Sensory processing disorder (SPD; also known as sensory integration dysfunction) describes a condition in which multisensory integration is not adequately processed in order to provide appropriate responses to the demands of the environment.
The senses provide information from various modalities--vision, audition, tactile, olfactory, taste, proprioception, interoception and vestibular system--that humans need to function. Sensory processing disorder is characterized by significant problems in organizing sensation coming from the body and the environment and is manifested by difficulties in the performance in one or more of the main areas of life: productivity, leisure and play or activities of daily living. Different people experience a wide range of difficulties when processing input coming from a variety of senses, particularly tactile (e.g., finding fabrics itchy and hard to wear while others do not), vestibular (e.g., experiencing motion sickness while riding a car) and proprioceptive (having difficulty grading the force to hold a pen in order to write).
Sensory integration was defined by occupational therapist Anna Jean Ayres in 1972 as "the neurological process that organizes sensation from one's own body and from the environment and makes it possible to use the body effectively within the environment". Sensory processing disorder is gaining recognition, although it is still not recognized by the Diagnostic and Statistical Manual. Despite its proponents, it is still debated as to whether SPD is actually an independent disorder or the observed symptoms of various other, more well-established, disorders.
Video Sensory processing disorder
Signs and symptoms
Symptoms may vary according to the disorder's type and subtype present. SPD can affect one sense or multiple senses. While many people can present one or two symptoms, sensory processing disorder has to have a clear functional impact on the person's life:
Signs of over-responsivity, including, for example, dislike of textures such as those found in fabrics, foods, grooming products or other materials found in daily living, to which most people would not react, and serious discomfort, sickness or threat induced by normal sounds, lights, movements, smells, tastes, or even inner sensations such as heartbeat.
Signs of under-responsivity, including sluggishness and lack of responsiveness; and Sensory cravings, including, for example, fidgeting, impulsiveness, and/or seeking or making loud, disturbing noises; Sensorimotor-based problems, including slow and uncoordinated movements or poor handwriting.
Sensory discrimination problems, that might manifest themselves in behaviors such as things constantly dropped.
Critics have noted that what proponents claim are symptoms of SPD are both broad and, in some cases, represent very common, and not necessarily abnormal or atypical, childhood characteristics. The checklist of symptoms on the website of the SPD Foundation, for example, includes such warning signs as "My infant/toddler has problems eating," "My child has difficulty being toilet trained," "My child is in constant motion," and "My child gets in everyone else's space and/or touches everything around him." -- "symptoms" which read much like the day-to-day complaints of an average parent.
- Difficulties with planning movement using feedforward information
Relationship to other disorders
Sensory processing issues represent a feature of a number of disorders, including anxiety problems, ADHD, food intolerances, behavioral disorders, and particularly, autism spectrum disorders. This pattern of comorbidities poses a significant challenge to those who claim that SPD is a identifiably specific disorder, rather than simply a term given to a set of symptoms common to other disorders. Dr. Catherine Lord, a leading autism expert and the director of the Center for Autism and the Developing Brain at New York-Presbyterian Hospital, argues that sensory issues are an important concern, but not a diagnosis in themselves. "I do think there's a value in attending to how a child is perceiving sensations, thinking about whether he could be uncomfortable. Where I get concerned is labeling that as a separate disorder."
Two studies have provided preliminary evidence suggesting that there may be measurable neurological differences between children diagnosed with SPD and control children classified as neurotypical or children diagnosed with autism. Despite this evidence, the fact that SPD researchers have yet to agree on a proven, standardized diagnostic tool undermines researchers' ability to define the boundaries of the disease and makes correlational studies, like the ones about structural brain abnormalities, less convincing.
Maps Sensory processing disorder
Causes
The exact cause of SPD is not known. However, it is known that the mid-brain and brain stem regions of the central nervous system are early centers in the processing pathway for multisensory integration, these brain regions are involved in processes including coordination, attention, arousal, and autonomic function. After sensory information passes through these centers, it is then routed to brain regions responsible for emotions, memory, and higher level cognitive functions. Sensory processing disorder not only affects interpretation and reaction to stimuli at the midbrain areas, but impacts several higher functions. Damage in any part of the brain involved in multisensory processing can cause difficulties to adequately process stimuli in a functional way.
Research
Current research in sensory processing is focused on finding the genetic and neurological causes of SPD. EEG and measuring event-related potential (ERP) are traditionally used to explore the causes behind the behaviors observed in SPD. Some of the proposed underlying causes by current research are: EEG recording
- Differences in tactile and auditory over responsivity show moderate genetic influences, with tactile over responsivity demonstrating greater heritability. Bivariate genetic analysis suggested different genetic factors for individual differences in auditory and tactile SOR.
- People with Sensory Processing Deficits have less sensory gating (electrophysiology) than typical subjects.
- People with sensory over-responsivity might have increased D2 receptor in the striatum, related to aversion to tactile stimuli and reduced habituation. In animal models, prenatal stress significantly increased tactile avoidance.
- Studies using event-related potentials (ERPs) in children with the sensory over responsivity subtype found atypical neural integration of sensory input. Different neural generators could be activated at an earlier stage of sensory information processing in people with SOR than in typically developing individuals. The automatic association of causally related sensory inputs that occurs at this early sensory-perceptual stage may not function properly in children with SOR. One hypothesis is that multisensory stimulation may activate a higher-level system in frontal cortex that involves attention and cognitive processing, rather than the automatic integration of multisensory stimuli observed in typically developing adults in auditory cortex.
- Recent research found an abnormal white matter microstructure in children with SPD, compared with typical children and those with other developmental disorders such as autism and ADHD.
Diagnosis
Although sensory processing disorder is accepted in the Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood (DC:0-3R), it is not recognized as a mental disorder in medical manuals such as the ICD-10 or the DSM-5.
Diagnosis is primarily arrived at by the use of standardized tests, standardized questionnaires, expert observational scales, and free play observation at an occupational therapy gym. Observation of functional activities might be carried at school and home as well.
Depending on the country, diagnosis is made by different professionals, such as occupational therapists, psychologists, learning specialists, physiotherapists and/or speech and language therapists. In some countries it is recommended to have a full psychological and neurological evaluation if symptoms are too severe.
Standardized tests
- Sensory Integration and Praxis Test (SIPT)
- DeGangi-Berk Test of Sensory Integration (TSI)
- Test of Sensory Functions in Infants (TSFI)
Standardized questionnaires
- Sensory Profile, (SP)
- Infant/Toddler Sensory Profile
- Adolescent/Adult Sensory Profile
- Sensory Profile School Companion
- Indicators of Developmental Risk Signals (INDIPCD-R)
- Sensory Processing Measure (SPM)
- Sensory Processing Measure Preeschool (SPM-P)
Other tests
- Clinical Observations of Motor and Postural Skills (COMPS)
- Developmental Test of Visual Perception: Second Edition (DTVP-2)
- Beery-Buktenica Developmental Test of Visual-Motor Integration, 6th Edition (BEERY VMI)
- Miller Function & Participation Scales
- Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOT-2)
- Behavior Rating Inventory of Executive Function (BRIEF)
The large number of different forms and tools of assessment listed here reflects what critics have argued is a fundamental problem with the diagnosis process: SPD researchers have yet to agree on a proven, standardized diagnostic tool, a problem that undermines the ability of researchers to define the boundaries of the disorder.
Classification
Sensory processing disorders have been classified by propoenents into three categories: sensory modulation disorder, sensory-based motor disorders and sensory discrimination disorders (as defined in the Diagnostic Classification of Mental Health and Developmental Disorders in Infancy and Early Childhood).
Sensory modulation disorder (SMD) Sensory modulation refers to a complex central nervous system process by which neural messages that convey information about the intensity, frequency, duration, complexity, and novelty of sensory stimuli are adjusted.
SMD consists of three subtypes:
- Sensory over-responsivity.
- Sensory under-responsivity
- Sensory craving/seeking.
Sensory-based motor disorder (SBMD) According to proponents, sensory-based motor disorder shows motor output that is disorganized as a result of incorrect processing of sensory information affecting postural control challenges, resulting in postural disorder, or developmental coordination disorder.
The SBMD subtypes are:
- Dyspraxia
- Postural disorder
Sensory discrimination disorder (SDD)
Sensory discrimination disorder involves the incorrect processing of sensory information. The SDD subtypes are:
1. Visual 2. Auditory 3. Tactile 4. Gustatory (taste) 5. Olfactory (smell) 6. Vestibular (balance) 7. Proprioceptive (feeling of where parts of the body are located in space)
Treatment
Sensory integration therapy
The main form of sensory integration therapy is a type of occupational therapy that places a child in a room specifically designed to stimulate and challenge all of the senses.
During the session, the therapist works closely with the child to provide a level of sensory stimulation that the child can cope with, and encourage movement within the room. Sensory integration therapy is driven by four main principles:
- Just right challenge (the child must be able to successfully meet the challenges that are presented through playful activities)
- Adaptive response (the child adapts his behavior with new and useful strategies in response to the challenges presented)
- Active engagement (the child will want to participate because the activities are fun)
- Child directed (the child's preferences are used to initiate therapeutic experiences within the session)
Sensory processing therapy This therapy retains all of the above-mentioned four principles and adds:
- Intensity (person attends therapy daily for a prolonged period of time)
- Developmental approach (therapist adapts to the developmental age of the person, against actual age)
- Test-retest systematic evaluation (all clients are evaluated before and after)
- Process driven vs. activity driven (therapist focuses on the "Just right" emotional connection and the process that reinforces the relationship)
- Parent education (parent education sessions are scheduled into the therapy process)
- "joie de vivre" (happiness of life is therapy's main goal, attained through social participation, self-regulation, and self-esteem)
- Combination of best practice interventions (is often accompanied by integrated listening system therapy, floor time, and electronic media such as Xbox Kinect, Nintendo Wii, Makoto II machine training and others)
The treatments themselves may involve a variety of activities and interventions (for example, prism lenses). Children with hypo-reactivity may be exposed to strong sensations such as stroking with a brush, vibrations or rubbing. Play may involve a range of materials to stimulate the senses such as play dough or finger painting. Children with hyper-reactivity, on the other hand, may be exposed to peaceful activities including quiet music and gentle rocking in a softly lit room. Treats and rewards may be used to encourage children to tolerate activities they would normally avoid. While occupational therapists using a sensory integration frame of reference work on increasing a child's ability to adequately process sensory input, other OTs may focus on environmental accommodations that parents and school staff can use to enhance the child's function at home, school, and in the community. These may include selecting soft, tag-free clothing, avoiding fluorescent lighting, and providing ear plugs for "emergency" use (such as for fire drills).
Evaluation of treatment effectiveness
Some of these treatments (for example, sensorimotor handling) have a questionable rationale and no empirical evidence. Other treatments (for example, prism lenses, physical exercise, and auditory integration training) have had studies with small positive outcomes, but few conclusions can be made about them due to methodological problems with the studies. In its overall review of the treatment effectiveness literature, AETNA concluded that "The effectiveness of these therapies is unproven.", while the American Academy of Pediatrics concluded that "parents should be informed that the amount of research regarding the effectiveness of sensory integration therapy is limited and inconclusive." A 2015 review concluded that SIT techniques exist "outside the bounds of established evidence-based practice" and that SIT is "quite possibly a misuse of limited resources."
Epidemiology
It has been estimated by proponents that up to 16.5% of elementary school aged children present elevated SOR behaviors in the tactile or auditory modalities. This figure is larger than what previous studies with smaller samples had shown: an estimate of 5-13% of elementary school aged children. Critics have noted that such a high incidence for just one of the subtypes of SPD raises questions about the degree to which SPD is a specific and clearly identifiable disorder.
Proponents have also claimed that adults may also show signs of sensory processing difficulties and would benefit for sensory processing therapies, although this work has yet to distinguish between those with SPD symptoms alone vs adults whose processing abnormalities are associated with other disorders, such as Autism Spectrum Disorder.
Controversy
There are concerns regarding the validity of the diagnosis. SPD is not included in the DSM-5 or ICD-10, the most widely used diagnostic sources in healthcare. The American Academy of Pediatrics (AAP) states that there is no universally accepted framework for diagnosis and recommends caution against using any "sensory" type therapies unless as a part of a comprehensive treatment plan. In fact, in a 2012 statement, the AAP states that "Because there is no universally accepted framework for diagnosis, sensory processing disorder generally should not be diagnosed." When an occupational therapist does recommend sensory integration therapy, the AAP instructs that the therapist is aware that, "parents should be informed that the amount of research regarding the effectiveness of sensory integration therapy is limited and inconclusive." As such, most health insurance considers sensory integration therapy to be "investigational" and will not cover it. In the United States and UK, sensory processing disorder is not likely to qualify an individual for disability benefits, so the supporters of sensory processing disorder recommend having a child diagnosed for a related disorder that will qualify them for disability insurance.
A 20 review of research on Sensory Integration Therapy (SIT) concluded that SIT is "ineffective and that its theoretical underpinnings and assessment practices are unvalidated."[citation needed] Moreover, some authors warned in 2015 that SIT techniques exist "outside the bounds of established evidence-based practice" and that SIT is "quite possible a misuse of limited resources."
Manuals
SPD is in Stanley Greenspan's Diagnostic Manual for Infancy and Early Childhood and as Regulation Disorders of Sensory Processing part of The Zero to Three's Diagnostic Classification. but is not recognized in the manuals ICD-10 or in the recently updated DSM-5. However, unusual reactivity to sensory input or unusual interest in sensory aspects is included as a possible but not necessary criterion for the diagnosis of autism.
Misdiagnosis
Some state that sensory processing disorder is a distinct diagnosis, while others argue that differences in sensory responsiveness are features of other diagnoses and it is not a standalone diagnosis. The neuroscientist David Eagleman has proposed that SPD may be a form of synesthesia, a perceptual condition in which the senses are blended.Specifically, Eagleman suggests that instead of a sensory input "connecting to [a person's] color area [in the brain], it's connecting to an area involving pain or aversion or nausea".
Researchers have described a treatable inherited sensory overstimulation disorder that meets diagnostic criteria for both attention deficit disorder and sensory integration dysfunction.
Distinguishing SPD from Autism
Recent studies have helped to physiologically differentiate typically developing children from children with SPD, and from children with autism. Approximately 1% of the United States child population has been diagnosed with autism, while approximately 5-16% of children have been found to have difficulty processing sensory input. In a recent study performed by Owen et al., diffusion tensor imaging (DTI) was used to exam white matter tracts in a group of children with sensory processing disorder compared to a group of typically developing children. Results of the study showed less white matter microstructure, particularly in the posterior cerebrum, in the children with SPD compared to the typically developing children. This finding illustrates a physiological variation in an area of the brain that involves sensory processing and integration, which may help to explain some of the challenges children with SPD have. This particular study suggested that DTI may be used in the diagnosis and differentiation of SPD and autism.
In a follow-up study pertaining to differentiation of SPD from autism, Chang et al. examined white matter tract differences in a group of children with SPD compared to a group of children with autism, and also in relation to a group of typically developing children. The results of this study showed significantly less white matter connectivity between the parietal and occipital lobes in the children with SPD and ASD compared to the typically developing children. As stated above, these connections play a large part in sensory perception and integration. However, the study only found reduced connectivity in the temporal lobe of the group of children with ASD. This area of the brain contributes to social-emotional processing. These findings reveal a significant association between white matter circuitry and cognitive progressing, particularly in the areas of auditory integration, social skills, memory, and attention. These findings may help guide treatment and provide more personalized interventions for children with SPD, ASD, and other diagnoses. However, more research needs to be done with larger groups and more attention to other neural circuitry changes.
Society
The American Occupational Therapy Association (AOTA) supports the use of a variety of methods of sensory integration for those with sensory processing disorder. The organization has supported the need for further research to increase insurance coverage for related therapies. They have also made efforts to educate the public about sensory integration therapy. The AOTA's practice guidelines currently support the use of sensory integration therapy and interprofessional education and collaboration in order to optimize treatment for those with sensory processing disorder. The AOTA provides several resources pertaining to sensory integration therapy, some of which includes a fact sheet, new research, and continuing education opportunities.
History
Sensory processing disorder as a specific form of atypical functioning was first described by occupational therapist Anna Jean Ayres (1920-1989).
Original model
Ayres's theoretical framework for what she called Sensory Integration Dysfunction was developed after six factor analytic studies of populations of children with learning disabilities, perceptual motor disabilities and normal developing children. Ayres created the following nosology based on the patterns that appeared on her factor analysis:
- Dyspraxia: poor motor planning (more related to the vestibular system and proprioception)
- Poor bilateral integration: inadequate use of both sides of the body simultaneously
- Tactile defensiveness: negative reaction to tactile stimuli
- Visual perceptual deficits: poor form and space perception and visual motor functions
- Somatodyspraxia: poor motor planning (related to poor information coming from the tactile and proprioceptive systems)
- Auditory-language problems
Both visual perceptual and auditory language deficits were thought to possess a strong cognitive component and a weak relationship to underlying sensory processing deficits, so they are not considered central deficits in many models of sensory processing.
In 1998, Mulligan found a similar pattern of deficits in a confirmatory factor analytic study.
Quadrant model
Dunn's nosology uses two criteria: response type (passive vs active) and sensory threshold to the stimuli (low or high) creating 4 subtypes or quadrants:
- High neurological thresholds
- Low registration: high threshold with passive response. Individuals who do not pick up on sensations and therefore partake in passive behavior.
- Sensation seeking: high threshold and active response. Those who actively seek out a rich sensory filled environment.
- Low neurological threshold
- Sensitivity to stimuli: low threshold with passive response. Individuals who become distracted and uncomfortable when exposed to sensation but do not actively limit or avoid exposure to the sensation.
- Sensation avoiding: low threshold and active response. Individuals actively limit their exposure to sensations and are therefore high self regulators.
Sensory processing model
In Miller's nosology "sensory integration dysfunction" was renamed into "Sensory processing disorder" to facilitate coordinated research work with other fields such as neurology since "the use of the term sensory integration often applies to a neurophysiologic cellular process rather than a behavioral response to sensory input as connoted by Ayres."
See also
References
- Van Hulle, C., Lemery-Chalfant, K., & Goldsmith, H. H. (2015). Trajectories of Sensory Over-Responsivity from Early to Middle Childhood: Birth and Temperament Risk Factors. Plos ONE, 10(6), 1-20. doi:10.1371/journal.pone.0129968
Further reading
- "Sensory processing disorder". Frontiers in Integrative Neuroscience - Research Topics. Retrieved 24 August 2013.
Source of article : Wikipedia
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