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Presented at the Illinois Academy of
Audiology Meeting
January 24, 2002
Chicago, Illinois
Correspondence:
Sam J. Marzo, M.D.
Assistant Professor
Department of Otolaryngology B Head and Neck Surgery
Loyola University
Introduction:
The purpose of this paper is to familiarize audiologists
with issues related to vertigo and sensorineural hearing
loss, and the potential role of intratympanic therapy in
treating specific disorders.
The theory behind intratympanic therapy is that by
instilling small amounts (<5 cc) of medication into the
middle ear, absorption into the inner ear occurs though the
round window. The medicine exerts its effect on the
ipsilateral cochlear and vestibular end organs.
The benefits of this therapy include; minimal to no systemic
side effects, predictable results, and the ability to treat
the patients in the clinic or outpatient setting.
Differential Diagnosis of Vertigo:
Dizziness and vertigo are common disorders. Dizziness can be
defined as a sensation of being off balance. Vertigo is more
specific and refers to a sensation of movement (usually
spinning) of the individual or their surrounding. Dizziness
can be secondary to neurological, cardiac, metabolic,
psychiatric, vestibular, or other disorders.
Vertigo is usually secondary to dysfunction of the
peripheral vestibular system, which includes five paired
organs - the horizontal, superior, and posterior
semicircular canals - which sense angular acceleration, and
the utricle and saccule - which sense horizontal and
vertical acceleration, respectively.
Assorted Dizziness Statistics:
1) Dizziness is the most common reasons for a physician
visit in patients over age 65 years.
2) Thirty percent of the population will experience vertigo
by the age of 65
3) Ninety million Americans will experience dizziness or
vertigo during their lives.
Benign Positional Paroxysmal Vertigo (BPPV):
The most common cause of vertigo is Benign Positional
Paroxysmal Vertigo (BPPV). This is characterized by a
sensation of spinning lasting only several seconds that
occurs with quick movements of the head such as rolling over
in bed, looking up, or looking down. BPPV is believed to
occur secondary to free floating otoconia (calcium carbonate
crystals normally within the utricle and saccule) that break
loose (spontaneously, or through trauma) and attach to, or
cause stimulation of, the posterior semicircular canal with
movement of the head. Many cases resolve spontaneously while
others are treated with various particle - repositioning
maneuvers.
Vestibular Neuronitis (VN):
The second most common cause of vertigo is Vestibular
Neuronitis (VN). This is characterized by the acute onset of
vertigo sometimes associated with nausea, and vomiting
lasting hours or even days. There can be hearing loss also,
in which case the condition is termed "labyrinthitis." The
vertigo usually dissipates over several days, and imbalance
can then persist for several weeks or months as recovery
ensues. VN is believed to be secondary to a viral
inflammation of the peripheral vestibular system. In half of
all cases, there has been a recent upper respiratory
infection. The disease is usually self-limiting.
Meniere’s Disease (MD):
The third most common cause of vertigo is Meniere’s Disease
(MD). Meniere’s disease is characterized by recurring
attacks of vertigo lasting approximately thirty minutes.
Meniere’s Disease is associated with unilateral hearing
fluctuation, aural pressure, and tinnitus. In 30% of cases,
Meniere’s disease is bilateral. Roughly 80% of patients with
Meniere’s disease do well with medical therapy. Medical
therapy includes a low salt diet (less than 2000 milligrams
of sodium/day), a potassium-sparing diuretic, and sometimes
vestibular suppressants. The other 20% of patients with
refractory vertigo secondary to Meniere’s disease can likely
benefit from surgical therapy.
It is well know that certain aminoglycoside antibiotics are
"ototoxic", toxic to the cochlear and vestibular systems.
Intramuscular streptomycin was found to be effective in
relieving vertigo for some patients with bilateral Meniere’s
disease. Although many patients receiving intramuscular
streptomycin had relief of vertigo, some patients developed
vestibular toxicity. The vestibular toxicity manifested as
oscillopsia (defined as the vertical movement of the horizon
when walking), ataxia, and imbalance in dark spaces (i.e.,
when visual information available was limited or
non-existent) or when navigating uneven terrain. To decrease
these systemic side effects, streptomycin (and later
gentamicin) was administered to the inner ear via a
transtympanic approach with promising results.
With the success of intratympanic gentamicin therapy for
Meniere’s disease, steroid therapy was later introduced.
Intratympanic steroids were later applied favorably to
patients with sudden sensorineural hearing loss (1). Since
then, several administration systems have been developed
(2). Intratympanic therapy has its origins in the medical
treatment of Meniere’s disease.
Perilymphatic Fistula (PLF):
The fourth most common cause of vertigo is Perilymphatic
Fistula (PLF). In this disorder, a leakage of perilymph can
occur through the round or oval window resulting in hearing
loss and vertigo. There can also be tinnitus and ear
pressure. Unlike MD, many patients with PLF will have
exacerbation of their symptoms with straining or exercise.
Most cases of PLF begin after trauma or after ear surgery,
with stapedectomy being most common. Spontaneous improvement
can occur, but many cases are managed by repairing and
patching the round or oval windows with surgery. Some cases
of PLF can go on to develop MD.
Miscellaneous:
Other causes of vertigo and imbalance are acute and chronic
otitis media, cholesteatoma, acoustic neuroma, migraine,
intracranial pathology and others. Correctly diagnosing the
various causes of vertigo is important, because serious,
potentially life – threatening diseases such as acoustic
neuroma, and cerebral vascular disease can exist. In many
cases of vertigo and imbalance, further testing and magnetic
resonance imaging are necessary to reach the correct
diagnosis.
Applications of intratympanic therapy for vertigo:
Intratympanic gentamicin therapy (ITGM) is an accepted
treatment for medically refractory MD. The author has used
this therapy with excellent vertigo control rates for
patients with new-onset MD, previously treated MD, or MD
that has recurred despite prior surgical therapy (3). The
author has also used intratympanic therapy to successfully
treat vertigo after perilymphatic fistula repair. Between
July 1997 and February 2002, 44 patients with medically
refractory vertigo were treated with ITGM, with a success
rate of 95%, and an increased rate of sensorineural hearing
loss of less than 5% (unpublished data).
ITGM Protocol:
The author’s needle puncture technique for delivering ITGM
is as follows: A history, physical examination, appropriate
imaging studies, baseline audiogram and
electronystagmography are obtained. The patient must have
refractory vertigo in one ear despite medical treatment.
The patient is placed in a recumbent position with the
treated ear upwards. The tympanic membrane is anesthetized
with topical lidocaine/prilocaine cream (EMLA cream) for 10
to 15 minutes. This cream is suctioned and the middle ear is
filled with 1 cc of buffered gentamicin solution, introduced
through the tympanic membrane via a 25 gauge spinal needle
on a 1-cc syringe. The patient is asked to avoid swallowing
and kept supine for 30 minutes. At the end of this time, any
remaining solution is suctioned from the ear canal and the
patient is sent home.
A follow-up appointment is scheduled in one month. If there
is persistent vertigo at that time, another treatment is
administered. The endpoint for treatment is control of
vertigo. At times it might be necessary to delay injections
due to hearing loss or ataxia.
ITGM provides a selective chemical ablation of the
ipsilateral vestibular end organ. Gentamicin is believed to
work via decreasing production of endolymph, or via a direct
toxic effect on type I vestibular hair cells (4). In
general, gentamicin exerts its effect in a delayed fashion,
beginning in three to five days. It is not clearly evident
the duration of time over which the medication works, but
the author believes the final result of an injection might
be evidenced in three to four weeks. Most patients require
1-2 injections. All methods of ITGM have an excellent
success rate, with vertigo control approaching approximately
85% (2).
In summary, ITGM therapy for vertigo has an excellent
vertigo control rate, can be administered in a clinic
setting, and has few side effects.
Differential diagnosis of sensorineural hearing loss:
Sensorineural hearing loss (SNHL) has many causes. It is
important to determine if the hearing loss is congenital,
hereditary, sudden, chronic, or progressive. Presbycusis and
noise exposure usually cause slow, progressive SNHL. Viral
or bacterial infections, blunt and surgical trauma may
precipitate sudden SNHL. Ototoxic medications may also cause
sudden SNHL, but a slowly progressive hearing loss,
secondary to ototoxic medications is possible too. Acoustic
neuroma usually causes a slow progressive hearing loss with
tinnitus and sometimes imbalance. When the etiology of SNHL
cannot be determined, the term "idiopathic" has been used.
Treatment of Sudden, Idiopathic SNHL:
There is evidence that idiopathic SNHL is secondary to
inflammation within the cochlear system, possibly secondary
to viral infection. Steroids have known anti-inflammatory
properties and have been advocated for treatment of sudden
SNHL.
Moskowitz et al (5) treated 36 patients with idiopathic
sudden sensorineural hearing loss with dexamethasone (an
anti-inflammatory synthetic gluco-corticoid, within the
family of steroids) and found that using this medication
resulted in hearing improvement.
Other studies have also found steroids to be beneficial (6).
Most studies advocate doses of steroid equivalent to 1
mg/kg/day of prednisone (an anti-inflammatory, synthetic
gluco-corticoid) tapering over 10 to 14 days. However, in
some cases there is no recovery (7).
Parnes has shown hearing improvement in various cases of
sudden SNHL using intratympanic dexamethasone (1). However,
many patients in his study required repeated injections
(ranging from 2 to 29), with a mean of 6 injections per
patient.
This author has used intratympanic dexamethasone delivered
via a needle puncture technique and has found patients tire
of coming back every 3-4 days for injections. Additionally,
the success rate has been poor.
Many variables are unknown regarding treating patients with
refractory sudden SNHL. One of the primary questions is,
should the cochlea receive bolus injections of steroids via
a transtympanic approach or should a steady dose of steroids
be administered over one to two weeks? Clearly a
double-blind study would be the best way to resolve this
issue, but this is a difficult protocol to embark upon
clinically, and it has not yet been accomplished.
The FDA recently approved a specially designed round window
catheter (Durect Corporation, Cupertino, CA) which has
application for sudden SNHL and MD (see Figure 1). The
catheter can be inserted into the round window via a
transcanal approach under local anesthesia. The catheter is
subsequently connected to a portable "pump" that the patient
wears for the next two weeks. The pump delivers a constant
dosage of medicine to the round window and the inner ear.
After insertion, this system is maintenance free, painless,
and can be removed in the clinic. The individual can
continue working.
Kopke et al (8) recently treated six patients with sudden
unilateral severe to profound SNHL refractory to oral
steroid therapy with the round window catheter and
methylprednisolone. All patients were treated within six
weeks of onset of hearing loss. Four out of six patients
improved to baseline hearing and five out of six had
improved speech discrimination. Certainly these results are
very encouraging.
The author has treated two patients with the round window
catheter with favorable results. Some authors have used this
protocol to treat tinnitus. Clearly, this application of
intratympanic therapy appears encouraging.
Conclusion:
In conclusion, intratympanic therapy potentially has
vast and varied application in the treatment of patients
with inner ear disorders. Clearly this therapy is in its
infancy, but preliminary results have been very encouraging.
All hearing health care professionals should be aware that
this therapy could have application for their patients with
hearing loss, vertigo, and possibly tinnitus.
References
1) Parnes L, et al. Corticosteroid pharmacokinetics in the
inner ear fluids: an animal study followed by clinical
application. Laryngoscope 1999;109 Suppl:1-17.
2) Silverstein H. Use of a new device, the microwick, to
deliver medication to the inner ear. ENT Journ
1999;78:595-600.
3) Marzo S, et al. Intratympanic therapy for persistent
vertigo after endolymphatic sac surgery. Otolaryngol Head
Neck Surg 2002;126:31-33.
4) Yamazaki T, et al. Intratympanic gentamicin therapy for
Meniere’s disease placed by tubal catheter with systemic
isosorbide. Arch Otorhinolaryngol 1988;245:170-174.
5) Moskowitz D, et al. Steroid use in idiopathic sudden
sensorineural hearing loss. Laryngoscope
1984:94:664-666.
6) Wilson W, et al. The efficacy of steroids in treatment of
idiopathic sudden hearing loss. Arch Otolaryngol
1980;106:772-776.
7) Wilkins S, et al. Evaluation of a "shot-gun" regimen for
sudden sensorineural hearing loss. Otolaryngol Head Neck
Surg 1987;97:474-480.
8) Kopke et al. Targeted topical steroid therapy in sudden
sensorineural hearing loss. Otol Neurotol
2001;22:475-479.
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