TEMPORAL BONE ANOMALIES

Eac atresia M/Cpresentation is Small dysmorphic pinna. TYPES: Bony Soft tissue Mixed stenosis -membranous & bony portions Middle ear findings depend on severity of atresia

4 yrs old boy with complaints of deformed right auricle 4 yrs old boy with complaints of deformed right auricle. HRCT temporal bone shows atresia of right bony external auditory canal with deformed right auricle.

Right middle ear ossicles and inner ear appears normal

1 year old boy HRCT TEMPORAL BONE shows atresia of mixed bony-soft tissue EAC on left side with dysplastic malleus and incus and descending 7 th nerve canal noted within post. Aspect of bony septum of EAC atresia .

Bony inner ear appears normal and no obvius oval window atresia.

SEQUALE OF EAC ATRESIA Small, dysmorphic pinna Middle ear findings depend on severity of atresia Small middle ear Fusion & rotation of malleus & incus Dysmorphlc malleus & incus Fusion of malleolar-incudal articulation Oval window atresia may be associated Congenital cholesteatoma behind atresia plate

SEQUALE OF EAC ATRESIA Facial nerve canal findings Aberrant course of tympanic &mastoid portions of facial nerve common Tympanic segment may be deluscent, overlying oval or round windows Mastoid segment usually anteriorly displaced May exit skull base into glenoid fossa, or lateral to styloid process Inner ear findings Inner ear &: lAC usually normal

COCHLEAR ANOMALY Michel deformity :complete labyrinthine aplasia Cochlear aplasia:cochlea is completely absent Common cavity deformity: no differentiation between the cochlea and the vestibule, both together forming a cystic cavity Cochleo-vestibular hypoplasia: Both the cochlea and the vestibule - small in size Incomplete partition type I (IP-I):cochlea lacks the entire modiolus and the cribriform area and appears cystic, along with a large cystic vestibule Incomplete partition type II (IP-II) (Mondini deformity): The cochlea consists of 1.5 turns, with the middle and apical turns coalescing to form a cystic apex (due to a defect in the interscalar septum), along with a dilated vestibule and enlarged vestibular aqueduct

4 yr old boy HRCT shows b/l cochlear dysplasia with incomplete cochlear turns