Making Sense out of Sensory Integration

After 30 years as an occupational therapist treating sensory integration difficulties to improve functional skills in children and adolescents, I still find understanding and explaining sensory integration disorders challenging.  Clearly describing and explaining sensory integration disorders promotes sensory integration intervention.  This blog post provides a basic understanding of sensory integration disorders as a foundation for my next several blog posts, which will discuss how specific Sensory Processing Disorders affect mental health and describe sensory integration intervention strategies. 
Sensory Integration difficulties are currently referred to as Sensory Processing Disorders and consist of 3 major categories of disorders.  An understanding of the differences, similarities, and relationship between the 3 major categories of Sensory Integration difficulties guides assessment and intervention.  The 3 major categories of Sensory Processing Disorders are Sensory Modulation, Sensory Discrimination, and Sensory Based Motor Disorders.  
Sensory Modulation is the most commonly assessed and treated category of Sensory Processing Disorder, and is often wrongly thought of as the only category of Sensory Integration assessment and intervention.  Quick, accurate assessment of Sensory Modulation Disorders can be done using the Sensory Profile, and research has shown that Sensory Modulation Disorders exist and relate to functional challenges.  Sensory Modulation Disorders include: Sensory Overresponsivity (significantly more than typical noticing of sensory input), Sensory Underresponsivity (significantly less than typical noticing of sensory input), and Sensory Seeking (a significantly greater than typical tendency to seek out sensory input).  The types of Sensory Modulation Disorder can be distinct, but some individuals demonstrate Sensory Overresponsivity, Underresponsivity, and Seeking.
 

Sensory Discrimination Disorders are an important but less understood category of sensory processing dysfunction that involve difficulties locating, differentiating, and using sensory stimuli functionally.  This can contribute to difficulties with body awareness, body scheme, disorganization, and difficulty learning.  The design below was done by a third grader with Sensory Discrimination Disorder who was asked to cut out body parts and assemble them into a picture of a girl.  This student was bright but showed an inability to identify which of her fingers I was touching with out using her vision, and her picture shows her disorganization in body scheme. Sensory Discrimination Disorders can involve the sense of: touch, proprioception (pressure touch and body awareness), vestibular (movement), vision, sound, taste, and/or smell.
 

The Sensory Based Motor Disorders category includes both Postural Disorders and Dyspraxia.  Postural disorders involve subtle balance difficulties and clumsiness. Dyspraxia, emphasized by the developer of Sensory Integration A. Jean Ayres, is difficulty initially learning new skills (e.g., such as shoe tying, printing, and typing). Dyspraxia can involve difficulties in ideation, motor planning, and/or execution, which are the three components in learning unfamiliar skills.
Ideation is understanding and deciding what to do with an object.  I like to describe the components of praxis by imagining you give playdoh to a child who has not used it much before.  The first thing the child would need to do involves ideation, deciding: “I want to make a snowman”.  Children with ideation problems  have difficulty choosing and beginning an action. 
Once the child decides to make a snowman he would do motor planning.  Motor planning a snowman involves identifying the sequential steps needed (first I’ll make a big ball and put it on the bottom, next put a medium ball on the bottom ball for a body, then a smaller ball on top of the middle ball for the head; after that I put 2 tiny balls on the upper sides of the top ball for eyes, a tiny ball below them in the middle for a nose, and 6 tiny balls in a half circle centered below the nose for a mouth).  The final process is execution, actually building the snowman out of playdoh.

Understanding that Sensory Processing Disorders can involve difficulties with Sensory Modulation, Sensory Discrimination, and/or Sensory Based Motor Disorders guides evaluation and treatment.  It helps with identifying an individual’s sensory integration challenges that negatively impact their functional skills.  Research suggests that the categories of sensory processing problems may occur individually or overlap, as shown by the final diagrams.
My next blog posts will discuss the affects of Sensory Discrimination and Motor Based Sensory Disorders in Child & Adolescent Mental Health and describe Sensory Integration intervention strategies.

References:
Ayres, A. J. (1985).  Developmental dyspraxia and adult-onset apraxia.  Torrance, CA: Sensory Integration International.
Ben-Sasson, A., Cermak, S.A., Orsmond, G.I., Tager-Flusberg, H., Carter, A.S., Kadlec, M.B., Dunn, W. (2007).  Extreme sensory modulation behaviors in toddlers with Autism Spectrum Disorders.  American Journal of Occupational Therapy, 61, 584-592.
Miller, L.J., Anzalone, M. E., Lane, S. J., Cermak, S. A., Osten, E. T. (2007).  Concept evolution in sensory integration: A proposed nosology for diagnosis.  American Journal of Occupational Therapy, 61(2), 135-140.
Schaaf, R.C., & Miller, L.J. (2005).  Occupational therapy using a sensory integrative approach for children with developmental disabilities.  Mental Retardation and Developmental Disabilities Research Reviews, 11, 143-148.
Silva, L.M. Schalock, M., Gabrielsen, C. (2011).  Early intervention for Autism with a parent-delivered qigong massage program: A randomized controlled trial.  American Journal of Occupational Therapy, 65(5), 550-559.