Hearing loss with semicircular canal fistula in exotoxin A-deficient Pseudomonas otitis media

Sensorineural Hearing Loss in Unilateral Mucosal Type of Chronic Otitis Media

Sensorineural hearing loss is relatively well established in the squamosal chronic otitis media. However, its association with mucosal COM is still debated. The present study aimed at evaluating the prevalence of sensorineural hearing loss in unilateral mucosal COM. The study was conducted at a tertiary care hospital in New Delhi, and 60 patients with unilateral mucosal chronic otitis media were recruited. Pure tone thresholds were ascertained for air and bone conduction in an acoustically treated room and matched against certain patient and disease characteristics. In this study, the combined prevalence of SNHL/Mixed Hearing loss in mucosal COM was found to be 8.3%. A statistically significant association between SNHL/Mixed HL was seen in the 40-50-year age group (p-0.004). Prevalence with a disease duration of more than 10 years was 33% (p-0.019). All the patients who presented with SNHL/Mixed HL had an actively discharging ear. 80% of the patients who presented with SNHL/Mixed HL had large perforations. SNHL/Mixed HL prevalence of 28.6% was found in smokers, compared to 5.7% in non-smokers (p-0.039). The risk of developing SNHL/Mixed HL increased with increasing patients' age, disease duration, and size of the perforation and smokers.

An Organ System-Based Synopsis of Pseudomonas aeruginosa Virulence

Driven in part by its metabolic versatility, high intrinsic antibiotic resistance, and a large repertoire of virulence factors, Pseudomonas aeruginosa is expertly adapted to thrive in a wide variety of environments, and in the process, making it a notorious opportunistic pathogen. Apart from the extensively studied chronic infection in the lungs of people with cystic fibrosis (CF), P. aeruginosa also causes multiple serious infections encompassing essentially all organs of the human body, among others, lung infection in patients with chronic obstructive pulmonary disease, primary ciliary dyskinesia and ventilator-associated pneumonia; bacteremia and sepsis; soft tissue infection in burns, open wounds and postsurgery patients; urinary tract infection; diabetic foot ulcers; chronic suppurative otitis media and otitis externa; and keratitis associated with extended contact lens use. Although well characterized in the context of CF, pathogenic processes mediated by various P. aeruginosa virulence factors in other organ systems remain poorly understood. In this review, we use an organ system-based approach to provide a synopsis of disease mechanisms exerted by P. aeruginosa virulence determinants that contribute to its success as a versatile pathogen.

Preoperative antibiotic and steroid therapy and hearing loss caused by semicircular canal transection in pseudomonas otitis media

OBJECTIVE: The purpose of this experiment was to determine whether preoperative administration of antibiotics and corticosteroids can attenuate the severity of hearing loss (HL) with semicircular canal (SC) transection in a guinea pig model of Pseudomonas aeruginosa (PA) otitis media (OM).

STUDY DESIGN AND SETTING: Prospective and controlled.

METHODS: OM was induced in 64 pigmented guinea pigs by bilateral, transtympanic injection of PA. Two to 4 days later, 1 horizontal SC was randomly transected. In the 1st series, antibiotic therapy was initiated either immediately before or after surgery. In the 2nd series, all animals received preoperative antibiotics, and half received dexamethasone before surgery. Hearing was tested before and after surgery.

RESULTS: PA was recovered in all ears. SC transection was associated with significant HL. HL was better in animals given antibiotics preoperatively (clicks, 16 versus 32 dB, P = 0.0220). Addition of preoperative steroids did not significantly further reduce HL (7 versus 14 dB for clicks, P = 0.6919).

CONCLUSIONS: HL caused by SC transection in PA OM may be attenuated with preoperative antibiotic therapy in the guinea pig.

Hearing loss and extent of labyrinthine injury in Pseudomonas otitis media

OBJECTIVES:

To determine if the severity of hearing loss due to semicircular canal transection (SCT) in Pseudomonas otitis media (POM) is a function of the extent of the labyrinthine injury.

METHODS:

POM was induced bilaterally in 45 guinea pigs. After 2 to 4 days, SCT was performed in one 1 on the horizontal canal, the superior canal, or both the horizontal and the superior canals. Auditory-evoked brainstem responses were measured before and after SCT.

RESULTS:

POM was induced bilaterally in all animals. Elevation of click thresholds was found in almost all SCT ears of all 3 groups; however, there were no significant differences between groups. Comparing the SCT ear to the contralateral, control ear, mean hearing losses in the horizontal, superior, and horizontal + superior SCT groups were 23 dB, 27 dB, and 24 dB, respectively.

CONCLUSIONS

Hearing loss does not correlate with extent of labyrinthine injury in POM in the guinea pig. EBM rating: B-2.

BDNF as otoprotectant in toxin-induced hearing loss

CONCLUSION

Brain-derived neurotrophic factor (BDNF) can prevent auditory brainstem response (ABR) threshold shift changes caused by Pseudomonas aeruginosa exotoxin A (PaExoA).

OBJECTIVE

Peptides of the neurotrophin family are known to prevent neuronal death during embryonic development by interacting with specific membrane receptors. The purpose of this study was to investigate whether a single dose of BDNF is an effective protectant against toxic effects of PaExoA-induced ABR threshold shifts.

MATERIALS AND METHODS

Eight groups of Sprague-Dawley rats were used. There were five control groups (n = 20) as follows. Group A (n = 4) received NaCl solution; group B (n = 3) received 4 µg BDNF; group C (n = 4) received 1 μg/20 μl PaExoA; group D (n = 4) received 2 μg/20 μl PaExoA; group E (n = 5) received 10 µg/20 µl PaExoA injected into the round window niche. Three treatment groups (n = 13) received a single dose of PaExoA and 4 µg of BDNF simultaneously. Group 1 (n = 3) received 1 μg/20 μl PaExoA + 4 µg of BDNF; group 2 (n = 5) received 2 μg/20 μl PaExoA + 4 µg BDNF; group 3 (n = 5) received 10 μg/20 μl PaExoA + 4 µg BDNF. ABR was used to measure efficacy by analyzing threshold shifts before and after injections.

RESULTS

A single dose of BDNF prevented changes in ABR thresholds following exposure to increasing concentrations of PaExoA injected into the middle ear.

Predictors for sensorineural hearing loss in patients with tubotympanic otitis, cholesteatoma, and tympanic membrane retractions

OBJECTIVE

To determine predicting value of otitis type, age, gender, ear suppuration, disease duration, mucosal changes, cholesteatoma spreading, labyrinthine fistula, size, localization of tympanic membrane perforation, type and stage of its retraction and ossicular chain disruption with sensorineural hearing loss in patients with tubotympanic otitis, cholesteatoma, and tympanic membrane retractions.

STUDY DESIGN

Retrospective case review study.

SETTING

Tertiary referral center.

PATIENTS

Approximately 264 adult patients with unilateral chronic ear disease, 60 adult patients with tympanic membrane retractions, 78 with cholesteatoma, and 126 with tubotympanic otitis.

INTERVENTIONS

Otomicroscopy, pure tone audiometry, impedancemetry were carried out preoperatively. Wall up, wall down tympanoplasty, or two-stage surgery was applied depending on pathology.

MAIN OUTCOME MEASURE

Bone conduction thresholds for 512 to 4,096 Hz.

RESULTS

Mean values of bone conduction thresholds for frequencies 512 to 4,096 Hz were significantly higher in otitis groups than in healthy ears (p = 0.000), without differences between the groups. Ossicular disruption correlated with sensorineural hearing loss in cholesteatoma and tubotympanic otitis for all frequencies; long incus process destruction in tubotympanic ears showed strong negative correlation with sensorineural hearing loss for 512 to 2,048 Hz (linear regression coefficient, intercept was -2.84, -2.48, and -2.41; p = 0.0024, 0.0207, and 0.0076, respectively). Perforation size correlated with sensorineural hearing loss for 512 to 2,048 Hz in tubotympanic otitis (Log regression p = 0.0008, 0.0252, and 0.0267; odds ratio, 1.13, 1.11, and 1.06). Atelectasis correlated with sensorineural hearing loss for 4,096 Hz (p = 0.022).

CONCLUSION

Predictors for sensorineural hearing loss in chronic otitis are otitis itself, age, ossicular disruption, especially of long incus process, extensive labyrinthine fistula, perforation size, and type of retraction.

Mitigation of hearing loss from semi-circular canal transection in pseudomonas otitis media with ciprofloxacin-dexamethasone irrigation

HYPOTHESIS

Irrigation of the mastoid with a quinolone antibiotic-steroid solution may mitigate hearing loss caused by iatrogenic semicircular canal injury in the presence of Pseudomonas aeruginosa (PA) otitis media (OM).

BACKGROUND

Studies have shown the cochlea to be more vulnerable to semicircular canal transection (SCT)-related hearing loss in the presence of PA OM. Prophylactic systemic antibiotics and steroids may decrease this hearing loss, but SCT is usually not planned. The aim of this study was to determine if irrigation with ciprofloxacin-dexamethasone (cipro-dex) could improve hearing outcomes following SCT in PA OM.

METHODS

PA OM was induced in 28 animals. After three to five days, unilateral SCT was performed in each animal, with sham SCT on the contralateral ear. At surgery, half of the animals (n = 14) underwent irrigation of the both mastoid bullae with cipro-dex; the second group of animals (n = 14) underwent irrigation of the bullae with sterile saline. Auditory thresholds were obtained immediately prior to SCT and 7-10 days after SCT.

RESULTS

SCT ears treated with cipro-dex showed a mean click threshold improvement of 4.6 dB from pre-transection to 7-10 days post-transection, whereas thresholds in the SCT ears treated with saline worsened by 7.5 dB (p = 0.15).

CONCLUSION

Irrigation of the guinea pig bulla with cipro-dex following SCT in the setting of PA OM appears safe and may yield beneficial effects on hearing.