August 3rd. 2012
Sensory integration dysfunction is characterized by difficulties in receiving, registering, modulating, interpreting, and acting on information that comes to the brain through various sensory receptors. Ever since Occupational Therapist and Developmental Psychologist Dr. Jean Ayres first described this condition in the 1960s, the diagnosis and treatments have been controversial.
Recently, the Council on Children with Disabilities of the American Academy of Pediatrics (AAP) released a statement entitled “Sensory integration therapies for children with developmental and behavioral disorders” (AAP, 2012). The Council acknowledged that there is no universally- accepted framework for the diagnosis of sensory processing disorder and that evidence for the efficacy of sensory-based therapies is limited; but it advised that occupational therapy with the use of sensory-based therapies may be acceptable as one component of a comprehensive treatment plan.
The aim of any therapy, including sensory, is to enhance function and participation, either by remediating (i.e. curing) the underlying impairment or by accommodation and adaptation. Traditional sensory integration therapy, as developed by Ayres, provides a child with various sensory experiences through the use of big rolls and balls, trampolines, and suspended equipment that provide intense proprioceptive (movement detection), vestibular (balance), and tactile (touch) experiences. These experiences are intended to remediate the child’s sensory processing ability and thus enable the child to better organize sensory input and respond appropriately.
There are differing opinions regarding the proven efficacy of sensory integration therapy, even within the Occupational Therapy field. In a thoughtful response to the AAP statement, Dr. Lucy Miller, Executive Director of the Sensory Processing Disorder Foundation, pointed out that the Council failed to cite significant research demonstrating the effectiveness of sensory processing disorder treatment (Miller, 2012).
In contrast, Nancy Pollock, an Occupational Therapist at the Canchild Centre for Childhood Disability Center at McMaster University in Hamilton, Ontario, says that, while there has been more effectiveness research conducted on sensory integration therapy than on any other intervention in the field of occupational therapy, to date the evidence of its effectiveness is weak at best (Pollock, 2009).
Most of the efficacy research on sensory treatments has been conducted on children with autism spectrum disorder, learning problems, attention deficit hyperactivity disorder, or isolated sensory processing problems. In contrast, there has been little research on children with cerebral palsy, probably because formal sensory processing disorder testing is difficult in individuals with motor impairments and it may be difficult to isolate central sensory processing problems from the complex motor, sensory, and cognitive issues that may be involved in cerebral palsy.
No experienced clinician doubts that there are children with developmental disabilities, including cerebral palsy, who have difficulty utilizing sensory information effectively. The challenge is to determine the best ways to address such difficulty.
Although the primary problem in cerebral palsy is motor, the condition is often accompanied by disturbances of sensation and perception as well. In addition to input from the major senses of vision and balance mechanisms in the inner ear, a necessary element of successful motor function is sensory feedback from muscles and tendons. In order to coordinate purposeful movements, the brain needs to know which muscles are contracting and what position a limb is in at any given time. This is accomplished by sensory receptors and nerves that carry this information to the spinal cord and from there to the brain’s sensory cortex.
From the sensory cortex this information travels to various areas of the brain where it is integrated with other sensory information (e.g. visual and vestibular), with memory (What happened the last time the arm moved in this way?), and with intellect (What needs to be accomplished with this movement?). Some motor responses to incoming sensory information from the skin, muscles, and tendons are instantaneous and occur without the brain’s involvement, such as pulling a finger away from a hot stove. Other motor responses need the brain’s input to modulate the response: that is, to continue, dampen, or correct an errant response. Much of the brain research on cerebral palsy has focused on the motor function alone. With the use of advanced brain imaging techniques it has become clear that the sensory network in the brain can also be impaired (Hoon, 2002).
As noted above, the emphasis on sensory therapy has been on children with autism, attention and learning problems, or isolated sensory processing problems. In these disorders, the primary sensory organs and their ascending sensory tracts to the brain (e.g. visual, vestibular, tactile, proprioceptive) are intact and working normally. Likewise, motor output is intact. That is, if appropriate motor commands are issued from the brain, the descending motor tracts and muscles should execute these commands just fine. The problem in these conditions occurs between the reception of sensory signals and the execution of motor commands. When various sensory signals reach the brain, they must be integrated with all of the other information stored in the brain and organized into meaningful thought and purposeful responses. This function is known as “sensory processing.” However, in cerebral palsy all or parts of the system can break down, not only at the sensory processing level in the brain, but equally likely at the incoming sensory and/or outgoing motor levels.
Dr. Miller asserts that, in some geographic locations, the treatment for sensory dysfunction may be limited to specific protocols that use techniques such as brushing, spinning, or wearing weighted vests, (not necessarily tailored to the individual or based on clinical reasoning). In contrast, she says that advanced Occupational Therapy clinicians focus on social participation, self-regulation, self-esteem/confidence and participation in everyday activities, and sometimes employ sensory therapies as part of a treatment program.
Incorporating the Ayres’ concepts of sensory processing and integration into an individually tailored program that focuses on function and participation through accommodation and adaptation makes good intuitive sense and, perhaps, will have growing research support.
Drawing from the AAP’s statement on sensory integration therapies as well as commentaries by Miller and Pollock, there are common conclusions and recommendations that can guide parents, therapists, and program administrators on best practice:
Ayres, A. J. (1972).Types of sensory integrative dysfunction among disabled learners. American Journal of Occupational Therapy, 26, 13-18
Section on Complementary and Integrative Medicine and Council on Children with Disabilities, American Academy of Pediatrics. (2012). Pediatrics, 129, 1186-1189.
Miller, L.J. (2012). Letter to the Editor Re: Sensory Integration Therapies for Children with Developmental and Behavioral Disorders. Pediatrics, published online May 31, 2012.
Hoon, A.H. (2002)Diffusion tensor imaging of periventricular leukomalacia shows affected sensory cortex white matter pathways. Neurology, 59, 752-756
Pollock, N.(2009). Sensory integration: A review of the current state of the evidence. Occupational Therapy Now, 11(5), 6-10.