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At least 127 records · Page 7Linked to original sources

Extent of reaction capacity of the vestibulo-ocular reflex.

On theoretical grounds, a high capacity of the vestibulo-ocular reflex, compensating for head velocities above 300 degrees/s, is assumed. However, in man the maximum eye speed, induced by solely vestibular stimuli, is only 100 degrees/s. With the usual clinical tests is seems impossible to get a sufficient strength of stimulus that would correspond to a strong physiological stimulus. With a systematic investigation with fistula symptoms finally a patient was found with an ideal mechanism of release of the fistula symptom. The maximum eye speed of the compensatory phase was 315 degrees/s. In this case, the vestibular phase was quicker than the so-called rapid phase. This now proven high reaction capacity constitutes the "missing link" between the hypothetical high capacity of the systems concept and the until now measured, only limited reactions after solely vestibular stimulation. For most physiological stimuli, i.e., quick head movements, the system can act as a simple reflex organ, being a velocity transducer with linear function thus successfully maintaining ocular fixation.

Aged↗

[A factor analysis of cochleovestibular findings. (author's transl)].

Using the variables auditory threshold, speech audiometry, SISI, ABLB, stapedius reflex, Carhart-test, Békésy audiometry and calorization three factors could be extracted: 1. The quality of peripheral speech-coding in combination with central processing; 2. the degree of damage of the inner ear (threshold, distance between hearing-threshold and reflex-threshold, SISI and calorization); 3. a retrocochlear factor. SISI and ABLB are both tests concerning the inner ear, but must be regarded separately as it is to be supposed that these two findings are caused be two different pathologic processes.

Audiometry↗

Inner ear pathology associated with Reye's syndrome.

Severe pathological changes were observed in the inner ear tissues of a 2-month-old patient who died of Reye's syndrome after 5 days of hospitalization. In the organ of Corti, the inner hair cells appeared to be more severely damaged than the outer hair cells. Various degrees of degeneration were observed in all non-sensory epithelial cells lining the cochlear duct. In most turns of the cochlear duct, Reissner's membrane was ruptured and/or collapsed onto the organ of Corti. Likewise, both sensory and non-sensory cells of the vestibular end organs were markedly degenerated. These observations suggest that the inner ear tissues are acutely affected in patients with Reye's syndrome, and that the changes may cause impairment of hearing and/or equilibrium in patients who recover.

Acoustic Maculae↗

Vestibular suppression in peripheral and central vestibular disorders.

Caloric tests have been carried out both in the presence of optic fixation and in total darkness upon normal subjects, patients with peripheral vestibular disorders and patients with central vestibular lesions. Nystagmic responses were recorded electronystagmographically and measurements made of latency and duration of response, maximum slow component velocity and beat frequency. The relative enhancement of the response in darkness is expressed as a fixation index: maximum slow component velocity in darkness maximum slow component velocity with fixation. Compared to the normal group the peripheral group were found to have abnormally high fixation indices, the central group abnormally low. A hypothesis has been developed of the nervous mechanisms underlying the suppressive effects of optic fixation in both peripheral and central lesions which accords well with the available clinical, anatomical and physiological data. The clinical implications of the findings are discussed both in respect of their localizing value and relevance to current innovations in the design of caloric tests.

Brain Neoplasms↗

Visual postural performance after loss of somatosensory and vestibular function.

Visual stabilisation of body sway in a patient with severe deficits of the vestibular system (due to gentamicin treatment) and the somatosensory system (due to polyneuropathy) was studied. With eyes open the patient was able to stand and walk slowly. With eyes closed he lost balance within one second. In order to optimise visual stabilisation he intuitively searched for nearby visual targets. His postural sway was recorded using posturography. His balance performance deteriorated significantly beyond a distance of 1 m between the eyes and the surrounding objects and with visual acuity below 0.3 (experimentally achieved with semitransparent plastic foils). With flicker illumination of decreasing frequencies of the visual surround he needed at least a visual input rate of 17 Hz in order to maintain an upright body position. The data provide clinical evidence for rapid visuo-spinal control of posture.

Adult↗

Flunarizine and cinnarizine as vestibular depressants. A statistical study.

The authors analysed the vestibular depressant activity of flunarizine and cinnarizine, as compared to a placebo, in 58 patients with peripheral labyrinthine disorders. The activity of the medications was judged by the reduction of the average velocity of the slow phase of the post-caloric nystagmus, before and after treatment. In spite of being administered in a smaller dosis, flunarizine appeared to have a more intense vestibular supressant activity, as judged by different statistical tests.

Caloric Tests↗

Vestibular habituation training and posturography in benign paroxysmal positioning vertigo.

A number of cases with typical positioning vertigo (BPPV) show a unilateral vestibular hypofunction (UVH) by caloric testing. However, treatment by habituation exercises (VHT) improves vertigo independently of the presence of UVH. Moreover, VHT has no influence upon the results of caloric and rotation tests. These findings prove the independence of the pathogenetic mechanisms of the peripheral vestibular disturbances UVH and BPPV.

Caloric Tests↗

Hearing impairments and vestibular abnormalities among children with subclinical cytomegalovirus.

This paper strengthens the importance of neonatal screening in the early identification and etiological specification of hearing loss by demonstrating that subclinical cytomegalovirus (CMV) is the most common viral agent causing sensorineural hearing loss (SNHL) among pediatric patients. Consequently, if hearing impairment is found on neonatal screening, viral studies should be done at once. In addition to a survey of previous literature, these points are presented from a retrospective study of 14 children with SNHL caused by focal CMV. Moreover, vestibular studies are presented which suggest that hearing and vestibular impairments may operate independently of one another or conjointly in patients infected with CMV.

Adolescent↗

Cochlear implant versus vestibular stimulation. Communication.

Results obtained with cochlear electrode implants in totally deaf patients indicate that this means of transmitting auditory information can be of great help in lipreading and remote sound contact. However, using an alternate approach involving fenestration of the labyrinth and acoustical stimulation of the vestibular nerve, we generated a signal in an animal model superior in quality to that generated by electrical stimulation of the cochlea of the cat. This communication raises the question of whether a vestibular signal could be processed so that a deaf person could hear and identify sounds.

Acoustic Stimulation↗

Primary intravestibular lipoma.

An intravestibular lipoma was discovered during destructive surgery for disabling vertigo in a case diagnosed as delayed endolymphatic hydrops. The author recommends that in cases that resemble Meniere's disease but have unusual symptoms, the existence of other lesions within the inner ear should be suspected.

Adult↗

The incidence and significance of the Tullio phenomenon in man.

The purpose of this study was to investigate the incidence and significance of the Tullio phenomenon in a group of human subjects. The subjects included 40 patients with complaints of auditory or vestibular symptoms. Ten otologically normal subjects were included in the study as a control group. All subjects underwent routine audiologic evaluation as well as electronystagmogram (ENG) testing. All subjects were then tested for the presence of the Tullio phenomenon by the method described. The results of this study showed that of the 40 subjects with known auditory or vestibular disorders, 90% (36) demonstrated nystagmus in response to high-intensity sound stimulation. All patients in the otologically normal control group demonstrated the presence of the Tullio phenomenon. No specific correlations were made between the presence of the Tullio phenomenon and specific audiologic or ENG findings. Studies on the effects of sound on the vestibular system are reviewed and lend support to the finding that the Tullio phenomenon may be a normal physiologic response in man under certain test conditions.

Acoustic Stimulation↗

Effects of droperidol in management of vestibular disorders.

The chemo-therapy of vestibular disease has involved a wide spectrum of pharmacological agents insofar as their mode of action is concerned. In our experience, however, droperidol is one pharmaceutical agent which is remarkably effective in depressing vestibular disturbance regardless of etiology. This medication (also called Inapsine) belongs to a relatively new class of compounds known as butyrophenones and its pharmacological action can best be described as a dopa blocking agent. The activity of droperidol on the nervous system first became evident when it was used in combination with the potent analgesic fentanyl citrate in order to produce an anesthetic condition that has been termed neuroleptanalgesia. This mixture (also called Innovar) is rapid in action and results in complete suppression of vestibular activity of both normal subjects and those with Ménière's disease as described by Dowdy, et al., in a preliminary report. These impressive results have prompted us to evaluate the effectiveness of this medication in the treatment of different disorders of the labyrinth. The patients chosen for evaluation were referred for vestibular examination at the Toronto General and St. Michael's Hospitals. Electronystagmography was used to record objectively the effects of the drugs being tested while subjective symptoms including side effects were also noted. These studies involved 20 patients receiving Innovar while 12 patients were tested with Inapsine. Innovar administered in a single dose (droperidol 5 mg, fentanyl 0.1 mg) to patients undergoing acute episodes of vestibular disease (vestibular neuronitis and Ménière's disease) was found effective in the following symptoms and/or signs: nausea, vertigo, nystagmus, the positive past-pointing test and the Romberg test. Innovar appeared to be effective in the amelioration of vomiting although the population was too small to demonstrate statistical significance in this regard. The drug mixture appeared to have no effect on improving auditory acuity and had no significant effects on tinnitus. Adverse reactions to the drug combination were unusual, and, occurring in three patients, were mild as manifested by drowsiness. Since the above findings confirmed the marked effectiveness of the fentanyl-droperidol mixture in the management of vestibular disease, it was decided to determine the relative effectiveness of the droperidol component alone and this was determined by comparing the effectiveness of the drug with placebo in a double-blind study. Review of our findings involving this double-blind study indicates significant responses to Inapsine. This therapy clearly provided the statistically significant response (p less than 0.1, Fisher's Exact Test). This was particularly apparent at the 60-minute evaluation point. While some of the patients receiving Inapsine had recovered earlier, by 60 minutes none of the placebo patients but all of the Inapsine patients had recovered from the vestibular symptoms of Ménière's disease...

Acute Disease↗