Severe-to-profound hearing loss : prevalence, rehabilitation, and audiovestibular characteristics

Severe-to-profound hearing loss (STPHL) can negatively impact a patient’s life in many ways. Adequate assessment and rehabilitation are imperative. Reliable numbers on prevalence are important to inform the need for adequate allocation of resources to this vulnerable group. Most patients with STPHL are equipped with hearing aids (HAs) and approximately 10% have received a cochlear implant (CI). The aims of this thesis were to establish a valid prevalence of STPHL in Sweden and to study aspects affecting audiological rehabilitation including asymmetric hearing loss. Furthermore, we wanted to explore the vestibular function in patients with acquired sensorineural STPHL. In the first study we collected audiograms from 20 of 21 regions in Sweden and found a STPHL prevalence of 0.28%. We could not find a correlation between prevalence and cochlear implantation rate across regions. The second study utilised data from the Swedish national quality register for adult patients with STPHL. Patients with sensorineural hearing loss are three times more likely to receive a CI than patients with mixed hearing loss. More than 90% of the patients in the register experience good or very good benefit from the rehabilitation independent of whether they have received HAs or a CI. In the third study we compared prevalence of asymmetric hearing between patients with bilateral STPHL and those with better hearing. Asymmetric hearing was more common when STPHL was present. We found that CIs were more frequent in patients with asymmetric STPHL. Lastly, the fourth study examined 47 patients with STPHL and 51 age- and sex-matched controls regarding vestibular function. Vestibular function was evaluated with the caloric test, video head impulse test (vHIT), and vestibular-evoked myogenic potentials (VEMP). The caloric test and vHIT showed statistically significant negative impact from STPHL, emphasizing that vestibular evaluation and subsequent rehabilitation should be considered for STPHL patients. In conclusion, this thesis has produced a valid prevalence of STPHL in Sweden. Additionally, it revealed that asymmetric hearing is common, and vestibular function may be affected in patients with STPHL.