This study retrospectively reviewed 50 patients with sudden sensorineural hearing loss (SSNHL) who received hyperbaric oxygen therapy (HBOT) in addition to conventional treatment. The study found that HBOT significantly improved hearing outcomes in patients with SSNHL. Patients who received HBOT within 14 days of onset of SSNHL saw the greatest hearing gain. Those with more severe initial hearing loss (>70 dB) also experienced greater improvement with HBOT. Younger patients (<50 years old) generally had better hearing outcomes than older patients.
4. The initial and final mean hearing levels at 500, 1000, 2000,
4000 and 6000 Hz of patients are presented in Table 2. The
mean hearing gain was highest at frequencies above 1000 Hz.
The mean hearing gain after treatment is shown in Table 3.
The average hearing gain at the five frequencies was signifi-
cantly higher in patients with initial level of 70 dB in com-
parison to patients with hearing levels of 70 dB.
Table 4 shows the mean hearing gain according to thera-
peutic delay of starting HBOT. Time of presentation ranged
between 1 and 60 days. The patients who received treatment
within 14 days had higher hearing gain
(76 ± 20.06 dBe51.9 ± 17.1 dB) as compared to patients with
therapeutic delay of 15e30 days
(77.85 ± 29.12 dBe59.85 ± 22.50 dB) and in patients who started
therapy after 30 days (77.8 ± 23.81 dBe64.5 ± 21.82 dB).
Table 5shows acorrelationbetweenthetime lagandseverity
on the improvement in mean hearing gain in patients. 82% pa-
tients presenting to us within 14 days showed maximum
improvement as compared to other subset of patients.
Average hearing gain of patients according to age group is
presented in Table 6 and was significantly high in patients
younger than 50 years.
No statistically significant difference was found among
patients with coexisting complaints of hypertension, diabetes,
smoking and presence of tinnitus or vertigo.
The hearing gain were 30 dB or more in 40%, between 20
and 30 dB in 20% and upto 20 dB in 34% of patients. There was
no response to HBOT in 6% patients (n ¼ 3).
The average number of hyperbaric sessions ranged from 10
to 25 with maximum number of patients showing improve-
ment after 10 exposures. Only one patient was given 25 ses-
sions of HBOT; however the patient did not show additional
improvement. In all patients the treatment was well tolerated
and no patient complained of any side effects. Hearing loss did
not worsen in any case.
4. Discussion
SSNHL is a loss of hearing greater than 30 dB in three contig-
uous frequencies occurring in less than 3 days.1e3
Most sud-
den hearing loss occurs within minutes to several hours. It is
considered as a clinical manifestation of possible several un-
derlying causes such as viral infection, vascular compromise,
intra-cochlear membrane rupture or inner ear disease.2e7
This
diversity demonstrates the prevailing uncertainty in aetiol-
ogies and an inability to predict the prognosis.
The high spontaneous recovery rate of SSNHL and its low
incidence make validation of empirical treatment modalities
difficult. Many treatment regimens have been proposed such
as antiviral agents, vasodilators, anti-inflammatory and oral
and intratympannic steroids. Hyperbaric oxygen therapy in
recent years has gained relevance for treating SSNHL in
combination with other agents.8e13
The Undersea Hyper-
baric Medicine Society (UHMS) has approved the use of HBOT
in SSNHL in October 2011.
HBOT increases oxygen tension (pO2) in blood by dissolving
in the plasma and diffuses into tissue fluids such as those
surrounding the sensory and neural elements of the coch-
lea.14e17
Gills showed oxygen induced osmosis as the mech-
anism for healing property of HBOT in such cases.11
Aslan et al and Bennett et al demonstrated that earlier the
treatment received, better is the prognosis.17
This was
confirmed in our study. The maximum recovery was in the 26
cases which received HBOT within 14 days after onset. They
showed significant mean hearing gain from 75.93 ± 20.06 dB to
51.90 ± 17.19 dB.
Topuz et al reported HBOT as more effective in severe
hearing loss.14
In our study, 64% cases had hearing loss of
70 dB and 81% of these patients showed improvement of
30 dB with mean hearing gain of 86 ± 11.9 dBe58.75 ± 13.0 dB.
We observed a significant correlation between patients with
severe hearing loss presenting to us within 2 weeks of onset.
82% of patients in this subset showed maximum
improvement.
Presence of tinnitus and vertigo has been reported to affect
reversibility of hearing loss in various studies.14,15
In our
study, 34% cases (n ¼ 17) with hearing loss had accompanied
tinnitus and vertigo but no significant difference was observed
between cases with and without these complaints.
Age has been found to be a prognostic factor for improve-
ment.18
In our study, patients in 50 year age group showed
better hearing gain as compared to patients with age of 50
years. Presence of diabetes, hypertension and other associ-
ated complaints in this age group might have been the
contributory factors to poor prognosis; however we were not
able to establish any correlations.
Table 2 e Mean hearing levels (MHL) at different
frequencies before and after treatment.
Frequency (Hz) Initial MHL Final MHL % Of patients
500 66.12 ± 22.0 49.16 ± 23.12 25
1000 64.68 ± 24.60 48.0 ± 20.46 40
2000 68.17 ± 21.90 52.83 ± 24.30 45
4000 74.0 ± 23.32 52.16 ± 21.00 65
6000 74.83 ± 19.76 54.83 ± 21.11 55
Table 3 e Change in mean hearing level before and after
treatment on basis of intensity.
Intensity
(db)
Pre MHL Post MHL % Of patients with
hearing
improvementa
40 35.5 ± 6.40 27.50 ± 3.53 16
41e70 60.55 ± 10.46 43.27 ± 11.6 33
70 86.50 ± 11.90 58.75 ± 13.0 81
a
Hearing improvement denotes 30 db gain in audiometry.
Table 4 e Change in mean hearing level before and after
treatment on basis of therapeutic delay.
Days of
onset
Pre MHL Post MHL % Of patients with
hearing improvement
14 75.93 ± 20.06 51.90 ± 17.19 56.25
14e30 77.85 ± 29.12 59.85 ± 22.50 42.10
30 77.8 ± 23.81 64.5 ± 21.82 25
a p o l l o m e d i c i n e x x x ( 2 0 1 4 ) 1 e5 3
Please cite this article in press as: Sahni T, et al., The role of hyperbaric oxygen therapy in Sudden Sensorineural Hearing Loss: A
retrospective review of 50 patients, Apollo Medicine (2014), http://dx.doi.org/10.1016/j.apme.2014.07.006
5. There is no consensus on the right number of treatments
with HBOT in the treatment of SSNHL. While some cases show
improvement within a few days other cases might need it
longer to achieve good results, however few studies report the
optimum number of sessions. In our study, maximum pa-
tients showed improvement after 10 exposures and
maximum improvement was seen on an average of 20 ses-
sions.19,20
We recommend that 20 sessions of HBOT may be
optimum for recovery in a majority of patients.
While the number of cases in this study is small, 94% of
patients in the study group showed statistically significant
improvement in hearing, when HBOT was administered along
with conventional therapy. While all patients were on oral
steroids the conventional treatment was not standardized in
our patients.
There appears to be a scientific rationale for use of HBOT in
SSNHL and our results are encouraging. We recommend
additional multicentric, prospective trials be carried out with
a standardized protocol to establish role of HBOT in SSNHL
patients.
5. Conclusion
This retrospective study reveals that the addition of HBOT to
conventional therapy significantly improves outcome inpatients
of SSNHL if started within 14 days. Improvement is best at fre-
quencies above 500 Hz and in hearing loss of above 70 dB. HBOT
was more effective in patients younger than 50 years of age.
Conflicts of interest
All authors have none to declare.
Acknowledgement
The Hyperbaric Oxygen Therapy Unit acknowledges the sup-
port given by the Department of ENT namely Dr Sindhu, Dr
Kishore, Dr Soni, Dr Raheja, Dr Nagpal, Dr Dhingra, Dr Prakash
Dr Ansari in this hospital and other clinicians from within
and outside Delhi.
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basis of severity and time lag.
Time lag Severity (% of patients showing improvement)
Days Mild Moderate Severe
14 45 50 82
15e30 35 43 50
30 0 33 25
Table 6 e Comparison of mean hearing level according to
age group.
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hearing
improvement
50 77.0 ± 19.30 52.0 ± 13.70 32
50 68.4 ± 17.22 49.4 ± 17.34 26
a p o l l o m e d i c i n e x x x ( 2 0 1 4 ) 1 e54
Please cite this article in press as: Sahni T, et al., The role of hyperbaric oxygen therapy in Sudden Sensorineural Hearing Loss: A
retrospective review of 50 patients, Apollo Medicine (2014), http://dx.doi.org/10.1016/j.apme.2014.07.006
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a p o l l o m e d i c i n e x x x ( 2 0 1 4 ) 1 e5 5
Please cite this article in press as: Sahni T, et al., The role of hyperbaric oxygen therapy in Sudden Sensorineural Hearing Loss: A
retrospective review of 50 patients, Apollo Medicine (2014), http://dx.doi.org/10.1016/j.apme.2014.07.006