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PubMedDate not supplied

Clinical study of the role of melanocytes in the inner ear of patients with Harada's disease.

Harada's disease is an autoimmune disorder involving melanocytes. Twenty patients with Harada's disease underwent otoneurological examination to investigate the inner ear involvement in Harada's disease and the function of the melanocytes in the inner ear. All 20 exhibited clinical and/or laboratory abnormal inner ear findings. The incidence of inner ear involvement in Harada's disease is very high. The melanocytes in the inner ear play important roles in both auditory and equilibrium function.

Adult↗
PubMed1989

Low-grade adenocarcinoma of probable endolymphatic sac origin A clinicopathologic study of 20 cases.

The clinical and histologic features of twenty cases of a type of papillary-cystic temporal bone neoplasm are reported. Ages of the patients ranged from 15 to 71 years. The tumors destroyed a large portion of the posterior temporal bone and included a prominent extension into the posterior cranial fossa. Patient histories indicated a slow growth rate of the lesions. Awareness of the parameters of this neoplasm, including the site of origin and probably histogenesis, may enable earlier diagnosis and more successful treatment of the tumor in the future.

Adenocarcinoma, Papillary↗
PubMed1985

Eye movements in patients with absent voluntary horizontal gaze.

Despite the complete absence of horizontal saccades, two patients with pontine gliomas had horizontal reflex eye movements within a range of +/- 20 degrees. The gain (peak eye velocity/peak stimulus velocity) and phase of the vestibulo-ocular reflex were normal, but the optokinetic gain was decreased. The latency, accuracy, and peak velocity of vertical saccades were normal. Apparently the voluntary gaze centers in the pontine reticular formation are not crucial for generating horizontal vestibular or vertical saccadic eye movements.

Adult↗
PubMed1979

A model of Alexander's law of vestibular nystagmus.

The observation that the amplitude of vestibular nystagmus grows as gaze is increased in the direction of the nystagmus fast phase and diminished with gaze in the opposite direction is known as "Alexander's law". We have developed an analog computer model to simulate Alexander's law in nystagmus secondary to dysfunction of a semicircular canal. The model utilizes relevant brainstem anatomy and physiology and includes gaze modulation of vestibular signals and push-pull integration to create eye position commands. When simulating normally functioning semicircular canals, the model produced no nystagmus. When simulating total impairment of the canal on one side with gaze directed maximally in the opposite direction, the model produced a large amplitude nystagmus with linear slow phases directed toward the affected side. As gaze was changed from far contralateral to ipsilateral, the nystagmus gradually diminished to zero. When simulating partial impairment of one canal, the nystagmus was smaller in amplitude and absent in ipsilateral gaze.

Brain Stem↗
PubMed1982

Nystagmus.

In the last ten to fifteen years refinements in the registration techniques for ocular movements have allowed a more precise definition of nystagmus forms and have thus brought new insight into their pathophysiology. As a result we can distinguish four types of disturbances of the subsystem for the slow movements, which are fundamental to nystagmus. This and other discoveries also have consequences for the practical diagnostics of neuro-ophthalmological diseases. In this article, with the help of a simple practical scheme, extra attention will be given to the clinically relevant new information needed to make the diagnosis or differential diagnosis of conditions in which nystagmus is one of the most important signs.

Adult↗
PubMed1986

The influence of eye movements and tactile information on postural sway in patients with peripheral vestibular lesions.

The statokinesigram of the 16 benign paroxysmal positional vertigo (BPPV) patients and the 28 vestibular deficits (VDS) patients were analyzed in comparison with the 20 normal subjects (NS). Velocity of the track (LNG/T), root mean square (RMS), and standard deviation area (SD-Area) were used as parameters. Fourteen different tests were done. When the result for each subject group were analyzed there were interesting differences between the compensated VDS and BPPV patients and between the untreated period and the compensated stage in each patient group. Comparing the data between NS and BPPV at the compensated stage, the latter group was unstable while watching LED with OKN on the tactile information plate (S-G plate). The significant differences were for RMS and SD-Area. The data of the NS and the untreated VDS show that the latter group was more unstable while watching LED with OKN than in the dark on the S-G plate. According to the data of the NS and the VDS at the compensated stage, the latter group was more unstable during OKN or watching LED which was almost the same as in the dark on both plate conditions. And it was more unstable while watching LED than during OKN on the S-G plate. The significant differences were for velocity of body sway (LNG/T). The neural region for compensation in BPPV patients might be on the visuo-oculomotor pathway through the peripheral retina. One of the most important regions for compensation in VDS patients might be in the rombencephalic reticular formation.

Eye Movements↗
PubMed2005

Immunologic work-up study for inner ear disorders: looking for a rational strategy.

CONCLUSIONS: For the evaluation of a patient with suspected immune-mediated inner ear disease (IMIED), an exhaustive immunologic work-up study is not recommended if financial resources are limited. Analysis of antinuclear antibodies (ANA) and the immunophenotype of peripheral blood lymphocytes (PBL) proved to be the most useful tests in our population to support the clinical diagnosis of IMIED. OBJECTIVE: Owing to the lack of specific serological markers for the diagnosis of IMIED, an exhaustive immunologic work-up study for patients with suspected IMIED is usually performed. The aim of this study was to estimate the use of resources and the costs involved in the routine laboratory tests used for the diagnosis of IMIED. MATERIAL AND METHODS: This was a comparative study of two groups of patients with a high suspicion of diverse clinical forms of IMIED who were subjected to different serologic test designs. The cost of the classical immunologic work-up study used for the diagnosis of IMIED (n=125) was estimated in comparison with that of a more restricted examination, based on a recently reported high-risk profile, involving the analysis of ANA and PBL (n=57). RESULTS: The diagnostic efficiency of the two protocols was similar. The cost of a complete immunologic work-up study was 241.77 euros and that of the limited analysis was 53.12 euros.

Adolescent↗
PubMed1989

The auditory brain stem response interaural latency difference (ILD) in patients with brain stem lesions.

The ABR interaural latency difference (ILD) from 15 patients with brain stem lesions was compared to the ILDs from patients with VIIIth nerve tumors, cochlear pathology, and a normal control group. All patients in the study had to meet the criteria of bilaterally symmetrical hearing for pure-tone thresholds in order to offset the effect of hearing loss on the ILD. Although the ILDs for the brain stem lesion group were larger than for the cochlear or normal groups, they were significantly smaller than for the VIIIth nerve tumor group. It appears that the ILD is not as sensitive a measure for detecting brain stem involvement as VIIIth nerve tumors.

Adult↗
PubMed1996

Comparison of labyrinthectomy and vestibular neurectomy in the control of vertigo.

One hundred twenty-six patients who were treated with labyrinthectomy (81 patients) or vestibular neurectomy (45) between the years 1979 and 1994 were reviewed. The cause for vertigo in 124 of the 126 patients was Meniere's disease (89 patients), labyrinthitis (15), delayed endolymphatic hydrops (8), vestibular neuritis (7), and failed labyrinthectomy (5). In the remaining 2 patients, a normal labyrinth was sacrificed to fistulize a petrous apex cyst. Both procedures were equally effective in relieving vertigo (labyrinthectomy 98.8%; neurectomy 97.8%), but the length of hospitalization, length of disability before return to work, and cost were twice as great with vestibular neurectomy than with labyrinthectomy. More patients exhibited prolonged ataxia following neurectomy (5 patients) than after labyrinthectomy (2). Vestibular neurectomy was associated with several complications: reversible facial paresis (15 patients), meningitis (1), cerebrospinal fluid leak (1), and epidural hematoma (1). Labyrinthectomy was complicated by postoperative hyponatremia in 1 patient. Selective vestibular neurectomy preserved hearing in 32 (82%) of 39 patients. Criteria for recommending either ablation procedure are discussed. The incidence of sequential involvement of the contralateral ear was 1.5%.

Aged↗
PubMed1995

Control of the head in response to tilt of the body in normal and labyrinthine-defective human subjects.

1. Head movement responses to discrete, unpredictable tilts of the trunk from earth upright were studied in normal and labyrinthine-defective (LD) subjects. Tilts of the seated, restrained trunk, were delivered in pitch and roll about head-centred axes and approximated raised cosine displacements with peak amplitudes of 20-30 deg and durations of 1.5-2 s. Subjects performed mental arithmetic with eyes closed or read earth-fixed text. 2. At the onset of tilt the head momentarily lagged behind the trunk because of inertia. Subsequently, head control varied widely with three broad types: (i) head relatively fixed to the trunk (in normal subjects and some patients); (ii) head unstable, falling in the direction of gimbal tilt (typical of acute patients for pitch motion); (iii) compensatory head movement in the opposite direction to gimbal tilt (observed consistently in normal subjects and in well-adapted patients). 3. EMG was well developed in subjects with compensatory head movement and consisted of an initial burst of activity at minimum latencies of 25-50 ms (means 72-108 ms), followed by a prolonged peak; both occurring in the 'side up' neck muscles, appropriate for righting the head. These muscles are shortened during the initial head lag so the responses cannot be stretch reflexes. In normal subjects their origin is predominantly labyrinthine but in patients they may be an 'unloading response' of the neck. 4. Head stability in space was superior with the visual task for all subjects but vision only partially compensated for labyrinthine signals in unstable patients. 5. Modelling the responses to tilt suggests that, in LD subjects, the short-latency burst could be driven by signals from the neck of the relative acceleration between head and trunk tilt. The longer latency EMG could be driven by a signal of head tilt in space. Normally, this signal is probably otolithic. In patients it could be synthesized from summing proprioceptive signals of position of head on trunk with trunk tilt.

Adaptation, Physiological↗
PubMed1985

Central compensation of vestibular deficits. III. Response characteristics of lateral vestibular neurons to roll tilt after contralateral labyrinth deafferentation.

The responses of lateral vestibular nucleus (LVN) neurons to stimulation of macular labyrinth receptors have been investigated in precollicular decerebrate cats after contralateral acute vestibular neurectomy (aVN). On the whole, 78 LVN neurons were tested during slow sinusoidal tilt of the animal at the standard parameters (0.026 Hz, 10 degrees peak displacement). The neurons were located in both the rostroventral (rvLVN) and the dorsocaudal parts (dcLVN) of Deiters' nucleus, which project mainly to the cervical and the lumbosacral cord, respectively. After contralateral aVN, the proportions of responsive units in rvLVN and dcLVN (100% and 75.4%, respectively) were similar to those obtained in control experiments with intact labyrinths. However, the mean discharge rate of the responsive units slightly decreased with respect to the value obtained in control experiments, the decrease being more prominent within the rvLVN. The average sensitivity (and to a lesser extent the gain) of responses of rvLVN neurons to the labyrinth input was almost twice that of the dcLVN units in preparations with the vestibular nerves intact; these regional differences disappeared after contralateral aVN, particularly due to a decrease in gain and sensitivity of responses in the rvLVN. The proportion of LVN neurons that were maximally excited by animal position increased from 74.0% in the control experiments to 82.8%. However, while in control experiments the proportion of units excited during side-down tilt was twice as high as that of the units excited by side-up tilt, the opposite occurred after contralateral aVN; this finding affected particularly the dcLVN. In addition the average phase lead of responses relative to the extreme animal displacements slightly decreased from +12.3 degrees in control experiments to +9.4 degrees. Among the LVN neurons recorded after contralateral aVN, 35 were antidromically activated by stimulating the spinal cord at T12 L1, while 43 units were not activated. The relation found in control experiments, i.e., that the faster the conduction velocity of vestibulospinal axon the lower was the unit discharge at rest, was lost after contralateral aVN, due to a decrease in resting discharge rate of the slow neurons. This finding, coupled with the observation that slow and fast units did not show any difference in their response gain to tilt, explains why the positive correlation between axonal conduction velocity and response sensitivity occurring in control experiments was lost after contralateral aVN.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗