ABSTRACT
BACKGROUND AND OBJECTIVES: Salicylates are well-known for producing reversible hearing loss and tinnitus. However, the site and mechanism of salicylate ototoxicity remain unresolved. Recent experiments suggest that reversible biochemical and/or metabolic changes in the cochlea seem to play an important role in salicylate ototoxicity. The purpose of this study was to investigate the site of lesion in salicylate ototoxicity by audiometric study. MATERIALS AND METHOD: ABRs and DPOAEs were observed after intraperitoneal injection of 500 mg/kg of sodium salicylate on 24 ears of guinea pigs. RESULTS: Salicylate produced a significant increase in the ABR threshold. Maximum changes were obtained in 4 hours, and recovered to the baseline in 24 hours after salicylate administration. The pattern of hearing loss shown by latency-intensity function was compatible with the cochlear type of hearing loss. The echo amplitude on DPOAEs at f2=2002, 4004 Hz was significantly decreased at 2, 4, 6, 8 hours, and returned to the baseline in 24 hours after salicylate administration. The time course of the change of DPOAEs was parallel with that of ABRs. CONCLUSION: These results reflect that the cochlear outer hair cells may be the main site of lesion in salicylate ototoxicity.
Subject(s)
Animals , Audiometry , Cochlea , Ear , Guinea Pigs , Guinea , Hair , Hearing Loss , Injections, Intraperitoneal , Salicylates , Sodium Salicylate , TinnitusABSTRACT
BACKGROUND AND OBJECTIVES: Partial resection of vestibular labyrinth has a great interest to all otologists and neurotologists. Various materials have been applied for occlusion of semicircular canals with different postoperative hearing results. However, the most suitable material for occlusion has not determined yet. Authors tried to compare the occlusion materials through a histologic study in experimental animals. MATERIALS AND METHOD: The lateral semicircular canal (LSCC) was transected, and the canal lumens were occluded with bone dust, muscle or bone wax in chinchillas. Thresholds for the auditory brainstem response (ABR) were measured after occlusion for two months, and histologic changes of LSCC were observed. RESULTS: Periosteal osteogenesis at the surgical defects of LSCC and perilymphatic fibrosis in the canal lumen were remarkable in the bone dust and muscle groups. The bone wax group showed minimal osteoneogenesis and some degree of perilymphatic inflammation (serous labyrinthitis). CONCLUSION: This study showed complications of each occlusion material. The proper selection of an occlusion material based on its characteristics seems to be important for a successful partial labyrinthectomy.
Subject(s)
Animals , Chinchilla , Dust , Evoked Potentials, Auditory, Brain Stem , Fibrosis , Hearing , Inflammation , Osteogenesis , Semicircular Canals , Vestibule, LabyrinthABSTRACT
BACKGROUND AND OBJECTIVES: Lateral semicircular canal (LSC) dysplasia is the most common congenital anomaly in the inner ear. The LSC dysplasia usually accompanies other inner ear anomalies, and the concurrent occurrence of the inner ear anomaly and the middle ear anomaly also has been reported. The purpose of this study was to investigate the LSC dysplasia among patients with middle ear cholesteatoma. MATERIALS AND METHOD: Medical record and temporal bone computed tomographic (CT) scan of cholesteatoma patients with the LSC dysplasia were analyzed retrospectively. RESULTS: There were four cases of the LSC dysplasia among 262 cholesteatoma patients (1.5%) during five years. Temporal bone CT scan showed short, dilated LSC and enlarged vestibule. The cochlea and the opposite side of the bony labyrinth were normal. All of the patients showed middle ear cholesteatoma occurring on the affected ear. Three patients showed mixed type of hearing loss, and the other one patient with Down's syndrome showed profound hearing loss on auditory brainstem response. In the velocity step test, two patients were normal, and one patient showed decreased response in the affected side. CONCLUSION: This study showed that the LSC dysplasia might be a relatively common inner ear anomaly encountered on the preoperative CT scan of cholesteatoma patients. The relationship between the LSC dysplasia and the development of middle ear cholesteatoma is not clear, and further studies are needed.
Subject(s)
Humans , Cholesteatoma , Cholesteatoma, Middle Ear , Cochlea , Down Syndrome , Ear , Ear, Inner , Ear, Middle , Evoked Potentials, Auditory, Brain Stem , Exercise Test , Hearing Loss , Medical Records , Retrospective Studies , Semicircular Canals , Temporal Bone , Tomography, X-Ray ComputedABSTRACT
BACKGROUND AND OBJECTIVES: Several studies have demonstrated that noise exposure may result in cochlear damage. The purpose of this study was to evaluate the effect of red Korean ginseng saponin (Krg-saponin), allopurinol and nimodipine on the auditory brainstem response (ABR) threshold changes after noise exposure. MATERIALS AND METHOD: Twenty-two healthy guinea pigs (44 ears) were divided into 4 groups; control, Krg-saponin (100 mg/kg, intraperitoneal), allopurinol (50 mg/kg, intraperitoneal) and nimodipine (2 mg/kg, subcutaneous) treated groups. Guinea pigs were exposed to 115 dB, 1500 Hz narrow band noise for 12 hours. ABR threshold shifts were observed for 24 hours after the noise exposure. RESULTS: Threshold shift after noise exposure was significantly reduced in Krg-saponin, allopurinol and nimodipine-treated groups, and allopurinol showed significantly greater effect on reducing threshold shift than nimodipine. Krg-saponin was less effective than allopurinol but more effective than nimodipine on reducing the threshold shift after noise exposure. CONCLUSION: The result suggests that the drug could block the formation of free oxygen radicals (FORs) and that scavenge FORs can be most effectively used to attenuate the noise-induced cochlear damage.
Subject(s)
Animals , Allopurinol , Auditory Threshold , Evoked Potentials, Auditory, Brain Stem , Guinea Pigs , Guinea , Nimodipine , Noise , Panax , Reactive Oxygen Species , SaponinsABSTRACT
We report a rare case of meningioma with extracranial extensions into the temporal bone and infratemporal fossa in a 66 years old woman. Clinical symptoms were mainly otologic, including progressive hearing loss, tinnitus and an external auditory canal mass that mimicked an aural polyp. Computed tomography (CT) scan showed destruction of the tegmen tympani and petrous apex. Magnetic resonance imaging (MRI) revealed extensive intracranial tumor with extracranial extensions into the temporal bone and infratemporal fossa. This case showed an infiltrative nature of extracranial meningioma and its otologic manifestations of temopral bone involvement.
Subject(s)
Aged , Female , Humans , Ear Canal , Hearing Loss , Magnetic Resonance Imaging , Meningioma , Polyps , Temporal Bone , TinnitusABSTRACT
BACKGROUND AND OBJECTIVES: Ginkgo biloba extract (EGb) has been known to have actions of increasing blood flow, free radicals scavenger and platelet activating factor antagonism. The purpose of this study was to evaluate the protective effect of the EGb in an experimentally induced hearing loss by noise. MATERIALS AND METHODS: Ten guinea pigs (EGb treated group and control group) were exposed to a narrow band noise (3,760-4,280 Hz), 6 hours daily for 6 days. An auditory evoked brainstem response (ABR) threshold was measured daily before and after a noise exposure. Two animals in each groups were sacrificed for a scanning electron microscopic (SEM) screening. RESULTS: The EGb treated group showed less changes in ABR threshold and SEM findings compared the control group. CONCLUSION: These findings suggest that the EGb may have a protective effect in noise induced hearing loss.
Subject(s)
Animals , Brain Stem , Free Radicals , Ginkgo biloba , Guinea Pigs , Hearing Loss , Hearing , Mass Screening , Noise , Platelet Activating FactorABSTRACT
BACKGROUND AND OBJECTIVES: Exposure to noise results in pertubations of cochlear microcirculation. There is evidence that these events are mediated, in part, by the calcium channel. The subsequent decrease in cochlear blood flow may lead to hypoxia and predispose to the formation of free oxygen radicals. Saponin extracted from Korean red ginseng is generally known to enhance blood flow and scavenge for free oxygen radicals. MATERIALS AND METHODS: We investigated the effect of saponin (100 mg/kg) on the cochlear damage induced by noise exposure (1500 Hz narrow band noise, 115 dB, 12hours) in guinea pigs through auditory brainstem response (ABR) and with scanning electron microscopy (SEM), RESULTS: After noise exposure, the saponin pre-treated group showed a significant decrease in the ARR threshold compared with the saponin non- treated group. Also, SEM findings of the cochlea showed that there was a minimal structural change in the outer hair cells in the saponin pre-treated group. CONCLUSION: Saponin extracted from Korean red ginseng can attenuate noise induced cochlear damage in guinea pigs.
Subject(s)
Animals , Hypoxia , Calcium Channels , Cochlea , Evoked Potentials, Auditory, Brain Stem , Guinea Pigs , Hair , Hearing Loss , Microcirculation , Microscopy , Microscopy, Electron, Scanning , Noise , Panax , Reactive Oxygen Species , SaponinsABSTRACT
BACKGROUND AND OBJECTIVES: Osteoma of the external auditory canal is an uncommon benign lesion and represents as a unilateral pedunculated mass in the outer half of the bony canal. The aim of this study is to evaluate the clinical, histopathological characteristics of osteoma and its treatment outcomes. MATERIAL AND METHODS: We have operated 9 patients who visited Chungnam National Universitv Hospital in the past 10 years with the complaints of osteoma arising from the external auditory canal. The medical records were retrospectively reviewed with regard to clinical characteristics, surgical findings, histopathological features and treatment outcomes. RESULTS: One patient showed regrowth of the tumor after surgery and CT scans demonstrated a hidden lobe embedded in soft tissue of the bony-cartilaginous junction. Five patients have had no connection with regard to tympanosquamous or tympanomastoid suture line, which had been known as the predilection site. CONCLUSION: Osteoma of the external auditory canal is a distinct benign tumor which can be removed easily. A precise preoperative evaluation of the extent of the tumor and a complete surgical removal under adequate exposure is the best way to ensure no recurrence or complication.
Subject(s)
Humans , Ear Canal , Medical Records , Osteoma , Recurrence , Retrospective Studies , Sutures , Tomography, X-Ray ComputedABSTRACT
BACKGROUND AND OBJECTIVES: Occlusion of semicircular canal has been used for otoneurologic and skull base surgery with preservation of postoperative hearing. However, research on healing process of the occluded bony semicircular canal is scarce. MATERIALS AND METHODS: We transected and occluded the lateral semicircular canal of guinea pigs using a surgical drill. Histopathologic changes of the temporal bones were observed up to the eighth postoperative week. RESULTS: The temporal bone specimens showed that ostcogenic cells proliferated from the perilymphatic fibrous mesh formed a new bone in the occluded portion of the lateral semicircular canal. Periosteal cells of the endosteum produced a compact bone layer lining the bony semicircular canal lumen. Periosteal layer produced a woven bone at the surgical defect of the lateral semicircular canal. CONCLUSION: This study shows that the perilymphatic fibrous mesh, the endosteum and the periosteal layer participated in osteogenesis in healing of the bony lateral semicircular canal after transection and occlusion.
Subject(s)
Animals , Ear, Inner , Guinea Pigs , Hearing , Osteogenesis , Semicircular Canals , Skull Base , Temporal BoneABSTRACT
BACKGROUND AND OBJECTIVES: Large doses or long-term use of salicylate may cause reversible tinnitus and hearing loss. The exact cause of salicylate ototoxicity in unknown. Decreased cochlear blood flow following reversible biochemical changes in the cochlea seems to play an important role in salicylate ototoxicity. Protopanaxatriol and protopanaxadiol saponin of the Panax ginseng are known to have a vasodilatory effect. We investigated the effect of Panax ginseng saponin on salicylate induced hearing loss in guinea pigs. MATERIALS AND METHODS: Guinea pigs were divided into two groups. The control group was injected with salicylate (300 mg/kg, IM) and the experimental group was pretreated with Panax ginseng saponin (100 mg/kg, IP) before salicylate injection. ABR threshold was measured hourly after salicylate injection. RESULTS: The control group showed a maximal hearing loss (20+/-3.54 dBnHL) in 3 hours after the salicylate injection. Comparing with the control group, the experimental group revealed a significantly different maximal hearing loss (5+/-3.54 dBnHL). CONCLUSION: These results suggest that the protopanaxatriol and protopanaxadiol saponin of the Panax ginseng can attenuate salicylate induced hearing loss.
Subject(s)
Animals , Cochlea , Guinea Pigs , Guinea , Hearing Loss , Panax , Saponins , TinnitusABSTRACT
BACKGROUND AND OBJECTIVES: There are many failed cases with distant metastases (DMs) of head and neck cancer. In such cases, patients usually have poor prognosis, with a median duration of survival between 4 and 6 months. To find out the correlation between the general clinical aspects and distant metastases in patients with head and neck cancer, we analyzed our previous experiences. MATERIALS AND METHOD: We reviewed records retrospectively in 41 of 460 patients with head and neck cancers from 1986 to 1995. DMs were confirmed with X-ray, CT, MRI, liver scan, FNAC, PCNA, and biopsy. We used the staging system of American Joint Committee on Cancer. RESULTS: 1) Clinically manifested DMs were found in 8.9% (41/460) of patients. 2) DMs were frequently observed in the oropharynx (13.8%), oral cavity (11.4%), and larynx (10.3%) cancer. 3) The lung is the most common site of DMs for head and neck cancer. Liver and bone are the only other sites of DMs that are commonly clinically diagnosed. 4) DMs usually occur within 2 years of the initial diagnosis. 5) The incidence of DMs was significantly higher in the advanced T, N stages and clinical stage than in the early T, N stages and clinical stage (p<0.05). CONCLUSION: The results of this study suggest that the advanced T, N stages and clinical stage may be some of the most critical factors influencing the eventual development of DMs.
Subject(s)
Humans , Biopsy , Diagnosis , Head and Neck Neoplasms , Head , Incidence , Joints , Larynx , Liver , Lung , Magnetic Resonance Imaging , Mouth , Neck , Neoplasm Metastasis , Oropharynx , Prognosis , Proliferating Cell Nuclear Antigen , Retrospective StudiesABSTRACT
The mechanism of salicylate ototoxicity appears to be multifactorial and decreased cochlear blood flow seems to play an important role. The purpose of the study was to assess an effect of allpurinol, a blocker of free oxygen radicals(FORs) formation, on salicylate ototxicity in guinea pig. ABR threshold shifts were observed in group 1, treated with salicylate(300mg/kg, IM) and group 2, pretreated with allopurinol(50mg/kg, PO, two times) before injection of salicylate(300mg/kg, IM). In group 1, significant ABR threshold shift was measured in 1 hour(p<0.05) and maximum threshold shift was noted in 2-3 hours, with complete recovery in 6 hours, after injection of salicylate. In group 2, there was a little ABR threshold shift through 6 hours after injection of salicylate, except average 5dB shift in 4 hours. ABR threshold shift was significantly greater in group 1 than in group 2, after injection of salicylate(p<0.05). With above result, allopurinol, a blocker of FORs formation, could attenuated the hearing loss after the administration of salicylate in guinea pig, and FORs might play a role in salicylateinduced hearing loss.
Subject(s)
Animals , Allopurinol , Guinea Pigs , Guinea , Hearing Loss , OxygenABSTRACT
BACKGROUND: The mechanism of salicylate ototoxicity is probably related to reversible biochemical or metabolic changes in the cochlea. Decreased cochlear blood flow seems to play an important role in salicylate ototoxicity. Several constituents of ginkgo extract have the action of increasing blood flow, antagonism of platelet activating factor and scavenger of free radicals. It might be thought that these activities of ginkgo extract could contribute to attenuate salicylate ototoxicity. OBJECTIVES: Whether the salicylate induced hearing loss could be attenuated by pretreatment with ginkgo extract. MATERIALS AND METHODS: Auditory brainstem response threshold changes were observed after the intramuscular injection of lysine salicylate(300mg/kg), or lysine salicylate with EGb 761(100mg/kg, single IP or 100mg/kg and 50mg/kg, IP, two times) pretreatment in each group of guinea pig. RESULTS: In the groups with Ginkgo extract pretreatment, the threshold changes were less severe and recovered earlier than in group with salicylate injection only(p<0.05). CONCLUSIONS: EGb 761 could attenuated the hearing loss after the injection of salicylate in guinea pig.
Subject(s)
Animals , Cochlea , Evoked Potentials, Auditory, Brain Stem , Free Radicals , Ginkgo biloba , Guinea Pigs , Guinea , Hearing Loss , Injections, Intramuscular , Lysine , Platelet Activating FactorABSTRACT
The transpetrosal transtentorial supra- and infratentorial combined approach has been used by many skull base surgeons for the total removal of large tumors in the cerebellopontine, petroclival, and dumbbell-shaped mass of the middle and posterior cranial bases. When surgeons use the retrolabyrinthine approach for hearing preservation, adequate exposure of the presigmoid dura might be hard to achive. In order to get a wider operating field with hearing preservation, the authors used the transpetrosal approach with partial labyrinthectomy for a large dermoid cyst in the cerebellopontine angle which extened to the middle cranial base through the Meckel's cave.
Subject(s)
Cerebellopontine Angle , Dermoid Cyst , Hearing , Skull BaseABSTRACT
No abstract available.