Hyaluronic acid hydrogel sustains the delivery of dexamethasone across the round window membrane.

BACKGROUND: The use of intratympanic (IT) steroids for the treatment of inner ear disorders is promising, but the clinical challenges of prolonged middle ear drug application have proven burdensome, and a sustainable delivery system is yet to be developed. METHOD: In this study, a guinea pig model was used to determine if dexamethasone in combination with a hyaluronic-acid (HA)-based hydrogel is an efficient, stable and sustainable dexamethasone delivery system to the inner ear. For each animal, right and left middle ear bullae were randomly selected to be filled with dexamethasone alone or dexamethasone-HA (Dex-HA) gel. Perilymph samples were collected at different time points and dexamethasone levels were determined using an ELISA. RESULTS: Dexamethasone was measurable in the perilymph samples up to 72 h after treatment. At 24 h after treatment, the perilymph dexamethasone concentrations were significantly higher (p = 0.01) in the ears treated with Dex-HA gel than in those treated with dexamethasone alone. While the perilymph dexamethasone concentration had decreased at 48 h after treatment with Dex-HA gel, the levels were still higher than those observed at 24 h in ears treated with dexamethasone alone. A high variability in dexamethasone concentration was observed between the samples, and the variability between matched ears receiving different treatments was remarkably lower than the variability within each treatment group, suggesting that individual parameters might play a major role in perilymph dexamethasone concentration. There was no statistically significant correlation between dexamethasone concentration and sex, weight or laterality. CONCLUSIONS: Our results show that the Dex-HA gel used in this study provides an effective and sustained dexamethasone release mechanism that might be utilized to treat conditions such as sudden sensorineural hearing loss. This could potentially reduce the morbidity and costs associated with IT treatment.

Antibiotic resistance and otomycosis in the draining ear: culture results by diagnosis.

OBJECTIVE: The objective of the study was to better define changes in the bacteriology of suppurative otitis in recent years and the role of cultures in the management of these patients. STUDY DESIGN: A retrospective review was performed. METHODS: Outpatient records from 170 patients collected over 3 years with information regarding the bacteria cultured, antibiotic resistance, and clinical diagnosis were analyzed. RESULTS: A large variety of organisms were seen, with Staphylococcus aureus, Corynebacterium sp, and Pseudomonas aeruginosa being the most common. Forty percent of cultures showed bacteria with moderate antibiotic resistance, whereas 5% were sensitive to only intravenous antibiotics. Resistant bacteria were found in all diagnosis categories and were significantly higher in cases of chronic mastoiditis. The rate of methicillin-resistant S aureus infections was 7.8% and was significantly higher in cases of chronic myringitis. Fungus was often cultured in patients without clinical signs of otomycosis. CONCLUSIONS: Community-acquired ear infections may be caused by antibiotic-resistant bacteria in a substantial number of patients. In our opinion, outpatient cultures play an important role in the management of suppurative otitis.

Laser myringoplasty for tympanic membrane atelectasis.

OBJECTIVE: To review our experience with laser myringoplasty using a potassium-titanyl-phosphate (KTP) laser for pars tensa atelectasis. STUDY DESIGN: Retrospective review. METHODS: A pulsed diode KTP laser (532 nm) was used to tighten the tympanic membrane after lysis of middle ear adhesions through a myringotomy. A tympanostomy tube was then placed. Operative reports and clinic notes were reviewed. RESULTS: We reviewed 34 procedures performed on 31 ears in 29 patients. The average time of follow-up was 10.5 months with a range of 1 to 30 months. Seventeen of 34 tubes (50%) extruded during the follow-up period. Eleven cases had follow-up with the tube extruded and TM intact. Two (18%) of those had progression of atelectasis. Two (6%) cases had operative perforations and both healed spontaneously. CONCLUSION: Laser myringoplasty using a KTP laser for pars tensa atelectasis appears to be beneficial in selected patients. Patients should be followed closely for early tube extrusion and recurrent disease.

Diagnosis and treatment of otitis media.

Diagnostic criteria for acute otitis media include rapid onset of symptoms, middle ear effusion, and signs and symptoms of middle ear inflammation. Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the most common bacterial isolates from the middle ear fluid of children with acute otitis media. Fever, otalgia, headache, irritability, cough, rhinitis, listlessness, anorexia, vomiting, diarrhea, and pulling at the ears are common, but nonspecific symptoms. Detection of middle ear effusion by pneumatic otoscopy is key in establishing the diagnosis. Observation is an acceptable option in healthy children with mild symptoms. Antibiotics are recommended in all children younger than six months, in those between six months and two years if the diagnosis is certain, and in children with severe infection. High-dosage amoxicillin (80 to 90 mg per kg per day) is recommended as first-line therapy. Macrolide antibiotics, clindamycin, and cephalosporins are alternatives in penicillin-sensitive children and in those with resistant infections. Patients who do not respond to treatment should be reassessed. Hearing and language testing is recommended in children with suspected hearing loss or persistent effusion for at least three months, and in those with developmental problems.

Identification and characterization of choline transporter-like protein 2, an inner ear glycoprotein of 68 and 72 kDa that is the target of antibody-induced hearing loss.

The Kresge Hearing Research Institute-3 (KHRI-3) antibody binds to a guinea pig inner ear supporting cell antigen (IESCA) and causes hearing loss. To gain insight into the mechanism of antibody-induced hearing loss, we used antibody immunoaffinity purification to isolate the IESCA, which was then sequenced by mass spectroscopy, revealing 10 guinea pig peptides identical to sequences in human choline transporter-like protein 2 (CTL2). Full-length CTL2 cDNA sequenced from guinea pig inner ear has 85.9% identity with the human cDNA. Consistent with its expression on the surface of supporting cells in the inner ear, CTL2 contains 10 predicted membrane-spanning regions with multiple N-glycosylation sites. The 68 and 72 kDa molecular forms of inner ear CTL2 are distinguished by sialic acid modification of the carbohydrate. The KHRI-3 antibody binds to an N-linked carbohydrate on CTL2 and presumably damages the organ of Corti by blocking the transporter function of this molecule. CTL2 mRNA and protein are abundantly expressed in human inner ear. Sera from patients with autoimmune hearing loss bind to guinea pig inner ear with the same pattern as CTL2 antibodies. Thus, CTL2 is a possible target of autoimmune hearing loss in humans.

Chemical and physical labyrinthectomy for Meniere's disease.

The use of intratympanic gentamicin is currently a popular and easily performed office procedure for the conservative treatment of the Meniere's disease patient who has failed medical therapy or who is not a candidate for surgical therapy. The procedure provides excellent control for the symptom of vertigo. Despite this success, there remains a significant risk of hearing loss irrespective of administered dose. In the future, antioxidant [42,43] or salicylate therapy may prevent aminoglycoside toxicity [44]. These prophylaxis methods have shown promise in the laboratory. Current methods do not allow for accurate drug delivery to the inner ear. Middle ear mucosal status, round window thickness or adhesion, patency of eustachian tube, and the effect of endolymphatic hydrops on ototoxicity are factors simply out of the control of the operator's hands. Judging by the number of recent articles, intratympanic gentamicin instillation will continue to be an area of interest for the otologist. Users should be encouraged to be consistent and conservative in gentamicin dosing. It is clear that vestibular ablation is not necessary for adequate control of vestibular symptoms and that larger doses may increase the risk of hearing loss. American Academy of Otolaryngology-Head and Neck Surgery guidelines [45] should be used and adhered to for reporting on the treatment of Meniere's disease, so that the literature may be more comparable. In the same light, a prospective standardized trial would be helpful in determining ultimate efficacy and risk to the patient. Transmastoid labyrinthectomy remains the surgical standard for extirpating the offending labyrinth when hearing preservation is not an issue. In appropriate patients, the procedure is a safe and effective method for relieving patients of vertiginous attacks. Most patients tolerate the procedure very well and are able to compensate fairly well over the course of several weeks to months.