NEURORADIOLOGY

Eleven year old male with sensorii-neural hearing loss in the left ear. HRCT Temporal Bone was performed. What is the diagnosis?

Diagnosis

Mondini Malformation – Left Ear

Discussion:

Strictly speaking, a Mondini malformation refers to development of only one and a half turns of the normal two and one half turns of the cochlea. The defect occurs during the seventh week of gestation after development of the basal turn (high frequency hearing is usually preserved). There is incomplete partition with resulting confluency of the middle and apical turns. The vestibule and semicircular canals may or may not be normal.

The term has become ambiguous as it has been used to describe a wide variety of cochlear anomalies. It should be reserved for a cochlea showing an incomplete partition: the absence of the interscalar septum results in confluence of the apical and middle turn. Mondini's malformation is associated in 20% of cases with anomalies of the vestibule, semicircular canals and endolymphatic duct/sac.

Dr Paresh Desai, Goa