Intratympanic steroid treatment: a review.Sudden sensorineural hearing loss SSHL is defined as a hearing loss of 30 dB or more, affecting at least 3 consecutive frequencies, occurring within 3 days without any identifiable cause. It is relatively common disease, affecting 5 to 20 perpersons per intratympanic steroid treatment a review. The cause, pathophysiology, and management of SSHL are still not known. On the treaatment, Cinamon, et al. Systemic steroid has many side effects:
Intratympanic steroid treatment: a review. - PubMed - NCBI
Sudden sensorineural hearing loss SSHL is defined as a hearing loss of 30 dB or more, affecting at least 3 consecutive frequencies, occurring within 3 days without any identifiable cause.
It is relatively common disease, affecting 5 to 20 per , persons per year. The cause, pathophysiology, and management of SSHL are still not known. On the contrary, Cinamon, et al. Systemic steroid has many side effects: The use of systemic steroid is contraindicated in patients with peptic ulcer, glaucoma, diabetes, tuberculosis, and those are pregnant.
Intratympanic administration delivers medication into the inner ear through round window membrane. In , Silverstein, et al. Since there had been no treatment option for the cases that are refractory to systemic steroid, the idea of topical administration of steroid via transtympanic route ignites numerous clinical trials for refractory cases and animal studies regarding the pharmacokinetics of steroid in the inner ear.
An online search for the PubMed databases using the following terms "sudden hearing loss, intratympanic steroid" resulted in 81 listings.
After excluding animal studies and review articles, we found 47 publications concerning clinical evaluation of the efficacy of intratympanic steroid injection ITS in SSHL patients since Table 1. Among these, 15 articles have been published in , showing an otologist's high interest on this subject in recent period. Many advantages of this procedure explains the enthusiasm for ITS. It can be done under local anesthesia at the office setting with relatively low cost, exerts its effect only at the affected ear, and bypasses systemic side effects of steroid.
The technique is minimally invasive, easily to perform, and well tolerated by patients. Furthermore, through the animal study, it was proven that the perilymphatic concentration of corticosteroid is much higher when the medications were administered through a transtympanic route compared with systemic administration.
Thus, the optimum protocols including the time to start ITS, types and doses of steroid, and administration method are still in controversial. Here, we conducted a literature review regarding published researches on ITS to date to provide update information of this valuable treatment tool for SSHL. Mechanism of Action Intratympanically injected steroid enters the scala tympani through the round window membrane, while most of them is lost through the eustachian tube to the pharynx.
Round window membrane is a semi-permeable membrane with outer squamous epithelial layer faces middle ear cavity and inner mesothelial layer continuous with the lining of the scala tympani. Thus, the round window membrane provides little barrier to the movement of most drugs or other molecules into the inner ear.
In humans, mucosal membranous veils often cover the RWM and may inhibit diffusion by adding an extra barrier. Numerous cochlear insults induces cochlear inflammatory processes via pro-inflammatory cytokines and chemokines and production of reactive oxygen species nitric oxide, etc.
Glucocorticoids also have a significant binding affinity for the mineralocorticoid receptor and affect ion homeostasis in the inner ear.
Methods of Administration Most authors favor simple intratympanic injection under local or topical anesthesia at office setting. The patients were positioned supine position with the head turned to the healthy side. All the procedure is performed under the microscopic view.
An air vent is made before the injection at anterosuperior portion of tympanic membrane with myringotomy knife. Steroid solution is injected at the uppermost portion of tympanic membrane in supine position using 1 mL tuberculin syringe with fine needle gauge spinal needle. Patients remains with the treated ear upwards for min, and were instructed to refrain from swallowing. A recent study 20 showed that absolute and relative drug levels in the perilymph were highly dependent on how long the drug remained in the middle ear.
Therefore, it is reasonable that the physician should insure that there is enough medicine in the middle ear. The protocol of steroid injection into middle ear differed in many aspects, including the technique of delivery, the duration of remaining in supine position after injection, the number and amount of injections, and the type of steroid used. Until now, there is no general consensus on these aspects. Reviewing clinical studies on ITS, we found total of 47 articles since Table 1 were found.
Thirty-six studies used simple intratympanic injection as a route of steroid administration, 3 studies injected steroid through ventilation tube, and 1 study injected steroid through laser assisted myringotomy. Considering the studies using simple intratympanic injection, total number of injection ranges from single shot up to 15 times of injections, while total of 4 times is most commonly used by authors 14 of 36 simple intratympanic injection studies.
The Type of Steroid Used: Methylprednisolone Parnes, et al. Of the tested drugs, methylprednisolone achieved the highest concentration for the longest duration in both endolymph and perilymph.
But on clinical application some patients complain a burning sensation after injecting methylprednisolone into middle ear due to its acidic property. To relieve these complaints, some authors give methylprednisone together with lidocaine, or buffered it with sodium bicarbonate to lessen acidity.
Recent meta-analysis report showed there was no apparent difference in the efficacy of dexamethasone relative to methylprednisolone. A direct comparison of these medications has not been done. Hyaluronic Acid Dissolving steroids in hyaluronic acid, was done in the clinical trials, to prolongs the presence of the drug in the tympanic cavity and facilitate transport across the round window membrane. It is difficult to insert the needle through the tube without touching the tube, hence the patient feels pain without prior anesthesia.
It is also difficult to confirm whether the tip was inside the mesotympanum because of the height of the tube blocks surgeon's view.
Healing of perforation after tube removal is reported to be prolonged with an average of 15 weeks, and it may be due to effect of steroid on the wound healing. The wide diameter of the perforation also allows the air to escape. Moreover, less discomfort is caused. However, the duration until closure is prolonged. These anatomic variations of the round window niche may explain the wide variations in the treatment outcomes found in the clinical setting. Several authors examined the round window niche endoscopically and performed lysis of any adhesions blocking access to the round window membrane.
Patient can self-instill medication through external auditory canal, which is absorbed via the MicroWick into the inner ear. This is a small vinyl catheter connected to a microinfusion pump that is inserted into the round window niche via a posterior tympanotomy under general anesthesia.
Microcatheter is no longer available because the FDA removed it from the market. Salvage therapy Most of the studies used intratympanic steroids as a salvage therapy for SSHL patients who failed the initial systemic therapy. Among the 47 articles that we have reviewed, 29 studies evaluated intratympanic steroid treatment of SSHL as a salvage therapy, and most of the studies showed at least some benefit from ITS treatment: Initial therapy Until now, 14 studies have tried ITS as a sole initial therapy 2 studies for patients with diabetes mellitus , and most studies presented at least some benefit suggesting ITS as initial therapy was equivalent to standard systemic steroid therapy: The only exception is Alimoglu, et al.
Combination therapy It is still unclear if combination therapy is superior to monotherapy. There have been 7 studies which examined the efficacy of ITS combined with systemic steroid therapy. In the 5 studies, the efficacy of combination therapy was not significantly higher than that of systemic steroid therapy. The other studies demonstrated higher hearing response rate in combination group compared to systemic steroid therapy.
Many studies reported better results when initial or salvage treatment was started within 2 weeks from the onset. Because the locally administered steroid penetrates through the round window membrane and spread from the basal turn to the apex. Thus, it is reasonable to expect that more hearing improvement might occur in higher frequencies than in lower frequencies.
The base of the cochlea is more vulnerable to trauma and free radicals than the apex. We can find some evidence of this hypothesis on the fact that hearing loss from noise, ototoxic drugs, or trauma easily occurs in the hightone, basal area of the cochlea. Moreover, outer and inner hair cells in the base of the cochlea develop ultra structural abnormalities more rapidly than those in the apical turns following severe, total cochlear ischemia. The loss of drug solution through eustachian tube is uncontrollable with a simple intratympanic injection technique.
Some patients complain pain even after anesthesia and transient vertigo associated with the injections. There are also very low risks of persistent tympanic membrane perforation, otitis media, otomycosis, mastoiditis, and potential for further hearing loss.
Conclusion Although prosperous studies have been reported in regard of ITS for the treatment of SSHL, it is difficult to draw conclusions from those studies because each studies use different steroid types and doses, treatment protocols, previous treatments, route of administration, and duration from onset of symptoms to treatment and improvement criteria.
Few studies have well designed format. Due to the ethical reasons, it is not possible to use a placebo control group. Although the study settings are varied among reviewed articles, most studies in this review consistently showed some benefit in hearing in salvage cases. In addition, it is suggested that intratympanic steroids are equivalent to systemic steroid therapy as initial treatment for SSHL. In patients with contraindications against the use of systemic steroid, ITS may be considered as valuable therapeutic option.
Further studies are necessary to elucidate the optimal protocol of administration. Sudden sensorineural hearing loss. Otolaryngol Clin North Am ; Natural history of sudden sensorineural hearing loss.
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