Validity of the Southern California Postrotary Nystagmus Test: misconceptions lead to incorrect conclusions.

I n her article entitled "Testing Vestibular Function: Problems With the Southern California Postrotary Nystagmus Test" (American Journal ofOccupational Therapy, July 1989), Helen Cohen concluded: "Although postrotatory nystagmus is indicative of vestibular system function, the SCPNT [Southern California Postrotary Nystagmus Test] does not provide a valid measure of that behavior. Therefore, results from this test are not valid indicators of vestibular function" (p. 475). Although Dr. Cohen is to be applauded for providing an excellent review of some aspects affecting the testing of pure vestibular responses and for attempting to educate therapists on the validity of a Widely used test, she has failed to recognize the distinction between the testing of pure vestibular responses and the purpose of the Southern California Postrotary Nystagmus Test (SCPNT) (Ayres, 1975). This distinction is central to the use and interpretation of results on the SCPNT. Ayres (1972, 1976, 1978, 1982) was consistent in conceptually and operationally defining the vestibular system in a much broader context than that described by Cohen, including the vestibular receptors "and all major neuronal mechanisms in· fluenced by sensory input from those receptors" (Ayres, 1978, p. 28). The vestibular receptors (semicircular canals and otoliths), vestibular nuclei, vestibulospinal pathways, vestibulocerebellar pathways, vestibuloocular pathways, and vestibulocortical projections are all considered to be components of the vestibular system (Clark, 1985). This view of the vestibular system emphasizes the global influences of vestibular stimuli processed within the central nervous Teri Wiss, Florence Clark