3.2 Basic features of the included researches
Table 1 shows the clinical features of the included researches. Of the
4290 participants, 1720 were categorized into the SSHL with vertigo
group, 2507 were categorized into the SSHL without vertigo group, and
the follow-up time to the beginningof deafness were between 1-11.4
months. In 23 studies, Siegel’s criteria was applied to assess the
degree of hearing improvement, and hearing improvement >15
db was judged to be effective. Fourteen
studies[4,8,11-17,19] and fourteen
studies[4,8,11-17,19,20,22,26,28] used
steroid-based systemic medication; seven
studies[3,7,21,23-26] used a combination of
medication and intratympanic steroid injections; four
studies[6,24,26,27] used medication in combination
with HBOT; and two studies used intratympanic steroid injections alone.
Among them, Hideaki Suzuki[24] divided the study
population into two groups: one receiving a combination of medication
with intradermal injection of steroid hormones and one receiving a
combination of medication with HBOT. Seiji
Hosokawa[26] divided the study population into
three groups: those receiving medication alone, those receiving a
combination of medication with intradermal injection of steroid
hormones, and those receiving a combination of medication with HBOT.
The included researches’ quality and risk of bias were assessed by the
Newcastle–Ottawa scale, and the total score of the 23
studies[3,4,6-8,11-28] ranged from 7–8 (Table 2).
All the studies depicted the incidences of better hearing outcomes in a
dichotomous pattern (groups without and with vertigo). The meta-analysis
of the data was conducted (Figure. 2A), and it presented a high degree
of heterogeneity, with I2=68.3%. For the analysis, a
random effects model was applied, and the meta-analysis showed that the
hearing recovery rate for SSHL without vertigo was 53.76%, and the
hearing recovery rate for SSHL with vertigo was 40.8%. A pronounced
difference (P = 0.000), OR = 2.13 (95% CI, 1.63-2.79;
I2 = 68.3%) was found. In addition, the patients were
classified into three subgroups according to treatment regimens (Figure
2B). A total of 12 studies[4,8,11-17,22,26,28]were conducted, and 1552 patients were included in the subgroup
receiving medication alone. In this subgroup, there were 544 patients
with vertigo and 1008 patients free from vertigo. The rate of hearing
recovery was 56.75% for SSHL free from vertigo and 35.48% for SSHL
suffering from vertigo (P = 0.018; OR = 2.65; 95% CI, 1.84-3.83;
I2 = 50.8%). A total of 4
studies[6,24,26,27] with 847 people were contained
in the subgroup analysis of patients with medical treatment combined
with hyperbaric chamber therapy. In this subgroup, there were 375
patients with vertigo and 472 patients free from vertigo. The rate of
hearing recoverywas 65.25% for SSHL with vertigo and 62.13% for SSHL
with vertigo (P = 0.018; OR = 1.76; 95% CI, 0.75-4.15;
I2 = 84.9%). In a total of
seven[3,7,21,23-26] studies, 1372 patients were
enrolled in the pharmacologic therapy combined with intracameral steroid
injection therapy subgroup, which included 663 patients with vertigo and
709 patients free from vertigo. The rate of hearing recoverywas 47.53%
for SSHL without vertigo and 35.74% for SSHL with vertigo; these two
groups were significantly different (P = 0.008), OR = 1.62 (95% CI,
1.02-2.58; I2 = 65.6%).
The existence of publication bias was evident in our data from 23
studies,and according to the omission regulation, sensitivity analyses
were further conducted to assess and correct for publication bias, with
the following results (Figure 3).
DISCUSSION
This paper included 23 research papers and 4290 patients, including 1720
patients with SSHL with vertigo and 2507 patients with SSHL free from
vertigo. The rate of hearing recovery was 53.76% in the group with SSHl
without vertigo and 40.8% in the group with SSHL with vertigo.
According to the statistical analysis, vertigo was obviously connected
with worse hearing recovery (OR = 2.13; 95% CI, 1.63-2.79;
I2 = 68.3%). These findings were consistent with
those of Yu[9] et al.
In the subgroup with medication alone, the rate of hearing recovery was
56.75% in the SSHL without vertigo group and 35.48% in the SSHL with
vertigo group. An obvious difference (P = 0.018), OR = 2.65 (95% CI,
1.84-3.83; I2 = 50.8%) was found. In the subgroup
treated with medication combined with hyperbaric chamber therapy, the
rate of hearing recovery was 65.25% in the group with SSHL without
vertigo and 62.13% in the group with SSHLwith vertigo; these values
were significantly different (P = 0.018), OR = 1.76 (95% CI, 0.75-4.15;
I2 = 84.9%). In the subgroup treated with medication
combined with intracameral steroid injection, the rate of hearing
recoverywas 47.53% in the group with SSHL without vertigo and 35.74%
in the group with SSHL with vertigo; these values were significantly
different (P = 0.008, OR = 1.62; 95% CI, 1.02-2.58;
I2 = 65.6%). In both subgroups of patients treated
with combination therapy, we found a significant reduction in the
prognostic association between vertigo and sudden sensorineural hearing
loss, which may suggest improved efficacy of combination therapy. In the
subgroup treated with pharmacological treatment combined with
intracameral steroid injection, the rate of hearing recovery was
significantly lower in people suffering from SSHL than in patients in
the other subgroups. We reviewed the seven papers included in this
subgroup and found that, in these seven papers, the level of initial
hearing loss in the target population was predominantly severe to
profound degree of hearing loss and that the degree of initial hearing
impairment in the population was greater than that in the other
subgroups, which might explain the lower rate of improvement in this
subgroup than in the other subgroups.
Sudden sensorineural hearing loss has always been a controversial
medical phenomenon and has subsequently become a research hotspot
attracting numerous people. Moreover, there is extensive heterogeneity
in terms of initial hearing loss, accompanying symptoms, and hearing
recovery in patients in clinical practice, which further exacerbates the
difficulty of related research. Clinicians have observed that patients
with severe hearing loss often have vertigo, which has been empirically
recognized as a negative factor in hearing recovery. Many researchers
have studied this issue. Anestis D.[12] reviewed
the hearing changes and long-term prognosis of 80 patients over a
15-year period in a retrospective analysis. The study showed that
treatment was ineffective in 80.6% of people suffering from SSHL
accompanied by vertigo; however, the ineffectiveness was only 56.1% in
people suffering from SSHL not accompanied by vertigo. Y-J TSA et
al.[29] concluded vertigo was a negative
prognostic indicator for SSHL in a follow-up research of 128 people
suffering from SSHL for an average of up to 11.4 months. Ryosuke
Kitoh[30] et al. conducted a multicenter,
large-sample epidemiological survey that investigated the clinical
features of 3,419 people suffering from SSHL and statistically analyzed
the correlation between the degree of severity of hearing loss and
patient prognosis. Vertigo symptoms were found to be significantly
associated with poor prognosis. Similarly, Jae Ho Chung et
al.[4] concluded that vertigo is a negative
predictor of hearing recovery in people suffering from SSHL and that the
labyrinth damage degree may be correlated with the severity of cochlear
impairment, with the likelihood of hearing recovery decreasing with
increasing labyrinth involvement. However, several scholars have shown
the opposite results. S HOSOKAWA et al.[6] studied
334 patients suffering from SSHL and reported that the rate of hearing
improvement was 62.4% in people suffering from vertigo and 72.8% in
people free from vertigo; moreover, no statistically obvious difference
in the difference between the two recovery rates (p=0.062) was found.
Suphi Bulğurcu et al.[31] studied 154 patients
with a mean follow-up of up to 7.4 months and found that patients with
vertigo had a lower but not statistically significant treatment success
rate. According to multivariate analysis, Adriana Perez Ferreira Neto[28] et al. reported that the level of statistical
significance between vertigo and a poor prognosis for hearing
restoration was marginal (p=0.088). These studies suggest that whether
vertigo serves as a poor prognostic element for SSHL remains
controversial.
Yu et al. (2018) published a meta-analysis discussing whether vertigo is
a poor prognostic element for SSHL. This meta-analysis included 10
articles with 4814 patients. They found that vertigo was obviously
connected with poorer hearing improvement (OR = 2.22; 95% CI,
1.54-3.20; I2 = 74%) [9]. With
the continuous updating of relevant researches, the meta-analysis was
conducted again, updating the previous articles and screening the
included literature to improve the stability of the conclusions. In the
end, we obtained the same conclusion as Yu et al.: vertigo is a negative
prognostic factor for SSHL.
Limitations of the article
At the beginning of this study, we attempted to analyze patient
subgroups for the presence of tinnitus, degree of hearing loss,
frequency band of hearing loss, frequency band of hearing loss, and
level of hearing benefit. We attempted to use subgroup analysis to
quantify the specificity of the SSHL population and in order to clarify
the appropriateness of the treatment regimen for a specific population.
However, we had to abandon these subgroups because of the paucity of
literature that could extract the relevant metrics.
Moreover, there is no standardization of treatment protocols among
studies on sudden sensorineural hearing loss. The means of intervention,
drug dosage, hormone type, duration of intervention, and severity of
hearing loss varied significantly among researchers, all of which may
have skewed the final results. This is a problem that cannot be avoided
in this study. Therefore, additional clinical studies are needed to
support subsequent researchers and obtain new conclusions.
CONCLUSION
Vertigo may be a negative factor in the hearing prognosis of people
suffering from SSHL. Moreover, the correlation between poor prognosis
and vertigo according to the SSHL became significantly reduced in both
subgroups after the combined treatment. The combination of hyperbaric
oxygen chamber therapy, intradermal injection of steroid hormone therapy
and medication had a significant effect on hearing prognosis in patients
with SSHL with vertigo.