Research Update: Post-Rotary Nystagmus and Autism

The SIPT Assessment and it’s precursor the SCSIT (Southern California Test of Sensory Integration) include the test of Post Rotary Nystagmus. A validity study by Mulligan of PRN as a measure of vestibular function published in 2011 revealed that

“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. “

PRN is just one of the tests within the SIPT battery, that can help to inform clinical reasoning and therefore treatment planning of Autism Spectrum Disorders (ASD).

The EASI, (Evaluation of Ayres’ Sensory Integration) is being developed to be a “Comprehensive, reliable, and valid assessment is essential for individually tailored, appropriate, and effective intervention planning and implementation.”

The EASI aims to “meet the need for a set of tests that will fully evaluate the constructs of ASI with psychometrically strong, internationally appropriate, and easily accessible measurement tools.” It is likely that the EASI will include a test of vestibular integrity, exploring the vestibular systems contribution function and participation in daily life.

from Introduction to the Evaluation in Ayres Sensory Integration^® (EASI)., Mailloux Z, Parham LD, Roley SS, Ruzzano L, Schaaf RC., Am J Occup Ther. 2018 Jan/Feb;72(1)(p1-p7).

Autism Spectrum Disorders (ASD) are a continuum of neurodevelopmental disorders characterised by “persistent deficits in social communication and social interaction across multiple contexts” (DSM-V Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.

Sensory impairments were previously not part of the core definition of Autism but the DSM classification now includes “hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of the environment.”

Within the field of Ayres’ Sensory Integration, sensory and motor deficits that co-occur with Autism have been recognised for longer; Smith Roley el al 2015, Lloyd, MacDonald and Lord 2013, Flanagan et al 2012, Siaperas et al 2011 and Adamson, O’Hare and Graham 2006.

Last year, in 2017, in Autism Research (10: 251–266), Carson et al described the growing interest in Autism and related sensori-motor alterations, now being recognised by other professional groups, that have traditionally been the focus of Occupational Therapist, Physiotherapists and Speech and Language Therapists using the theory of Ayres’ Sensory Integration to assess and then plan intervention.

Carson et al explored the rotational vestibulo-ocular reflex (rVOR), which functions to maintain stable vision during head movements, to understand any alterations and their underlying neurobiology.

from the abstract, “In this study, we assessed post-rotary nystagmus elicited by continuous whole body rotation among children with high-functioning ASD and typically developing children. Children with ASD exhibited increased rVOR gain, the ratio of eye velocity to head velocity, indicating a possible lack of cerebellar inhibitory input to brainstem vestibular nuclei in this population. The ASD group also showed less regular or periodic horizontal eye movements as indexed by greater variance accounted for by multiple higher frequency bandwidths as well as greater entropy scores compared to typically developing children. The decreased regularity or dysrhythmia in the temporal structure of nystagmus beats in children with ASD may be due to alterations in cerebellum and brainstem circuitry. These findings could potentially serve as a model to better understand the functional effects of differences in these brain structures in ASD. “