As a clinical test of the interactions between the optokinetic and vestibular systems, a new test of optokinetic nystagmus elicited by pendular stimuli (P-OKN test) was developed and carried out in 194 patients with central nervous system disorders and compared with the OKN test by linear acceleration stimuli.
Most patients with central nervous system disorders with decreased P-OKN gain showed diminution of OKN during linear acceleration. However, in several cases, normal P-OKN accompanied, by abnormal accelerated OKN and/or abnormal P-OKN accompanied by normal accelerated OKN findings were observed. We concluded that the difference between the P-OKN and the accelerated OKN tests may be associated with different alertness during the optokinetic stimuli, especially due to the short stimulation time and also the increased and decreased velocities respectively. Moreover, the difference between look nystagmus and stare nystagmus may be involved. The P-OKN test is a simple and useful short test for detecting abnormalities of oculomotor system, and may become a good screening and follow-up test for central nervous system disorders.
