Advancement in post-meningitic lateral semicircular canal labyrinthitis ossificans

Objective: To assess whether lateral semicircular canal (LSCC) ossification is more advanced than that in the cochlear basal turn, in order to judge the value of the former as a predictor. Methods: Retrospective review of 33 paediatric patients from our cochlear implant programme, with profound sensorineural hearing loss after bacterial meningitis. Magnetic resonance imaging (MRI), computed tomography (CT) scans and operative findings were reviewed. Results: On CT, LSCC ossification scores were more advanced than those for the cochlear basal turn in 69.9 per cent of implanted ears. Forty-five per cent (15/33) of children had ossification at surgery. In predicting this, the sensitivity of CT LSCC ossification was 90 per cent and that of MRI LSCC ossification was 83.3 per cent. Conclusions: The more advanced ossification found in the LSCC, compared with that in the cochlear basal turn, adds to previous findings of LSCC pathology predicting cochlear ossification. Surprisingly, CT of the LSCC appears to be no less valuable than MRI in pre-operative cochlear implant assessment of post-meningitic children.