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Biomedical subjects

J Thell

Publications and source records attributed to J Thell.

6 recordsLinked to original sources
PubMed1988

Artifacts in electronystagmographic recordings.

Electronystagmography is an important part of the otoneurological investigation. It is mandatory that it is performed in an efficient way, avoiding the many pitfalls and sources of error that the method entails. High quality results crave that the patient is well informed and motivated, relaxed and not under the influence of tranquillizers, hypnotics or alcohol. The technician should be familiar with the equipment, in order to avoid mistakes concerning shielding, time constant and filtering. The most common errors, however, tend to appear in the patient-equipment contact, i.e. the electrodes. A thorough preparation of the skin and high quality Ag/AgCl electrodes and use of electrolyte paste are necessary.

Electrodes↗
PubMed1988

Vestibular and audiologic functions in gentamicin-treated Menière's disease.

Fifteen patients with disabling Meniere's disease were treated with local intratympanic administration of gentamicin once daily. They had suffered from frequent attacks of vertigo and vomiting, the hearing in the affected ears was decreased permanently, and spontaneous nystagmus was observed. The number of treatment days ranged between 3 and 11. Follow-up time was 1 to 6 years. For evaluation of the treatment, audiologic and vestibular examinations were used, including the broad frequency-band rotatory test (0.4-4.5 Hz). Fourteen patients were free from vertigo after treatment. In 5 patients, there was an increased hearing loss, and in 10 it remained unchanged. Tinnitus and fullness sensations were diminished. After treatment, all ears were unresponsive to caloric stimulation. The clinical examination and rotatory testing in light with sinusoidal stimulation revealed good central compensation of the vestibular loss. However, with pseudorandomized oscillations in darkness, the broad frequency-band rotatory test quantified the loss of peripheral vestibular function and was able to detect the side of the lesion in eight of nine patients.

Administration, Topical↗
PubMedDate not supplied

The effect of stimulus predictability and age on human tracking eye movements.

Human tracking eye movements were recorded in healthy volunteers of varying age. The target motion was either predictable (pure sinusoids or sinusoidal frequency sweep) or unpredictable (pseudorandomized). Gain and phase values for the tracking and the smooth pursuit eye movement signal were calculated as a function of target frequency from 0.2 to 2 Hz. Max. target velocity was 20 or 40 deg/sec. In the low frequency area the smooth pursuit gain for predictable stimulation was higher than the gain elicited by the pseudorandomized stimulation. In the high-frequency area, gain values did not differ significantly. For the predictable stimulation, the phase of the smooth component was always a lag, increasing with increasing frequency. At low frequencies of the pseudorandomized signal a phase lead was observed. At higher frequencies the lead turned into a lag that was greater than for the predictable stimulation. The young and old groups showed reduced smooth pursuit gain values, compared with the main group specially when the target waveform was pseudorandomized. The reduced smooth pursuit ability was mostly compensated for by an increased amount of saccades.

Adult↗
PubMedDate not supplied

Vestibulo-oculomotor disturbances in trigeminal neuralgia and hemifacial spasm.

Patients with hemifacial spasm and trigeminal neuralgia later treated with microvascular decompression and surgical interposition for their vascular loop disturbance were investigated preoperatively with electronystagmography, saccade test and audiometry. Some of them underwent an extended investigation including computerized broad-frequency rotatory test with visual suppression and a computerized smooth pursuit test, both tests using sinusoidal as well as randomized movement patterns as stimulus. The patients showed a high frequency of vestibulo-oculomotor disturbances indicating that the vascular loop, in addition to pressure on the trigeminal and facial nerves, also exerted pressure on the statoacoustic nerve and/or the brain-stem. It can be deduced that the vascular loop may give purely VIII nerve disturbances treatable with surgery, the problem being, however, to establish the diagnosis.

Audiometry, Pure-Tone↗
PubMedDate not supplied

Otoneurological findings in psycho-organic syndrome caused by industrial solvent exposure.

Nine subjects with long-term (8-30 years) occupational exposure to industrial solvents and a confirmed diagnosis of psycho-organic syndrome (POS) have been studied with audiological and otoneurological test batteries. The results were compared to a matched control group of nine industrial workers not exposed to solvents and to normal data from healthy volunteers. In the clinical examination, the Romberg test identified 5/9 workers as pathologic and concurrently the stabilometry showed significantly larger sway areas in the POS-group. In the audiological test battery, the significantly pathologic tests were discrimination of interrupted speech and evoked cortical responses to frequency glides (CRA-delta-f). The saccade test disclosed abnormal findings in 5/9 workers. In the smooth pursuit test, abnormality was found at some test frequencies using pseudorandomized stimulus. The VOR-suppression test was significantly abnormal at all test frequencies. The test battery used strongly indicates CNS lesions due to industrial solvents.

Adult↗