Prognostic indicators for sensorineural hearing loss in temporal bone histiocytosis

Objective: Our review aims: (1) to highlight the suspicion of sensorineural hearing loss (SNHL) in temporal bone Langerhans' cell histiocytosis (LCH); (2) to assess the evolution of SNHL in this pathology; (3) to identify radiologic findings of the otic capsule invasion by LCH; (4) to determine prognostic factors for SNHL in temporal bone LCH. Methods: We performed a literature review through MEDLINE for SNHL in temporal bone LCH related articles that were published between 1954 and 2008. We identified 12 related studies of which 18 patients were noted. We also added our case to this series. The information from the reports was analyzed to characterize the clinical and demographic data and to focus on the sensorineural hearing aspect of the disease and on the damage of the semicircular canals (SCC) and the cochlea. Results: Ten percent of patients with temporal bone LCH presented SNHL The mean age of patients is 3.5 years among children and 35.5 years among adults. Male to female ratio is 1:1.14. There were 13 unilateral cases, 6 bilateral cases and I case of multisystemic histiocytosis. Cochlea and SSCs were involved in 4 and 20 temporal bones, respectively. The lateral SCC is the most frequently eroded canal. In 23 ears hearing level was reported: 15 ears had a SNHL and the remaining was a mixed or a conductive hearing loss type. 10 ears suffered from a profound hearing loss and none of them improved after treatment regardless otic capsule affected structures. In all cases of normal hearing, moderate hearing loss and severe hearing loss before treatment cochlea have not been affected. However a single or two semicircular canals invasions have been noted. Where it is reported (15 out of 25 temporal bone) there was a radiological healing of the otic capsule lesion after treatment. Remineralization occurs 6 months after treatment. Conclusion: In LCH, hearing loss level before treatment can be considered as a prognostic indicator for hearing in response to treatment. Even though bone mineralization is essential for a hearing improvement, radiological healing is not a prognostic factor for better hearing level after treatment. (C) 2009 Elsevier Ireland Ltd. All rights reserved.