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A Journal on Otorhinolaryngology, Head and Neck Surgery,
Plastic Reconstructive Surgery, Otoneurosurgery
Indexed/Abstracted in: EMBASE, Scopus
Otorinolaringologia 1998 December;48(4):177-81
ENG investigations about after optokinetic nystagmus in man
Taborelli G., Pasquale G., D'Agostino R., Melagrana A.
From the Divisione ORL, Istituto «G. Gaslini» Genova Quarto
Background. We carried out research regarding the presence, in man, of optokinetic after nystagmus (OKAN) following OKAN1 and OKAN2 (respectively homolateral and counterlateral optokinetic after nystagmus to the former OKN: optokinetic nystagmus).
Methods. We examined 50 patients with a completely negative otovestibular neurological and ophtalmologic anamnesis. We submitted each patient to an unbroken OKN stimulation (at an angular velocity of 30 degrees/sec.) which lasted 30 minutes.
25 patients were stimulated by clockwise OKN and 25 by counterclockwise OKN, in 27 cases the OKN was of “stare” type and in 23 cases it was of “look” type.
We recorded the OKAN al least 15 minutes after extinguishing the light with a Tonnies electronistagmograph.
Results. We observed the comparison of OKAN1 in all patients (100%) while OKAN2 was clear in 23 cases (46%). In 7 patients (14%) we point out OKAN3 and OKAN4 (respectively contralateral and homolateral optokinetic after nystagmus to the OKAN2).
Conclusions. Unlike monkeys the modest results obtained in man could be justified by a lower adopted optokinetic stimulation and by a great development of the encephalic cortex which carries out a regulating and modulator and perhaps inhibitory action of the evocation of OKAN.
In the cases in which OKAN2, OKAN3 and OKAN4 have not been observed we could suppose the evocation of a cyclic course reaction, a sort of nystagmusbereitschaft which, however does not express a real nystagmus.