OKP法による視運動性眼振のコンピューター解析

抄録

Recently, a computer system has frequently been used in the medical science. In the field of otoneurology the computer system has been employed for quantitative analysis of various parameters in the electronystagmographic (ENG) tracings of nystagmus or abnormal eye movement.
The computer has been used for analysis of optokinetic pattern (OKP) test that is one of our routine examinations on patients with vertigo.
This paper presents a new method of computer diagnosis of OKP test.
Horizontal optokinetic nystagmus (OKN) induced in the modified OKP test is input as a signal wave to the computer system with the analog to digital converter the noise of the OKN is reduced by auto-corelation, and then a power spectrum is calculated from its signal wave using the fast Fourier tranform (FFT) or the maximum entropy method (MEM).
The power spectra of 10 normal subjects and 67 patients were analyzed on a DEC PDP11/23 computer system. OKPs were classified into 5 groups by referring to their power spectra and cut-off point was set in each group by this autoanalysis system. Data in the computer system can be called out on demand and it takes less than one miniute to ask the power spectrum by using our auto-corelation and FFT program.
MEM is logically superior to FFT in resolvability. However, there is basically not any difference between FFT and MEM in the case of which spectrum is gentle. It seems to be better to use FFT in the analysis of the OKP considering the display time.
This new method is of practical use and can be expected to facilitate the more objective OKP diagnosis than the conventinal method. Especially it is useful to compare the OKP of both sides in a patient, to compare the OKP of each case with normal subject and to follow up the patient with the data of his OKP spectum.