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
2160 South First Avenue
Maywood, Illinois 60153
Phone: 708-216-1676
Fax: 708-216-4834
Email: smarzo@luc.edu
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 (
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.
