Lateral semicircular canal–vestibule dysplasia

Case contributed by Dr Zaidah Mohd Ismail

Presentation

Premature baby girl born at 34 weeks of gestation. At 3 months old, she presented with left facial nerve palsy clinically. Noted to have moderate sensory neural hearing loss on the right side and normal hearing on the left side.

Patient Data

Age: 3 months
Gender: Female

Plagiocephaly seen. The superior and posterior semicircular canals are normal in appearance bilaterally. The normal lateral semicircular canals are not seen. There is fusion of both vestibules and lateral semicircular canals bilaterally forming dilated dysplastic lateral semicircular canals with dysplastic vestibules on both sides. Normal two and a half turns of both cochlea noted. Both internal acoustic meatus and facial canals are symmetrical and intact. Both ossicles are also symmetrical and grossly normal. Poor pneumatization of both mastoid air cells seen.

Correlating with the HRCT temporal bones, the superior and posterior semicircular canals are normal in appearance bilaterally. The normal lateral semicircular canals are not seen. There is fusion of both vestibules and lateral semicircular canals bilaterally forming dilated dysplastic lateral semicircular canals with dysplastic vestibules on both sides. Normal two and a half turns of both cochlea noted. The membranous labyrinth signal intensity within both cochlea and semicircular canals are within normal limit. Both 7th and 8th cranial nerves are visualised. Visualised brain parenchyma is normal.

Case Discussion

The occurrence of an isolated vestibular anomaly with normal appearance of the cochlea is rare as compared to the cochleovestibular anomaly. The vestibular system involves the vestibules which contain the saccules and the utricles and also the semicircular canals (superior, posterior and lateral). The patients with this anomaly can present with normal hearing, sensory neural hearing loss (SNHL), conductive hearing loss (CHL), mixed hearing loss (MHL) or imbalance.

The development of the cochlea is completed by the age of 8th week, the vestibule by the age of 11th week and the semicircular canals by the age between 19th to 22nd weeks of gestation. The superior semicircular canal develops first. Of all these structures, the lateral semicircular canal is the last to form and the most frequent to have anomalous development.

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Case information

rID: 50853
Case created: 24th Jan 2017
Last edited: 30th Jan 2017
Inclusion in quiz mode: Excluded

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