Functional assessment of sensory functions after photothrombotic stroke in the barrel field of mice.

Motor, sensory and cognitive deficits are common impairments observed in human stroke as well as in animal stroke models. Using a battery of behavioural tests we assessed sensorimotor deficits after photothrombotic stroke localized within or beyond cortical representation of mouse sensory vibrissae. We found restricted, modality specific behavioural consequences in the acute post-stroke period. Among incorporated tests, adhesive removal test, novelty exploration test and sensory labyrinth task were sensitive to the somatosensory cortical deficits. Injured animals explored new objects significantly longer, they also needed distinctly more time to contact and to remove the adhesive tape placed on whiskers contralateral to the infarct. Moreover, we observed that after stroke animals were unable to solve the sensory labyrinth depending only upon tactile sensation from whiskers with injured cortical representation. Spontaneous recovery could be observed within the first post-stroke week for adhesive tape removal and within 14 days for labyrinth performance. However, for the novel object exploration we did not observed the recovery for the period of 18 days after stroke. Moreover, new object exploration test performance differed between the somatosensory and visual cortical impairments. We suggest that those three tests might be valuable in assessing the usefulness of therapies designed to support brain repair after experimental stroke.

Prognosis of patients with idiopathic sudden hearing loss: role of vestibular assessment.

OBJECTIVE: To evaluate the correlation between caloric and vestibular evoked myogenic potential test results, initial audiogram data, and early hearing recovery, in patients with idiopathic sudden hearing loss. MATERIALS AND METHODS: One hundred and four patients with unilateral idiopathic sudden hearing loss underwent complete neurotological evaluation. Results for vestibular evoked myogenic potential and caloric testing were compared with patients' initial and final audiograms. RESULTS: Overall, abnormal vestibular evoked myogenic potential responses occurred in 28.8 per cent of patients, whereas abnormal caloric test results occurred in 50 per cent. A statistically significant relationship was found between the type of inner ear lesion and the incidence of profound hearing loss. Moreover, a negative correlation was found between the extent of the inner ear lesion and the likelihood of early recovery. CONCLUSION: In patients with idiopathic sudden hearing loss, the extent of the inner ear lesion tends to correlate with the severity of cochlear damage. Vestibular assessment may be valuable in predicting the final outcome.

Auditory and vestibular assessment of patients with Ménière's disease who suffer Tumarkin attacks.

Tumarkin attacks are a feature of Ménière's disease that generate a significant degree of disability. The surprising nature of these events is the main reason behind their associated morbidity. In this study we set out to evaluate auditory and vestibular function, as well as disability, in a population of patients who suffer Tumarkin attacks. We found that patients who suffer Tumarkin attacks are more disabled and experience severer and more frequent autonomic symptoms and that their hearing level is significantly worse in the asymptomatic ear, especially at low frequencies. Accordingly, we consider that treatment must be carefully planned to be as conservative as possible in terms of hearing and that psychiatric and/or psychological treatment must always be considered as an adjuvant therapy.

[Assessment of functioning of the internal ear in patients with labyrinthine hydrops and in normal subjects by means of phase audiometry].

A method for the diagnosis of labyrinthine hydrops is proposed that takes advantage of specific physiological features of internal ear functioning. Namely, the basal membrane of the inner ear exposed to a low-frequency tone undergoes synchronous sinusoidal oscillations along its entire length; simultaneously, sensitivity of the organ of Corti changes periodically. Under normal conditions, perception of 1,000 Hz tonal signals at the background of a low-frequency masker varied substantially depending on the phase during which the signal came. In the maximum discharging phase that corresponded to a 270 degree deviation of the basal membrane from its initial position, it was maximally displaced towards the vestibule staircase, and perception of the test tone was most affected. Patients with hydrops of the internal ear exhibited phase-independent constant perception of high-frequency tonal signals against the background test tone. It is concluded that the method of phase audiometry can be used in large research centres for the comprehensive evaluation of cochlear-vestibular function during hydrops formation.

Clinical examination of labyrinthine-defective patients out of the vertigo attack: sensitivity and specificity of three low-cost methods.

Many reports have appeared in the medical literature concerning the clinical examination at the bedside of patients with vertigo and, even if few controversial opinions exist, the observation of one or more kinds of nystagmus is generally regarded as suggesting an organic aetiology. So far, the presence of nystagmus has been generally considered to be crucially important for clinicians who are daily asked to differentiate between an "organic" cause of vertigo (for example, a labyrinthine dysfunction) and a "non-organic" cause of vertigo, such as a panic disorder. Albeit, it should not be forgotten that the central nervous system is able to resolve the asymmetry of vestibulo-ocular reflexes, due to a peripheral vestibular failure, by means of compensatory mechanisms so that nystagmus is rapidly abolished after the acute attack of vertigo. In addition, visual fixation elicits sub-cortical inhibitory pathways to the vestibular nuclei so that spontaneous nystagmus is remarkably reduced by light. In order to more easily detect nystagmus, attempts have been made to minimize the interference of visual fixation by means of positive lenses (Frenzel's glasses) and light occluding masks with infrared cameras (videonystagmoscopy) which have in part replaced direct observation of the patient's eyes, albeit no systematic validation of the advantages has been reported yet. To investigate the usefulness of these 3 low-cost methods to detect nystagmus, 528 outpatients presenting peripheral vestibular hypofunction, diagnosed by a complete audiological and vestibular examination, including caloric tests, were enrolled in the present study, while 133 subjects with normal vestibular function acted as a control group. All patients and control subjects underwent a standardized clinical examination based on search for spontaneous, positioning and head-shaking nystagmus detected by direct observation of patient's eyes, Frenzel's glasses and videonystagmoscopy. Specificity of the three techniques were 35.6, 43.7 and 91.6, whilst sensitivity was 88.7, 88.7 and 84.2, respectively. Finally, discriminant analysis based on the presence/absence of at least one kind of nystagmus was computed for each technique and showed that videonystagmoscopy allowed the examiner to correctly classify both pathological and normal subjects more frequently (> 77% of cases) than the other two methods (about 50%). It is concluded that only videonystagmoscopy is an acceptable technique for screening a labyrinth defect in a population of outpatients with vertigo.

Expression of aquaporin 1 and 5 in the developing mouse inner ear and audiovestibular assessment of an Aqp5 null mutant.

To examine the potential roles of aquaporins 1 and 5 (AQP1 and AQP5, respectively) in inner ear development and function, we defined their spatial and temporal expression patterns in the developing mouse inner ear and examined the morphologic and physiologic effects of loss of Aqp5 function. Standard in situ hybridization (ISH) and immunohistochemical (IHC) assays were used for expression studies with routine morphologic, behavioral, and physiologic assessments of hearing and balance in Aqp5 null mutant mice. AQP1 was first detected at embryonic day 10.5 (E10.5) in the otocyst but eventually localized to specific nonsensory portions of the inner ear and connective tissue cells surrounding the membranous labyrinth. AQP5 displayed specific cochlear expression, first detectable at E15.5 in the nonsensory epithelium and later restricted to the lateral wall of the cochlear duct near the spiral prominence. AQP5 expression continued through postnatal periods with a change of expression domain to the stria vascularis between postnatal day 7 (P7) and P14. By in situ hybridization and immunohistochemical techniques, subtle differences between transcript and protein expression patterns were noted for both AQP1 and 5. Although AQP5 is dynamically expressed in the developing mouse inner ear, adult Aqp5 knockout mice show normal hearing when tested and normal inner ear structural development. These results suggest redundant or alternative mechanisms that likely regulate water homeostasis in the developing and mature inner ear.

The application of frequency and time domain kurtosis to the assessment of hazardous noise exposures.

Five computer-synthesized broadband noises, each having the same average spectrum and the same unweighted Leq of 100 dB SPL but very different temporal structures, were used to produce hearing loss in chinchillas. Despite the same exposure energies and spectra, each noise exposure produced a different magnitude and frequency distribution of hearing loss and sensory cell loss. The results indicate that the statistical properties of a signal are important in the determination of hearing loss. When the audiometric and histological results are compared to a metric based upon kurtosis measured in the time and the frequency domain for each exposure, there is a clear indication that these statistical metrics are good predictors of the relative magnitude and frequency distribution of the acoustic trauma.

Screening and assessment of childhood deafness: experience from a centralized multi-disciplinary service.

A paediatric hearing assessment unit was set up in Lothian in 1978 to provide a clear referral pathway for children with suspected sensorineural hearing impairment and particularly for those children detected by the health visitor screening test. Over a 6-year-period the incidence of bilateral sensorineural deafness was 1.3/1000 suggesting that all children in the region were being seen. The mean age of diagnosis fell significantly over this period. Children in high risk groups, through adverse perinatal events or a positive family history, were not detected any earlier than other children. They were therefore not contributing to this improved earlier age of diagnosis. These findings support the continuation of health visitor screening but changes in practice are needed to encourage earlier diagnosis in high-risk groups.

[Test battery for objective assessment and differential diagnosis in the early stage of suspected development of presenile dementia of the Alzheimer type]. / Testbatterie zur Objektivierung und Differentialdiagnostik im Frühstadium einer angenommenen präsenilen Demenzentwicklung vom Alzheimertyp.

The clinical diagnosis of organic brain syndromes (especially of primary degenerative dementia) in their early stages is uncertain or only tentative. We used a set of relatively simple tests to support the hypothesis that the disturbance of several operational brain functions precedes memory decline in primary degenerative dementia. Twenty-one patients with early stage, presenile onset of DAT, 14 patients with cardiovascular disease (CVD) and a questionable dementia, an age-matched control group (EC, n = 15), and a younger control group (YC, n = 16) were examined in the following tests: labyrinth learning test, tactile and visual pattern recognition, different reaction time tasks, eye-tracking, finger-tapping, alpha-EEG-blockade, photic driving, flicker fusion frequency, and interaction tasks. The test demonstrated that the patients performed more slowly for all tasks than did control subjects. The CVD patients performed better than the DAT group, but they were also significantly worse in the tests compared with healthy elder subjects. This test battery was found purposeful for early diagnosis of both primary degenerative and other forms of dementia, and may also be helpful to exclude other forms of organic brain syndromes.

[Causes and assessment of hearing impairment]. / Ursachen und Untersuchung der Schwerhörigkeit.

Hearing loss is a very common disorder. It is discussed, using the aid of a topical classification. An introductory description of new basic knowledge about the peripheral hearing organ is given first. Such knowledge has had an important influence on the understanding and the evaluation of hearing loss. The diagnosis of conductive hearing loss is relatively easy to make. It represents mainly a quantitative disorder without much loss of qualitative information, and it can often be improved surgically. Conversely, sensorineural hearing loss is always associated with a loss in the quality of the acoustic information. Its most common causes are functional disturbances of the cochlea. The mechanical elements within the cochlea seem to be particularly vulnerable. The differentiation between a cochlear and a retrocochlear hearing loss can be made with confidence using modern audiological tests. This differentiation is particularly important for the early diagnosis of acoustic tumors.

Quantitative assessment of inner ear pathology following ototoxic drugs or acoustic trauma.

Techniques currently used in the assessment of structural and/or functional damage to the peripheral auditory system are summarized. Two histological approaches are described: one which allows light microscopic evaluation of all structures of the auditory periphery, and a second which concentrates on the sensory cells and their innervation. The latter technique allows electron microscopic analysis of selected regions after a thorough light microscopic survey. Two electrophysiological methods are described as well: a single-fiber approach which provides detailed information about cochlear condition at all frequency locations and a simpler and faster evoked-potential approach which is well suited to screening for cochlear changes. The correlations between structural and functional changes are described using examples from studies of acoustic injury of the inner ear.