Instructional Session: ISW4

Wednesday 4 July 2018, 16.45-17.45

Cochlear implantation in ossified cochlea

Mr Sunil Narayan Dutt, Clinical Director of ENT, Apollo Hospitals, Bangalore, India
Mr Mohan Kameswaran, Madras ENT Research Foundation, India

Cochlear implantation in an ossified cochlea is a challenging proposition. The challenges are both in terms of surgery to find cochlear lumen to insert the electrode and of mapping and hence re/habilitation. The commonest cause of labyrinthitis ossificans (LO) is meningitis in the developing world. Meningitis results in deafness in about 6 to 37% of patients and nearly 10% develop bilatertal profound hearing loss (Dodge et al, 1984). Meningitis caused by Streptococcus pneumoniae causes severe to profound hearing loss in about 31% and is irreversible in the majority of patients (Douglas et al, 2008). Cochlear ossification begins in the basal turn postinfection from as early as 3 days and may occur much later and is usually progressive up to a year (Nabili and Brodie, 1999 and Tinling et al, 2004).

Cochlear implantation in postmeningitic deafness with impending ossification is hence a surgical emergency. An MRI scan would reveal septations due to fibrosis in the basal turn that would necessitate the need for a CT scan for delineating the degree of ossification.

In this instructional course, the instructor will discuss in detail a protocol for evaluation and management of deafness due to meningitis. Six different case scenarios of cochlear implantation in labyrinthitis ossificans will be presented in detail with videos. The degrees of difficulty related to finding the lumen of the scala tympani or scala vestibuli of the basal turn, or the lumen of the second turn and the use of test guages and the choice of electrodes will be presented.