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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4455_Библиотеки_им_академика_М_И_Перельмана
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232 Disorders of the Auditory System
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A
Figure 5–9. Pure-tone thresholds and speech audiometry for a 54-year-old male diagnosed with a
left-sided superior semicircular canal dehiscence (Case 5–9). Results are shown for both preoperative
(A) and postoperative (B) testing. Note the improvement in hearing at 4000 Hz when preoperative
results are compared to postoperative results at this frequency. continues
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B
Figure 5–9. continued
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Medical Recommendations
and Management
It was recommended that the patient have
a collaborative otolaryngologic and neurosurgical consultation regarding repair
of the dehiscent canal.
Additional Comments
The patient elected to undergo surgery.
The surgical procedure involved exposing
the dehiscence and grafting with a fastsetting cement. The patient has done well
since the surgery with essentially no return
of vertiginous symptoms and an essential closure of the conductive component
observed prior to surgery (see Figure 5–9B).
Case 5–10: Superior
Semicircular Canal
Dehiscence
History
A 41-year-old male was seen for consultation regarding a bilateral decrease in his
hearing sensitivity and chronic vertigo.
He had worn hearing aids for 12 years
prior to the present evaluation, but was
seen for consultation due to a worsening
of his symptoms. He reported the presence of a “whooshing” tinnitus in the left
ear. He also experienced vertigo associated with loud noises, where he reported
he experienced his eyes “bouncing.” He
did have a significant left-sided head
injury to the temporal bone as a child;
however, no other significant audiologic
or otologic history was reported.
evaluation indicated a mild to moderate sloping to a moderately-severe sensorineural hearing loss bilaterally (Figure
5–10A). Word recognition ability was
considered fair for both ears. Tympanograms were performed and revealed normal pressure, volume, and compliance
measures bilaterally, suggesting normal
middle ear status for both ears. It should
be noted that the patient did report vertigo while the tympanometric testing was
being performed on the left ear; therefore,
a fistula test was performed. The fistula
test was subjectively positive for the left
ear; however, the patient did not demonstrate a typical nystagmus pattern during
the testing procedure.
Additionally, a VNG test was performed, which was abnormal, suggesting primarily central findings based on
abnormal ocular motor findings, with the
remainder of the positional and caloric
exam being unremarkable. In addition, a
VEMP examination was ordered to evaluate for possible SSCD. Test results were
normal and symmetric at suprathreshold
levels (100 dB nHL); however, the left
ear responses were present down to low
levels (60 dB nHL) consistent with SSCD
(Figure 5–10B).
Medical Examination
The patient presented with a normal
otolaryngologic examination. Based on
the unusual patient presentation, a highresolution MRI was ordered to rule out retrocochlear involvement and a CT scan was
ordered to evaluate for possible SSCD.
Audiology
An otoscopic check was unremarkable
bilaterally. A comprehensive audiologic
Impression
Left-sided superior semicircular canal
dehiscence.
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A
Figure 5–10. Pure-tone thresholds, speech audiometry, and tympanometry results (A) and ves-
tibular evoked myogenic potentials (B) for a 41-year-old male diagnosed with a left-sided superior
semicircular canal dehiscence (Case 5–10). There were no significant differences in postoperative
audiologic results. continues
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B
Figure 5–10. continued
Audiologic Recommendations
and Management
Continued use of binaural amplification
and audiologic follow-up as needed following medical consultation.
Medical Recommendations
and Management
It was recommended that the patient have
a collaborative otolaryngologic and neurosurgical consultation regarding repair
of the dehiscent canal.
Additional Comments
The patient elected to undergo surgery.
The surgical procedure involved exposing the dehiscence and grafting with a
fast-setting cement. The patient did present with complications during surgery,
which included a hematoma. Although
the patient reported significant improvement in his vertigo, he did present with a
Grade 2–3 facial nerve weakness on the
left side, a significantly unsteady gate,
and changes in speech following surgery. Since that time, however, all of these
symptoms essentially have resolved and
his hearing has remained stable.
sudden idioPathic
sensoRineuRal
heaRing loss
Introduction
Sudden sensorineural hearing loss (SSHL)
is a disease in which very little is known
about the etiology or proper treatment, yet
it is considered a medical emergency that
should be promptly evaluated. Although
sudden hearing loss of any degree is significant, SSHL can formally be defined as
sensorineural loss of at least 30 dB within
a 72-hr time period (Whitaker, 1980; Wilson, Byl, & Laird, 1980). Although some
of the diseases/disorders discussed in the
text thus far may cause acute onset hearing loss, SSHL is idiopathic in nature.
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Symptoms
Sudden sensorineural hearing loss presents with a rapid onset of unilateral hearing loss that is sensorineural in nature.
Some patients may experience a popping
sensation prior to the hearing loss, while
others notice hearing loss upon awakening from sleep. Vertigo and tinnitus may
also accompany SSHL, and some patients
may complain of aural fullness or pressure. An upper respiratory infection often
precedes many cases of SSHL.
Incidence and Prevalence
The incidence of sudden sensorineural hearing loss is reported to be 5 to 20
in every 100,000 people (Stachler et al.,
2012). Sudden sensorineural hearing
loss is more common in the elderly (Byl,
1977) and may be bilateral in 4% to 17% of
patients (Jaffe, 1973).
may present with SSHL (Berg, Cohen,
Hammerschlag, & Waltzman, 1986). However, in these cases, the SSHL is not typically idiopathic as the neoplastic condition is likely identified and diagnosed. In
general, the etiology of a sudden hearing
loss, whether idiopathic or of an identifiable cause, can be placed into six broad
categories: (1) viral and infectious (i.e.,
mumps, herpes viruses, rubella, toxoplasmosis); (2) autoimmune (i.e., Cogan’s
syndrome, AIED, lupus); (3) labyrinthine
membrane rupture/trauma (i.e., perilymph fistula, barotrauma, temporal bone
fracture, ear surgery complications); (4)
vascular (i.e., vascular spasm, occlusion,
rupture, sickle cell disease, vertebrobasilar disease); (5) neurologic (multiple sclerosis, focal pontine ischemia, migraine);
and (6) neoplastic (acoustic neuroma and
other tumors affecting the auditory system) (see Wynne, 2003).
Site of Lesion
Etiology and Pathology
This disease is considered idiopathic, but
is likely to be multifactorial. The history
of the patient may provide some indication of a potential etiology; however, in
most cases, a clear etiologic factor cannot be identified. Vascular compromise
to the inner ear due to microembolism or
vasospasm may have a role in this disease
and some historical therapies have been
directed at improving cochlear blood supply. The relationship of infection preceding many cases of SSHL makes a viral
etiology theory reasonable. Toxic, immunologic, and neurologic insults also are
thought to be involved in the disease process in many cases. Approximately 10%
of patients with vestibular schwannomas
The cause of this disease has yet to be
elucidated, thus identifying the site at
which damage occurs has also been difficult. Postmortem analysis of the temporal
bones of a group of patients who suffered
from SSHL revealed global degeneration
of the cochlear duct structures near the
basal turn of the cochlea (Beal, Hemenway,
& Lindsay, 1967; Schuknecht, Kimura,
& Naufal, 1973). Although the cochlea is
often the site of this disorder, there also
can be eighth nerve and central sites of
involvement. As discussed in Chapter 6,
“Auditory Nerve Disorders,” acoustic
neuromas can present as a sudden sensorineural loss. It is also significant that
multiple sclerosis has been linked to SSHL
(Marangos, 1996), which would implicate
a potential central site of lesion as well.
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Audiology
Patients who present with SSHL should
have a comprehensive audiologic evaluation, OAEs, and immittance audiometry
performed as soon as possible. The use of
these measures may help to differentiate
between cochlear versus retrocochlear
involvement. Sudden hearing loss refers
to hearing loss of sensorineural origin that
is ≥ 30 dB HL at three or more consecutive
frequencies and occurs over a period of
time of 72 hr or less (Stachler et al., 2012).
Because it is possible that SSHL can have a
retrocochlear basis, it may be worthwhile
to consider performing an ABR if there is
sufficient residual hearing. This is usually a
judgment call and is dependent on history
and otologic consultation. It is also important to discriminate between sudden hearing loss and suddenly noticed hearing loss.
Medical Examination
Sudden sensorineural hearing loss represents a medical emergency and all efforts
should be taken to evaluate and initiate
treatment as soon as possible. The diagnosis of SSHL is made primarily through
careful history and exclusion of other common causes of hearing loss. The history of
a rapid unilateral sensorineural loss is a
key portion of the history. Specific questions should be asked to rule out other
potential diagnoses, such as perilymph
fistula, ototoxicity, Ménière’s disease,
infectious etiologies, and retrocochlear
pathology. A thorough head and neck
examination augments the medical history and typically is unremarkable. Neurotologic examination of vestibular function typically is normal. Laboratory tests
may be performed to detect an autoim-
mune etiology, but if done, they typically
are normal. An MRI should be performed
to rule out retrocochlear pathology.
Audiologic Management
Serial audiograms should be performed
to monitor recovery. Patients with stable
hearing losses that show no improvement after 3 to 6 months may benefit
from amplification. Profoundly deafened
ears may also benefit from a CROS or BiCROS aid, depending on the degree of
hearing in the opposite ear. The CROS
hearing aid is indicated for patients with
normal hearing sensitivity on the uninvolved side, while the Bi-CROS would be
recommended for individuals with some
degree of hearing loss in the “better” ear.
CROS or Bi-CROS aids are often beneficial
to the patient because they are able to capture sound from the side of the deaf ear
and transmit it to the better ear. Approximately 50% of patients with idiopathic
SSHL have partial or total spontaneous
recovery; however, predicting which
patients will recover can be difficult. Byl
(1984) examined prognostic factors in
hearing recovery and found that patients
with profound hearing loss and delayed
treatment as well as those at the extremes
of the age range had a much poorer prognosis for recovery. Unfortunately, sudden
sensorineural hearing loss is a common
disease and requires prompt evaluation
and treatment, exclusion of retrocochlear
pathology, and careful follow-up to detect
contralateral disease. It is important that
amplification not be provided too quickly
as it may cause additional damage. Rather,
it is recommended that amplification be
applied following confirmed stability of
the patient’s hearing thresholds.
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Medical Management
Many patients who experience idiopathic
SSHL do not seek medical attention or
they present long after the onset of symptoms. Those individuals who do seek
medical attention are often seen initially
by their primary care physicians and may
receive treatment for otitis media. In many
patients with idiopathic SSHL, the hearing loss will resolve without intervention.
However, it is difficult to predict which
patients will have spontaneous recovery.
There are several negative prognostic factors that have been identified with respect
to recovery from idiopathic hearing loss
including degree of hearing loss, age (>60
years), time of treatment (>10-day delay),
and presence of hypertension (Edizer,
Çelebi, Hamit, Baki, & Yig˘it, 2015). For
patients who do present for evaluation,
treatment is directed at salvaging hearing through the use of steroids, which
can be delivered systemically or through
an intratympanic perfusion. Antivirals
frequently are used in treatment as well;
however, no clear therapeutic benefit of
this approach has been shown consistently (Tucci, Farmer, Kitch, & Witsell,
2002). A host of other antioxidants and
vasodilators have been used historically,
but without proven efficacy.
initially treated by his primary care physician with antibiotics for otitis media with
no improvement noted. He also reported
constant tinnitus in the right ear coincident
with the onset of his hearing loss, with no
improvement in the tinnitus since its onset.
Audiology
An otoscopic check was unremarkable.
Tympanograms were performed and
revealed normal pressure, volume, and
compliance, suggesting normal middle
ear status bilaterally (Figure 5–11A).
A comprehensive audiologic evaluation
demonstrated normal peripheral hearing
sensitivity in the left ear with the exception of a mild hearing loss at 8000 Hz
and a moderately-severe midfrequency
sensorineural hearing loss in the right
ear with recovery to a mild loss at 4000
Hz and normal hearing at 8000 Hz. Word
recognition was good in the left ear and
poor in the right ear. Speech recognition
thresholds were in good agreement with
pure-tone averages bilaterally.
Medical Examination
The patient presented with an essentially
normal otolaryngologic examination.
Impression
Case 5–11: Sudden
Sensorineural Hearing Loss
History
A 32-year-old male was seen for evaluation due to a sudden right-sided hearing
loss. The patient reported a sudden onset
of hearing loss approximately three weeks
prior to his audiologic evaluation. He was
Sudden right-sided hearing loss with
unknown etiology.
Audiologic Recommendations
and Management
It was recommended that the patient
undergo imaging to rule out retrocochlear
involvement. Results from the MRI were
negative.
240 Disorders of the Auditory System
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A
Figure 5–11. Pure-tone thresholds, speech audiometry, and tympanometry for a 32-year-old male
(Case 5–11), who had experienced a sudden sensorineural hearing loss (A) and then improvement
following treatment (B). continues
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B
Figure 5–11. continued
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