|Sensory processing disorder|
Example of how visual, auditory and somatosensory information merge into multisensory integration representation in the superior colliculus
|Classification and external resources|
Sensory processing disorder (SPD; also known as sensory integration dysfunction) is a condition that exists when 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, vestibular system; that humans need to function. Sensory processing disorder is characterized by significant problems to organize sensation coming from the body and the environment and 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 disorders are classified into three broad categories: sensory modulation disorder, sensory-based motor disorders and sensory discrimination disorders.
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. Those with SMD present difficulties processing the degree of intensity, duration, frequency, etc., of information and may exhibit behaviors with a fearful and/or anxious pattern, negative and/or stubborn behaviors, self-absorbed behaviors that are difficult to engage, or creative or actively seeking sensation.
SMD consists of three subtypes:
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, and/or developmental coordination disorder.
The SBMD subtypes are:
Sensory discrimination disorder involves the incorrect processing of sensory information. Incorrect processing of visual or auditory input, for example, may be seen in inattentiveness, disorganization, and poor school performance.
The SDD subtypes are:
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.
People suffering from over-responsivity might:
People suffering from under-responsivity:
People suffering from sensory craving might:
People suffering from sensory motor based problems might:
People suffering from sensory discrimination problems might:
Other signs and symptoms
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 Disorders not only affects interpretation and reaction to stimuli at the midbrain areas, but impact 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.
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:
A study conducted by UC of San Francisco shows promise into learning more about how and why people are affected the Sensory Processing Disorder. According to research by the University there is substantial evidence to show the there are quantifiable differences in the brains of people with SPD compared to those who do not have the disorder. In the study, researchers used an advanced form of MRI called diffusion tensor imaging (DTI), this measures microscopic movement of water molecules within the brain in order to give information about the brain’s white matter tracts (Bunim). The study examined a group of 16 boys between the ages of 8 and 11. These children all have SPD but none of the children also have a diagnosis of Autism. The results of the MRI detected abnormal white matter tracts in the SPD children, particularly in areas in the back of the brain. There are areas that serve as connections for the auditory, visual and tactile systems involved in sensory processing, including their connections between the left and right halves of the brain.
Sensory processing disorder is currently accepted in the Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood (DC:0-3R) and 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. Some scales that are not exclusively used in SPD evaluations are used to measure visual perception, function, neurology and motor skills.
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.
Several therapies have been developed to treat SPD.
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:
This therapy retains all of the above-mentioned four principles and adds:
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. Although replicable treatments have been described and valid outcome measures are known, gaps exist in knowledge related to sensory integration dysfunction and therapy. Empirical support is limited, therefore systematic evaluation is needed if these interventions are used.
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 may have trouble calming down prior to going to sleep. Exposing the child to peaceful activities such as quiet music, gentle rocking, yoga, or deep breathing in a softly lit room can help calm them and ease them to sleep.
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).
There is a growing evidence base that points to and supports the notion that adults also show signs of sensory processing difficulties. In the United Kingdom early research and improved clinical outcomes for clients assessed as having sensory processing difficulties is indicating that the therapy may be an appropriate treatment. The adult clients show a range of presentations including autism and Asperger's syndrome, as well as developmental coordination disorder and some mental health difficulties. Therapists suggest that these presentations may arise from the difficulties adults with sensory processing difficulties encounter trying to negotiate the challenges and demands of engaging in everyday life. It is important when treating adults not only to focus upon sensory regulation but to also help them develop and maintain social supports. Adults who are sensory over-responsive have very high correlated anxiety and depression levels compared to adults who do not have sensory over-responsiveness. This is correlated to the perceived absence of social supporters. Sensory processing disorder can also be correlated with sleep quality in adults. This correlation can be seen especially in adults who have low neurological thresholds (sensory sensitivity and sensory avoidance). These individuals are more sensitive to tactile, auditory and visual stimuli which often impacts their quality of sleep.
It is estimated that up to 16.5% of elementary school aged children present elevated SOR behaviors in the tactile and/or auditory modalities. However, this figure might represent an underestimation of Sensory Over Responsivity prevalence, since this study did not include children with developmental disorders or those delivered preterm, who are more likely to present it.
This figure is, nonetheless, larger than what previous studies with smaller samples had shown: an estimate of 5–13% of elementary school aged children. Incidence for the remaining subtypes is currently unknown.
Because comorbid conditions are common with sensory integration issues, a person may have other conditions as well. People who receive the diagnosis of sensory processing disorder may also have signs of anxiety problems, ADHD, food intolerances, behavioral disorders and other disorders.
Sensory processing disorder is a common comorbidity with autism spectrum disorders       and is now included as part of the symptomatology in the DSMV.
The abnormally high synchrony between the sensory cortices involved in perception and subcortical regions relaying information from the sensory organs to the cortex is pointed as having a central role in the hypersensitivity and other sensory symptoms that define Autism Spectrum Disorder  Sensory modulation has been the main subtype studied. Differences are greater for under-responsivity (for example, walking into things) than for over-responsivity (for example, distress from loud noises) or for sensory seeking (for example, rhythmic movements). The responses may be more common in children: a pair of studies found that autistic children had impaired tactile perception while autistic adults did not.
The Sensory Experiences Questionnaire has been developed to help identify the sensory processing patterns of children who may have autism. 
It is speculated that SPD may be a misdiagnosis for persons with attention problems. For example, a student who fails to repeat what has been said in class (due to boredom or distraction) might be referred for evaluation for sensory integration dysfunction. The student might then be evaluated by an occupational therapist to determine why he is having difficulty focusing and attending, and perhaps also evaluated by an audiologist or a speech-language pathologist for auditory processing issues or language processing issues. Similarly, a child may be mistakenly labeled "Attention deficit hyperactivity disorder (ADHD)" because impulsivity has been observed, when actually this impulsivity is limited to sensory seeking or avoiding. A child might regularly jump out of his seat in class despite multiple warnings and threats because his poor proprioception (body awareness) causes him to fall out of his seat, and his anxiety over this potential problem causes him to avoid sitting whenever possible. If the same child is able to remain seated after being given an inflatable bumpy cushion to sit on (which gives him more sensory input), or, is able to remain seated at home or in a particular classroom but not in his main classroom, it is a sign that more evaluation is needed to determine the cause of his impulsivity.
Various conditions can involve SPD, such as obsessive compulsive disorder, schizophrenia, succinic semialdehyde dehydrogenase deficiency, primary nocturnal enuresis, prenatal alcohol exposure, learning difficulties and people with traumatic brain injury or who have had cochlear implants placed. and may have genetic conditions such as fragile X syndrome.
SPD is in Stanley Greenspan’s Diagnostic Manual for Infancy and Early Childhood and as Regulation Disorders of Sensory Processing part of the 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 criterium for the diagnosis of autism.
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 diagnose. The American Academy of Pediatrics, for example, advises against a diagnosis of SPD. However difficulty tolerating or processing sensory information is a characteristic that may be seen in many developmental behavioral disorders, including autism spectrum disorder, attention-deficit/hyperactivity disorder, developmental coordination disorder, or childhood anxiety disorder. 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.
Over 130 articles on sensory integration have been published in peer-reviewed (mostly occupational therapy) journals. The difficulties of designing double-blind research studies of sensory integration dysfunction have been addressed by Temple Grandin and others. More research is needed.
Because the amount of research regarding the effectiveness of SPD therapy is limited and inconclusive, the American Academy of Pediatrics advises pediatricians to inform families about these limitations, talk with families about a trial period for SPD therapy, and teach families how to evaluate therapy effectiveness.
Sensory processing disorders were first described in-depth by occupational therapist Anna Jean Ayres (1920–1989). According to Ayres's writings, an individual with SPD would have a decreased ability to organize sensory information as it comes in through the senses.
Ayres's theoretical framework for what she called Sensory integration 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:
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 performed a study on 10,000 sets of data, each representing an individual child. She performed confirmatory and exploratory factor analyses and found similar patterns of deficits with her data as Ayres did.
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:
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."  The current nosology of sensory processing disorders was developed by Miller, based on neurological underlying principles.
A wide variety of approaches have incorporated sensation in order to influence learning and behavior.
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|リンク元||「sensory abnormality」「知覚障害」「sensory neglect」|