Download USE OF MULTIFREQUENCY MULTICOMPONENT

USE OF MULTIFREQUENCY MULTICOMPONENT
TYMPANOMETRY IN THE AUDIOLOGICAL PROFILING
OF FAMILIES WITH HISTORY OF OTOSCLEROSIS :
AN EXPLORATORY STUDY
Roopa Nagarajan, (Professor and Course Chairperson), L-147
Vidya Ramkumar, (Lecturer), L-1093
Ramya Kapooria, Student (II M.Sc ASLP), L-1156
Supraba. J, Student (II M.Sc ASLP), L-1551
Department of Speech, Language and Hearing Sciences
Sri Ramachandra University
Porur, Chennai-600 116
Address for correspondence
[email protected]
Paper submitted for 43rd ISHA Con
Use of multifrequency multicomponent tympanometry in the audiological
profiling of families with history of otosclerosis : An exploratory study
The term otosclerosis refers to abnormal bone homeostasis of the otic capsule that
leads to a bony fixation of the stapedial footplate in the oval window (Ali et al, 2007).
Shambaugh, (1956) reported that age of onset is between 15-45 years and female to
male ratio is approximately 2:1. Investigators in Tunisia (Ali et al, 2007) and Israel
(Brownstein et al, 2006) have tried to establish the gene loci for otosclerosis. These
involved phenotyping several generations of family members using otological and
audiological investigations. Studies have also been initiated in India (Tomek et al,
1998) to identify the gene loci specific to Indian population.
The clinical diagnosis of otosclerosis is made based on family history, otoscopic
examination and audiological evaluation, though the confirmation is done after
surgical exploration or postmortem. Audiologically, bilateral conductive hearing loss
with onset in adulthood, presence of Carharts’s notch, absent stapedial reflexes, and
type A tympanogram suggests the possibility of otosclerosis(Naumann, Porcellini,
Fisch, 2005). The primary acoustic consequence in its early stages is the increase in
stiffness reactance component of the total middle ear impedance. The diphasic ‘onoff’ reflex appears to be a sensitive indicator only in early stages of otosclerosis
(Terkildsen et al, 1994).There have been suggestions that multifrequency
tympanometry which allows the estimation of middle ear resonance frequency may
be a useful tool in identifying otosclerosis (Ogut et al ,2008).
NEED
Investigators have identified different gene loci across different populations for
otosclerosis (Chen et al, 2002., Bogaert et al, 2006., Brownstein et al, 2006) and the
loci for otosclerosis is found to vary across races. These studies have included
traditional audiological testing procedures such as pure tone audiometry,
tympanometry and acoustic reflex for phenotyping. They have reported a wide range
of audiological findings ranging from normal to severe hearing loss, conductive to
mixed hearing loss, absent reflexes, and A, As or Ad type tympanogram. None of
these studies have incorporated Multifrequency and Multicomponent (MFMC)
tympanometry, even though it could be a useful tool in identifying stiffness related
pathologies such as otosclerosis. Hence, it is worthwhile to study the use of MFMC
tympanometry in Indian families with history of otosclerosis.
AIM
To explore the usefulness of MFMC tympanometry as a part of the audiological test
battery in profiling individuals with otosclerosis.
METHOD
The opportunity to explore the usefulness of MFMC tympanometry presented itself
when a geneticist requested for audiological phenotyping of a family with history of
otosclerosis. Forty five individuals (21F & 24M) in the age range 19 to 84 years
(mean 42.53, SD 19.11) belonging to three generations of one family participated in
the study. The number of individuals in the age group of 10-19, 20-29, 30-39, 40-49,
50-59, 70-79 and 80-89 years were 10,2,10,13,3 and 2 respectively. For each
individual a detailed case history that included information about complaint or history
of reduced hearing sensitivity, difficulty in understanding speech, ear pain, blockage
or discharge, tinnitus and intolerance to loud sounds was obtained. Any complaint of
giddiness or vomiting, head ache, diabetes, hypertension and family history of
hearing loss was recorded.
Pure tone audiometry was done using GSI 61 with TDH-50P earphones and Radio
Ear B71 bone vibrator. Immittance audiometry using 226Hz probe tone and MFMC
tympanometry was carried out using GSI Tympstar Middle Ear Analyzer. Frequency
sweep and pressure sweep method were used to measure the resonant frequency of
middle ear and was classified based on Holte, 1990. Multicomponent tympanogram
was obtained using 678Hz probe tone and was interpreted with reference to the
Vanhuyse model (Vanhuyse et al, 1975).
RESULTS
Six participants had undergone ear surgery for improving hearing subsequent to
some loss in hearing in young adulthood. However, no written records were available
to confirm that they had undergone stapedectomy. Otoscopic examination detected
no abnormality in 44 of the 45 participants. One individual showed Schwartz sign.
Seventeen participants had normal hearing bilaterally. Four had unilateral hearing
loss and 24 participants had bilateral hearing loss. Among the 56 ears with hearing
loss, sensorineural loss was predominant (38.8%), followed by mixed loss (11.1%)
and conductive loss (7.7%). Hearing sensitivity varied from normal in 38 ears
(42.2%) to severe to profound loss in 11 ears (12.2%). Low frequency probe tone
tympanometry revealed type A tympanogram in 85% of the ears and Ad type
tympanogram in 13.3% ears. No participant demonstrated As type tympanogram or a
negative on off reflex. Acoustic reflexes were absent in all participants having
hearing loss.
Data from MFMC tympanometry showed that 57(63%) ears had normal resonant
frequency, 32(35%) ears had high resonant frequency and 1(1 %) ear had low
resonant frequency. Thirty two of ninety ears showed high resonant frequency with
1B1G pattern, suggesting that these ears may have some stiffness related condition.
One unexpected finding was the presence of high resonant frequencies in five ears
with normal hearing in the 40-49 age group. All ears that underwent surgery had
normal resonant frequency.
DISCUSSION
Results showed that three participants showed Carhart’s notch and one had
Schwartz sign. One participant in the 20-29 age group demonstrated impedance
signature. However there was much variation in the hearing thresholds, type and
degree of loss. As a rule the younger members of the family had milder degrees of
hearing loss when compared to the older members. This is not surprising as long
standing otosclerosis often manifests as severe mixed loss and presbycusis could
account for the degree of hearing loss.
Low frequency tympanometry was not very supportive of patterns seen in typical
otosclerosis. Diphasic reflex and As tympanogram were not seen in any of the
participants. It is well documented that 226 Hz probe is not very accurate in detecting
stiffness related pathologies such as otosclerosis but higher probe tone frequencies
are more diagnostic. In this study irrespective of type and degree of hearing loss,
high middle ear resonant frequency was obtained in 35% of ears. There were two
interesting findings; a) in the 6 ears that had been operated, the resonant frequency
was normal; b) in 5 ears, high resonant frequency was noticed in the presence of
normal hearing thresholds. These individuals were in the 40-49 years age range. It
could be speculated that these ears could have some change in middle ear status
tending towards increased stiffness that have as yet not manifested in the
audiogram.
The results of this study suggest MFMC tympanometry could provide additional
information especially if other audiological tests were inconclusive in individuals with
suspected otosclerosis. The study also raises some intriguing questions;Can MFMC
tympanometry help in detecting otosclerotic changes before they are manifested in
routine audiological tests?;Would normalization of resonant frequency be an
indicator of good surgical outcome?Should MFMC be always included in a battery of
audiological tests in genetic/family based studies on otosclerosis?
CONCLUSION
This study was initiated to investigate the audiological phenotype in a family with
history of otosclerosis and in part to provide support to a parallel study for identifying
the genetic loci. Taking into consideration the results of the study, it would be useful
to consider MFMC tympanometry as a part of routine audiological testing in order to
provide more reliable diagnosis on stiffness related conditions pre surgically.