A patient with transient global amnesia also had transient bilateral gaze nystagmus which was detected both by conventional bedside examination and upon electronystagmographic recording. The nystagmus was absent one week later indicating recovery of the temporary brain stem deficit. The recording of objective evidence of brain stem dysfunction in the form of gaze nystagmus in a patient who had transient global amnesia, suggests that both were due to a transient ischemic attack involving the cerebral blood supply in the vertebrobasilar distribution.

Aged↗

PubMedDate not supplied

Measurement of optokinetic nystagmus for otoneurological diagnosis.

Optokinetic nystagmus was recorded and measured in 101 subjects comprising six diagnostic categories: 1) normal, screened for otologic disease, 2) chronic unilateral labyrinthectomy, 3) unilateral Menière's disease, 4) neurologically confirmed focal brainstem lesion, 5) brainstem-cerebellar syndrome, and 6) focal unilateral supratentorial lesion. For the OKN test, each subject looked at a translucent screen onto which a field of parallel black and white bars was back-projected. The array of bars could be projected vertically or horizontally to allow for study of nystagmus beating right and left or up and down. The speed of movement of the bars varied over a range from 20 to 140 degrees/sec of visual angle, in each axis for both directions. An analysis of the slow phase velocity of OKN indicated that patients with brainstem disease produced significantly lower eye speeds than did normal subjects or patients with chronic peripheral vestibular disease. The latter groups could not be distinguished. The responses of patients with cortical lesions fell midway between these two extremes and were significantly different from those of the brainstem group. Directional preponderance of nystagmus proved to be significantly related to the side of lesion for both the labyrinthine and cortical groups. However, the absolute value of the difference in slow phase velocity for nystagmus beating toward or away from the side of lesion was no greater than the difference between right and left-beating nystagmus in normal subjects. While the results provide statistical confirmation for the findings of earlier investigations, it is noted that for purposes of clinical diagnosis, the test is of value only in the context of the otoneurological test battery. Distribution of results for individuals in the various groups overlap considerably. The designation of a numerical cutoff for differential diagnosis leads to error rates far in excess of what may be confidently attributed to chance.

Adolescent↗

PubMedDate not supplied

Observations on optokinetic nystagmus in patients with congenital nystagmus.

Nystagmus responses to horizontal optokinetic stimuli are studied in 15 patients with congenital nystagmus (CN). Varying waveforms of CN designed to prolong foveation are evident. Pendular, jerk, and inverted responses are recorded alone and in combination. As in acquired brain disease, flat and asymmetric optokinetic responses occur, but in the study group other features of CN are also invariably present, especially inversion. Optokinetic inversion may be confined to CN.

Electronystagmography↗

PubMedDate not supplied

The reproducibility of caloric tests of vestibular function in young and old subjects.

The test-retest repeatability of the hot caloric response alone and of the hot and cold caloric responses combined, was evaluated in 29 subjects, over a 6-month period. The subjects were from two different age groups, 20-30 years (15 subjects) and 65-75 years (14 subjects). Intersubject variability was statistically significant in both age groups, though of greater magnitude in the older subjects. Once a vestibular caloric response baseline was established, for any given subject, there was reasonably reliable test-retest repeatability over time, in both age groups, with coefficients of reliability greater than 0.90.

Adult↗