1990 Volume 49 Issue 2 Pages 222-235
Opsoclonus was analyzed in two patients with acute encephalitis in the initial, extreme and recovery stages and the ENG and VTR findings were compared.
In the initial stage ocular oscillation was mainly in the horizontal direction, with an amplitude of 5-30 degrees and a frequency of 7-8 Hz. It started suddenly several days after the patients developed fatigue and fever. A series of 1-10 beats of eye movements with some pause of various durations was repeated.Head rolling from side to side with a small amplitude was sometimes accompanied by eye oscillations. The patients had oscillopsia and an unsteady and staggering gait.
The extreme stage started a few days after the initial stage. There was typical opsoclonus, consisting of multidirected but mainly vertical or diagonal oscillations of the eyes. The amplitude was large and reached 80 degrees. The frequency varied from 3-9 Hz. There were almost no pauses. The patients were unable to sit up, and their heads trembled in the same direction as the eye movements. Myoclonic jerks and ataxia of the trunk and extremities were maximum.
In the recovery stage, the eye oscillations gradually decreased, and flutter-like oscillations (FLO) appeared. They were mainly horizontal, 5-20 degrees in amplitude, and their frequencies were 7-8 Hz. Pauses of various durations followed each series of 1-10 beats. The patients were able to stand and walk.
Opsoclonus was triggered in all three stages by visual fixation, intention to move the eyes, mental excitation and sound stimulation.
