Clinical Practice Guideline
for
OTOSCLEROSIS/STAPEDECTOMY
Developed for the
Aerospace
Medical Association
by their constituent organization
American
Society of Aerospace Medicine Specialists
Overview: Otosclerosis is characterized by an
abnormal deposition of bone at the footplate of the stapes. It is a disease of unknown etiology and
appears to affect genetically predisposed individuals. This bony deposition leads to fixation of the
stapes at the oval window preventing normal transmission of sound. It is the leading cause of conductive hearing
loss in adults who do not have a middle ear effusion. Stapes fixation was first described by
Valsalva in 1704 during an autopsy on a deaf patient, and in 1860 Toynbee first
described the condition causing a hearing loss by fixation of the stapes. In 1894 Politzer first referred to the
fixation of the stapes as otosclerosis.
Successful surgery for this condition dates back to Holmgren who
fathered the practice of fenestration surgery in 1923. Although the major concern with otosclerosis
is conductive hearing loss, it can also cause a sensorineural hearing loss when
it invades the otic capsule.
Additionally an estimated 10-30% of patients will also present with vestibular
symptoms or demonstrate abnormalities on vestibular testing.
The
overall prevalence of histologic otosclerosis is about 10%. Around 10% of these are affected clinically
making the overall prevalence of noticeable hearing loss secondary to
otosclerosis approximately 1% in the US population. This disease is more common in Caucasians
than in other races. Women more commonly
seek medical attention for hearing loss secondary to otosclerosis; however,
studies looking at histologic prevalence of otosclerosis show no difference in
men versus women. However, pregnancy
seems to hasten presentation. The
incidence of otosclerosis also increases with age. The most common age group presenting with
hearing loss from otosclerosis is 15-45 years; however, it has been reported to
manifest as early as 7 years and as late as the mid 50s. Approximately 80% of patients will develop
bilateral otosclerosis, though the progression of each ear may be
different. Diagnosis is based on history
and clinical exam. Clinical exam may
show a reddish blush on the promontory mucosa (Schwartze’s
sign—associated with active disease).
Screening with 512-Hz and 256-Hz forks will often show a reverse Rinne
test. Audiometric screening includes air
conduction, bone conduction, acoustic reflexes and speech audiometry. Typically depending on how advanced the
disease is, the audiogram will show varying degrees of
conductive hearing loss. As mentioned
above some advanced forms may cause a sensorineural hearing loss. Acoustic reflexes are absent due to stapes
fixation. In recent years, imaging
studies have played a greater role with high-resolution CT (HRCT) being the
radiologic method of choice in the assessment of the labyrinthine windows and
otic capsule. Recent estimates demonstrate
the sensitivity of CT for the diagnosis of otosclerosis to be at least 90%1. The differential diagnosis for conductive
hearing loss in patients without discernable ear pathology includes the
following: congenital malleus/incus fixation, congenital stapes fixation, other
congenital ossicular abnormalities (1st or 2nd arch
syndromes), post-inflammatory ossicular fixation, ossicular
discontinuity, osteogenesis imperfecta
tarda, Paget’s disease, and osteopetrosis.
For
many people with otosclerosis, no treatment is indicated initially. As the hearing loss progresses, the patient
may opt to try hearing aids. Use of
hearing aids in the cockpit environment may be a handicap as the aviator will
be unable to tune out unwanted sounds and transmissions. In fact the phenomenon of “Paracusis of
Willis” allows patients with otosclerosis to hear better in a noisy environment
than in a quiet locations. Hearing aids
work by essentially amplifying all sound transmitted to the ear, and even
distorting the sound at times. However,
modern hearing aids can offer a variety of noise filters for different
listening environments. The currently
popular surgical treatment for otosclerosis is stapedectomy, first performed by
John Shea in 1956. This procedure is
still commonly performed, with some modifications, by many ENT surgeons
throughout the world. With increasing
availability of good surgical care and of adequate screening tests, the average
age of presenting patients has declined over the past fifty years (52 to 50) as
has the number of years with noticeable hearing loss (18 to 11).
There
are actually three surgical options for otosclerosis: total stapedectomy,
partial stapedectomy, and stapedotomy.
The different designations correspond to the amount of footplate
removed. Partial stapedectomy involves
removal of the posterior third of the footplate while stapedotomy involves
drilling or lasering a hole in the
stapes footplate, inserting a prosthesis through the
hole to the oval window and anchoring it to the incus. The technique chosen depends on the degree of
sclerosis and surgeon preference; most perform a stapedotomy. In experienced hands, the success rate of
these procedures is in excess of 90% as measured by return of hearing to normal
or near normal. Over time, a small
percentage of patients have a return of hearing loss symptoms or develop
complications such as dizziness, sensorineural
hearing loss, distortion of sound or tympanic membrane complications. Depending on the cause, a revision procedure
is often accomplished. Expected outcomes
for these patients are not as good as with the primary procedure; successful
hearing results range from 16% to 80% with a mean of 53%, with the variability
in results due to the indication for the revision.
Aeromedical
Concerns: Loss of normal hearing capability is a
concern in aircrew. Otosclerosis may
progress to the point of hearing loss or more rarely vestibular symptoms
significant enough to compromise flight safety.
Most aircrew delay surgical intervention because of
the Paracusis of Willis phenomenon.
However, when the hearing begins to compromise communications, they will
present for surgical or audiometric remediation. Surgery offers freedom from having to use
amplification. Fortunately complications
following surgery are rare, but may be significant. These include the following: acute otitis
media, suppurative labyrinthitis and meningitis, vertigo, reparative granuloma,
perilymph fistula, facial paralysis, fluctuating conductive hearing loss,
persistent perforation of the tympanic membrane, taste disturbance and dry
mouth, postoperative fibrosis, incus necrosis, and delayed sudden
deafness. Vertigo may occur immediately
after stapedectomy, or its onset may be delayed by weeks or years. Vertigo that is not resolved with treatment
is incompatible with flying duties.
Perilymph fistula postoperative risk is 0.34—9.0%, with symptoms similar
to those of endolymphatic hydrops (hearing loss, vertigo, ear fullness, and
tinnitus) and may be incompatible with flying duty if definitive treatment is
not achieved. Facial nerve paralysis may
cause dry eye which may present significant problems for aviators flying in dry
cockpit conditions, or facial droop which may interfere with wear of aviator
masks. Persistent perforation of one
tympanic membrane could lead to alternobaric vertigo and is not compatible with
flying duties.
Return
to aviation duties following stapedectomy or stapedotomy has been controversial
within the aeromedical community for the past forty years. In the 1960s and 1970s, concern with barometric
pressure changes causing a perilymph fistula led to Air Force policy that
prevented return to flying duties for aviators after these procedures. As more and more affected individuals had
this procedure for a return to flying duties, pressure mounted on medical
authorities to develop a more reasonable policy. Dr. Rayman’s
proposed criteria in his 1972 paper led the way to a consistent and reasonable
approach to these airmen. Revising
policy has been a long process, but results so far have been very encouraging
with the dreaded complication of a perilymph fistula being very rare in the
carefully selected group of aviators.
Medical Work-up: Medical evaluation of an
aviator with otosclerosis should include a complete history to include all
hearing and vertiginous symptoms and impact on activities of daily living and
aviation duties. There should also be
discussion of all attempted treatments such as hearing aids. The exam need to include a complete
audiologic exam to include air conduction threshold measurement; bone
conduction threshold measurement (if indicated); speech reception threshold;
speech discrimination testing; acoustic impedance testing and ENG if clinically
indicated. Also, a complete report of
the ENT exam is required as are any consultative reports from the ENT physician
and audiologist. Finally, all surgical
reports to include details of technique used, type of prosthesis and type of
graft used are required.
Aeromedical
Disposition:
Air
Force: Otosclerosis
and stapedectomy are not specifically mentioned in AFI 48-123, but it is noted
that a history of surgery involving the middle ear is disqualifying. Also, hearing defects are well described as
are conditions that interfere with auditory or vestibular functions.
If
the otosclerosis results in hearing loss and/or vertigo, then waiver guidelines
for those diagnoses should be followed as well.
If the aviator undergoes successful surgical treatment, an evaluation at
the USAF Aeromedical Consultation Service (ACS) is required for single seat
high performance aircrew and FC I/IA candidates, and may be scheduled no
earlier than 12 weeks postoperatively.
Evaluation at the ACS will include evaluation by an otolaryngologist
with review of all medical records, pre and post-operative testing, and
surgical report. Diagnostic audiology
including air conduction threshold measurement; bone conduction threshold
measurement (if indicated); speech reception threshold; speech discrimination
testing; acoustic impedance testing and ENG will be accomplished if
indicated. An altitude chamber flight
with a flight surgeon is required only for those who have had the traditional
stapedectomy surgery, to test for perilymph fistula.
For those who have undergone the newer stapedotomy surgery, an
altitude chamber evaluation is not required.
If a chamber flight is performed, it should include a rapid descent
(5000 feet/min) from 10,000 feet. A rapid decompression is also required. Additional tests are done as clinically or
aeromedically indicated. If ACS evaluation
reveals no post-op sequelae, the aviator may be recommended for an unrestricted
waiver.
Army:
The
inability to clearly hear cockpit radio transmissions and warning tones can
have a significant impact on flight safety and this is the Army’s concern regarding
this condition. Waivers will be
considered depending on the degree of hearing loss and functional
capability. Stapedectomies present
problems because the operation creates an opening into the labyrinth, and
involves the placement of a prosthesis in most cases. There is a risk of postoperative perilymph
fistula, as well as subsequent shifting of the prosthesis, both of which can
result in sudden attacks of vertigo. Bilateral stapedectomy is not waiverable.
Initial flight applicants with a history of stapedectomy are considered
disqualified, no exception to policy granted.
Navy:
Stapedectomy
done to treat otosclerosis is considered disqualifying (CD) and requires a
waiver. Designated aviators are grounded for three months following
stapedectomy, before waiver being recommended to SG1 (pilot). For Naval Flight
Officer (NFO) and other Class II (non-pilot) personnel, a waiver is also
considered for duty involving flying after three months. Waiver criteria
include being asymptomatic, passing a current flight physical, and that the
prosthesis used was not a wire loop/gelfoam (a piston
prosthesis and tissue graft is preferred versus a blood seal). No waiver will
be recommended if there are signs of vestibular dysfunction, spontaneous
nystagmus, or sudden/progressive neurosensory hearing loss. Bilateral
stapedectomy is not waived. Applicants with a history of stapedectomy are CD,
no waiver. Information required for waiver includes ENT consult, audiology
consult (must include speech reception thresholds and speech discrimination
scores), and surgical report.
Civilian:
In the US civilian sector as long as one can clear their
ears and does not have any vertigo they can fly. To pass the FAA's hearing standards one must
only pass one of three different tests. The most commonly performed test is the
Conversational Voice Test where the airman must be able to repeat what the
Aviation Medical Examiner (AME) says while they are standing 6 feet from the
AME facing the opposite direction. The
next test that can be given is the standard Audiometry exam with a better ear
worse ear standard, The Better ear
being: 500 hz: 35 db, 1000 hz: 30 db, 2000 hz: 30 db ,3000 hz: 40 db; Worse ear: 500 hz: 35 db, 1000 hz: 50, 2000 hz: 50, 3000 hz: 60. The last
test is the Speech discrimination test where the airman must hear at least 70%
in one ear at 65 db. The airman may take
any of these tests wearing hearing aids and if they pass with the aids they are
given a medical certificate with the restriction MUST WEAR HEARING AMPLIFICATION.
The airman can also attempt to pass the
hearing test taking a medical flight test in which case they will be issued a
Statement of Demonstrated Ability.
Waiver
Experience:
Air
Force: A
review of AIMWTS revealed a total of 29 cases submitted for a waiver with the
diagnosis of otosclerosis. This total
included one FC I case, 19 FC II cases, and nine FC III cases, all receiving a
waiver. In ten of the cases, the airman
had surgery, which was a stapedectomy in each case and there were four cases
where it was stated the airman was wearing a hearing aid. There were a total of six females in the
database.
Army: Otosclerosis
with or without stapedectomy has been an uncommon diagnosis in this population.
Of the 16,852 rated aircrew with a
current flight physical in 2010, none carried the diagnosis of otosclerosis or
had undergone stapedectomy.
Historically, going back to 1987, there have been 15 cases of
otosclerosis among rated US Army aircrew, all of whom were retained except for
one.
Navy:
Not
available at this time.
Civilian: As of May 31, 2011
there were 52 first-class, 44 second-class and 113 third-class airmen currently
issued with this condition.
|
ICD 9 codes for Otosclerosis and
Stapedectomy |
|
|
387 |
Otosclerosis |
|
387.9 |
Otosclerosis,
unspecified |
|
19.1 |
Stapedectomy |
|
19.19 |
Other
stapedectomy |
|
19.9 |
Stapedotomy |
References:
Vicente AO, Yamashita HK, Albernz
PLM, and Penido NO.
Computed
tomography in the diagnosis of otosclerosis.
Otolaryngol Head Neck Surg,
2006; 134:685-92.
Isaacson
JE and Vora NM.
Differential Diagnosis and Treatment of Hearing Loss. Am Fam Physician, 2003; 68:1125-32.
Muller
C and Gadre A.
Otosclerosis – Grand Rounds Presentation at UTMB Dept. of
Otolaryngology, 4 June 2003.
House
JW and Cunningham CD. Otosclerosis, Ch.
156 in Cummings: Otolaryngology: Head and Neck Surgery, 4th edition,
2005.
Saim L and Nadol JB. Vestibular
Symptoms in Otosclerosis – Correlation of Otosclerotic
Involvement of Vestibular Apparatus and Scarpa’s
Ganglion Cell Count. Am
J Otology, 1996; 17:263-70.
Jahn,
AF and Vernick D. Otosclerosis: Diagnosis and Treatment,
AAOHNS SIPAC, 1986; Pg 1-78.
Rayman
RB, Hastings JD, Kruyer WB, et al.
Clinical Aviation Medicine, 4th ed. New York; Professional
Publishing Group, Ltd. 2006, 138-40.
Lippy
WH, Berenholz LP and Burkey
JM. Otosclerosis in the 1960s,
1970s, 1980s, and 1990s. The
Laryngoscope, 1999; 109:1307-09.
Quaranta N, Besozzi G, Fallacara RA, and Quaranta A. Air and Bone
Conduction After Stapedotomy and Partial Stapedectomy
for Otosclerosis. Otolaryngol Head Neck Surg,
2005; 133(1): 116-20.
Battista
RA, Wiet RJ and Joy J. Revision Stapedectomy. Otolaryngol Clin N Am, 2006; 39:677-97.
Wiet RJ,
Harvey SA, and Bauer GP. Complication in Stapes
Surgery. Otolaryngol
Clin N Am, 1993; 26(3):471-90.
Hanna
HH and Collins FG. Effect of Barometric
Pressure Change on the Ear Following Stapedectomy. Aerospace Med, 1974; 45:548-50.
Rayman
RB. Stapedectomy: A Threat to Flying
Safety? Aerospace Med, 1972; 43:545-50.
Schall
DG. On Combat Pilots,
Letter to the Editor. Am J Otology, 1997; 18:687-88.
Katzav J, Lippy
WH, Shamiss A and Davidson BZ. Stapedectomy in Combat
Pilots. Am
J Otology, 1996; 17:847-49.
Thiringer JK and Arriage MA. Stapedectomy in military aircrew. Otolaryngol Head Neck Surg,
1998; 118:9-14.
Shea
JJ. Forty Years of Stapes Surgery. Am J Otology, 1998; 19:52-55.
Prepared
by Drs. David Schall and Dan Van Syoc
November
14, 2011