Incomplete partition type 1 - cystic cochleovestibular malformation

Case contributed by Dr Varun Babu


Bilateral profound sensorineural hearing loss for pre cochlear implant imaging

Patient Data

Age: 9 months
Gender: Female

Right ear

  • Inner ear: absent modiolus. Cystic dilated cochlea with thinning of the cochlear nerve. The vestibular apparatus is poorly developed with dilated lateral semicircular canal and thinned out anterior and posterior canals. Normal round window niche. Normal facial nerve course. Normal vestibular nerve. 
  • External and middle ear are normal. 

Left ear

  • Inner ear: absent modiolus. Cystic dilated cochlear with thinning of cochlear nerve.  Dilated lateral semicircular canal. Stenotic posterior semicircular canal. Normal facial nerve and vestibular nerve. Normal round window niche. 
  • External and middle ear are normal. 

Heavy T2 weighted images clearly delineate the presence of both vestibulocochlear nerves. The cochlear nerves appear thinned out but intact. The vestibular apparatus shows the changes identified in CT. The internal auditory meati are normal. No cerebellopontine angle mass lesions. 

Few other incidental neuroparenchymal findings identified include:

  • parallel oriented dilated lateral ventricles with thinned out / partially absent posterior corpus callosum. 
  • prominent extra axial CSF space in the posterior fossa with mild bilateral cerebellar hypoplasia. Normal vermis. 

Case Discussion

All the imaging features point towards cystic cochleovestibular anomaly classified as incomplete partition type 1 (pseudo Mondini). Pre cochlear implant imaging needs a structured approach. The high resolution CT of temporal bones is the preferred modality of choice to identify ear anomalies. Addition of MRI (mainly heavy T2 weighted images CISS / FIESTA)  enables additional evaluation of the vestibulocochlear neural anatomy and morphology. 

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Case information

rID: 47169
Published: 2nd Aug 2016
Last edited: 14th Aug 2019
System: Head & Neck
Inclusion in quiz mode: Included

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