Vectorial electronystagmography : A new representation of the caloric test

Abstract

The study of thermally induced nystagmus has been a subject of great interest to neurootologists the world over. Points of debate in the interpretation of the test include the amount of water used, duration of irrigation (Jongkees, 1942, 50 ml. : Aschan, 1956 & Stahle, 1956,1958, 30 seconds), and evaluation of the nystagmus pattern.

This multiplicity in nystagmus analysis makes comparison of readings and interchange of data difficult, and attempts have therefore been made to develop simplified formats for their representation. Claussen, for example, developed the “butterfly scheme” in an effort to codify nystagmus values.

The use of personal computer graphics enables one to convert this seemingly unrelated mass of data into a visually aesthetic, simple format. We used nystagmus frequency, culmination and per-rotatory values in an effort to study basic trends in various topodiagnosed groups. The cases were divided according to the butterfly scheme into peripheral, central, combined and undifferentiated. They were then processed as Mac Spin TM data m order to obtain the following graphics. Finally, other parameters based on clinical history and examination findings were studied in an effort to arrive at group tendancies.