, there is a lack of consensus regarding the use of both computed tomography and magnetic resonance imaging in the pre-operative assessment of cochlear implant candidates. METHODS: Twenty-five patients underwent high-resolution computed tomography and magnetic resonance imaging. 'Control scores' describing the expected visualisation of specific features by computed tomography and magnetic resonance imaging were established. An independent radiological review of all computed tomography and magnetic resonance imaging scan features was then compared to the control scores and the findings recorded. RESULTS: Agreement with control scores occurred in 83 per cent (20 out of 24) of computed tomography scans and 91 per cent (21 out of 23) of magnetic resonance imaging scans. Radiological abnormalities were demonstrated in 16 per cent of brain scans and 18 per cent of temporal bone investigations. CONCLUSION: Assessment in the paediatric setting constitutes a special situation given the likelihood of congenital temporal bone abnormalities and associated co-morbidities that may be relevant to surgery and prognosis following cochlear implantation. Both computed tomography and magnetic resonance imaging contribute valuable information and remain necessary in paediatric cochlear implant pre-operative assessment.

Imaging of cervical extradural en-plaque meningioma. A case report.

Meningioma is one of the most common spinal extramedullary tumors, largely intradural. An extradural localization is possible but less frequent. There are two morphologically different types of meningioma: one is round, and the other is the "en-plaque" form, that grows along the dura mater like a sheet. The "en-plaque" form, is unusual. We report on an unusual case of epidural and extraspinal "en-plaque" meningioma, describing the MRI and CT features and discussing the possible principal differential diagnosis (neurolymphomatosis, plexiform neurofibromas/schwannomas and metastasis).

The use of lyophilized dura in reconstruction of the orbital floor.

The results and experiences with the use of lyophilised human dura in 52 cases are reported. Experimental work carried out on rabbits demonstrate that human lyodura is replaced by a layer of connective tissue. Both, the results of animal experiments as well as those experienced in 52 clinical cases suggest that lyodura is an excellent material for the reconstruction of defects of the orbital floor.