General characteristics of studies
Our initial trial for the literature search yielded 276 citations, 49 of
which were duplicate studies. During screening, 209 studies were
excluded based on the selection criteria (n = 183 after records title
screening and n = 26 after abstract screening). Among the remaining 18
studies, 13 were excluded because of inappropriate study design (n = 9),
no original data (n = 1), or because they were not written in English (n
= 3). Therefore, five studies (n = 253) met the selection criteria and
were included in the final analysis (Figure 1).
The major characteristics of the five articles 6,
14-17 are summarized in Table 1. The year of publication for the
identified studies ranged from 1990 to 2018. The follow-up duration
ranged from 1 to 12 months. The studies were conducted in Egypt,
Germany, Israel, South Korea, and USA.
Three studies 14-16 compared the outcomes of the
steroid treatment (ST) group with those of placebo (PL) or non-steroid
treatment (NST) group. Three studies 6, 14-18 compared
the outcomes among a combination of corticosteroids plus other
treatments with those of other treatments alone. In two
studies,6, 17 the outcomes of combined treatment of
steroid treatment plus vestibular rehabilitation therapy (ST plus VRT)
were compared to those of vestibular rehabilitation therapy alone (VRT
only). One study 16 compared the outcomes of combined
treatment of ST plus valacyclovir treatment (ST plus VA) with those of
valacyclovir treatment alone (VA only). Since the number of studies was
small for each comparison group, the results of each follow-up period
and comparison group were considered and analyzed as separate studies.