Patterns of nystagmus conversion in sudden sensorineural hearing loss with vertigo

The patients with sudden sensorineural hearing loss (SSNHL) may complain of vertigo. Although there have been many reports on SSNHL with vertigo (SSNHL_V), changes in the pattern of nystagmus have not been studied as yet. This study is a retrospective study and aims to investigate the characteristic changes in type of nystagmus and clinical features in patients with SSNHL_V who experienced a change in their nystagmus pattern during follow-up. Among 50 patients with SSNHL_V between January 2012 and December 2015, we identified 15 patients with SSNHL_V whose pattern of nystagmus changed. Initial nystagmus was classified into 5 subgroups: paretic type, irritative type, persistent geotropic direction-changing positional nystagmus (PG-DCPN), persistent apogeotropic direction changing positional nystagmus (PA-DCPN), and posterior semicircular canal benign paroxysmal positional vertigo. The most common pattern of initial nystagmus was PG-DCPN(n=7). The change of initial nystagmus pattern occurred on day 2 to 75 from symptom onset, and 2 (of 15) patients showed further conversion. The most common pattern of final nystagmus was PA-DCPN (n=9). Hearing improvement after treatment was not significantly different (P=.59) between SSNHL_V patients with nystagmus change (25 +/- 17 dB, n=15) and those without nystagmus change (28 +/- 18 dB, n=35). In conclusion, clinician's attention is required in evaluating the vertigo symptom in patients with SSNHL_V because the initial patterns of nystagmus can be converted to another type of nystagmus. The presence of nystagmus change during follow-up may not be a prognosticator for hearing recovery in patients with SSNHL_V.