Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4606_Библиотеки_им_академика_М_И_Перельмана
.pdf
72
https://t.me/medicina_free
H. Sakano and B. T. Crane
The classical presentation is not always detailed by the patient. This is particu-
larly true early in the disease presentation. Often in retrospect, the disease seems to
present with a predominance of either vestibular or auditory complaints [77]. In the
series by Kitahara etal., 50% of patients presented with vertigo and hearing loss
together, 19% with vertigo only, and 26% with only deafness [78]. These variable
initial presentations have led to the usage of the terms cochlear or vestibular
Menière’s disease. These subtypes are not widely used, and considered by the AAOHNS Committee on Hearing and Equilibrium [79], to be an inappropriate application of the diagnosis [78]. Furthermore, there is no pathologic correlation for these
subtypes [57]. The terms recurrent vestibulopathy or atypical Menière’s disease
have been used for individuals with less than the classic triad of hearing loss, vertigo, and aural fullness or tinnitus.
The clinical course of Menière’s disease is highly variable. Patients often have a
cluster of attacks separated by long remissions. Silverstein etal. [80] found that
vertigo ceased spontaneously in 57% of patients in 2years, and 71% after 8.3years.
Attacks are often clustered in time. Severity of symptoms range from minimal
inconvenience to complete incapacitation, the AAO-HNS has provided staging
guidelines (Box 4.2) [79, 81]. In addition to the incapacitating effects of the physical manifestations of Menière’s disease (vertigo, disequilibrium, hearing loss, tinnitus, and pressure), the disease is emotionally disabling [82].
Box 4.2 AAO-HNS Criteria for Menière’s Disease Severity [79, 81]
In 1996, the Committee on Hearing and Equilibrium reafrmed and claried
the 1985 guidelines, adding initial staging and reporting guidelines.
Vertigo
(a) Any treatment should be evaluated no sooner than 24 months
(b) Formula to obtain numeric value for vertigo: ratio of average number of
denitive spells per month after therapy divided by denitive spells per
month before therapy (averaged over a 24-month period) ×
100 = numeric value
(c) Numeric value scale
Numeric value Control level Class
0 Complete control of denitive spells A
41–80 Limited control of denitive spells B
81–120 Insignicant control of denitive spells C
>120 D
Secondary treatment initiated E
4 Menière’s Disease
https://t.me/medicina_free
Disability
(a) No disability
(b) Mild disability: intermittent or continuous dizziness/unsteadiness that
precludes working in a hazardous environment
(c) Moderate disability: intermittent or continuous dizziness that results in a
sedentary occupation
(d) Severe disability: symptoms so severe as to exclude gainful employment
Hearing
(a) Hearing is measured by a four-frequency pure-tone average (PTA) of 500
Hz, 1, 2, and 3kHz
(b) Pretreatment hearing level: worst hearing level during 6 months prior
to surgery
(c) Posttreatment hearing level: poorest hearing level measured 18–24
months after institution of therapy
(d) Hearing classication:
• Unchanged ≤10-dB PTA improvement or worsening or ≤15% speech
discrimination improvement or worsening
• Improved >10-dB PTA improvement or >15% discrimination
improvement
• Worse >10-dB PTA worsening or >15% discrimination worsening
73
In 1996, the Committee on Hearing and Equilibrium reafrmed and claried
the guidelines, adding initial staging and reporting guidelines.
Initial hearing level
Stage Four-tone average (dB)
1 ≤25
2 26–40
3 41–70
4 >70
Functional Level Scale
Regarding my current state of overall function, not just during attacks.
1. My dizziness has no effect on my activities at all.
2. When I am dizzy, I have to stop for a while, but it soon passes and I can
resume my activities. I continue to work, drive, and engage in any activity
I choose without restriction. I have not changed any plans or activities to
accommodate my dizziness.
74
https://t.me/medicina_free
3. When I am dizzy, I have to stop what I am doing for a while, but it does
pass and I can resume activities. I continue to work, drive, and engage in
most activities I choose, but I have had to change some plans and make
some allowance for my dizziness.
4. I am able to work, drive, travel, and take care of a family or engage in most
activities, but I must exert a great deal of effort to do so. I must constantly
make adjustments in my activities and budget my energies. I am barely
making it.
5. I am unable to work, drive, or take care of a family. I am unable to do most
of the active things that I used to do. Even essential activities must be limited. I am disabled.
6. I have been disabled for 1 year or longer and/or I receive compensation
because of my dizziness or balance problem.
H. Sakano and B. T. Crane
History
Incapacitating, spinning vertigo, usually in the horizontal axis, is the most distressing complaint of the affected patient [64]. As is typical of peripheral vestibular
dysfunction, the symptoms are exacerbated with any head movement. There is often
accompanying nausea, vomiting, diarrhea, and sweating. Between attacks, patients
may be entirely asymptomatic or may describe periods of disequilibrium, lightheadedness, and tilt.
Sudden unexplained falls without loss of consciousness or associated vertigo are
occasionally described. Tumarkin [83] attributed these to acute utriculosaccular
dysfunction, so-called otolithic crises of Tumarkin or drop attacks. It is thought that,
as a consequence of an abrupt change in otolithic input, an erroneous vertical gravity reference occurs. This in turn generates an inappropriate postural adjustment via
the vestibulospinal pathway, resulting in a sudden fall [84, 85]. Attacks are so sudden that injury can occur. The patient often describes being pushed or feeling the
world moving. The spells are short lived with little vertigo associated. Drop attacks
have been reported in 2–6% of persons with Menière’s disease. They tend to occur
in clusters and then spontaneously remit.
Lermoyez described an unusual clinical presentation in which tinnitus and hearing loss precede and worsen with the onset of vertigo. When the vertiginous episode
occurs, the tinnitus and hearing loss dramatically resolve. The temporal bone studies of one individual with such attacks noted hydrops and membrane ruptures isolated to the basal turns of the cochlea and the saccule [86].
Acute Menière’s attacks are rarely observed by physicians [87]. Horizontal nystagmus is the cardinal nding, but the direction varies over the course of the attack
so it is not useful in determining the involved ear [88].
4 Menière’s Disease
https://t.me/medicina_free
75
Hearing Loss andTinnitus
The sensorineural hearing loss in Menière’s disease is typically uctuating and progressive. It often occurs coincident with the sensation of fullness or pressure in the
ear. A pattern of low-frequency uctuating loss and a coincident nonchanging, highfrequency loss is described, a “peaked” or “tent-like” audiogram. This peak classically occurs at 2kHz. Over time, the hearing loss attens and becomes less variable
[77]. Only 1–2% of patients progress to profound deafness.
Additional features include diplacusis, a difference in the perception of pitch
between the ears (43.6%) and recruitment (56%) [64].
Tinnitus tends to be nonpulsatile and variously described as whistling or roaring.
It may be continuous or intermittent. Tinnitus often begins, gets louder, or changes
pitch as an attack approaches. Following the attack there is frequently a period of
improvement.
Investigations
Videonystagmography (VNG)
Recording of eye movements after caloric and rotational stimulation are a commonly available and reliable method of assessing vestibular function. The caloric
test can often localize the involved ear. A signicant caloric response reduction is
found in 48–73.5% of patients with Menière’s disease [89]. Complete absence
caloric response is reported in 6–11% of patients. In most cases, the caloric asymmetry is only slight [90].
Head Thrust Testing
The head thrust popularized by Halmagyi is a very sensitive test for unilateral vestibular dysfunction [91]. However, in Menière’s disease, the asymmetry is subtle
and only present in 29% of Menière’s patients [92].
Electrocochleography
The summating potential (SP), as recorded by electrocochleography in response to
clicks or tone bursts, in Menière’s patients, is larger and more negative. This is
thought to reect the distention of the basilar membrane into the scala tympani,
causing an increase in the normal asymmetry of its vibration. The most commonly
76
https://t.me/medicina_free
used value is the ratio of amplitudes of the summating potential and the eighth cranial nerve action potential (AP), the SP/AP ratio. This is based on the observed
variability in the amplitude of the summating potential considering variables such
as recording technique and electrode placement. The SP/AP ratio has been used to
reduce the intertest variability, resulting in a more linear response. The summating
potential becomes relatively larger in hydrops; thus, the SP/AP ratio increases [93].
The ratios are elevated in 62% of patients with Menière’s and 21% of control subjects. ECoG sensitivity can range 66.7–85.7% and specicity range from 80% to
100% [25]. Elevated ratios can also be observed in other potential causes of endolymphatic hydrops and vertigo (i.e., spontaneous intracranial hypotension) [94].
The difculty in obtaining reproducible recordings, the variability of the wave
amplitudes noted with patient age, hearing loss and stage of disease, as well as the
availability of reliable, less invasive diagnostic methods, have resulted in electrocochleography infrequently being used for this purpose [95, 96] although some still
advocate for it [97].
H. Sakano and B. T. Crane
Dehydrating Agents
The assumption that an increase in endolymph volume, with its effect on labyrinthine membrane behavior, produces, in part, the hearing loss and vestibular decit
in Menière’s disease has led to the administration of dehydrating agents (e.g., urea,
glycerol, and furosemide). The goal is to reduce the volume abnormalities in the
inner ear and produce a measurable change in response. Improvement has been
measured with audiometrics, reduction in summating potential negativity (as
recorded with electrocochleography), or a change in the gain of the vestibulooccular response to rotational stimulation. The reported sensitivity and specicity of
the test varies widely. Klockhoff reports a 60% sensitivity in cases of known
Menière’s disease [98]. Psychological factors are a signicant factor, leading some
to question the usefulness of the test [95, 99].
Vestibular Evoked Myopotentials (VEMP)
VEMP are generated by playing loud clicks in the ear which move the stapes footplate and stimulate the saccule. This is the start of a disynaptic pathway that passes
through the vestibular nuclei then to synapses which relax the sternocleidomastoid
muscle. The saccule is the second most common site affected by hydrops which has
caused VEMP to be investigated as a potential diagnostic tool. In the normal ear, the
best response is near 500 Hz. Ears affected by Menière’s disease have elevated
VEMP thresholds with attened tuning [100]. The interaural amplitude difference
in the response has been implicated as a staging tool for Menière’s disease [101].
The most reliable nding seems to be that cervical VEMP (cVEMP) has reduced
amplitudes [102, 103]. Delayed or absent VEMPs are only seen in half of Menière’s
4 Menière’s Disease
https://t.me/medicina_free
patients compared to >90% of normal patients [104]. Although these tests show differences between populations, they currently have limited diagnostic value due to
the large individual variation in individual responses [105].
77
Treatment
Therapy is aimed at the reduction of its associated symptoms. The optimal curative
treatment should stop vertigo, abolish tinnitus, and reverse hearing loss.
Unfortunately, long-term hearing impairment does not seem amenable to treatment
[82]. Currently, almost all proven therapy is directed at relieving vertigo which is
usually the most distressing symptom.
Evaluating treatments for vertigo in Menière’s disease patients has been made
difcult by the natural history of the disease which improves spontaneously in
60–80% of cases and many treatments have a signicant placebo effect [67, 106,
107]. This is further supported by the 71% improvement in symptoms by patients
who refused surgery [80], and placebo-controlled studies of endolymphatic sac surgery [15, 108] and medical therapy [109]. The large variety of Menière’s disease
treatments exist due to extreme clinical variability, and difculty in assessing
effectiveness.
Dietary Modication andDiuretics
Salt restriction and diuresis may be a reasonable initial therapy for Menière’s disease [110, 111]. The goal of salt restriction and diuretics is to reduce endolymph
volume by uid removal and/or reduced production. Despite the popularity of these
treatments neither salt restriction [112] nor diuretics [113–115] has had their efcacy conrmed by double-blind placebo controlled studies. Carbonic anhydrase
inhibitors such as acetazolamide were recommended based on the localization of
carbonic anhydrase in the dark cells and the stria vascularis. However, their use has
not proved to be clinically more effective than other diuretics [116]. Despite the lack
of hard evidence to their efcacy, the authors feel low salt diet and diuresis is an
appropriate and effective treatment for Menière’s disease with a low risk of side
effects. Decreased caffeine intake may also have some efcacy [117].
Vasodilators
In the belief that Menière’s disease was the result of strial ischemia, vasodilating
agents have been used. Betahistine, an oral preparation of histamine, is one such
medication [118]. Betahistine has historically been a popular Menière’s treatment in
Europe [119]. In the United States, the drug is available only through compounding
78
https://t.me/medicina_free
pharmacies and was often not covered by insurance making it infrequently prescribed. A recent large multicenter European trial demonstrated it was no more
effective than a placebo [120], which strongly suggests it is an ineffective treatment.
H. Sakano and B. T. Crane
Symptomatic Treatment
Antivertiginous medications, antiemetics, sedatives, antidepressants, and psychiatric treatment have been reported to be benecial in reducing the severity of the
vertigo and vegetative symptoms and in improving tolerance of Menière’s symptoms [121]. Although this strategy is commonly used, it is the authors’ experience
that the results are often not satisfactory to the patient. Sedatives and antiemetics
can help ease the symptoms during an active vertigo event.
Local Overpressure Therapy
One approach to decrease hydrops is by pulsing pressure in the middle ear. As early
as 30years ago, overpressure in the middle ear was reported to decrease Menière’s
symptoms during acute vertigo attacks [122]. The mechanism of vertigo reduction
is unclear, and it may facilitate endolymph absorption [123]. Since 2000, the Meniett
device has been approved for use by the United States Food and Drug Administration.
The device is a handheld air pressure generator that the patient administers as
needed. The pressure is delivered in complex pulses up to 20cm of water which is
delivered over a 5min period. The device requires a ventilation tube to be placed in
the tympanic membrane prior to starting therapy. A randomized controlled trial
demonstrated that the Meniett device had a signicant decrease in vertigo symptoms for the rst 3months of therapy but afterward was similar to placebo [124].
More recent studies suggested it might have a role, but only when combined with
another therapy [125], and it is no more effective than a placebo on its own [126].
In any case, it is currently rarely used and a recently survey revealed more than twothirds of neurotologists never recommend it to patients [127].
It should also be noted that simple placement of a ventilation tube with no additional therapy has been reported in control vertigo symptoms in many patients with
Menière’s disease [128, 129].
Transtympanic Therapy
Transtympanic injection (also referred to as intratympanic injection) is commonly
performed with either dexamethasone or gentamycin for control of vertigo symptoms. The term “chemical labyrinthectomy” is often applied to intratympanic gentamicin treatment, but it may not be an appropriate assessment of the effect of
4 Menière’s Disease
https://t.me/medicina_free
Fig. 4.4 Response to head thrusts that excited each of the six semicircular canals in a typical
subject measured 49days after a single intratympanic injection of gentamicin in the right ear.
(Figure reproduced from Carey etal. 2002 [131])
79
gentamicin on the labyrinth in titrated therapy. Installation of aminoglycosides into
the middle ear was described by Schuknecht in 1957 with streptomycin injection
through a microcatheter placed through the tympanic membrane [21]. Control of
vertigo was achieved in these patients, but severe hearing loss in the treated ear also
occurred in most patients. Although streptomycin is still used in some clinics and
has excellent control of vertigo symptoms [130], the risk of profound hearing loss
has led most to focus on gentamicin and dexamethasone.
Gentamicin has a vestibulotoxicity that is high relative to its cochleotoxicity;
thus, it can be used to control vestibular symptoms while often sparing the hearing.
The gentamicin can be administered through either a tympanostomy tube or directly
injected through the tympanic membrane. Peripheral vestibular decits are evident
on head thrust testing after even a single dose of gentamicin (Fig.4.4) [131]. The
concentration of the medication used and frequency of injection vary by series. The
risk of hearing loss varies greatly by series depending on the dose and frequency of
treatment. Lange [132] reported elimination of vertigo in 90% of 92 patients, but the
incidence of hearing loss and level of vestibular function were not specied. Beck
and Schmidt [133] sought to determine if complete ablation of vestibular function,
as measured with ice water caloric response, was needed for vertigo control. They
found that it was not, and that this end point led to severe to profound hearing loss
in 58% of patients. Wu and Minor [24] found complete control of vertigo in 90%
80
https://t.me/medicina_free
with profound sensory neural hearing loss in only 3% of patients. Nedzelski etal.
[134] found control of vertigo was achieved in 83% of patients with substantial
control in the remaining subjects. There was a 10% incidence of profound hearing
loss in the treated ear. The current trend is away from multiple doses of gentamicin
and toward a single injection regimen with additional doses only if needed to control symptoms (“titration therapy”). The risk of hearing loss with gentamicin using
many current protocols is similar to the natural history of Menière’s disease [24,
110, 135], and a recent meta-analysis found the risk of hearing loss to be clinically
negligible [136]. Gentamicin was found to be superior to dexamethasone for vertigo
control in a randomized controlled trial [137]. In cases when gentamicin is not
effective, it is likely because the medication is not getting into the inner ear [138].
Intratympanic injection of dexamethasone is considered by many to be a reasonable procedure to offer when vertigo is intractable, but the patient still has some
functional hearing. The mechanism for steroid effect on vertigo symptoms is not
currently clear. There is some evidence that Menière’s has an autoimmune component, which the steroids may address. Several studies have reported a benecial
effect of intratympanic injection of dexamethasone in the control of vertigo from
Menière’s disease [139–142]. The risk of hearing loss or other complication from
the steroid injection appears to be minimal. A small randomized trial has shown
complete resolution of vertigo symptoms was achieve in 82% of patients getting
dexamethasone vs. 57% with saline injection [143]. Dexamethasone injections may
need to be repeated every 3 months to maintain free of vertigo symptoms, although
the optimal dosing frequency is variable and unknown. Concentrations used have
varied from 2 to 24mg/mL but 10mg/mL is typical. Sustained release formations
of dexamethasone for Menière’s treatment have been developed [144], but it remains
to be shown if these will be more effective than ordinary dexamethasone.
H. Sakano and B. T. Crane
Endolymphatic Sac Surgery
Surgical decompression of the endolymph for Menière’s was rst described by
Portmann in 1926 [8]. During the more than three quarters of a century that this
technique has been practiced, there have been numerous variations on the concept.
Despite signicant investigation into techniques to decompress the endolymph, the
etiology of endolymphatic hydrops as part of the pathophysiology of Menière’s
disease is still an active area of controversy and debate. Several theories have been
proposed which include release of external compression on the sac, neovascularization of the perisaccular region, allowing passive diffusion of endolymph, and creation of an osmotic gradient out of the sac [145]. However, histologic evidence
reveals that the hydrops is not relieved after shunt placement [17].
Several variations on endolymphatic sac surgery have been described. Simple
decompression, wide decompression that includes the sigmoid sinus [146], cannulating the endolymphatic duct, endolymphatic drainage to the subarachnoid space,
drainage to the mastoid, and removal of the extraosseous portion of the sac [147]
4 Menière’s Disease
https://t.me/medicina_free
have all been advocated. A variety of prostheses have also been proposed from
simple silastic sheets, tubes, and one-way valves designed to allow ow selectively
in either the mastoid or subarachnoid direction.
Thomsen etal. conducted a double-blind, placebo controlled study revealed that
a mastoidectomy alone has the same efcacy as an endolymphatic shunt in a group
of 30 patients with 15 randomly selected for each operation [15]. The efcacy of the
procedure remains controversial with other authors re-examining the Thomsen etal.
data and claiming a signicant result would have been found if a different criteria
for success were employed [148] or if different statistical methods were used [16].
A later randomized prospective trial demonstrated that endolymphatic shunt surgery was no more effective than placing a ventilating tube in the tympanic membrane [149]. A recent systematic review found little evidence to support
endolymphatic sac surgery [150].
81
Vestibular Nerve Section
Several approaches to the vestibular nerve have been described. The earliest
approach was the retrosigmoid, with the rst large series by Walter Dandy in the
1930s [9]. The terms retrosigmoid and suboccipital are now used interchangeably.
The middle fossa approach to the internal auditory canal and superior vestibular
nerve was developed by William House [151] and later modied to include sectioning of the inferior vestibular nerve [152]. A retrolabyrinthine approach has also been
described [153].
Vestibular nerve section has a complete vertigo control rate of about 85–95%
with 80–90% of patients maintaining their preoperative hearing after the procedure
[154–156]. The procedure can also be done via endoscope which may decrease
morbidity [157]. It offers much greater vertigo control rates than endolymphatic
shunt procedures, but is also a more invasive and technically challenging procedure.
It has been reported to have poor long term hearing preservation and has a risk of
complications including facial weakness and cerebrospinal uid leak [158]. A
recent survey found nerve sections are now performed very infrequently by neurotologists [127], perhaps due to the rising popularity of transtympanic therapies
which are effective and less invasive.
Labyrinthectomy
The most destructive procedure for treatment of Menière’s is labyrinthectomy due
to the uniform destruction of hearing and vestibular function. Ideal candidates are
those that have no functional hearing and have failed more conservative treatments
such as gentamicin injection. Despite this morbidity, the procedure has a higher rate
of vertigo control than vestibular neurectomy [158, 159] and thus should be favored
Соседние файлы в папке Библиотека им академика М.И. Перельмана