Computer analysis of ENG spectral features from patients with congenital nystagmus.

Power spectral estimation from electromystagmographic recording of eye position is proposed as a simple digital processing method to quantify both the amplitude and the frequency features of eye motion in patients affected by the oculomotor disorder of congenital nystagmus (CN). Different basic wave shapes clinically identified and studied in the literature are shown to have slightly different power spectra, which can be used to characterize the CN disorder from nystagmus waveforms. This treatment, statistical in nature, does not depend strongly on the detailed structure of each recorded wave shape, thus emphasizing that accurate descriptive analysis of all patient's waveforms characteristics adds little to the comprehension of CN. We show that the power spectral estimation also represents a useful tool in modelling both the CN defect and the non-defective oculomotor system, and in assessing the effect of the surgical treatment of CN through the differences in the power spectra before and after surgery.