Nystagmus Reaction Research Articles

Screening testing and computerized vestibulometry in vestibular neuronitis

Introduction. The demonstrative example of unilateral peripheral vestibulopathy is vestibular neuronitis. This disease of infectious-toxic origin has the involvement of vestibular ganglia neurons or vestibular nerve fibers. The overwhelming moment in topic diagnostics of vestibular impairments is within-patient comparison anamnesis data and vestibulometry results. In cases of vestibular neuronitis exception of central vestibular system pathology is mandatory. Objective. To attain objectification of disequilibrium in vestibular neuronitis by means of registration and assessment of oculogyric and postural reactions. Materials and methods. Vestibular passport trials are recommended in the examination of patients with acute vertiginous complaints. Special attention has been given to the revelation of impairments of command eye movements, disturbances of ocular pursuit, spontaneous nystagmus, and catch-up saccades in Halmagyi – Curthoys test. Possible impairments of static and dynamic balance control are assessed in modified Romberg test and Unterberger test. Gaze tests with registration of saccadic and pursuit eye movements, spontaneous and optokinetic nystagmus reactions as well bithermal caloric test are carried out in computerized electrooculography and videooculography. Deviations of body gravity center are analyzed with the help of sensory organization test in computerized dynamic posturography. Results and discussion. The results of screening and computerized vestibular testing of 24 patients are presented. High diagnostic value of registration and analysis of oculogyric reactions as well as postural control signs is demonstrated in cases of acute vestibular neuronitis and acerbation of its chronic recurrent variant. The key objective symptom, which confirms peripheral level of vestibular dysfunction, is spontaneous nystagmus registration in elimination of gaze fixation. Unsteadiness in static and dynamic trials confirms the vestibular decompensation extent in acute phase of vestibular ganglia / neurons pathology in cases of vestibular neuronitis. Decompensation signs revelation of this peripheral vestibular dysfunction needs urgent medicine: possible etiotropic and obligate symptomatic therapy as well as spare vestibular rehabilitation exercises. Conclusion. Combination of oculogyric impairments and disturbances of postural control enables to improve accuracy of diagnostics in decompensated stage of vestibular neuronitis.

The effectiveness of microsurgery for Meniere's disease

Meniere's disease is a noninflammatory disease, manifested by episodes of dizziness, nystagmus reaction, vegetative disorders, static disturbances, hearing loss, tinnitus. The etiology and pathophysiology of this condition are not fully understood. However, it is based on an increase in endolymph production. To date, a large number of measures have been proposed to prevent the development of dizziness attacks. Starting from lifestyle changes, medical approaches, as well as surgical interventions. But far from always, even a combination of the above methods allows patients to reduce the number of episodes of dizziness, thereby improving the quality of life. At the Department of Otorhinolaryngology of the State Institution «Zaporizhzhya Medical Academy of Postgraduate Education of the Ministry of Health of Ukraine» microsurgical methods of treating this pathology are proposed. The operations of chordoplexusectomy and grommet of the tympanic membrane give a persistent positive clinical effect, which is confirmed in the longterm postoperative period in the observed patients.

Distinct activation of the sympathetic adreno-medullar system and hypothalamus pituitary adrenal axis following the caloric vestibular test in healthy subjects.

IntroductionThe vestibular acute stress induces reversible alert-like reactions that involve the sympathetic adrenal-medullar system and hypothalamic-pituitary-adrenal axis responses. The present study aimed to evaluate salivary α-amylase and salivary cortisol production in relation with cardiovascular reactivity induced by acute stress in healthy subjects.Material and methodsForty-eight young healthy male volunteers were examined under basal conditions and at various times after reaching the maximal nystagmic reaction following air caloric vestibular test. Heart rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were recorded at the same time as measurement of the salivary α-amylase and salivary cortisol. At the end of the caloric vestibular test session, perceived stress scale questionnaires were administered to measure the self-perceived stress impact induced by the task, and individual scores were compared with those measured on the enrollment day.ResultsFollowing caloric vestibular test-evoked vertigo, salivary α-amylase and cortisol showed distinct trends in their production after acute stress: Student’s t-test was used to compare the α-amylase vs cortisol slopes of the respective interpolated regression lines, and the difference was significant (t = -3.283; p<0.001); an increase in salivary cortisol production corresponded with a decrease in the salivary α-amylase concentration. In addition, salivary biomarker modifications were associated with consistent changes in the heart rate, systolic blood pressure and mean arterial pressure.ConclusionsUsing the air caloric vestibular test task as a stressor, the present study demonstrated a connection between the acute hormonal stress response to vestibular stimulation and cardiovascular output. However, further research is needed before we can define the potential importance of the consistent cardiovascular activity changes evoked by vestibular stimulation and the possible functional consequences for cardiovascular regulation and orthostatic tolerance in humans.

The spectrum of ocular motor abnormalities as the only clinical sign of brainstem lesions

Background The widespread use of magnetic resonance imaging (MRI) revealed an increasing variety of ocular motor abnormalities as the only clinical sign of (mainly ischemic) brainstem lesions. Methods This paper reviews the variety of such abnormalities. Results Ocular motor abnormalities as the only clinical sign of MRI-documented brainstem lesions include complete and partial 3rd, 4th and 6th nerve palsies, vertical gaze palsies, crossed vertical gaze palsy, monocular elevation paresis, internuclear ophthalmoplegia, horizontal gaze palsy, horizontal gaze palsy with facial palsy, 1 1 2 -syndrome, 1 1 2 -syndrome with facial palsy (“ 8 1 2 -syndrome”), upbeat nystagmus, horizontal-rotatory nystagmus, horizontal nystagmus, skew deviation, and ocular tilt reaction. Conclusions Brainstem lesions causing isolated ocular motor abnormalities may be divided into 4 main groups. (A) Lesions involving infranuclear ocular motor nerve segments cause complete and partial 3rd, 4th and 6th nerve palsies. (B) Lesions affecting nuclei related to eye movements such as 3rd and 6th nerve nucleus, rostral interstitial nucleus of the medial longitudinal fasciculus, interstitial nucleus of Cajal, nucleus intercalatus Staderini are followed by horizontal and vertical gaze palsies, upbeat nystagmus, horizontal-rotatory nystagmus. (C) Lesions interrupting internuclear connections lead to internuclear ophthalmoplegia, monocular elevation paresis, skew deviation and ocular tilt reaction. (D) Combined lesions of nuclear and internuclear or infranuclear structures are the anatomical basis of 1 1 2 -syndrome, 8 1 2 -syndrome, or horizontal gaze palsy with facial palsy. The clinical significance of these disorders is not known.

Ramsay Hunt syndrome

Ramsay Hunt syndrome is defined as herpes zoster oticus associated with an acute peripheral facial nerve paresis and quite often with other cranial nerve lesions. The combination of motor, sensory and autonomic involvement leads to a variety of neurological damage patterns, i. e. facial muscle paresis, hearing and balance disorders, sensory problems and disturbances of taste as well as lacrimal and nasal secretion. Additional variability of the clinical picture of Ramsay Hunt syndrome is produced by varying patterns of skin involvement explained by individual anastomoses between cranial and cervical nerves. Knowledge of these findings and an early diagnosis of Ramsay Hunt syndrome are important as prognosis of cranial nerve damage depends on the time at which acyclovir-corticosteroid therapy is started.

Comparison of Cinnarizine/Dimenhydrinate Fixed Combination with the Respective Monotherapies for Vertigo of Various Origins

Vertigo may arise from dysfunction in the peripheral and/or the central vestibular system. Simultaneous activity of a medication at both sites will serve to improve the efficacy of antivertigo treatment. The aim of this study was to compare the efficacy and tolerability of a fixed combination of the peripherally acting cinnarizine (20 mg) plus the centrally acting dimenhydrinate (40 mg) with those of equally dosed monotherapies in the treatment of vertigo of various origins. This prospective, randomized, double-blind, active-controlled, multicentre study included patients who assessed at least one vertigo symptom as being of at least medium intensity (≥2) on a 5-point visual analogue scale (VAS; ranging from 0 = not present to 4 = very strong) and who had pathological vestibulospinal movement patterns and/or nystagmus reactions. Patients were randomly assigned to receive either cinnarizine 20 mg/dimenhydrinate 40 mg as a fixed combination, cinnarizine 20 mg as monotherapy or dimenhydrinate 40 mg as monotherapy, each three times daily for 4 weeks. Patients were examined at baseline (t(0)), and after 1 week (t(1w)) and 4 weeks (t(4w)) of treatment. The primary efficacy endpoint was the decrease in mean vertigo score (MVS) at t(4w), which was calculated by averaging the total score for 12 individual vertigo symptoms, each assessed using the 5-point VAS. The study included 182 patients, of whom 177 were evaluable for efficacy. The mean ± SD reduction in MVS after 4 weeks of treatment with the fixed combination (-1.44 ± 0.56) was significantly greater than the reductions with each of the active treatments alone (cinnarizine -1.04 ± 0.53; dimenhydrinate -1.06 ± 0.56; p = 0.0001, both comparisons). Cinnarizine 20 mg/dimenhydrinate 40 mg as a fixed combination was associated with a significantly higher responder rate (78% of patients with MVS ≤0.5 at t(4w)) than the monotherapies. The odds ratios for MVS ≤0.5 at t(4w) in the cinnarizine or dimenhydrinate groups versus the fixed combination group were 0.345 and 0.214, respectively. The fixed combination reduced concomitant vegetative symptoms significantly more effectively than cinnarizine at both t(1w) (p < 0.05) and t(4w) (p < 0.01). Nine patients reported 15 adverse events (AEs) [three AEs for the fixed combination, six AEs each for cinnarizine and dimenhydrinate]. At t(4w) the tolerability of the treatments was rated as very good or good by almost all patients in all groups (fixed combination and dimenhydrinate 96.6% each; cinnarizine 98.3%). The fixed combination of cinnarizine 20 mg/dimenhydrinate 40 mg was an effective and well tolerated treatment for patients with vestibular vertigo of central and/or peripheral origin. The efficacy of the fixed combination exceeded that of each of the equally dosed active substances given as monotherapy, leading to higher responder rates, and showed a very good and comparable tolerability with a similar or even smaller rate of adverse events than the active substances given alone.

Zervikopropriozeptive Provokation von horizontalen und vertikalen Nystagmen bei Probanden

The cervico-ocular reflex (COR) has been confirmed in numerous animal experiments. On the other hand, its clinical assessment is disputed. Anteflexion and retroflexion of the head are among the main movements of the atlanto-occipital joint. We investigated whether these head movements produce neck proprioceptive stimulation in the vestibular system. We investigated 50 students under the experimental conditions of strictly cervical provocation. The trunk was rotated, anteflexed, and retroflexed into its end positions for 60 s under video-oculographic control without changing the head-space relationship. During the cervical provocation, horizontal, vertical, or rotational nystagmus within a time window of 5-30 s after the start of the provocation was detected as a target parameter. The results showed that, compared to the baseline, there was a significant increase in vertical and horizontal nystagmus after the cervical provocation. The horizontal nystagmus reaction, rather than the vertical, was increased significantly by the maximum trunk rotation. In addition, we found a significant amount of vertical rather than horizontal nystagmus under trunk flexion provocation. Under cervical provocation of test subjects, we were able to elicit horizontal and vertical nystagmus (upbeat nystagmus) via cervico-ocular roots. Due to a neck proprioceptive activation of the vestibular system we interpret our result as a "cervico-tonic provocation nystagmus".

Vestibular Neuritis and Bilateral Vestibulopathy

Vestibular neuritis is the second most common cause of peripheral vestibular vertigo. The key signs and symptoms are the acute onset of sustained rotatory vertigo without hearing loss, postural imbalance with Romberg's sign, and peripheral type nystagmus. Head thrust and caloric tests show ipsilateral hyporesponsiveness, but hearing test shows normal. Either an inflammation of the vestibular nerve or labyrinthine ischemia was proposed as a cause of vestibular neuritis. Recovery after vestibular neuritis is usually incomplete. Despite the assumed viral cause, the effects of corticosteroids, antiviral agents, or the two in combination are uncertain. Bilateral vestibulopathy is a rare disorder of the peripheral labyrinth or the eighth nerve. The most frequent etiologies include ototoxicity, autoimmune disorders, meningitis, neuropathies, sequential vestibular neuritis, cerebellar degeneration, tumors, and miscellaneous otological diseases. The two key symptoms are unsteadiness of gait and oscillopsia associated with head movements or when walking. The diagnosis is made with the simple bedside tests for defective vestibulo-ocular reflex (head thrust and dynamic visual acuity tests). Bilateral vestibulopathy is confirmed by the absence of nystagmus reaction to both caloric and rotatory chair tests. The spontaneous recovery is relatively rare and incomplete. Vestibular rehabilitation is supportive of the improvement, but the efficacy of physical therapy is limited.

The minimal ice water caloric test compared with established vestibular caloric test procedures

Caloric testing of the vestibular labyrinth is usually performed by classical caloric test procedures (CCTP) using water warmed to 30 degrees C and 44 degrees C. Ice water irrigation (4 degrees C) is usually not performed, although it might be useful as a bedside test. To verify the validity of the Minimal Ice Water Caloric Test (MIWCT), comparative video-oculographic investigations were performed in 22 healthy subjects using ice water (0.5 ml, 1.0 ml, 2 ml), CCTP, and cold air (27 degrees C). Frequency, amplitude, slow phase velocity (SPV), the onset, and the duration of nystagmus were documented. After addition of three ice cubes, the temperature of conventional tap water (16 degrees C) fell within 13 min to 4 degrees C. In pessimum position the subjects demonstrated no nystagmus response. Compared to CCTP, MIWCT was associated with a significantly later onset of nystagmus and a significant prolongation of the nystagmus reaction. In contrast to air stimulation (27 degrees C), a significant Spearman's correlation was noted between MIWCT (1 and 2 ml) and established CCTP in respect of essential nystagmus parameters (frequency, amplitude and SPV). Furthermore, MIWCT (0.5 and 1 ml) showed a higher sensitivity and specificity with regard to the detection of canal paresis based on Jongkees' formula compared to stimulation with air 27 degrees C. Thus, MIWCT appears to be a suitable procedure for bedside investigation of vestibular function outside the vestibular laboratory, e.g. in a hospital ward, where bedridden patients with vertigo occasionally require vestibular testing.

Changes In Blood Neurotransmitter And Steroid Levels During Evoked Vertigo

Experimental evidence suggests that steroids as well as various neurotransmitters are critically involved in the functioning of the vestibular system in health and disease. Yet there are no pertinent human data. We hypothesized that changes in the serum levels of cortisol and plasma levels of excitatory and inhibitory neurotransmitters may occur during evoked vertigo. Ten healthy volunteers (median age 37, range 21-57) entered the study. Subjects were investigated at rest and at the time of maximal nystagmic reaction during caloric irrigation. The determination of glutamate, aspartate, and gamma-aminobutyric acid (GABA) was performed by reverse phase high-performance liquid chromatography, whereas cortisol measurements were performed with an immunoenzymatic assay with fluorescence polarization. During evoked vertigo, cortisol levels increased from a baseline value of 11.86 (+/-1.272) microg/dl to 14.375 (+/-2.183) microg/dl (p < 0.01), whereas all neurotransmitter levels decreased significantly. Glutamate levels, for instance, fell from a resting value of 25.99 (+/-6.30) ng/ml to 17.40 (+/-5.50) ng/ml (p < 0.001), and aspartate and GABA decreased as well. Evoked vertigo is consistently associated with an increase in steroid serum levels and accompanying decreases in the plasma levels of glutamate, aspartate, and GABA. The possible underlying mechanisms and the functional significance of these findings are discussed.

Influence of Proprioceptive Signals from the Neck Muscles on the Organization of Vestibuloocular Reactions

To gain insight into the influence of the cervical proprioceptive factor on the organization of vestibuloocular reactions, the oculomotor reflexes were studied in patients with asymmetrically increased tone of the neck muscles. It was established that, in the absolute majority of these spasmodic torticollis patients, the active cervicoocular reflex (a-COR) was more intense than the vestibuloocular reflex (VOR). The a-COR was predominant in the direction to the side opposite to the forced turn of the head; i.e., when the head is turned by overcoming the force of the tense cervical muscles, the most powerful nystagmic reaction takes place.

Mechanism of posterior semicircular canal stimulation in patients with benign paroxysmal positional vertigo.

A quantitative study of the stimuli and vestibulo-ocular response associated with benign paroxysmal positional vertigo (BPPV) was made to test and further develop the canalithiasis theory of BPPV. The angular velocities of the head in the planes of the semicircular canals during the Dix-Hallpike test were measured in four healthy subjects using electromagnetic sensors to record the position of the head in a six degrees of freedom paradigm. Next, the nystagmus reactions in seven patients diagnosed with idiopathic BPPV were recorded with video-oculography. The characteristics of the vestibulo-ocular reflex (VOR) response were analyzed using three-dimensional vector techniques. The angular velocity of the head was primarily, but not exclusively, in the plane of the posterior semicircular canal (PSC) in question. Both the anterior and horizontal canals were also stimulated by a lesser degree. The duration of the motion stimulus in the PSC was <1.3 s with peak angular velocities of 150 deg/s. The eye respon...

Mechanism of Posterior Semicircular Canal Stimulation in Patients with Benign Paroxysmal Positional Vertigo

A quantitative study of the stimuli and vestibulo-ocular response associated with benign paroxysmal positional vertigo (BPPV) was made to test and further develop the canalithiasis theory of BPPV. The angular velocities of the head in the planes of the semicircular canals during the Dix-Hallpike test were measured in four healthy subjects using electromagnetic sensors to record the position of the head in a six degrees of freedom paradigm. Next, the nystagmus reactions in seven patients diagnosed with idiopathic BPPV were recorded with video-oculography. The characteristics of the vestibulo-ocular reflex (VOR) response were analyzed using three-dimensional vector techniques. The angular velocity of the head was primarily, but not exclusively, in the plane of the posterior semicircular canal (PSC) in question. Both the anterior and horizontal canals were also stimulated by a lesser degree. The duration of the motion stimulus in the PSC was <1.3 s with peak angular velocities of 150 deg/s. The eye response in BPPV patients began 4 s after the test and had a duration of 15-20 s. Peak slow-component eye velocities of about 42 deg/s were reached 3-5 s after onset of nystagmus. The motion of the eye, as predicted by the cupulolithiasis theory, is disconjugated and has torsional, vertical, and horizontal components. In the eye ipsilateral to the tested ear it is primarily torsional (0.80, 0.54, 0.16) and in the contralateral eye it is mainly vertical (0.57, 0.73, 0.08). These results suggest that particles, initially resting on the floor of the cupula dome in the PSC, are perturbed by the Dix-Hallpike test and disperse freely into the endolymph where they are propelled by gravity into the canal lumen. This creates abnormal pressure on the cupula and the specific VOR activation of the ipsilateral superior oblique and the contralateral inferior rectus muscles, whose force vectors are indistinguishable from the measured eye motion vectors. The estimated pressure exerted on the crista is approximately 10-2 dyn/cm2.

The effect of age on inhibition of visual fixation of the rotatory-induced nystagmus reaction

The interactive functions between sensory systems show changes that depend on the development of the growing body. Important conditions for the development of the visual suppression of vestibular evoked nystagmus reactions are the maturation of the visual system, the presence of a functioning vestibular system and close connections between both systems. Response to vestibular, visual and combined vestibular and visual stimulation does not only change during early childhood. We have also learnt from studies of adults of different ages that there are characteristic changes in nystagmus reactions to vestibular stimulation, in optokinetic reactions and in vestibular-spinal functions during the whole period of life. 272 randomly selected neuro-otologic routine patients aged between one year and four months and eighty-eight years and ten months were included in the study to analyse age-related changes of visual suppression during rotatory stimulation. The rotatory stimulation consisted of an sinusoidal stimulus pattern with amplitudes of +/- 180 degrees and a period duration of 20s. The vestibular stimulation was performed in total darkness and with a visual target which was attached to the chair in front of the patient's eyes. The results of this study demonstrate that the amplitudes of nystagmus reactions, evoked by sinusoidal harmonic acceleration, can be quantitatively suppressed by visual fixation. The degree of suppression depends on age. The fixation indices provide the ability to measure the degree of this suppression in percent. The trend to better fixation suppression increases up to the end of the age of forty. The ability to suppress vestibular nystagmus decreases, however, after reaching the fortieth year of life. The analysis of smooth pursuit shows after the sixtieth year of life a continuous rise in the number of saccades with increasing age. These changes are caused by aging processes in cerebral tissues which lead to functional changes e.g. in the interactive functions between sensory systems.

垂直半規管刺激性回転検査 正常耳での回転後眼振の観察

We developed a new type of rotatory chair system to examine vertical semicircular canal-stimulative postrotatory nystagmus in normal ears. The subjects sat on the rotatory chair with their heads and backs tilting backward 60 from the vertical line, and their heads at 30°, 45°, or 60°to the plane of rotation. The rotation was performed with an initial acceleration of 10°/sec 2 for 10 sec and a terminal acceleration of 100° or 180°/sec 2 following a period of constant velocity for 20 sec in each position with either clockwise or counter-clockwise rotation. In this position, we were able to examine isolated excitatory single canals for all four of the vertical semicircular canals. The postrotatory nystagmus was analyzed with an infrared video recording system. There were no remarkable differences in the maximum slow phase eye velocity and the duration of postrotatory nystagmus between terminal acceleration of 100°/sec 2 and that of 180°/sec 2. Moreover, there were no obvious differences in the balance of nystagmic reactions, after stimulative rotation for the anterior or posterior semicircular canal, between the left and the right sides.However, the degree of postrotatory nystagmic reaction in each posterior semicircular canal was usually much more than that in each anterior semicircular canal in most normal subjects.

Ａｆｔｅｒｎｙｓｔａｇｍｕｓをめぐる問題の序

Afternystagmus, the concept of which has not yet been clearly defined, may be interpreted as a phenomenon which fits in phase II, or the reversal phase, of experimentally-induced nystagmus such as rotational or postrotational nystagmus or caloric nystagmus, in addition to optokinetic afternystagmus and its reversal phase and headshaking (after-) nystagmus including the reversal phase. A feature common to these phases of nystagmus may be the appearance of a temporary nystagmic reaction following, either immediately or after a definite interval of time (“latent period”), the elimination of an optokinetic stimulus or a physical vestibular stimulus that induces deviation of the cupula and then following the subsequent disappearance of excitement of the peripheral sensory organs, i.e., optic organ and vestibular labyrinth, that respond to these stimuli. Afternystagmus in this sense has never been generalized and the phenomenon may not actually be so simple. A panel discussion of this phenomenon and the neural mechanisms involved was held at the 51st Annual Meeting of the Japan Society for Equilibrium Research, which opened in Maebashi, Gunma prefecture on November 7, 1992

Nystagmus reactions after rotatory vestibular stimulation (modified Veits extended rotation method) in patients with normal equilibrium. Part II: Directional preponderance in nystagmus reactions

Based on the absolute values of the different nystagmus reactions, measured after having used the rotational test on 70 healthy subjects, the directional preponderance (DP) was calculated in the present study according to the equation of Jongkees and Philippszoon. It could be shown that a DP of less than +/- 30% can be regarded as a normal standard only if it refers to the summarised nystagmic reaction of the per- and first postrotatory phase (Per+PI) of the test. Depending on the different parameters (frequency, amplitude or slow phase velocity of the nystagmus reactions), higher standard values have to be accepted for the different phases of the rotational test. The differentiation between healthy persons on the one hand and patients with an acute loss of vestibular function on the other can be best achieved by evaluating the nystagmographic reactions via the amplitude. Summing up, the modified rotational test also proved to be a very sensitive method in follow-up examinations of patients with vestibular lesions to differentiate between acute and compensated or regenerated stages of the disease.

Nystagmus reactions after rotatory vestibular stimulation (modified Veits long-term rotation) in patients with normal equilibrium. Part I: Absolute values of the nystagmus reactions

In this study the nystagmographic findings of 70 healthy subjects--obtained after having used the rotatory test (modified method of Veits)--are summarised and visualised by means of easily appreciated graphs. In accordance with the recommendations of the ADANO, the test was carried out as a continuous turning of the chair, first clockwise and then counterclockwise, with an accelerating stimulus of 3 degrees/s2 and a sudden stop after a period of constant rotation with a speed of 90 degrees/s (trapezoidal stimulus). This was done for the absolute values of the following nystagmus parameters: frequency, amplitude and slow phase velocity of the nystagmus reaction. The limits of a normal nystagmus reaction are evaluated by the 5%- or 95%-percentiles on the one side and the mean values combined with the standard deviation mean value +/- 2 standard deviations on the other. It is shown that the rotatory test with its different phases enables very sensitive selection between healthy subjects and patients with an acute peripheral vestibular lesion. The intraindividual variability of the nystagmus reactions proved to be lower than that between our control persons (interindividual variability). By our method of employing the rotatory test it can be shown that the interfering phenomenon of habituation does not influence the nystagmographic results.

The temporal course of nystagmus reactions after rotational stimulation (modified Veits long rotational method). Part II. Recommendations for the simplification of nystagmus evaluation in the rotational test

In this study, on the basis of the graphics showing the time course of the nystagmus reactions following rotatory stimuli (Part I), some practical proposals are made on how the nystagmus responses following the rotatory test can be routinely analysed more quickly. The recommendations are oriented to the requirement that the selection of defined 30-second-intervals during the per- and postrotatory phase for the nystagmus analysis should reflect the total reaction in healthy subjects as well as in patients with acute vestibular lesions in a representative manner. It is also shown that reducing the analysis intervals to only 15 seconds or selecting unfavourable segments, can lead to an unacceptable falsification of the results.

Time course of nystagmus reactions after rotational stimulation (modified Veits long rotation method). I. Comparison of the nystagmus reactions of probands with normal equilibrium with those of patients with vestibular disorders

In the present study, all the nystagmus reactions following the rotatory test are represented graphically after being split up into successive time intervals of 5 seconds each. The range of reactions is illustrated by comparing healthy subjects with patients with acute lesions of the vestibular system. It has been shown that during the rotatory test no signs of habituation were to be seen. The use of the parameter "fast phase velocity" (FPV) of the nystagmus to analyze the nystagmus reactions did not prove meaningful. In particular the findings in patients with acute vestibular lesions show that the nystagmus reactions following rotatory stimuli of appropriate intensity increase only to a limited extent. When interpreting the results, the influence of spontaneous nystagmus which usually underlies acute vestibular disease, is discussed in detail.