Validity of the Postrotary Nystagmus Test for Measuring Vestibular Function

This study examined the validity of the Postrotary Nystagmus (PRN) test as a measure of vestibular functioning by examining the relations of scores from the PRN test with those from other variables measuring similar functions and through conducting a group comparison study. The PRN test is one of 17 tests included in the Sensory Integration and Praxis Tests (SIPT). Using SIPT scores from 575 children, sensory motor performance among children with depressed, average duration, and prolonged nystagmus was compared. The results indicated that children with low-duration postrotary nystagmus scored more poorly than children with average or prolonged postrotary nystagmus on other SIPT tests measuring aspects of vestibular function. Statistically significant, although weak correlation, coefficients were also obtained, demonstrating low-duration postrotary nystagmus may be associated with sensory motor deficits. The results of this study contribute to evidence supporting the PRN test’s validity as a measure of some aspects of vestibular functioning. Shelley Mulligan, PhD, OTR/L, is Associate Professor and Chair, Department of Occupational Therapy, University of New Hampshire, Durham, New Hampshire. Originally submitted January 19, 2010. Accepted for publication May 20, 2010. Posted online August 30, 2010. The author has no financial or proprietary interest in the materials presented herein. Address correspondence to Shelley Mulligan at [email protected]. doi: 10.3928/15394492-20100823-02 The vestibular system in humans supports several important functions related to balance, postural control, and mobility, thereby affecting one’s ability to successfully engage in daily life activities. Occupational therapists have an important role in the evaluation and treatment of individuals with vestibular disorders. In her theory of sensory integration, Ayres (1972, 2005) described the vestibular system as being closely linked to the visual and proprioceptive sensory systems. With the integration of sensory input from these systems, she described vestibular processing as being essential for coordinating eye movements, for postural control including muscle tone and balance, and for contributing to one’s gravitational security or comfort with movement. These body functions provide a foundation for smooth, coordinated movement, and allow children in the context of their daily lives to explore, play, develop fine and gross motor skills, and move efficiently within their multiple environments. Vestibular processing problems are commonly reported in children with neurodevelopmental disorders, such as developmental coordination disorder (Przysucha, Taylor, & Weber, 2008), autism (Molloy, Dietrich, & Bhattacharya, 2003; Noterdaeme, Mildenberger, Minow, & Amorosa, 2002), attention disorders (Mangeot et al., 2001; Mulligan, 1996), and learning disorders (Ayres, 1978; Mulligan, 1998). Children described as having sensory integration dysfunction commonly experience occupational performance problems believed to originate within the vestibular system or with the integration of vestibular sensory input with visual and proprioceptive input. For example, Miller, Anzalone, Lane, Cermak, and Olsten (2007) described some children with sensory modulation difficulties as being either overor under-responsive to vestibular sensory input. White, Mulligan, Merrill, and Wright (2007) found that vestibular processing difficulties in children with sensory processing disorders were associated with dif-