On Pathological Spontaneous and Positional Nystagmus

Spontaneous Nystagmus in Normal Subjects

“…In addition, some authors [2,4,13] did not differ entiate spontaneous nystagmus from positional nystag mus. Mulch and Lewitzki [13] defined spontaneous nys tagmus as the occurrence of at least 3 consecutive nystag mus beats; Bos et al [4], Coats [7] and Eviatar et al [8] defined it as nystagmus lasting for 30 s, and Fluur and Eriksson [ 1 ] defined it as nystagmus lasting for 60 s. In the present study, we defined spontaneous nystagmus as nys tagmus that was unaffected by posture and was present in one or the other of 3 conditions: with the eyes closed, with the eyes open in darkness, and with the eyes open and fixed in the primary position; Eviatar et al [8], Stahle [ 16] and Coats [17] also defined nystagmus thus. We consid ered nystagmus significant if consecutive nystagmus beats lasting at least 30 s were recorded.…”

“…Spontaneous nystagmus is considered evidence of a pathological distur bance of the vestibular system. In previous studies, the incidence of spontaneous nystagmus in normal subjects has ranged from 1 to 80% [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The conditions under which spontaneous nystagmus was recorded, such as the position of the subject, the position of the eyes (midposi tion or eccentric position) and whether the recordings were made with the eyes fixed or unfixed, are variable in previous studies.…”

“…Milojevic [5] considered nystagmus to have pathological significance. Bos et al [4] classified nystagmus as patho logical if the SPEV of nystagmus was higher than 6°/s. In the present study, the SPEV of spontaneous nystagmus was less than 6°/s in all but 1 subject.…”

“…However, spontaneous nystagmus has also been detected by electro nystagmography (ENG) in normal subjects [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The reported incidence of spontaneous nystagmus has varied depending on the criteria used to define 'significant' nys tagmus.…”

Localization of Static Positional Nystagmus With the Ocular Fixation Test

“…We consider as significant an SPN recorded for longer than 60 seconds with a slow component velocity (SCV) in darkness whose average is equal to or greater than 7°/s. This lower limit was chosen considering the fact that a physiologic positional nystagmus can be observed up to a velocity of 6°/s 23‐25 . For each recording, we obtained the values of SCV in darkness and during fixation using the manual override of the device.…”