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 d B 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, indi-cating 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.

Survival in Primary Carcinoma of the External and Middle Ear Is Strongly Dependent on Stage at Diagnosi

Conclusion: Early-stage detection of temporal bone carcinoma improves the survival rate. When detected at an advanced stage, predicted prognosis is poor even with a combination of surgery, radiotherapy and chemotherapy. Objectives: We evaluated treatment strategies and survival rates in cases of carcinomas of the external and middle ear. Method: Retrospective review of patients treated at Ehime University Hospital during the 32 years from 1977 to 2008. Subjects were 41 patients, consisting of 21 men and 20 women with a mean age of 63.2 years. Modified Pittsburgh staging system: stage I in 11 cases (27%), stage II in 4 (10%), stage III in 6 (15%) and stage IV in 20 (49%). Histopathology: squamous cell carcinoma (SCC) in 35 cases, adenoid cystic carcinoma (ACC) in 3, and adenocarcinoma (AC) in 3. Thirty-eight patients were treated by surgery. Radiation was added postoperatively in 23 patients. Three patients were treated by chemoradiotherapy. Results: The survival rate of carcinomas detected at an advanced stage was poor with a disease-specific 5-year survival rate of 100% in early-stage disease (stage I and II) versus 20.8% in stage III and 27.5% in stage IV disease, irrespective of histopathology of the tumor.