|Ahead of print
Dandy–Walker malformation presenting with hearing loss: A unique imaging diagnosis
Harsimran Bhatia1, Purnima Aggarwal2
1 Present address: Department of Radiodiagnosis, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh, India
2 Department of Radiodiagnosis, Government Medical College and Hospital, Sector 32, Chandigarh, India
|Date of Submission||16-Dec-2020|
|Date of Decision||18-Dec-2020|
|Date of Acceptance||29-Dec-2020|
|Date of Web Publication||12-Jul-2021|
Department of Radiodiagnosis, Post Graduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh.
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Dandy–Walker malformation (DWM) is a common congenital posterior fossa anomaly, however, its association with concomitant bilateral inner ear anomalies has been rarely reported so far. We present such a case that showed characteristic imaging features of DWM along with uncommon vestibulocochlear anomalies like cochlear hypoplasia and Internal Auditory Canal atresia.
Keywords: Cochlear hypoplasia, Dandy–Walker malformation, internal auditory canal (IAC) atresia, inner ear anomalies, macrocephaly
A 3-year-old boy presented to the pediatric OPD with complaints of decreased hearing since birth and delayed motor milestones. Perinatal period was insignificant. Examination revealed an enlarged head circumference and bilateral profound sensorineural hearing loss (SNHL) on audiometry.
Magnetic resonance imaging (MRI) brain revealed a cystically enlarged posterior fossa communicating with a dilated fourth ventricle and a hypoplastic cerebellar vermis. An occipital bone defect was noted along with a high cervical meningocele. There was gross hydrocephalus along with severe thinning of the corpus callosum [Figure 1]. Features on MRI suggested a diagnosis of Dandy–Walker malformation (DWM). High-resolution computerized tomography (HRCT) of the temporal bone, however, revealed interesting unexpected findings. There were multiple anomalies involving bilateral (B/L) inner ear structures. The cochlea was hypoplastic bilaterally, consisted of less than two turns, and had an absent modiolus. Labyrinthine segment of the facial canal was anteriorly displaced with an atretic (absent) Internal Auditory Canal on the right. While the vestibule and semicircular canals (SCC) were absent on right, the left vestibule was dilated and fused with a dysplastic appearing lateral SCC (that lacked a normal bony island) [Figure 2].
|Figure 1: A: Axial T2W MRI showing cystically dilated posterior fossa (red arrow) communicating with a dilated fourth ventricle (blue arrow); B: Sagittal T2W MRI showing gross hydrocephalus with thinned out corpus callosum (yellow arrow), hypoplastic cerebellar vermis (blue arrow), and high cervical meningocele (red arrow); C: Axial HRCT temporal bone showing the occipital bony defect (blue arrow)|
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|Figure 2: A: Coronal HRCT section: Less than two turns of the cochlea bilaterally (red arrows); B, C: Axial sections (Magnified views) of inner ears, B: Right inner ear: Hypoplastic cochlea (red arrow) with the absence of ipsilateral vestibule, SCCs, and IAC (yellow arrow); anteriorly displaced facial canal (blue arrow); C: Left inner ear: Dilated vestibule fused with dysplastic lateral SCC (yellow arrow), hypoplastic cochlea (red arrow), and normal IAC (blue arrow)|
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DWM is a common congenital posterior fossa anomaly, presenting with macrocephaly in the first few months of life., Characteristic imaging features help clinch a definitive diagnosis. Although often associated with concomitant brain abnormalities, association with inner ear anomalies has been rarely reported.
SNHL is a major cause of childhood disability worldwide, with an estimated prevalence of 1 in 2000 neonates and inner ear malformations, accounting for about 5–15% of these cases., Cochlear hypoplasia with internal auditory canal (IAC) atresia in itself is an uncommon entity and its association with DWM, is indeed a unique imaging diagnosis. HRCT with its 3D reconstruction algorithm and high spatial resolution, not only delineates the bony labyrinth anatomy, instead, facial canal course, middle ear status, and mastoid pneumatisation are also well depicted, thus predicting feasibility for cochlear implantation [Figure 3]. Due to the gross degree of malformations observed, the child was not considered a suitable candidate for the same and was advised to use conventional hearing aids.
|Figure 3: Normal inner ear anatomy, magnified views of the axial HRCT temporal bone sections. A: Axial section of left inner ear showing a normal lateral SCC with a bony island within (red arrow) and vestibule (yellow arrow); B: Axial section of right inner ear showing: normal trifoliate cochlea with a modiolus (red arrow) and normal IAC (blue arrow); C: Coronal HRCT section showing: Normal turns of the left cochlea (red arrow) and normal right SCCs (yellow arrow)|
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]