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At least 883 records · Page 49Linked to original sources
PubMed1983

Vestibular asymmetry. Some theoretical and practical considerations.

Pathological vestibular asymmetry can be divided into static and dynamic types. Static asymmetry results from a unilateral change of the resting neural input. Acute, chronic, and recovery stages can be recognized if one interprets the direction and intensity of the resultant spontaneous nystagmus relative to the clinical picture. Static asymmetry is additive with induced asymmetry and manifests itself as directional preponderance or as the direction-fixed or direction-changing feature of positional nystagmus. Dynamic asymmetry refers to abnormal asymmetry induced by normal head movements. For example, with unilateral hypofunction, a greater gain is observed with head movement toward the unaffected side, suggesting nonlinearity as specified by Eswald's second law. Visually induced vestibular asymmetry is a form of dynamic asymmetry generated by convergence of visual-vestibular information, and causing symptoms in certain "motion-active" visual environments.

Eye Movements↗
PubMed1988

Venous communications of the cochlea after acute occlusion of the vein of the cochlear aqueduct.

The vein of the cochlear aqueduct (VCAQ) is the principal drainage vein of the cochlea in the guinea pig. Morphological observations of the VCAQ and its adjacent structures were made by studying serial sections of the cochlea. We detected the presence of two collateral vessels from the mucoperiosteal veins of the middle ear which communicated with the VCAQ. Following acute occlusion of the VCAQ, marked dilatations of these vessels were observed in corrosion cast preparations. Our findings suggest that these vessels act as collateral veins following acute venous congestion of the inner ear.

Animals↗
PubMed1976

Adverse reactions to short-course regimens containing streptomycin, isoniazid, pyrazinamide and rifampicin in Hong Kong.

Three studies of drug toxicity were made in Chinese adults with pulmonary tuberculosis admitted concurrently to short-course antituberculosis regimens. The first was of streptomycin plus isoniazid plus pyrazinamide given daily (SHZ regimen), three times a week (S3H3Z3 regimen) or twice a week (S2H2Z2 regimen). The second was of pyrazinamide in the SHZ regimen and PAS in the standard daily combination of streptomycin plus isoniazid plus PAS (SPH regimen). The third was of the SHZ regimen and these 3 drugs plus rifampicin daily (SHRZ regimen). In study 1 (174 SHZ, 185 S3H3Z3, 182 S2H2Z2 patients), the incidence of arthralgia was associated with the number of doses per week (P less than 0.001). The incidence of other reactions, most of which were cutaneous or vestibular, or symptomless increases in the serum alanine transaminase (AIT) concentration, was similar on all 3 regimens. In study 2 (142 SHZ, 137 SPH patients), hepatic reactions occurred on the SHZ but not on the SPH regimen (P less than 0.002), serum AIT concentrations were distributed over a higher range on the SHZ regimen, and 2 patients had jaundice. Gastrointestinal reactions were more frequent on the SPH regimen (P = 0.06). Arthralgia was commoner on the SHZ regimen (P less than 0.05). In study 3 (38 SHZ, 41 SHRZ patients), the incidence of hepatic reactions, jaundice and arthralgia was similar in the 2 regimens. On the pyrazinamide regimens combined, hepatic reactions were marginally more frequent in patients with Australia antigen or antibody either before or during chemotherapy (P = 0.09). Serum uric acid concentrations were higher in patients on daily than on intermittent pyrazinamide (P less than 0.005), and in patients with arthralgia on the daily pyrazinamide regimen than in matched controls (P = 0.07).

Aminosalicylic Acids↗
PubMed1984

The vertical vestibulo-ocular reflex and ocular resonance.

A technique is described for the measurement of retinal image motion under conditions of forced angular vibration of the head in pitch at frequencies between 10 and 100 Hz. The experimental technique has been used in nine normal subjects, and in two subjects with vestibular dysfunction; one with unilateral, the other with bilateral deficit. Eye movements compensatory in phase were recorded at frequencies between 10 and 25 Hz in all normal subjects. The ratio of angular retinal image motion to angular head motion (ocular gain) over these frequencies was in the range 0.82-0.94. When the head was vibrated at frequencies above 30 Hz angular motion of the retinal image exceeded that of the head and showed progressive phase delay. Ocular gain reached a peak of 3.0 at 70 Hz and a less clearly defined peak of 1.3 at about 35 Hz. These findings are suggestive of mechanical resonances within the orbit, possibly involving intra-ocular structures.

Adolescent↗
PubMed1982

Variability and habituation of nystagmic responses to hot caloric stimulation of normal subjects. Evidence that this test may be inapplicable to monitoring drug-induced vestibular toxicity.

Experiments were performed on 25 otoneurologically "normal' subjects to evaluate the hot caloric test as a screening test for aminoglycoside vestibular toxicity. Using portable equipment under non-ideal conditions, it was found that there was a large inter-subject variability in nystagmic response and that, instead of a random test-retest variability, a systematic variation in response occurred on repeated caloric stimulation with water at 44 degrees C. A response decline (habituation) evident in both the maximum slow phase velocity and the maximum frequency occurred at second test, although the inter-test interval ranged from 24 to 72 hours. After a 3-month interval with no intervening tests, the mean value of the maximum frequency reverted back to the original level. However, there was still a significant reduction in maximum slow phase velocity at this time. Some individuals had a sustained reduction in both parameters. Hence it is concluded that the hot caloric test, used under the conditions described in this study, is not a suitable serial screening method for aminoglycoside vestibular toxicity. The reproducibility of this test under other conditions, or any other caloric test, should be established in normal subjects before employing it as a serial screen for aminoglycoside vestibular toxicity.

Adult↗
PubMedDate not supplied

Adaptation of the acoustic reflex.

Acoustic reflex adaptation is reviewed in normal and abnormal auditory systems. The measurement variables affecting the acoustic reflex threshold are discussed with reference to the intensity level above reflex threshold at which the adaptation is measured. The effects of the activator frequency and activator intensity level on the time course of normal reflex adaptation are reviewed. The diagnostic application of acoustic reflex adaptation is discussed with reference to the different definitions of abnormality found in the literature. The acoustic reflex patterns, including absence, threshold, and adaptation of the reflex, are reported in patients with different degrees of hearing loss, in order to identify the false-positive rates associated with cochlear hearing losses. Finally, the diagnostic accuracy of acoustic reflexes is discussed in subjects having lesions of the CNVIII, brain stem, CNVII, and neuromuscular systems. In summary, a method is advocated for measuring acoustic reflex adaptation over 10 seconds, which allows analysis at both 5 and 10 seconds. Further research is needed on procedural variables including activator intensity level and ipsilateral recording methods, which may increase the diagnostic accuracy of acoustic reflex adaptation.

Adaptation, Physiological↗
PubMedDate not supplied

CT cisternography in congenital perilymphatic fistula of the inner ear.

Perilymphatic fistulas of the inner ear constitute abnormal leaks of perilymphatic fluid into the middle ear or mastoid air cell system and represent a rare cause of otorrhea. We report the case of a 5-month-old child presenting with sudden otorrhea. High resolution CT cisternography showed a malformation of the middle ear and a passage of contrast-enhanced CSF into the tympanic cavity through the left oval window. Surgery confirmed a tear of the tympanic membrane as well as a stapes malformation with aplasia of the crura and an associated perilymphatic fistula through a defect in the stapes footplate. The fistula was closed with adipose tissue from the ear lobe.

Cerebrospinal Fluid Otorrhea↗
PubMed1985

Late onset multiple sclerosis. A clinical study of 16 pathologically proven cases.

In 70 pathologically proven MS cases, we found 16 cases with onset after 45. Sex ratio (3/1) was the same in the late onset cases and early onset control group. There was no positive family history of MS. The diagnosis was more frequently never considered in late onset cases (3/16) than in control cases (3/54). Mean duration of the disease was 8.6 +/- 6 years (8.1 +/- 6 in female patients). This was significantly shorter (P less than 0.05) than in the control group. In addition, in remittent-progressive courses and in progressive courses, it appeared that the duration of the disease was shorter in late onset MS - although this was not statistically significant. Progressive courses (8 cases) and acute courses (4 cases) were more frequent (P less than 0.05) than in control cases. Initial signs and symptoms were not significantly different from those of control cases. The length of the evolution of the disease was higher in cases with vestibular-cerebellar onset. New signs and symptoms occurred at the same rate in the late onset cases as in the control cases. Although motor, sensory and bladder disturbances were more frequent in the late onset cases than in the control cases, this was not statistically significant. Amyotrophy was more frequent in late onset MS; on the contrary optic neuritis, vestibulo-cerebellar disturbances and nystagmus were less frequent in late onset MS than in the control group (P less than 0.05).

Brain↗
PubMed1978

Electronystagmographic criteria in neuro-otological diagnosis. 2. Central nervous system lesions.

Direct current electronystagmographic recordings of spontaneous nystagmus in light, in darkness, and with eye closure have been carried out on (a) 33 patients with acoustic neurinomata pressing on the brain stem, and (b) 10 patients with lesions involving the brain stem at a high level. Patterns of response characteristics of each group have been identified in 21 out of 28 cases of group a, the spontaneous nystagmus present in light was abolished by eye closure and inhibited in darkness, nystagmus being absent in the remaining five; in group b the greater proportion (70-80%) of patients presented with spontaneous nystagmus in light which was abolished by both eye closure and darkness.

Aged↗