Experimental study of transient cochlear ischemia as a cause of sudden deafness

The etiology of sudden deafness or idiopathic sudden sensorineural hearing loss (ISSHL) remains unclear. Over the past 15 years, we have investigated the mechanisms of ischemic-induced hearing loss using a gerbil model of transient cochlear ischemia. In the gerbil, cochlear ischemia can be induced by occluding the bilateral vertebral arteries simultaneously at the neck, because the posterior communicating arteries of the Circle of Willis close spontaneously around 1 mo after birth. When 15 min ischemia was loaded on this animal, permanent hearing loss of about 25 dB and the death of hair cells, especially inner hair cells were induced. These pathological changes were mainly due to lack of an energy source, glutamate excitotoxicity, and the production of free radicals, especially superoxide and nitrous oxide species. Ischemic damage could be prevented by various procedures, such as cooling the cochlea, intratympanic administration of insulin-like growth factor 1 or AM-111 (an anti-apoptotic agent), and systemic administration of prednisolone (steroid), edarabone (free radical scavenger), ginsenoside Rb1 (Kanpo), hematopoietic stem cells, glia-cell derived neurotrophic factor, and liposome-encapsulated hemoglobin (artificial red blood cells). We also found that the cochlea was protected by the ischemic tolerance, indicating that minor cochlear ischemia alleviates or prevents inner ear damage in subsequent severe cochlear ischemia. As ISSHL usually occurs suddenly, with no preceding sign or symptom, we suggest that most ISSHL cases are caused by circulatory disturbance, probably at the stria vascularis.

Elective regional lymphadenectomy for advanced auricular squamous cell carcinoma

AIM: To investigate the rate of occult lymph node disease in elective parotidectomy and neck dissection specimens in patients with advanced auricular cutaneous squamous cell carcinoma (cSCC).

METHODS: At a single institution, from 2000 to 2010, 17 patients with advanced auricular cSCC were considered high risk for occult regional parotid and/or neck nodal metastases and, thus, underwent an auriculectomy and elective regional lymphadenectomy (parotidectomy and/or neck dissection). Indications for elective regional lymphadenectomy were large tumor size, locally invasive tumors, post-surgical and post-radiation recurrence, and being an immunosuppressed patient. We determined the presence of microscopic disease in the regional (parotid and neck dissection) pathology specimens.

RESULTS: There were 17 advanced auricular cSCC patients analyzed for this study. Fifteen (88%) patients were men. The average age was 69 (range: 33 to 86). Ten (59%) patients presented with post-surgical recurrence. Five (29%) patients presented with post-radiation recurrence. Four (24%) patients presented with both post-surgical and post-radiation recurrence. Four (24%) patients were immunosuppressed (2 (12%) were liver transplant patients, 2 (12%) were chronic lymphocytic leukemia patients, and 1 (6%) was both). The subsite distribution of cSCC included helix (3, 18%), antihelix (2, 12%), conchal bowl (7, 41%), tragus (2, 12%), and postauricular sulcus (3, 18%). Four (24%) patients presented with multifocal auricular cSCC. No patients had bilateral disease. All patients were confirmed to have cSCC on final pathology. The tumors were well (5, 29%), moderately (10, 59%), and poorly (2, 12%) differentiated SCC. The average size of the cSCC tumor was 2.9 cm (range: 1.7 to 7 cm). Twelve (70%) tumors were greater than 2 cm. Six (35%) patients underwent partial auriculectomy. Eleven (65%) patients underwent total auriculectomy. Eight (47%) patients underwent elective parotidectomy and elective neck dissections; 3 (18%) underwent only elective parotidectomy; 3 (18%) underwent only an elective neck dissection; 2 (12%) underwent an elective parotidectomy and therapeutic neck dissection; and 1 (6%) underwent a therapeutic parotidectomy and an elective neck dissection. None of the elective parotidectomy or neck dissection specimens were found to contain any malignant disease. All therapeutic parotidectomy and neck dissection specimens contained metastatic SCC. Fourteen (82%) underwent parotidectomy. Of these, 10 (71%) underwent superficial parotidectomy whereas 4 (29%) underwent total parotidectomy. Fourteen (82%) underwent neck dissections [levels II/Va (1, 7%), levels II/III/Va (2, 14%), levels I/II/III/Va (2, 14%), and complete levels I-V (9, 64%)]. Three (18%) underwent concurrent temporal bone resections for tumor extension from the auricle. The average follow-up for our patients was 44 mo (range: 4 to 123 mo). At the time of the review, 6 (35%) patients were alive and 11 (65%) had passed away.

CONCLUSION: This study suggests that, in patients with advanced auricular cutaneous SCC, elective regional lymphadenectomy is not necessary. However, furtherprospective studies are necessary to assess the necessity.

Endolymphatic hydrops in Meniere’s disease secondary to otitis media and visualized by gadolinium-enhanced magnetic resonance imaging

Aimed to test the hypothesis that endolymphatic hydrops in Meniere’s disease (MD) may be secondary to otitis media, history of a patient who developed MD as a complication of otitis media was reviewed. The inner ear was imaged using a 3.0 Tesla MR system post-intravenous injection of gadolinium-tetraazacyclododecane-tetraacetic acid (Gd-DOTA) in a standard single dosage (0.1 mmol/kg). Both t2-spc-rst-tra-iso (T2-weighted) and heavily T2-weighted 3-dimensional fluid-attenuated inversion recovery magnetic resonance imaging [hT(2)W-3D-FLAIR] sequences were applied. As a result, in the T2-weighted images, the perilymph and endolymph, cerebrospinal fluid surrounding the eighth nerve (N8), and middle ear granulation tissue showed intense signals. In the hT(2)W-3D-FLAIR images, evident enhancement by Gd-DOTA was observed in the middle ear cavity and the perilymphatic compartments of the cochlea. Cochlear endolymphatic hydrops was implicated by the enlarged scala media in the basal turn. In general, the Gd-DOTA uptake in the vestibule was weak, and signs of vestibular endolymphatic hydrops were obvious. The N8 on the diseased side was also significantly enhanced. To conclude, endolymphatic hydrops in MD may be induced by otitis media. Cochlear endolymphatic hydrops in MD secondary to otitis media may not follow the classical pattern.

Antimicrobial potential of Terminalia chebula Retz. fruit extracts against ear pathogens

AIM: To evaluate the antimicrobial potential of Terminalia chebula (T. chebula) extracts against pathogens causing otitis externa and compare it with ear drops.

METHODS: Four different extracts, methanol, ethanol, acetone and aqueous (hot and cold) extracts, from the T. chebula were tested for their antimicrobial activity through the agar well diffusion method and minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) values were determined through the macrodilution broth method against six different microorganism, five bacterial (one gram positive and four gram negative) and one yeast.

RESULTS: Organic and aqueous fruit extracts displayed activity against all five tested bacterial ear pathogens with a maximum zone of inhibition of 31.6 mm against Staphylococcus aureus, followed by Acinetobacter sp. (24.6 mm), Pseudomonas aeruginosa (23.6 mm), Proteus mirabilis (21 mm) and Escherichia coli (19.3 mm). Of the four solvents evaluated, acetonic fruit extract of T. chebula was found to be best. The MIC values ranged between 0.78 mg/mL and 50 mg/mL for the different bacterial ear pathogens and MBC values ranged between 1.56 mg/mL and 50 mg/mL. The acetonic fruit extract showed larger inhibition zones compared to the herbal ear drops, Kan pip with lowest MIC of 0.78 mg/mL and MBC of 1.56 mg/mL.

CONCLUSION: Acetonic extract of T. chebula fruit may be used to treat otitis externa. However, more detailed studies, such as in vivo testing and pharmacokinetics properties, are needed to determine its therapeutic potential.

Effects of p27Kip1- and p53- shRNAs on kanamycin damaged mouse cochlea

AIM: To study the effects of adeno-associated virus (AAV) delivered short hairpin RNAs (shRNAs) on adult CD-1 mouse cochlea damaged by aminoglycoside antibiotic kanamycin.

METHODS: Three different shRNAs were designed (p27 ^Kip1, p53 and p27 ^Kip1+p53) and tested in COS cells. A total of 20 adult CD-1 mice were used in the experiment. Mice were divided into five different groups (four animals/group) depending on the AAV-shRNA construct they received and whether they received kanamycin or not. Saline and AAV-EGFP injected animals were used as controls. All constructs were injected through the round window membrane (RWM) into the cochlea. Cochleae were harvested after 1 mo. Apoptosis was detected with Tunel labeling from paraffin-embedded cochlear tissue sections.

RESULTS: AAV2/2-p27 ^Kip1-shRNA and AAV2/2-p53-shRNA were tested in COS cells. Western blotting analysis confirmed that both constructs silenced their target genes effectively in the cell culture. AAV2/2-shRNA constructs were injected into the cochlea of CD-1 mice through the intact RWM. Cotransduction of individual AAV2/2-shRNAs with AAV2/2-EGFP resulted in EGFP expression in the organ of Corti. Kanamycin treatment had no effect on the expression pattern of the EGFP. AAV2/2-shRNA treated mice (either with p53 or p27^Kip1and p53 together) showed fewer apoptotic hair cells in the cochlea than the control group (P < 0.05; AAV2/2-p53-shRNA vs saline P = 0.00014; AAV2/2-p27+p53-shRNA vs saline P = 0.0011). AAV2/2-p27-shRNA injected cochleae showed no significant difference in the number of apoptotic cells when compared to the saline injected cochleae.

CONCLUSION: Silencing of p53 protein in the kanamycin treated ears may decrease cell death in the organ of Corti.

What is the purpose of launching the World Journal of Otorhinolaryngology?

We are pleased to announce the launching of the World Journal of Otorhinolaryngology (WJO) as a new member of the World Series journal family. The WJO is a peer-reviewed open-access journal dedicated to publishing original research articles, review articles, clinical studies, and case reports in all areas of otorhinolaryngology. Please consider submitting your research findings in otorhinolaryngology to the WJO.