**6. Choice of drug**

Two corticosteroids are used by the majority of the researchers: dexamethasone and methylprednisolone. The concentration is varied between 4 mg/ ml and 25 mg/ml for dexamethasone and between 32 mg/ ml and 62,5 mg/ml for methylprednisolone.

Parnes in pharmacokinetic animal study compared intracochlear levels of three glucocortiocoids: dexamethasone (Dexa), methylprednisolone (MP), and hydrocortisone

Intratympanic Corticosteroid for Neurosensorial Hearing Loss Treatment 387

given in anticipation of ototoxicity that could be associated with systemic aminoglycoside antibiotic or cisplatinum and other chemotherapeutic agents. They can also be used after

Intratympanic corticosteroids for sudden hearing loss and Meniere's disease has been the subject of retrospective, uncontrolled studies and a few controlled studies with small numbers of subjects. Hamid in 2001 with a single injection of high concentration of Dexamethasone (24mg/ml) for patients with Meniere's disease, was able to get control of vertigo in 90% of cases with an improvement of hearing threshold, the percentage of discrimination and sensation of fullness (29) (26). In his study, 90% of patients had vertigo control, 90% had improved speech discrimination, and 90% had decreased aural pressure. Garduno (30), compared intra tympanic Dexamethasone versus placebo in Meniere disease. He obtained full control of vertigo in 82% of cases against 57% with placebo with significant differences. He also noted a reduction of tinnitus in 48% of cases and hearing improvement

In sudden deafness, Ahn (31) compared two groups: systemic corticosteroids alone versus intratympanic corticosteroids associated with systemic treatment. He found no significant difference in overall response, but noted a significant improvement on the low frequencies in intratympanic treatment group. HONG (32) compared intratympanic corticosteroids alone versus systemic corticosteroids alone also found no difference, but noted a significant improvement over the low frequencies. Alatas (33) concluded that intratympanic dexamethasone is an effective therapy for low frequency hearing loss. Hunchaisri (34) concluded that it may have benefits for patients with sudden sensorineural hearing loss who

In diabetic patients with sudden sensorineural hearing loss, intratympanic corticoid injection is as effective as systemic steroid treatment and it can avoid undesirable side effects (35). Han studied three groups of diabetics and compared prednisolone administered by oral, intravenous and intra tympanic Dexamethasone. He noted a better outcome with intratympanic treatment without significant difference. However, systemic treatment was discontinued in 6 patients due to problems of hyperglycemia. This disadvantage is not

Many studies concluded that using the continuous intratympanic dexamethasone by MicroWick is effective, safe and efficient for treatment of sudden idiopathic sensorineural

There is an increasing number of series evaluating intratympanic (IT) steroids as first line or salvage therapy in ISSHL with some studies presenting control groups and randomized

The effect of intratympanic corticosteroids on tinnitus is difficult to assess due to limited work. Shulman (37) treated tinnitus with intratympanic dexamethasone and obtained

injuries (28).

**9. Results** 

in 35% of cases.

failed systemic steroid therapy.

hearing loss (26) (19).

controlled trials (Table 1).

observed with the intratympanic treatment.

control of tinnitus in 50% cases (for 1 year and over).

(24). When correcting for the lower Dexa concentration (4 mg/mL) compared to MP (40 mg/mL) in their study and for the higher potency, dexamethasone is expected to reach higher effective levels in perilymph after application to the round window membrane. In addition, contrary to Dexa, MP solution is not stable but hydrolyzed after some days in the pump cartridge (19) (25).
