Spectral analysis of dual jerk waveforms in congenital nystagmus.
Congenital nystagmus (CN) is a disorder of the ocular motility characterized by oscillatory eye movements preventing the correct fixation of a target. Many typical waveforms of eye position recordings have been recognized and classified in the literature: in jerk CN a slow phase eye movement is followed by a fast phase, giving rise to a typical saw-tooth waveform, while in pendular CN the eyes exhibit a periodic motion, giving rise to an approximately sinusoidal waveform. Dual jerk waveforms seemed to show small, rapid oscillations superimposed on a jerk-like wave-form, thus being originally classified as a mixture of jerk and pendular CN. On the contrary, a theoretical model of CN has appeared recently, which suggests a possible interpretation of the small amplitude oscillations in dual jerk waveforms as consecutive pieces of growing and decaying exponentials. By spectral analysis of dual jerk waveforms in a number of patients with CN, we show that the oscillations are truly sinusoidal in nature, thus suggesting the possibility of a different explanation of dual jerk waveforms in CN.
D000293:Adolescent; D002648:Child; D004584:Electronystagmography; D005123:Eye / Q000503:physiopathology; D006801:Humans; D008297:Male; D008433:Mathematics; D008954:Models, Biological; D009759:Nystagmus, Pathologic / Q000151:congenital / Q000503:physiopathology*