Dose-dependent effects of D-methionine for rescuing noise-induced permanent threshold shift in guinea-pigs.

The purpose of this study was to examine the dose-response effectiveness of d-methionine (d-met) in rescuing a noise-induced permanent threshold shift (PTS) and cochlear biochemistry following noise exposure. One hour after being exposed to continuous broadband white noise at 105dB sound pressure level (SPL) for 6h, guinea-pigs were treated five times at 12-h intervals with 200, 400, or 600mg/kg d-met or sterile 0.9% saline (each group, N=6) by intraperitoneal injection. Six guinea-pigs with normal hearing that were not exposed to noise served as control animals. Although administration of d-met 200mg/kg did not significantly reduce the mean PTS, treatment with d-met 600mg/kg achieved a complete rescue response. The level of rescue from noise-induced PTS following treatment with 200, 400, or 600mg/kg d-met was dose dependent. The attenuation of the noise-induced decreases in the activities of the Na(+), K(+)-ATPase and Ca(2+)-ATPase following treatment with 200, 400, or 600mg/kg d-met was also dose dependent. Likewise, d-met-dose-dependent decreases in mean lipid peroxidation and nitric oxide levels were observed in the d-met treated groups. Significant attenuation of increased oxidative stress and decreased ATPase activities was concurrent with the d-met-mediated improvements in noise-induced auditory dysfunction.

Sudden sensorineural hearing loss in a patient with primary antiphospholipid syndrome.

OBJECTIVE: Despite multiple systemic manifestations, sudden sensorineural hearing loss in a patient with antiphospholipid syndrome is rarely reported. PATIENT: A 46-year-old man with primary antiphospholipid syndrome had a sudden onset of hearing loss and tinnitus in the right ear in December 2005, because he discontinued use of warfarin and acetylsalicylic acid for a few days. RESULTS: Audiometry revealed saucer-type sensorineural hearing loss with a pure tone average of 73 dB in the right ear, and flat-type hearing loss with a pure tone average of 25 dB in the left ear. Electronystagmography displayed multiple central signs and bilateral canal paresis, while a vestibular evoked myogenic potential test revealed bilateral delayed responses. After admission, the patient was re-treated with warfarin and acetylsalicylic acid. Follow-up audiometry showed recovery of right-sided hearing, with a pure tone average of 12 dB, three days after presentation. CONCLUSION: Consensus exists on the effectiveness of anticoagulant agents in aiding a favourable outcome of sudden sensorineural hearing loss in patients with antiphospholipid syndrome.

Toxic effects of potassium bromate and thioglycolate on vestibuloocular reflex systems of Guinea pigs and humans.

Potassium bromate (KBrO(3)) and thioglycolate are two components of hair curling solution. The neurotoxic effects of KBrO(3) and thioglycolate on the vestibuloocular reflex (VOR) system have not been elucidated. In this paper, we report the adverse effects of KBrO(3) and thioglycolate on the VOR system of Hartley-strain guinea pigs. The function of the VOR system was evaluated by caloric test coupled with the electronystagmographic recordings after subcutaneous injection of 20 or 50 mg/kg KBrO(3) or 15 mg/kg thioglycolate, either alone or in combination once daily for 14 consecutive days. The results showed that KBrO(3) produced abnormal caloric responses in a concentration-dependent manner and thioglycolate enhanced this abnormality. Our clinical patients, 10 female hairdressers exposed to the hair curling solution for 10-30 years revealed a similar dysfunction in the caloric test. The possible mechanism of this adverse effect was studied: the cerebellar-regulated functions such as motor equilibrium performance and spontaneous locomotor activity of guinea pigs were reduced, the enzymatic Na(+)/K(+)-ATPase and Ca(2+)-ATPase activities of cerebellar tissues were significantly decreased, and the loss of Purkinje cells as well as the derangement of the granular cell layer of the cerebellar cortex was revealed after treatment with KBrO(3) plus thioglycolate. These findings imply that KBrO(3) plus thioglycolate is toxic to the VOR system, mediated by, at least in part, the dysfunction of a higher cerebellar regulatory mechanism. We suggest that the caloric test is a noninvasive method for monitoring the consequences of hazardous exposure of hair curling solution in humans. Our clinical findings together with the animal study imply that clinicians should be alert to the risk of bromate exposure in hairdressers, especially those with vertigo, tinnitus, or hearing loss.

Three-dimensional analysis of post-caloric nystagmus caused by postural change.

In order to record caloric nystagmus (CN) using three-dimensional videonystagmography (3D VNG) 14 subjects were placed in the supine position with the head tilted up 30 degrees relative to the earth's horizontal plane. After the primary-phase CN had terminated, the subjects were repositioned from a supine to a sitting position, with the head anteflexed 30 degrees for recording the post-caloric nystagmus (PCN). In addition, 8 of the original subjects were placed in the supine position but with the head turned 40 degrees to the left so that the irrigated (right) ear was oriented upwards. After the primary-phase CN had terminated, the subjects were rotated by 180 degrees so that the irrigated ear was oriented downwards to record PCN. The results indicated that both methods successfully provoked horizontal and vertical CN. For torsional CN, the irrigated ear up/down method produced a higher provocation rate (75%) than the supine/sitting method (50%), but the difference was not significant. Comparing the provocation rate of the PCN for the horizontal component revealed that the two methods do not differ significantly. However, when comparing the provocation rates of PCN for the vertical component, the irrigated ear up/down method showed a higher rate (82%) than the supine/sitting method (18%). Thus using 3D VNG coupled with postural change during caloric testing, the horizontal or vertical components of PCN can be successfully provoked.

Mechanism of hearing loss in irradiated ears: a long-term longitudinal study.

A 10-year longitudinal follow-up study of hearing was conducted in patients with nasopharyngeal carcinoma (NPC) in order to elucidate the mechanism of hearing loss in irradiated ears. Ten NPC patients were subjected to a battery of audiological tests before irradiation and 6 months, 5 years, and 10 years after irradiation. The tests included pure tone audiometry, tympanometry, eustachian tube function testing, and myringotomy to confirm middle ear effusion. The prevalences of otitis media with effusion (OME) were 25%, 25%, 40%, and 25% at the 4 testing periods described above, respectively. The prevalences of chronic otitis media were 0%, 0%, 15%, and 25%, respectively. In myringotomized ears (n = 17), the mean hearing levels for both air conduction and bone conduction were preserved from the preirradiation period to 10 years after irradiation. In contrast, in grommeted ears (n = 3), the mean hearing levels for both air conduction and bone conduction deteriorated progressively from the preirradiation period to 10 years after irradiation. We conclude that hearing can be preserved in NPC patients 10 years after irradiation if middle ear inflammation is well controlled. We do not recommend grommet insertion in irradiated NPC patients with OME, as it may result in persistent otorrhea and hearing deterioration.

Role of clonazepam in the treatment of idiopathic downbeat nystagmus.

OBJECTIVE/HYPOTHESIS: Downbeat nystagmus is defined as spontaneous nystagmus present with fixation in the primary position or lateral gaze. Those who have downbeat nystagmus but negative magnetic resonance imaging results are termed as idiopathic. Patients with idiopathic downbeat nystagmus, although unconcerned with their etiology, have visual symptoms such as oscillopsia, diplopia, or blurred vision. The purpose of this study is to evaluate the efficacy of clonazepam in treating idiopathic downbeat nystagmus. METHODS: Patients with downbeat nystagmus were rechecked by electronystagmography (ENG); then 0.5 mg clonazepam was administered orally. One hour later, follow-up ENG was performed again to evaluate the evolution of the downbeat nystagmus. If the test was effective, then 1.0 mg clonazepam twice daily was administered to the patients. RESULTS: Seven cases had downbeat nystagmus, including idiopathic in five, cerebellar degeneration in one, and cerebellopontine angle tumor in one. The efficacy rate for the clonazepam test was 100% in five cases of idiopathic downbeat nystagmus, whereas it was ineffective in the case of cerebellar degeneration. After long-term therapy with clonazepam, all patients with idiopathic downbeat nystagmus experienced elimination of oscillopsia, relief of diplopia, and improvement of visual acuity. Although temporary relief of downbeat nystagmus was observed 1 hour after the clonazepam test, downbeat nystagmus was not eliminated permanently. CONCLUSION: We recommend long-term therapy by clonazepam with a dosage of 1.0 mg twice daily in cases of idiopathic downbeat nystagmus. Reducing the downbeat nystagmus as well as eliminating the oscillopsia can be anticipated.

Neurotoxicity of mercury sulfide in the vestibular ocular reflex system of guinea pigs.

A traditional Chinese mineral medicine, cinnabar, naturally occurring mercuric sulfide (HgS), is still occasionally prescribed, but the neurotoxic effects of HgS have not been elucidated. In this paper, an animal model of the purified HgS intoxication was established in guinea pigs in order to study neurotoxicity and pathophysiology of the vestibular ocular reflex system (VOR). Guinea pigs were dosed with HgS by gastric gavage (0.01, 0.1 and 1.0 g/kg per day) for 7 consecutive days. By means of caloric testing coupled with the electronystagmographic (ENG) recording in guinea pigs, we have found that HgS at a dose of 0.1 g/kg induced reversible caloric hypofunction pattern and at a higher dose of 1.0 g/kg induced irreversible hypofunction of caloric test. Monitoring the mercury contents of various tissues (blood, kidney, liver and cerebellum) by continuous flow and cold vapor atomic absorption spectrometry (AAS) revealed that a certain amount of HgS could be absorbed from the gastrointestinal tract and was detectable in these tissues. In addition to the induced dysfunction of VOR system, HgS also caused disturbance of motor performance in guinea pigs. In enzyme assay, Na+/K+-ATPase activity of cerebellum was also significantly inhibited by HgS. Morphological studies showed partial cell loss only in the cerebellar Purkinje cell layer, but not in the granule cell layer, nor in the vestibular labyrinth. All of these findings suggest that cerebellar Purkinje cells are the sensitive target site responsible for HgS-inducing dysfunctions of both VOR system and the motor performance in guinea pigs. Thus, it is concluded that caloric test coupled with ENG recording in VOR system is certainly a sensitive biomarker for monitoring the neurotoxicity of HgS.

Failure of grommet insertion in post-irradiation otitis media with effusion.

Nasopharyngeal carcinoma (NPC) survivors with post-irradiation otitis media with effusion (OME; 100 ears) were divided into 2 groups. One group underwent grommet insertion, and the other group was treated by repeated myringotomies plus aspiration to evaluate the outcome of the OME. Computed tomography, magnetic resonance imaging, audiometry, and local checks of the ear, nose, and nasopharyngeal fields were performed to evaluate the sinus and middle ear conditions over a long-term (more than 10 years) follow-up period. The results in these NPC survivors with OME indicated that the prevalence of middle ear complications in the myringotomized group (33%) was less than that in the grommeted group (90%). Grommets alone cannot eradicate inflammation outside the middle ear cavity, but rather, they can aggravate it by superinfection. We therefore recommend that controlling the radiation-induced inflammation in areas such as the ears, nose, sinuses, and nasopharynx is most important. In conclusion, post-irradiation OME should be treated in a different way from conventional OME. Restated, grommet insertion is contraindicated in post-irradiation OME.

Effect of smoking on the treatment of vertigo.

OBJECTIVE: To study the effect of smoking on patients with vertigo. SETTING: University hospital. PATIENTS: Thirty patients with vertigo who smoke and 30 patients with vertigo who don't smoke were age-, sex-, and diagnosis-matched and given the same medication consecutively for 3 months. Then treatment efficacy was compared between two groups to investigate the relationship between smoking and vertigo. RESULTS: The efficacy of treatment of vertigo in the smoking group (30%) was lower than the nonsmoking group (74%). Intractable vertigo is related to smoking behavior but unrelated to either smoking year or tobacco year (exposure to smoking). CONCLUSIONS: For patients with vertigo who smoke during the course of treatment, the treatment may be ineffective. Therefore, neurotologists should inquire about the smoking history in vertigo patients and advise them to abstain from smoking.

Intracranial relapse of nasopharyngeal carcinoma manifested as sudden deafness.

OBJECTIVE: To differentiate tumor relapse from postirradiation sudden deafness (PISD) in patients with nasopharyngeal carcinoma (NPC). STUDY DESIGN: A retrospective study from December 1991 to November 1999. SETTING: University hospital. PATIENTS: Twenty-five irradiated NPC patients with sudden deafness were investigated. All patients received local examination of ears, nose, nasopharynx, and throat fields, as well as a battery of audiologic and neurotologic tests. RESULTS: Three patients with sudden deafness within 3 years after irradiation received a diagnosis of tumor relapse. Magnetic resonance imaging revealed cerebellopontine angle metastasis in one and intracranial invasion in two. Comparison of the remaining 22 NPC patients who had PISD showed that the mean interval between the completion of irradiation to the onset of sudden deafness was 10+/-5 years. CONCLUSION: Magnetic resonance imaging should be performed to exclude intracranial relapse if sudden deafness develops in a patient with NPC within 5 years after irradiation.

Frequency and predictors of physician consultations for headache.

We conducted a population-based headache questionnaire survey including questions on physician consultation for headache in Taipei, Taiwan from August 1997 to June 1998. The participants comprised 3377 subjects aged > or = 15 years, of whom 328 (9.7%) had a diagnosis of migraine and 1754 (52%) had a diagnosis of non-migraine headache. Migraineurs had a higher physician consultation rate (once or more in the past year) than the subjects with non-migraine headache (54% vs. 31%, P < 0.0001). When frequency > or = 10 times was taken as 10 times, the analysis showed that migraineurs consulted physicians more often than non-migraine headache subjects (2.36 vs. 0.96, P = 0.04). A small proportion of the subjects with either migraine (12%) or non-migraine headache (6%) accounted for 50% of total consultations within their groups. In addition to old age, low education levels, living in a rural area, migrainous features (nausea and photophobia), and work day loss, predictors of physician consultations also included 'having been troubled with headache' (odds ratio (OR) = 1.7) and co-morbidity with hypertension (OR = 1.8) or heart disease (OR = 2.2). Low copayment and unrestricted access to medical care, as well as cultural factors played an important role in the high consultation rates in our headache subjects. Moreover, this study found self-perception of headache impact and co-morbid illnesses were important factors affecting the decision to consult physicians about headache.

Prevalence of migraine in Taipei, Taiwan: a population-based survey.

We conducted the first population-based migraine survey in Taipei, Taiwan, using a validated questionnaire administered by interviewers during the period from August 1997 to June 1998. Our target population comprised all individuals (age > or = 15 years) in 1400 randomly selected households. Migraine diagnoses were made according to the classification criteria of migraine without aura proposed by the International Headache Society, 1988, except that attacks with a duration of between 2 h and 4 h were also included. Of the 4434 eligible subjects in the 1211 respondent households, 3377 (76%) completed the questionnaire. After adjustment for age and sex distribution according to the population structure, the prevalence of migraine was 9.1% (F/M 14.4%/4.5%). Fifty-four percent of the subjects with migraine had consulted a physician about their headaches in the past year. However, only 18% of them reported that their migraine had been diagnosed by physicians. This study found that Taipei residents have the highest migraine prevalence of all Chinese populations studied, although it is still in the low range of prevalence compared with the results from Western countries.

Meningeal carcinomatosis manifested as bilateral progressive sensorineural hearing loss.

OBJECTIVE: Meningeal carcinomatosis is defined as the diffuse infiltration of the leptomeninges and subarachnoid space by malignant cells metastasizing from systemic cancer. The authors describe a rare case of meningeal carcinomatosis initially appearing as bilateral progressive sensorineural hearing loss. PATIENT: A 57-year-old man with lung cancer was referred to the authors' clinic because of progressive hearing loss, tinnitus, dizziness, and blurred vision for 1 month. RESULTS: Magnetic resonance imaging revealed abnormal leptomeningeal enhancement. Meningeal carcinomatosis was diagnosed by the detection of malignant cells in the cerebrospinal fluid after lumbar puncture. The patient died 1 year after diagnosis. CONCLUSIONS: Meningeal carcinomatosis must be considered in the differential diagnosis in cancer patients with bilateral progressive sensorineural hearing loss. Gadolinium-enhanced magnetic resonance imaging is a useful complementary diagnostic tool before lumbar puncture.

Abnormalities of post-caloric nystagmus induced by postural change.

Post-caloric nystagmus, the reverse secondary phase of caloric nystagmus after the cessation of primary-phase nystagmus, can easily be elicited by postural change. It has been related to the mechanism of vestibular adaptation, and exaggerated responses have been shown in some neurological disorders. Post-caloric nystagmus induced by postural change was analyzed in normal young adults (16 ears), elderly people (age > or = 65 years, 18 ears), patients with central lesions (40 ears) and patients with peripheral vestibulopathy (25 ears). The duration, maximum frequency and maximum slow-phase velocity of the primary phase of caloric nystagmus and of post-caloric nystagmus were documented. The duration, frequency and velocity ratios of post-caloric to primary-phase nystagmus were calculated. The results showed that post-caloric nystagmus induced by postural change was observed in 14 ears (88%) of normal young adults, 10 ears (56%) of elderly patients, 31 ears (78%) of patients with central lesions and 22 ears (88%) of patients with peripheral lesions. The duration and slow-phase velocity ratios for the central lesion group were found to be relatively higher than those for the control group (p < 0.05). A significant positive correlation between the intensities of post-caloric and primary-phase nystagmus was found in all groups except in the central lesion group. Abnormalities of post-caloric nystagmus induced by postural change may occur in the form of exaggerated response or failure of elicitation, which were observed with various central neuro-otological lesions and as a result of the aging process.

Vestibular neuritis: three-dimensional videonystagmography and vestibular evoked myogenic potential results.

Eight patients diagnosed with vestibular neuritis received the newly developed three-dimensional videonystagmography (3D VNG) and vestibular evoked myogenic potential (VEMP) examination in order to localize the lesion site. Two (25%) of the 8 patients exhibited spontaneous nystagmus with 3 components, indicating that both the horizontal semicircular canal (HSCC) and anterior semicircular canal (ASCC) were affected. The remaining 6 patients (75%) displayed only horizontal nystagmus, meaning that only the HSCC was involved. Seven (88%) of the 8 patients had bilateral normal VEMPs, revealing sparing of the posterior semicircular canal (PSCC). In a comparative study, another seven patients with vestibular neuritis 1 year post-treatment also received the caloric test, 3D VNG and VEMP examination. Only one patient exhibited spontaneous nystagmus. An absent caloric response of the lesioned side persisted in 5 (71%) of the 7 patients. However, all patients showed normal VEMPs bilaterally. 3D VNG and VEMP examination indicates that vestibular neuritis mainly affects the superior division of the vestibular nerve, which innervates the HSCC and ASCC. Meanwhile, the function of the PSCC and saccule, innervated by the inferior vestibular nerve, is preserved.