Defining SPD and its Subtypes

Position Statement on Terminology Related to Sensory Integration Dysfunction

Lucy Jane Miller, Ph.D., OTR, Executive Director of the KID Foundation and Associate Professor at the University of Colorado Health Sciences Center
Sharon Cermak, Ed.D., OTR/L, Professor at Boston University
Shelly Lane, Ph.D., OTR/L, Professor at Virginia Commonwealth University
Marie Anzalone, Sc.D., OTR, Assistant Professor at Columbia University
Jane Koomar, Ph.D., OTR/L, Director of OTA-Watertown and President of the Spiral Foundation

Introduction

As the field of Sensory Integration Dysfunction has matured and researchers have learned more about this condition, many people have realized that it is time to clarify terminology. Although occupational therapists (OTs) usually understand one another when using the term Sensory Integration Dysfunction (sometimes abbreviated DSI), physicians and other health professionals without familiarity with the theory, assessments, and intervention frequently do not share the same knowledge base and may hold a more neurobiological view of the term sensory integration (SI). Since physicians are responsible for the total care of the child, and in many cases provide a referral for OT services that requires a diagnosis, using a diagnostic term that is more consistent with a physician's perspective seems appropriate. However, due to the wealth of literature related to SI in occupational therapy theory and intervention, the continued use of the term SI when applied to those aspects of SI seems appropriate. This will enable us to retain historical and current information published related to the SI frame of reference within our profession.

We are, therefore, proposing to update the diagnostic terminology used in sensory integration. This article describes a proposed system for sensory integration terminology differentiating the disorder from both the theory and the intervention (using occupational therapy with an SI frame of reference).

The new nosology proposed for the diagnostic categories uses Sensory Processing Disorder as a global umbrella term that includes all forms of this disorder, including three primary diagnostic groups (Sensory Modulation Disorder, Sensory Discrimination Disorder, and Sensory-Based Motor Disorder), and the subtypes found within each (see figure below).

Figure: A New Taxonomy for the Identification of Sensory Processing Disorders

Detailed Description

Dr. A. Jean Ayres, a researcher and pioneer of this field, coined the term Sensory Integration Dysfunction. She used the term throughout her professional career (1954-1988) to describe atypical social, emotional, motor, and functional patterns of behavior that were related to poor processing of sensory stimuli.

Dr. Ayres chose the term for two reasons. First, it related to her hypothesized theoretical model, which posited an underlying neurological impairment in the ability to transfer sensory information efficiently between sensory systems in the brain. Second, the term referred to her proposed intervention model, which used sensory stimuli in one domain to affect performance in another domain (e.g., the use of deep pressure/proprioceptive input to decrease over-responsivity in the tactile domain). During intervention — occupational therapy using a sensory integration frame of reference — two or more sensory domains are actively used concurrently. Often, action in one or more sensory systems (or provision of one or more sensory stimuli) supports the child as she or he makes an adaptive response to a challenging situation involving another sensory system. An adaptive response occurs when a child engages in activities of increasing difficulty and makes a successful response.

Over the years, in practice, the root term "sensory integration" has been commonly used in four different ways. It is used to refer to:

• A theory (sensory integration theory)
• A diagnosis (based on a sensory integration assessment)
• A functional pattern (normal sensory integration abilities)
• A remediation approach (sensory integration intervention)

Notably, none of these uses correspond to the neurobiologic meaning of the term sensory integration, which refers to a neuronal process that occurs at a cellular level, and that we can only observe only by using invasive electrophysiologic recording techniques (e.g., such as those used in animal research). Sensory integration in this connotation depends on the convergence of excitatory signals from multiple sensory modalities onto a) a single neuron, or b) networks of neurons. Sites where convergence of sensory input from different sensory modalities occurs are present in many regions of the brain .

We selected the term Sensory Processing Disorder for two reasons. First, common use in the neurobiology literature indicates deficits in taking in, interpreting, and responding appropriately to sensory input. Second, the lay use of the word "process" refers to a particular method of doing something, generally involving a number of steps or operations that lead to a specific outcome. We propose that the word "process" within the context of Sensory Processing Disorder captures the series of steps that are disrupted as a result of impairments in sensory detection, modulation, and/or interpretation in children with this disorder. In this disorder, atypical behaviors occur in the "process" of discerning a sensory stimulus and making a motor or behavioral response. At this time, we believe that Sensory Processing Disorder constitutes a more effective label for facilitating communication between OTs and other professionals.

In summary, we propose that:

• The theory is referred to as "Sensory Integration theory based on the work of Dr. A. Jean Ayres."
• The diagnostic label is Sensory Processing Disorder (SPD).
• The assessment terminology include either the term "integration" or "processing." Because the primary assessment (age 4.5 to 8 years) for Sensory Processing Disorder is the Sensory Integration and Praxis Tests (SIPT), use of the term sensory integration is logical in that context. Therapists who are certified in SIPT administration would refer to themselves as "certified in sensory integration assessment." However, those who do comprehensive evaluations that include tests and supplemental clinical observations of sensory functioning other than the SIPT may find it more interpretable by other professionals to report findings related to Sensory Processing Disorder and include sections on symptoms of Sensory Modulation Disorder, Sensory Discrimination Disorder, or Sensory-Based Motor Disorder (as relevant to the individual child being evaluated).
• The intervention label be used only with therapy that is based on Dr. Ayres’ original principles and further advanced as our understanding has evolved to include such elements as a focus on functional performance, participation in natural contexts, and family-centered care. Recommended is that the intervention description include both the discipline and the frame of reference; for example: "occupational therapy (OT) using principles of sensory integration," or "OT using a sensory integration frame of reference/approach." Only therapists with specific education (preferably with advanced training, including a mentored experience) in this intervention should use this therapeutic method. Centers or programs specializing in OT using a sensory integration frame of reference will continue to be identified as such.

We propose this change as a way to clarify diagnostic categories for children with sensory symptomatology. We are actively engaging with current diagnostic classification system revision committees, advocating for inclusion of this new nosology, in part or in whole, in revised taxonomies when they are published (e.g., future editions of the Diagnostic and Statistical Manual and the Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood). Formal recognition of this differential diagnosis will stimulate multi-disciplinary research into the underlying mechanisms of this poorly understood condition and facilitate acquiring services and supports for children with this disorder and their families.

We hope that individuals in the community concerned about sensory integration dysfunction — parents, occupational therapists, physicians, educators and others — will consider this nosology. We see the transition in this terminology as a process that will continue to evolve as we obtain more empirical data that better defines this disorder. The field should continue to discuss this issue and grow, adapting new terminology as needed based on research and practice needs.

References

Kandel, E.R., Schwartz, J.H., & Jessell, T.M. (Eds.). (1991). Principles of neural science (3rd ed.). East Norwalk, CT: Appleton & Lange.

Miller, L.J., & Lane, S.J. (2000). Toward a consensus in terminology in sensory integration theory and practice: Part 1: Taxonomy of neurophysiological processes. Sensory Integration Special Interest Section Quarterly, 23(1), 1-4.

Schroeder, C.E., Lindsley, R.W., Specht, C., Marcovici, A., Smiley, J.F., & Javitt, D.C. (2001). Somatosensory input to auditory association cortex in the macaque monkey. Journal of Neurophysiology, 85(3), 1322-1327.

Wallace, M.T., Meredith, M.A., & Stein, B.E. (1992). Integration of multiple sensory modalities in cat cortex. Experimental Brain Research, 91(3), 484-488.

Please note:

This article was also published in SI Focus magazine, Summer 2004.