The Effect of Repetition on Measurements of Post‐rotational Turning Sensation and Nystagmus in Man

Abstract

The effects of repetition on the post-rotational turning sensation and nystagmus obtained after deceleration from constant angular velocities are described. In a first series of tests decelerative stimuli from constant angular velocities of 60, 30, 15 and 7-50/sec. were given to two groups of subjects but in a different order, and the mean responses obtained from both groups showed that habituation might occur in the course of a single test.In a second series with a different group of subjects, the test was repeated on each of nine consecutive days. The effects of habituation were again seen and there was a progressive decline in the responses which were obtained. The administration of l-hyoscine (0 7 mg. base) 1 hr. before the test on the sixth day produced little additional effect in habituated subjects.POST-ROTATIONAL turning sensation and nystagmus may be readily elicited in the normal individual by sudden deceleration from a constant angular velocity using a turning chair or similar device. This test of labyrinthine function was first described by van Egmond, Groen and Jongkees [1948] and called by them 'Cupulometry' because the measurable responses produced by such impulsive decelerations are caused by the deflection of the cupulae of the horizontal semi-circular canals by the momentum of the endolymph. It was intended for clinical use as a substitute for the Barany test because it allowed the stimulus response relationship of the end organ to be determined with 'physiological' stimuli, which were said to lie between 3 and 600/sec.The duration of the post-rotational turning sensation elicited by the chosen decelerative stimuli was reported by the subject, and the duration of the nystagmic response was estimated directly by an observer in the turning room. According to Hulk and Jongkees [1948] plots of the duration of turning and of the duration of nystagmus against logarithm of turntable speed were linear for impulses of between 3 and 60°/sec.However, in constructing plots of the mean sensation and nystagmus 'cupulogram', Hulk and Jongkees did not give the individual points from which the graphs were derived, nor did they give estimates of scatter. They expressed their results as 'slope values' (1I/l) using a formula developed by Groen and quoted a mean of 7 sec. (range 5-16) for turning sensation and of 11 (range 6-24) for nystagmus. Further, they took the intercept on the abscissa as indicating the threshold of the individual both for subjective turning sensation and for nystagmus, giving a mean of 2-50/sec. for turning sensation (range 0-75-5), and of 8 for nystagmus (range 5-30). The values * This work was carried out with the aid of a grant from the Clinical Studies

SOME EFFECTS OF l‐HYOSCINE HYDROBROMIDE ON POST‐ROTATORY SENSATION AND NYSTAGMUS IN MAN

“…Although later experiments [Brand, 1968] have indicated that the relationship between stimulus and response over the range of impulse intensities used in this test is not exponential for all subjects [Hulk and Jongkees, 1948], the mean values obtained in the present experiment gave a reasonable approximation to a simple exponential. As our interest lay in the effect of hyoscine on the overall stimulus response relationship, it was considered justifiable to calculate the linear regression equation of duration of after-sensation against log.…”

Physiological Postrotatory Nystagmus

“…There are also several studies performed in man [3,4,13,15,17]. However, the results are not as concordant as in animals.…”

Vestibular Dysfunction and Psychopathology

“…For example, galvanic nystagmus has a small amplitude, low frequency, and short duration; thus it is difficult to observe with the naked eye (Toglia 1976). The recent development of highly sensitive recording methods, such as photoelectric nystagmography (PENG), however, has increased the clinical value of this form of vestibular examination (Henriksson et al 1972;Pfaltz 1970;Sekitani and Tanaka 1975;Gabersek and Jorbert 1965), and the characteristics of normal reactions are now more firmly established (Breson, Elberling, and Fangel 1971;Njiokiktjien and Folkerts 1971;Henriksson et al 1972;Weiss and Tole 1973). Under certain conditions, galvanic test results can distinguish neuronal lesions from end-organ lesions (Pfaltz and Koike 1968;Henriksson et al 1972).…”

“…Indeed, maximum SES (MSES), the speed of the slow phase during the peak of the NR, pinpoints asymmetry, particu-larly canal paresis, more reliably than duration does (Aschan, Bergstedt, and Stahle 1956;Jongkees, Maas, and Philipszoon 1962;Jongkees and Philipszoon 1964;Jung and Kornhuber 1964;Baloh and Honrubia 1979). Moreover, SES is the most sensitive measure of response habituation to repeated stimulation (Collins 1964;Young and Henn 1974;Brand 1968), and reflects habituation facilitated by optokinetic stimuli (Pfaltz and Kato 1974).…”