Electrophysiological findings in patients with sudden deafness: a survey.
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The combination of hearing loss, recruitment, poor speech discrimination and tinnitus, which is characteristic of acute cochlear disorders, can be accounted for on the basis of a decoupling of hair cells from their drive system, the tectorial membrane. Decoupling may either be caused by a temporary reduction of ciliary stiffness (shown to occur during periods of noise-induced temporary threshold shifts) or by temporary and/or chronic ciliary pathology (demonstrated to exist in cases of antibiotic ototoxicity and in endolymphatic hydrops). Since ciliary coupling is elastic in nature, the decoupling is only partial. The hearing loss and the tinnitus are manifestations of the reduced coupling per se, the magnitude of the loss depending on the degree of decoupling and the number of hair cells involved. Recruitment and poor speech discrimination result from center-clipping of the signal waveform applied to an involved hair cell, the direct corollary of partial, ciliary decoupling.
Probably one of the greatest problems in hearing aid fitting is to try to adapt hearing amplification to the recruiting ear. Sound is not loud enough, and then it is too loud. Microchips have permitted hearing aids to be smaller and smaller. However, they still remain either linear output- or input-compression types. Log-linear amplification permits the "smart aid" to automatically decrease the gain as the input power of speech or noise increases. This together with a patented low-frequency signal processor permits maximum discrimination with minimal violation of the patient's threshold of discomfort. This is a considerable step in ameliorating the major problem of the recruiting ear.
The authors studied eye movement responses to loud (110dB) clicks in 4 patients with Tullio effect due to superior semicircular canal dehiscence and in 9 normal subjects, by averaging the electro-oculogram. All 4 patients had small (0.1-0.3 deg) but easily reproducible vertical vestibulo-ocular reflex eye movement responses to the clicks. Normal subjects had responses that were at least 10 times smaller. The click-evoked vestibulo-ocular reflex test is a simple, robust way to screen dizzy patients for symptomatic superior semicircular dehiscence.
OBJECTIVE: The efficacy and tolerability profiles of sumatriptan and other 5HT(1B/1D) agonists (triptans) have been well established. However, the determinants for optimal response to sumatriptan are unknown. The Sumatriptan Naratriptan Aggregate Patient (SNAP) database contains data from 128 clinical trials including 28,407 migraine sufferers treating over 130,000 attacks. The authors analyzed these data to identify factors predicting response (headache relief and pain-free response) to sumatriptan. METHODS: The authors assessed 24 possible univariate predictors of headache response in 3,706 patients (18 years and older) receiving sumatriptan tablets 100 mg or placebo in a double-blind study using recursive partitioning and logistic regression techniques. RESULTS: The authors found seven predictors of headache relief 2 hours postdose. Moderate pain at baseline was the strongest predictor (adjusted p = 3.32 x 10(-35)), followed by absence of a disability requiring bedrest (adjusted p = 3.11 x 10(-18)). Other predictors included absence at baseline of vomiting, pulsating pain, nausea, or photophobia/phonophobia, and onset of headache during daytime hours. Logistic regression confirmed that treatment with sumatriptan was the strongest predictor of headache relief, with significant baseline covariates being pain severity, level of disability, and presence or absence of vomiting. A similar pattern of results was reported for predictors of pain-free response 2 hours after taking sumatriptan. CONCLUSIONS: Pretreatment pain severity is the most important predicting factor for response to sumatriptan in migraine attacks: the lower baseline severity, the better.
BACKGROUND: Menstrually associated migraine (MAM) is often prolonged and difficult to manage with conventional therapies. Frovatriptan is a new selective 5HT(1B/1D) receptor agonist indicated for short-term management of migraine. It has a long half-life and good tolerability. These characteristics suggest that frovatriptan may be useful for the intermittent prevention of MAM. METHODS: The study was a randomized, double-blind, placebo-controlled, three-way crossover design. Patients treated each of three perimenstrual periods (PMPs) with placebo, frovatriptan 2.5 mg QD, and frovatriptan 2.5 mg BID. The 6-day treatment started 2 days before the anticipated start of MAM headache. The primary efficacy endpoint was incidence of MAM headache during the 6-day PMP. RESULTS: The population comprised 546 women (mean age, 37.6 years). Use of frovatriptan reduced the occurrence of MAM headache. The incidence of MAM headache during the 6-day PMP was 67% for placebo, 52% for frovatriptan 2.5 mg QD, and 41% for frovatriptan 2.5 mg BID. Both frovatriptan regimens were superior to placebo (p < 0.0001), and the BID regimen was superior to the QD regimen (p < 0.001). Both frovatriptan regimens also reduced MAM severity (p < 0.0001), duration (p < 0.0001), and the use of rescue medication (p < 0.01 QD; p < 0.0001 BID) in a dose-dependent manner. The incidence and type of adverse events for both regimens were similar to placebo and consistent with those reported for short-term migraine management. CONCLUSION: Frovatriptan given prophylactically for 6 days was effective in reducing the incidence of menstrually associated migraine. More than half of patients who used frovatriptan 2.5 mg BID had no menstrually associated migraine headache during the 6-day perimenstrual period. The findings are consistent with the long duration of action and good tolerability of frovatriptan observed in short-term migraine management.
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Two patients with unprovoked drop attacks were found to have dehiscence of the superior semicircular canal on CT of the temporal bone. Both had conductive hearing loss, preservation of stapedius reflex, and abnormal vestibular evoked myogenic potentials. Neither had sound- or pressure-induced nystagmus. Repair of the dehiscence in one case stopped the drop attacks, supporting a causal relationship between the dehiscence and the drop attacks.
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Torok studied the ratio obtained between the responses to two different heat stimulation intensities of the same temperature. A decrease in response to the strong stimulus (i.e., a diminished ratio) was called "vestibular decruitment," and was regarded as a topodiagnostic indicator of central vestibular lesion, reflecting "adaptation" or "fatigue." The authors studied the reliability of vestibular decruitment obtained by Torok's technique in the indication of central vestibular pathology. Twenty-eight normal individuals and 30 patients previously diagnosed by other methods with diffuse pathology of the central nervous system were evaluated. The results obtained show that the two stimuli used are both supraliminal and of different intensity regarding the labyrinth. In no case was vestibular recruitment obtained. In view of the high percentage of normal individuals (57.14%) who presented vestibular decruitment, we consider the latter to lack topodiagnostic value as an indicator of either central or vestibular pathology; the smaller response to the mass stimulus might be explained by the vestibular habituation phenomenon that occurs on applying Torok's technique in both normal individuals and in patients with central vestibular pathology.
Cogan's syndrome (CS) presents typical and atypical types. Typically, there are episodes of nonsyphilitic keratitis and audiovestibular dysfunction. Atypically, there are inflammatory changes in other eye structures and other organ systems, particularly the cardiovascular system. The temporal bone pathology in a case of CS shows changes that are similar to those observed in other autoimmune disorders associated with audiovestibular dysfunction. The following pathologic features characterize autoimmune inner ear disease: 1. acute labyrinthitis resulting in atrophy of inner ear tissues including the sense organs and their supporting structures; 2. endolymphatic hydrops; 3. focal and diffuse proliferation of fibrous tissue and bone; and 4. retrograde neuronal degeneration. These pathologic findings are consistent with an inflammatory (and possibly ischemic) attack on the membranous labyrinth.
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Questions are raised about the technical and psychological interpretation of loudness match measures in the assessment of tinnitus "intensity". The effect of hearing threshold on loudness matches expressed in sensation level (SL) was investigated by selecting subjects with different degrees of hearing loss. The loudness match expressed in SL was found to be a function of threshold. Correlations were then determined between psychological scales of tinnitus complaint (reported loudness, distress, intrusiveness, and others) and loudness match expressed in HL, SL, sones, or personal loudness units (PLUs). Only matches expressed in PLUs were significantly correlated with reported loudness or other psychological scales. The PLU transformation, derived from an individually determined loudness function, produces values that are generally independent of other audiometric measures. It is therefore recommended for assessing tinnitus "intensity".