The human body is comprised of various tissues functioning on an interrelated basis. Internal controls regulate function via the brain, master controller. It mediates all body activities, those on the conscious level and numbers operating on an non-conscious level. Connection to our world comes through sensors, classically touch, smell, taste, hearing, and vision. When these sensors suffer interference, sensory processing disorder sets in.
Sensors connect to the brain by afferent nerves. Efferent nerves adjust sensor sensitivity or initiate whole body response. Processing errors may activate inappropriate nerves causing wrong responses. Response mismatch underlies any processing disorder. The following discussion on SPD is non-medical and readers are directed to medical resources for definitive information.
Defining Sensory Processing Disorder
Dr. A. Jean Ayres, psychologist and occupational therapist, as early as the 60s observed patients with processing problems and proposed sensory integration therapy to reprogram the brain’s response to that mismatch. She focused on children, utilizing OTs trained in her methodology. The characteristics of the disorder have been reorganized several times. People with sensory processing problems have difficulty with coordination, sensory management (sometimes involving “seeking” and “avoidance” behaviors), and sensory adaptation. The focus has been on children.
Understanding Sensory Processing Disorder Triggers
The dysfunction mechanism is not clearly understood. Current NIH Grant foci seek to go beyond the classic sensory nervous system pathways and explore internal senses, including
thermosensation, body position, proprioception, pain, itch, and general visceral sensation.
NIH seeks to investigate multisensory processing effects on perception, behavior, and interpersonal relationships.
It seeks to encourage basic, behavioral, and/or clinical research projects examining the interactions between cognitive, affective, or motor processes, and multiple sensory modalities.
The direction for research reveals that we don’t know what we don’t know.
Processing Disorder Symptoms
DHD, SPD, CAPD, and a host of other “Ds” name abnormal responses that we can see. We see them most clearly in children that have missed normal development markers or with behavioral problems, but many adults have processing difficulties. A MVA victim looks normal six months after trauma, but can no longer sort out conversation in background noise. A head trauma victim can no longer enter certain environments because a previous pleasant smell now causes nausea when it is present. Tactile stimulation on one area of the body causes problematic sensation in another part of the body. Visual stimulation suffers misinterpretation, causing fear.
“Mental” Issue Versus “Adaptation” Issue
In children, the processing problem may be defined by speech and language delays, poor academics, or inappropriate social skills. Perhaps we could define the dysfunction as a failure of the brain’s processing to find and program a socially acceptable response to stimuli causing a “missed” appropriate response. Processing problems are not either/or but are alternative points on a continuum with “mental” and “academic” problems fitting somewhere on an adaptation success continuum. The development of a variety of behavioral scales to define ADHD and the like may reflect this concept.
Suffering with Processing Disorders
Children do not “suffer” with sensory processing disorder problems, because they have grown up with those difficulties. When adults have processing problems resulting from trauma, stroke, or disease processes, there is a “before and after” awareness in them individually. Brains vary. Each sufferer will be managed differently. External surface behavior belies actual problems. When the brain cannot manage the problem, a somatic sensory problem may become a component, resulting in life-coping issues, difficulties with friends, co-workers, and family, poor health, depression, etc. Mental health providers may address appropriate coping skills. Adaptive, work-arounds, and coping skills become a patient-specific therapy plan for problem amelioration.
Autism Spectrum Disorder
ASD includes a variety of behaviors we would characterize as inappropriate sensory processing disorder responses. These interfere with communication, interpersonal relationships, development of appropriate responses, and repetition of coping-skill “mistakes,” in work, school, and home. Symptoms may present in early youth, but processing problems continue through adulthood. Autism is only one processing problem. Asperger’s syndrome is another. It is a mistake to consider all processing problems as part of ASD. The recognition that processing problems have some commonality is a big step in assessing sensory processing dysfunction. Perhaps the development of assessment tools to evaluate sensory processing disorder problems in adults with ASD symptoms will benefit non-ASD adults with perceptual deficits.
Unidentified Etiology
We recognize that we don’t know causes. We do know that males are more susceptible. Having a sibling with the same problem increases likelihood of a person having a related problem. Children with older parents may be more susceptible. There may be a relationship of their condition and the presence of ASD, ADHD, language disorders, learning problems, PTSD, tuberous sclerosis, fragile X syndrome, etc. One service provider suggests 15 specific behavioral symptoms, 13 physical symptoms, and 9 psychosocial symptoms as red flags for possible presence of a processing malady in childhood. Unfortunately, 9 long-term consequences may continue into adulthood. Adult onset with trauma, circulation anomaly, or disease process will demonstrate some of these long-term effects.
Interaction Effects
A problem with etiology determination may relate to the concept of interaction effect. Does an environmental stimulation cause the brain to either short-circuit or change its afferent-efferent triggering mechanism and, in the process, cause subsequent processing to be misapplied? Is there a genetic switch that alters brain processing by changing synaptic activity between neurons? In the case of trauma, is there an actual break in neurons at the micro-analysis level? No specific red flag has been identified as causative or interactive with ADHD children in a review of 51 comprehensive studies. This points out the difficulty in identifying a culprit for inducing a processing disorder.
In effect, there is a problem. We call it a sensory processing disorder, but the sensory system is both external and internal. The brain’s processing of sensory information is disrupted, most likely impaired permanently at some level. We can measure external sensation, but actual internal measurement has eluded us. We have coping and adaptive therapies that may ameliorate some symptoms.
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