Delayed restoration of maximum speech discrimination scores in patients with idiopathic sudden sensorineural hearing loss

ObjectiveTo assess possible delayed recovery of the maximum speech discrimination score (SDS) when the audiometric threshold ceases to change.MethodsWe retrospectively examined 20 patients with idiopathic sudden sensorineural hearing loss (ISSNHL) (gender: 9 males and 11 females, age: 24–71 years). The findings of pure-tone average (PTA), maximum SDS, auditory brainstem responses (ABRs), and tinnitus handicap inventory (THI) were compared among the three periods of 1–3 months, 6–8 months, and 11–13 months after ISSNHL onset.ResultsNo significant differences were noted in PTA, whereas an increase of greater than or equal to 10% in maximum SDS was recognized in 9 patients (45%) from the period of 1–3 months to the period of 11–13 months. Four of the 9 patients showed 20% or more recovery of maximum SDS. No significant differences were observed in the interpeak latency difference between waves I and V and the interaural latency difference of wave V in ABRs, whereas an improvement in the THI grade was recognized in 11 patients (55%) from the period of 1–3 months to the period of 11–13 months.ConclusionThe present study suggested the incidence of maximum SDS restoration over 1 year after ISSNHL onset. These findings may be because of the effects of auditory plasticity via the central auditory pathway.