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Original Article
The role of hyperbaric oxygen therapy in SuddenSensorineural Hearing Loss: A retrospective reviewof 50 patients
Tarun Sahni a,*, Rachin Aggarwal b, Anil Kumar Monga c, Rajeev Puri d,Pavithra Shivkumar e, Shweta Gupta f, Sapna Verma f
a Senior Consultant, Department of Internal and Hyperbaric Medicine, Indraprastha Apollo Hospital, Sarita Vihar,
Delhi-Mathura Road, New Delhi 110076, Indiab Department of Internal and Hyperbaric Medicine, Indraprastha Apollo Hospital, Sarita Vihar, Delhi-Mathura Road,
New Delhi 110076, Indiac Department of ENT, Sir Ganga Ram Hospital, New Delhi 110060, Indiad Prof., Department of ENT, Indraprastha Apollo Hospital, Sarita Vihar, Delhi-Mathura Road, New Delhi 110076,
Indiae Department of Genetics, Dr.ALM Post Graduate Institute of Basic Medical Sciences, University of Madras,
Chennai 600113, Indiaf Research Associate, Department of Hyperbaric Medicine, Indraprastha Apollo Hospital, Sarita Vihar,
Delhi-Mathura Road, New Delhi 110076, India
a r t i c l e i n f o
Article history:
Received 11 July 2014
Accepted 19 July 2014
Available online xxx
Keywords:
Hearing loss
Hyperbaric oxygen
Sensorineural
Inner ear
* Corresponding author. Tel.: þ91 981003801E-mail addresses: [email protected], sshwet
Please cite this article in press as: Sahni Tretrospective review of 50 patients, Apol
http://dx.doi.org/10.1016/j.apme.2014.07.0060976-0016/Copyright © 2014, Indraprastha M
a b s t r a c t
Background: Sudden Sensorineural Hearing Loss (SSNHL) is a hearing impairment of more
than 30 dB occurring within a period of upto 3 days in three consecutive pure tone fre-
quencies. Hyperbaric oxygen therapy (HBOT) in recent years has gained relevance for
treating SSNHL in combination with other agents. The aim of this study is to review the
outcomes in patients with SSNHL treated with HBOT at our centre.
Materials & methods: Records of 50 patients with SSNHL who received HBOT with conven-
tional management were retrospectively reviewed. They were treated in a multiplace hy-
perbaric chamber at 2.4 ATA, for 90 min once a day. Pre and post treatment audiograms at
500, 1000, 2000, 4000 and 6000 Hz were compared to assess improvement. Hearing gain in
relation to severity, age of patients, therapeutic delay and coexisting symptoms in prog-
nosis was evaluated.
Results: 94% patients had overall hearing improvement. 82% patients of severe hearing loss
presenting to us within 2 weeks of onset showed maximum gain. Those who received
treatment within 14 days showed highest gain from 76 ± 20.06 dB to 51.9 ± 17.1 dB as
compared to other patients. The hearing gain was greater at frequencies above 500 Hz.
Patients younger than 50 years showed greater gain of 25 ± 13.2 dB as compared to those
older than 50 years with gain of 19 ± 10.2 dB.
0; fax: þ91 (0)11 [email protected] (T. Sahni).
, et al., The role of hyperbaric oxygen therapy in Sudden Sensorineural Hearing Loss: Alo Medicine (2014), http://dx.doi.org/10.1016/j.apme.2014.07.006
edical Corporation Ltd. All rights reserved.
a p o l l o m e d i c i n e x x x ( 2 0 1 4 ) 1e52
Please cite this article in press as: Sahni Tretrospective review of 50 patients, Apoll
Conclusion: Addition of HBOT to standard treatment significantly improves outcome of
SSNHL in a subset of patients. We recommend additional multicentric, prospective studies
be carried out to define the role of HBOT in SSNHL.
Copyright © 2014, Indraprastha Medical Corporation Ltd. All rights reserved.
Table 1 e Clinical profile of patients with sudden
1. Introduction
Sudden Sensorineural Hearing Loss (SSNHL) is hearing
impairment of more than 30 dB of three consecutive pure tone
frequencies developing within 3 days or less.1e3 It is a clinical
manifestation with proposed diverse aetiologies such as viral
infection, vascular compromise, intra-cochlear membrane
rupture or inner ear disease among others.3e5 It is more
common in young and middle aged people with unilateral ear
involvement in more than 90% cases.1,5e8
Due to lack of definite cause of SSNHL, its treatment is
largely empirical and includes use of a wide variety of thera-
pies like systemic and intratympannic steroids, vasodilators,
osmotic drugs, antiviral and anticoagulants to counteract
possible inflammatory mechanism, modify hydrostatic pres-
sure and improving cochlear blood flow.8e12 The possible final
goal of any treatment modality of SSNHL has been the resto-
ration of oxygen tension in the cochlea to encourage healing
and return of hearing to normal levels.
Hyperbaric oxygen therapy (HBOT) is a treatment modality
involving the intermittent inhalation of 100% oxygen in
chambers pressurized above 1 atmosphere absolute (ATA).
HBOT has been used as an adjunctive therapy for SSNHL as it
raises the amount of oxygen in the inner ear by diffusion
which activates cell metabolism leading to restoration of ionic
balance and electrophysiological functions of cochlea.2,13e16
This study aims to analyse retrospective data of this
centre to evaluate the efficacy of addition of HBOT to con-
ventional treatment in patients with SSNHL and identify
specific groups of patients likely to benefit from the addition
of this therapy.
sensorineural hearing loss.
Variables n ¼ 50 %
Gender Male 28 56
Female 22 44
Age �50 yrs 34 68
>50 yrs 16 32
Affected ear Right 37 74
Left 13 26
Time lag �14 days 26 52
15e30 days 17 34
>30 days 07 14
Severity Mild 06 12
Moderate 12 24
Severe 32 64
Presence of associated complaints Tinnitus 13 26
Vertigo 04 08
Coexisting illnesses Hypertension 05 10
Diabetes 08 16
CAD 04 08
Smoking 11 22
2. Materials and methods
In this retrospective studywe reviewed records of 150 patients
with SSNHL who presented to our unit during the period
2006e2011. 50 Patients who met the following inclusion
criteria were taken for the study: unilateral onset of SSNHL of
30 dB or greater in atleast three contiguous frequencies, un-
known cause of hearing loss and no previous surgery in the
affected ear. These patients received HBOT in addition to
conventional treatment as prescribed by the referring ENT
Surgeon. The conventional treatment however was not stan-
dardized for patients in our study. HBOT was administered in
a multiplace chamber at 2.40 ATA for 90 min once daily for
atleast 10 days. The data collected included demographics,
initial symptoms of hearing loss, tinnitus, vertigo or any other
coexisting symptom, pure tone audiogram (PTA) and duration
of onset of hearing loss from starting of HBOT.
, et al., The role of hypero Medicine (2014), http:
The patient's audiograms were reviewed before starting
treatment and after 10 sessions of HBOT. If the audiogram
showed improvement after 10 treatments, patients were
advised for additional 10 sessions of HBOT, this process was
repeated after further 10 sessions and a maximum of 30
sessions were given if they continuously showed improve-
ment. All patients were assessed with PTA at 500, 1000, 2000,
4000 and 6000 Hz and hearing gain at these frequencies was
calculated separately. The level of hearing loss at these 5
frequencies was evaluated in 3 groups: <40 dB (mild), be-
tween 41 and 70 dB (moderate), >70 dB (severe). The average
of mean hearing gain of patients according to age group and
therapeutic delay along with presence of associated com-
plaints as contributory factors to prognosis of SSNHL was
assessed.
Data of study was evaluated using descriptive statistical
methods i.e. mean and standard deviation.
3. Results
The clinical profile of the patients in our study is shown in
Table 1. The 50 subjects in our study were in the age range of
18e75 (28 males and 22 females). The co-morbid factors in
them were hypertension (8% cases), Diabetes Mellitus (16%
cases) and coronary artery disease (8%). There was history of
smoking in 22% of cases and 34% additionally complained of
tinnitus and vertigo.
baric oxygen therapy in Sudden Sensorineural Hearing Loss: A//dx.doi.org/10.1016/j.apme.2014.07.006
Table 3 e Change in mean hearing level before and aftertreatment on basis of intensity.
Intensity(db)
Pre MHL Post MHL % Of patients withhearing
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.
a p o l l o m e d i c i n e x x x ( 2 0 1 4 ) 1e5 3
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.
Themean 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).
Table5showsacorrelationbetweenthe time 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
patientswith 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-cochlearmembrane 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
Table 2 e Mean hearing levels (MHL) at differentfrequencies 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
Please cite this article in press as: Sahni T, et al., The role of hyperbretrospective review of 50 patients, Apollo Medicine (2014), http:
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 significantmean 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 dBwithmean 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 differencewas 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 >50years. 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 4 e Change in mean hearing level before and aftertreatment on basis of therapeutic delay.
Days ofonset
Pre MHL Post MHL % Of patients withhearing 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
aric oxygen therapy in Sudden Sensorineural Hearing Loss: A//dx.doi.org/10.1016/j.apme.2014.07.006
Table 5 e Correlation between hearing improvement onbasis 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 toage group.
Age group (yr) Pre MHL Post MHL % Patients withhearing
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 ) 1e54
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 HBOTwas 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 therapysignificantly improvesoutcome 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
wasmore 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
Please cite this article in press as: Sahni T, et al., The role of hyperretrospective review of 50 patients, Apollo Medicine (2014), http:
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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aric oxygen therapy in Sudden Sensorineural Hearing Loss: A//dx.doi.org/10.1016/j.apme.2014.07.006
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