Cochlear Implantation: Systematic Approach to Preoperative Radiologic Evaluation.

Sensorineural hearing loss results from abnormalities that affect the hair cells of the membranous labyrinth, inner ear malformations, and conditions affecting the auditory pathway from the cochlear nerve to the processing centers of the brain. Cochlear implantation is increasingly being performed for hearing rehabilitation owing to expanding indications and a growing number of children and adults with sensorineural hearing loss. An adequate understanding of the temporal bone anatomy and diseases that affect the inner ear is paramount for alerting the operating surgeon about variants and imaging findings that can influence the surgical technique, affect the choice of cochlear implant and electrode type, and help avoid inadvertent complications. In this article, imaging protocols for sensorineural hearing loss and the normal inner ear anatomy are reviewed, with a brief description of cochlear implant devices and surgical techniques. In addition, congenital inner ear malformations and acquired causes of sensorineural hearing loss are discussed, with a focus on imaging findings that may affect surgical planning and outcomes. The anatomic factors and variations that are associated with surgical challenges and may predispose patients to periprocedural complications also are highlighted. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Abusive head trauma: neuroimaging mimics and diagnostic complexities.

Traumatic brain injury is responsible for approximately half of all childhood deaths from infancy to puberty, the majority of which are attributable to abusive head trauma (AHT). Due to the broad way patients present and the lack of a clear mechanism of injury in some cases, neuroimaging plays an integral role in the diagnostic pathway of these children. However, this nonspecific nature also presages the existence of numerous conditions that mimic both the clinical and neuroimaging findings seen in AHT. This propensity for misdiagnosis is compounded by the lack of pathognomonic patterns and clear diagnostic criteria. The repercussions of this are severe and have a profound stigmatic effect. The authors present an exhaustive review of the literature complemented by illustrative cases from their institutions with the aim of providing a framework with which to approach the neuroimaging and diagnosis of AHT.

Warsaw breakage syndrome: Further clinical and genetic delineation.

Warsaw breakage syndrome (WBS) is a recently recognized DDX11-related rare cohesinopathy, characterized by severe prenatal and postnatal growth restriction, microcephaly, developmental delay, cochlear anomalies, and sensorineural hearing loss. Only seven cases have been reported in the English literature, and thus the information on the phenotype and genotype of this interesting condition is limited. We provide clinical and molecular information on five additional unrelated patients carrying novel bi-allelic variants in the DDX11 gene, identified via whole exome sequencing. One of the variants was found to be a novel Saudi founder variant. All identified variants were classified as pathogenic or likely pathogenic except for one that was initially classified as a variant of unknown significance (VOUS) (p.Arg378Pro). Functional characterization of this VOUS using heterologous expression of wild type and mutant DDX11 revealed a marked effect on protein stability, thus confirming pathogenicity of this variant. The phenotypic data of the seven WBS reported patients were compared to our patients for further phenotypic delineation. Although all the reported patients had cochlear hypoplasia, one patient also had posterior labyrinthine anomaly. We conclude that while the cardinal clinical features in WBS (microcephaly, growth retardation, and cochlear anomalies) are almost universally present, the breakage phenotype is highly variable and can be absent in some cases. This report further expands the knowledge of the phenotypic and molecular features of WBS.

Validation of the finding of hypertrophy of the clava in infantile neuroaxonal dystrophy/PLA2G6 by biometric analysis.

INTRODUCTION: Infantile neuroaxonal dystrophy (INAD), an autosomal recessive neurodegenerative disorder due to PLA2G6 mutation, is classified both as a PLA2G6-associated neurodegeneration (PLAN) disorder and as one of the neurodegeneration with brain iron accumulation (NBIA) disorders. Age of onset and clinical presentation in INAD is variable. Typically described imaging features of cerebellar atrophy, cerebellar cortex bright FLAIR signal, and globus pallidus iron deposition are variable or late findings. We characterize clinical and neuroimaging phenotypes in nine children with confirmed PLA2G6 mutations and show a useful imaging feature, clava hypertrophy, which may aid in earlier identification of patients. Measurements of the clava confirm actual enlargement, rather than apparent enlargement due to volume loss of the other brain stem structures. METHODS: A retrospective clinical and MRI review was performed. Brain stem measurements were performed and compared with age-matched controls. RESULTS: We identified nine patients, all with novel PLA2G6 gene mutations. MRI, available in eight, showed clava hypertrophy, regardless of age or the absence of other more typically described neuroimaging findings. Brain autopsy in our cohort confirmed prominent spheroid bodies in the clava nuclei. CONCLUSION: Clava hypertrophy is an important early imaging feature which may aid in indentification of children who would benefit from specific testing for PLA2G6 mutations.

Skull base development and craniosynostosis.

Abnormal skull shape resulting in craniofacial deformity is a relatively common clinical finding, with deformity either positional (positional plagiocephaly) or related to premature ossification and fusion of the skull sutures (craniosynostosis). Growth restriction occurring at a stenosed suture is associated with exaggerated growth at the open sutures, resulting in fairly predictable craniofacial phenotypes in single-suture non-syndromic pathologies. Multi-suture syndromic subtypes are not so easy to understand without imaging. Imaging is performed to define the site and extent of craniosynostosis, to determine the presence or absence of underlying brain anomalies, and to evaluate both pre- and postoperative complications of craniosynostosis. Evidence for intracranial hypertension may be seen both pre- and postoperatively, associated with jugular foraminal stenosis, sinovenous occlusion, hydrocephalus and Chiari 1 malformations. Following clinical assessment, imaging evaluation may include radiographs, high-frequency US of the involved sutures, low-dose (20-30 mAs) CT with three-dimensional reformatted images, MRI and nuclear medicine brain imaging. Anomalous or vigorous collateral venous drainage may be mapped preoperatively with CT or MR venography or catheter angiography.

Neurometabolic diseases of childhood.

Metabolic diseases affecting the pediatric brain are complex conditions, the underlying mechanisms leading to structural damage are diverse and the diagnostic imaging manifestations are often non-specific; hence early, sensitive and specific diagnosis can be challenging for the radiologist. However, misdiagnosis or a delayed diagnosis can result in a devastating, irreversible injury to the developing brain. Based upon the inborn error, neurometabolic diseases can be subdivided in various groups depending on the predominantly involved tissue (e.g., white matter in leukodystrophies or leukoencephalopathies), the involved metabolic processes (e.g., organic acidurias and aminoacidopathies) and primary age of the child at presentation (e.g., neurometabolic disorders of the newborn). This manuscript summarizes these topics.

Subcutaneous fat pads on body MRI--an early sign of congenital disorder of glycosylation PMM2-CDG (CDG1a).

Infants with phosphomannomutase 2 - congenital disorder of glycosylation (PMM2-CDG), formerly known as CDG1a, present with failure to thrive, visceral dysfunction, thromboembolic events and developmental delays noted before 6 months of age. Diagnosis is often delayed due to the considerable variability in phenotype. Characteristic, but not universal, features include inverted nipples and abnormal subcutaneous fat pads. Neuroimaging performed in the first 4 months of life may be normal, although cerebellar and brainstem atrophy is usual after 3 months of age. Cerebellar and brainstem atrophy have been noted as early as 11 days of life. We present an infant whose typical subcutaneous and retroperitoneal fat deposits were clinically occult, but identified on body MRI.

Neonatal neuroimaging findings in inborn errors of metabolism.

Individually, metabolic disorders are rare, but overall they account for a significant number of neonatal disorders affecting the central nervous system. The neonatal clinical manifestations of inborn errors of metabolism (IEMs) are characterized by nonspecific systemic symptoms that may mimic more common acute neonatal disorders like sepsis, severe heart insufficiency, or neonatal hypoxic-ischemic encephalopathy. Certain IEMs presenting in the neonatal period may also be complicated by sepsis and cardiomyopathy. Early diagnosis is mandatory to prevent death and permanent long-term neurological impairments. Although neuroimaging findings are rarely specific, they play a key role in suggesting the correct diagnosis, limiting the differential diagnosis, and may consequently allow early initiation of targeted metabolic and genetic laboratory investigations and treatment. Neuroimaging may be especially helpful to distinguish metabolic disorders from other more common causes of neonatal encephalopathy, as a newborn may present with an IEM prior to the availability of the newborn screening results. It is therefore important that neonatologists, pediatric neurologists, and pediatric neuroradiologists are familiar with the neuroimaging findings of metabolic disorders presenting in the neonatal time period.

Abnormal corpus callosum in neonates after hypoxic-ischemic injury.

BACKGROUND: Literature regarding callosal injury after hypoxic-ischemic injury (HII) is scant. OBJECTIVE: To present the MRI and US findings of callosal injury after HII. MATERIALS AND METHODS: MRI and US studies of 76 neonates were evaluated for HII and 53 were considered positive. RESULTS: Of the 53 neonates with HII, 40 demonstrated restricted diffusion on DWI; of these, 30 revealed callosal involvement. Nine of the 13 neonates with normal DWI, whose routine MRI images were compatible with HII, were imaged after 1 week of age. Five out of ten neonates imaged during the 1st week of life who did not show callosal restriction on DWI had predominantly basal ganglia injury. Callosal US images were regarded as abnormal in 16 out of the 53 neonates with HII, 15 of which revealed concomitant restricted diffusion on DWI. CONCLUSION: Callosal injuries are common after HII. DWI is effective in confirming these injuries and easily demonstrates injury if performed prior to 1 week of age. The restricted diffusion demonstrated after this time could be attributed to continued injury. US is not a sensitive modality for callosal injury detection; however, abnormally increased callosal echogenicity might be a specific marker of injury in this setting.

Hearing Instability in Children with Congenital Cytomegalovirus: Evidence and Neural Consequences.

OBJECTIVE/HYPOTHESIS: Sensorineural hearing loss (SNHL) is a common sequela of congenital cytomegalovirus (cCMV), potentially exacerbating neurocognitive delay. The objectives of this study were to assess: (1) age at which SNHL in children with cCMV; (2) stimulability of the auditory system in children with cCMV following cochlear implantation (CI); and (3) whether features of magnetic resonance imaging (MRI) potentially are predictive of hearing outcomes. METHODS: In this retrospective study of a prospectively acquired cohort, 123 children with cCMV who were referred for hearing loss at a single tertiary referral hospital over 20 years were compared with an unmatched comparative group of 90 children with GJB2-related deafness. Outcome measures were results of newborn hearing screening (NHS), behavioral audiograms, and, in a subgroup of cochlear implant (CI) users, responses from the auditory nerve and brainstem evoked by CI at initial activation, as well as lesional volume of FLAIR-hyperintense signal alterations on MRI. RESULTS: All but 3 of 123 children with cCMV had confirmed and persistent SNHL. At birth, 113 children with cCMV underwent NHS, 31 (27%) passed in both ears and 23 (20%) passed in one ear (no NHS data in 10 children). At the first audiologic assessment, 32 of 123 (26%) had normal hearing bilaterally; 35 of 123 (28%) had unilateral SNHL; and 57 of 123 (46%) had bilateral SNHL. More than half (67 of 123, 54%) experienced hearing deterioration in at least one ear. Survival analyses suggested that 60% of children who developed SNHL did so by 2.5 years and 80% by 5 years. In the children who passed NHS in one or both ears, 50% developed hearing loss by 3.5 years in the ear, which passed unilaterally (n = 23 ears), and 50% by 5 years in bilateral passes (n = 62 ears). Hearing loss was significant enough in all but one child with isolated high-frequency loss for rehabilitation to be indicated. Hearing thresholds in individual ears were in the CI range in 83% (102 of 123), although duration of deafness was sufficient to preclude implantation at our center in 13 children with unilateral SNHL. Hearing aids were indicated in 16% (20 of 123). Responses from the auditory nerve and brainstem to initial CI stimulation were similar in children with cCMV-related SNHL compared with GJB2-related SNHL. Characteristic white matter changes on MRI were seen in all children with cCMV-related SNHL (n = 91), but the lesion volume in each cortical hemisphere did not predict degree of SNHL. CONCLUSIONS: cCMV-related SNHL is often not detected by NHS but occurs with high prevalence in early childhood. Electrophysiological measures suggest equivalent stimulability of the auditory nerve and brainstem with CI in children with cCMV and GJB2-related SNHL. Hyperintense white matter lesions on FLAIR MRI are consistently present in children with cCMV-related SNHL but cannot be used to predict its time course or degree. Combined, the data show early and rapid deterioration of hearing in children with cCMV-related SNHL with potential for good CI outcomes if SNHL is identified and managed without delay. Findings support universal newborn screening for cCMV followed by careful audiological monitoring. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:S1-S24, 2022.

Ectopic cervical thymus in children: Clinical and radiographic features.

OBJECTIVES: Ectopic thymus is rare and can be a diagnostic challenge. This study evaluated the management of children radiographically diagnosed with ectopic cervical thymus. METHODS: A retrospective review of 100 patients was performed. Data related to clinical presentation, radiological imaging, pathology, and management were collected. Changes in lesion volume were tracked over time. Clinical characteristics were compared based on lesion location in the neck using analysis of variance modelling. RESULTS: There were 115 lesions with radiographic features of ectopic cervical thymus (15 children had bilateral lesions). Diagnosis was based on ultrasound in 98% of patients, magnetic resonance imaging in 18%, and computed tomography in 11%. Mean (SD) follow-up duration was 2 (2.2) years. Forty-four percent (51/115) of lesions involved the thyroid gland, 29% (33/115) were in the central neck but separate from the thyroid, 18% (21/115) had mediastinal extension, and 8% (9/115) involved the submandibular region. Location was unclear for two patients. Submandibular lesions were on average 12.4 cm3 larger (95% CI, 8.2, 16.6) than mediastinal lesions at diagnosis, P ≤ .001. Volume of thymic tissue decreased over time, from a mean (standard deviation [SD]) volume of 4.3 cm3 (9.2) at initial ultrasound to 2.7 cm3 (6.1) at final ultrasound (paired t-test, P = .008). Only two patients required surgery: one for compressive symptoms, and the other to rule out malignancy. CONCLUSION: Ninety-eight percent of children with ectopic cervical thymus were managed conservatively without issues. We propose a classification system based on location to ease communication among clinicians and to help follow these lesions over time. LEVEL OF EVIDENCE: 4, case series Laryngoscope, 130:1577-1582, 2020.

Cranioorbital Morphology Caused by Coronal Ring Suture Synostosis.

BACKGROUND: Minor cranial sutural synostosis is currently regarded as a rare diagnosis. As clinical awareness grows, a greater number of cases are being documented. This study aims to describe the variants of unicoronal synostosis with regard to major and minor sutural involvement and secondary effects on cranial and orbital morphology. The information is aimed to improve clinical diagnosis and management. METHODS: A retrospective study was conducted collecting preoperative computed tomographic scans of patients diagnosed with unicoronal synostosis and listed for surgical interventions, identified from a craniofacial database. Within these patients, different synostotic variants were identified based on which suture was affected. Scans of normal pediatric skulls (trauma) were used for a control group. Computed tomographic scans were analyzed for sutural involvement, cranial base deflection, and ipsilateral and contralateral orbital height and width. One-way analysis of variance was used to detect differences between synostotic variants and controls. RESULTS: A total of 57 preoperative computed tomographic scans of patients with unicoronal synostosis were reviewed, in addition to 18 computed tomographic scans of normal skulls (control group). Four variants of unicoronal synostosis were identified: frontoparietal, frontosphenoidal, frontoparietal and frontosphenoidal, and frontosphenoidal and frontoparietal. The last two variants differ in their temporal involvement in the direction of sutural synostosis and ultimately cranial and orbital morphology. Three variants have been previously identified, but the fourth is presented for the first time. CONCLUSIONS: An understanding of the variants of unicoronal synostosis and their temporal relationships is integral for accurate clinical diagnosis and surgical correction. Recommendations for treatment are based on discrete changes in orbital morphology.

Vestibular and balance function is often impaired in children with profound unilateral sensorineural hearing loss.

RATIONALE: Children with unilateral deafness could have concurrent vestibular dysfunction which would be associated with balance deficits and potentially impair overall development. The prevalence of vestibular and balance deficits remains to be defined in these children. METHODS: Twenty children with unilateral deafness underwent comprehensive vestibular and balance evaluation. RESULTS: Retrospective review revealed that more than half of the cohort demonstrated some abnormality of the vestibular end organs (otoliths and horizontal canal), with the prevalence of end organ specific dysfunction ranging from 17 to 48% depending on organ tested and method used. In most children, impairment occurred only on the deaf side. Children with unilateral deafness also displayed significantly poorer balance function than their normal hearing peers. CONCLUSIONS: The prevalence of vestibular dysfunction in children with unilateral deafness is high and similar to that of children with bilateral deafness. Vestibular and balance evaluation should be routine and the functional impact of combined vestibulo-cochlear sensory deficits considered.

Efficacy of a selective imaging paradigm prior to pediatric cochlear implantation.

OBJECTIVES/HYPOTHESIS: There is no consensus on the necessary preoperative imaging in children being evaluated for cochlear implantation (CI). Dual-imaging protocols that implement both magnetic resonance imaging (MRI) and high resolution computed tomography (HRCT) create diagnostic redundancy in the face of potentially unnecessary radiation and anaesthetic exposure. The objectives of the current study were to examine the efficacy of an MRI-predominant with selective HRCT imaging protocol. STUDY DESIGN: Retrospective review. METHODS: The protocol was implemented over a 4-year period, during which HRCT was obtained in addition to MRI only if specific risk factors on clinical assessment were identified or if imaging findings in need of further evaluation were detected on initial MRI evaluation. Retrospective review of operative reports and prospective review of imaging were performed; anesthetic exposure and costing information were also obtained. RESULTS: Of the 240 patients who underwent assessment, seven (2.9%) had combined HRCT and MRI performed concurrently based on initial clinical assessment, 15 (6.3%) underwent HRCT based on imaging anomalies found on MRI, and MRI alone was ordered for the remaining 218 (90.1%). All patients were implanted without complication. Overall, radiation exposure, general anesthesia (GA), and healthcare costs were reduced. CONCLUSIONS: MRI alone can be used in the vast majority of cases for preoperative evaluation of pediatric CI candidates resulting in a significant reduction in healthcare costs, radiation, and GA exposure in children. The additional need for HRCT occurs in a small proportion and can be predicted up front on clinical assessment or on initial MRI. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:2627-2633, 2019.

Children with unilateral cochlear nerve canal stenosis have bilateral cochleovestibular anomalies.

OBJECTIVES/HYPOTHESIS: To investigate the cochleovestibular apparatus bilaterally in children with isolated unilateral bony cochlear nerve canal (bCNC) stenosis. STUDY DESIGN: Retrospective review. METHODS: Imaging studies of children with unilateral bCNC stenosis (<1.0 mm) on computed tomography imaging (N = 36) were compared with controls imaged due to trauma without temporal bone injury (N = 32). Twenty-six measurements were obtained in each ear, assessing the bony internal auditory canal (IAC), cochlea, and vestibular end-organs, and were analyzed using one-way analysis of variance for intersubject comparisons and paired t tests for intrasubject comparisons with a Bonferroni adjustment for multiple comparisons (P = .0006). RESULTS: Patients with bCNC stenosis had a smaller IAC (P < .000) and cochlea (P < .000) on the stenotic side as compared with controls. Although the vestibular end-organ was also smaller in bCNC ears, this difference was not significant. The contralateral ear also had a smaller bCNC (P < .000) and cochlea (P < .000) as compared with controls, although to a lesser degree than the stenotic side. CONCLUSIONS: Children with unilateral bCNC stenosis have abnormal biometry of both the cochlea and the vestibular end-organ in the affected and the normal contralateral ear as compared with controls. LEVEL OF EVIDENCE: 3b Laryngoscope, 129:2403-2408, 2019.

Transmastoid access in branchio-oto-renal syndrome: A reappraisal of computed tomography imaging.

OBJECTIVE: To evaluate for temporal bone abnormalities that might affect transmastoid surgery such as cochlear implantation in cases of branchio-oto-renal syndrome (BOR). STUDY DESIGN: Retrospective review. METHODS: Qualitative assessment of temporal bone computed tomography imaging was performed by a neuroradiologist for 30 individuals with BOR (60 ears) and 20 controls with normal hearing (20 ears). Transmastoid access was assessed categorically across 4 features: tip development, cortex pneumatization, tegmen height, and facial recess pneumatization. The appearance of 4 standard landmarks (Koerner's septum, antrum, prominence of the horizontal semicircular canal, incudal short process) was also dichotomized as normal or abnormal. Data were compared using Fisher's exact testing. RESULTS: Mastoid height differed between the groups with tip underdevelopment noted in 72% of BOR ears vs. 40% of controls (p = 0.02), and a low tegmen was seen in 68% of BOR ears and 25% of controls (p < 0.01). Significant differences in pneumatization were also found for the mastoid cortex (28% non-pneumatized in BOR vs. 5% in controls; p = 0.03) and the facial recess (27% non-pneumatized in BOR vs. 0% in controls; p = 0.01). Standard landmarks were easily identified in all of the control mastoids. In the BOR group, Koerner's septum was abnormally located or absent in 45%, and the antrum was severely hypoplastic or absent in 50%. Similarly, the prominence of the horizontal semicircular canal and the short process of the incus were dysplastic in 73% (44/60) and 62% (37/60), respectively. CONCLUSIONS: Mastoid abnormalities are common in BOR syndrome. Restricted transmastoid access and abnormal or absent mastoid landmarks should be anticipated in those patients with BOR who become cochlear implant candidates. LEVEL OF EVIDENCE: 4.

BRAT1 Mutation: The First Reported Case of Chinese Origin and Review of the Literature.

Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL) (OMIM#614498) is caused by homozygous or compound heterozygous mutation in the BRAT1 gene (OMIM#614506) on chromosome 7p22. We report a newborn female infant born to non-consanguineous Chinese parents who presented with hypertonia, dysmorphic features, progressive encephalopathy with refractory seizures, and worsening episodic apnea, leading to intubation and eventually death at 10 weeks of age. Whole exome sequencing revealed homozygous BRAT1 mutation, c.1395G>C (p.Thr465Thr), predicted to cause splice site disruption. Neuropathological assessment demonstrated microcephaly, severe neuronal loss, and background gliosis in the dorsal region of the putamen. Disruption of BRAT1 function in RMFSL has been proposed to cause dysfunction in the DNA damage response pathway and impair mitochondrial homeostasis. To our best knowledge this is the first reported case of Chinese origin. We review all published cases with BRAT1 mutation reported in the English literature and known BRAT1 functions which provide insight into the pathophysiology of the disease.

Imaging the complications of bone marrow transplantation in children.

Bone marrow transplantation is frequently performed to restore hematologic and immunologic competence after chemotherapy and radiation therapy for a range of childhood malignancies, as well as to treat various congenital conditions in which hematologic and immunologic functions are depressed or absent. Potentially devastating complications may occur during the pre-engraftment period after bone marrow transplantation, when marrow aplasia may supervene for several weeks until engraftment occurs, as well as during the post-engraftment period (the 3 months after engraftment) and in subsequent months and years. Complications of bone marrow transplantation may be classified either according to the time interval between transplantation and the occurrence of the complication or according to the organ system affected. The range of complications that may affect the central nervous system and the rest of the body may be detected with ultrasonography, computed tomography, and magnetic resonance imaging. Neurologic, paranasal sinus, pulmonary, and abdominopelvic complications all may be seen after bone marrow transplantation. Graft-versus-host disease and lymphoproliferative disorders also may occur. The increasing use of bone marrow transplantation mandates that the radiologist be familiar with the full range of potential complications and their imaging appearances.