Sensory Integration Dysfunction
Sensory Integration Dysfunction (SID, also called sensory processing disorder) is a neurological disorder causing difficulties with processing information from the five classic senses (vision, auditory, touch, olfaction, and taste), the sense of movement (vestibular system), and/or the positional sense (proprioception).
For those with SID, sensory information is sensed normally, but perceived abnormally. This is not the same as blindness or deafness, because, unlike those disorders, sensory information is sensed by people with SID, but the information tends to be analyzed by the brain in an unusual way that may cause distress or confusion.
SID can be a disorder on its own, but it can also be a characteristic of other neurological conditions, including autism spectrum disorders, dyslexia, Developmental Dyspraxia, Tourette's Syndrome, multiple sclerosis, and speech delays, among many others.
Unlike many neurological problems that require validation by a licensed psychiatrist or physician, this condition is most often diagnosed by an occupational therapist. It is increasingly being diagnosed by developmental pediatricians, pediatric neurologists, and child psychologists. While it has not yet been included in the American Psychiatric Association's Diagnostic and Statistical Manual as a discrete diagnosis,  Regulatory-Sensory Processing Disorder is an accepted diagnosis in Stanley Greenspans Diagnostic Manual for Infancy and  Early Childhood and the Zero to Threes Diagnostic Classification.
There is no known cure; however, there are many treatments available.

# Meaning of sensory integration
Sensory integration is the ability to take in information through the senses of touch, movement, smell, taste, vision, and hearing, and to combine the resulting perceptions with prior information, memories, and knowledge already stored in the brain, in order to derive coherent meaning from processing the stimuli.
The mid-brain and brainstem regions of the central nervous system are early centers in the processing pathway for sensory 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 (SPD)
There are now 3 types of Sensory Processing Disorders, as classified by Stanley I. Greenspan as supported by the research of Lucy, J. Miller, Ph.D., OTR.  These new terms are meant to increase understanding between Occupational Therapists and other professionals who frequently encournter SPD and physicians and other health professionals who approach sensory integration from a more neurobiological vantage.
This understanding is critical as physicians are responsible for diagnosing SPD, which is a necessary step in accessing reimbursement (eventually from insurance companies) for professional services to treat SPD.
Sensory Processing Disorder is being used as a global umbrella term that includes all forms of this disorder, including three primary diagnostic groups:
- Type I - Sensory Modulation Disorder
- Type II - Sensory Based Motor Disorder
- Type III - Sensory Discrimination Disorder
Type I - Sensory Modulation Disorder (SMD). Over, or under responding to sensory stimuli or seeking sensory stimulation.  This group may include 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.
Type II - Sensory Based Motor Disorder (SBMD). Shows motor output that is disorganized as a result of incorrect processing of sensory information.
Type III - Sensory Discrimination Disorder (SDD). Sensory discrimination or postural control challenges and/or dyspraxia seen in inattentiveness, disorganization, poor school performance.
This information is adapted from research and publications by: Lucy, J. Miller, Ph.D., OTR, Marie Anzalone, Sc.D., OTR, Sharon A. Cermak, Ed.D., OTR/L, Shelly J. ,Lane, Ph.D, OTR, Beth Osten, M.S,m OTR/L, Serena Wieder, Ph.D., Stanley I. Greenspan, M.D..

## Sensory modulation
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.
Behaviorally, this is manifested in the tendency to generate responses that are appropriately graded in relation to incoming sensations, neither underreacting nor overreacting to them.

### Sensory Modulation Problems
- Sensory registration problems - This refers to the process by which the central nervous system attends to stimuli. This usually involves an orienting response. Sensory registration problems are characterized by failure to notice stimuli that ordinarily are salient to most people.
- Sensory defensiveness - A condition characterized by overresponsivity in one or more systems.
- Gravitational insecurity - A sensory modulation condition in which there is a tendency to react negatively and fearfully to movement experiences, particularly those involving a change in head position and movement backward or upward through space.
(Case-Smith, (2005)

# Hyposensitivities and hypersensitivities
Sensory integration disorders vary between individuals in their characteristics and intensity. Some people are so mildly afflicted, the disorder is barely noticeable, while others are so impaired they have trouble with daily functioning.
Children can be born hypersensitive or hyposensitive to varying degrees and may have trouble in one sensory modality, a few, or all of them. Hypersensitivity is also known as sensory defensiveness. Examples of hypersensitivity include feeling pain from clothing rubbing against skin, an inability to tolerate normal lighting in a room, a dislike of being touched (especially light touch) and discomfort when one looks directly into the eyes of another person.
Hyposensitivity is characterized by an unusually high tolerance for environmental stimuli. A child with hyposensitivity might appear restless and seek sensory stimulation.
In treating sensory dysfunctions, a "just right" challenge is used: giving the child just the right amount of challenge to motivate him and stimulate changes in the way the system processes sensory information but not so much as to make him shut down or go into sensory overload.
The "just right" challenge is absent if the activity and the child's perception of activity do not match. In addition, deep pressure is often calming for children who have sensory dysfunctions. It is recommended that therapists use a variety of tactile materials, a quiet, subdued voice, and slow, linear movements, tailoring the approach to the child's unique sensory needs.
While occupational therapy sessions focus on increasing a child's ability to tolerate a variety of sensory experiences, both the activities and environment should be assessed for a "just right" fit with the child. Overwhelming environmental stimuli such as flickering fluorescent lighting and bothersome clothing tags should be eliminated whenever possible to increase the child's comfort and ability to engage productively. Meanwhile, the occupational therapist and parents should jointly create a "sensory diet," a term coined by occupational therapist A. Jean Ayres.
The sensory diet is a schedule of daily activities that gives the child the sensory fuel his body needs to get into an organized state and stay there. According to SI theory, rather than just relying on individual treatment sessions, ensuring that a carefully designed program of sensory input throughout the day is implemented at home and at school can create profound, lasting changes in the child's nervous system.
Parents can help their child by realizing that play is an important part of their child's development. Therapy involves working with an occupational therapist and the child will engage in activities that provide vestibular, proprioceptive and tactile stimulation. Therapy is individualized to meet the child's specific needs for development. Emphasis is put on automatic sensory processes in the course of a goal-directed activity.  The children are engaged in therapy as play which may include activities such as: finger painting, using Play-Doh type modeling clay, swinging, playing in bins of rice or water, climbing, etc.

# Relation to other disorders

## Autism spectrum disorders
Unusual responses to sensory stimuli are more common and prominent in autistic children, though there is no good evidence that sensory symptoms differentiate autism from other developmental disorders.

## Other disorders
Some argue that sensory related disorders may be misdiagnosed as Attention-Deficit/Hyperactivity Disorder (ADHD) but they can coexist, as well as emotional problems, aggressiveness and speech-related disorders such as apraxia. Sensory processing, they argue, is foundational, like the roots of a tree, and gives rise to a myriad of behaviors and symptoms such as hyperactivity and speech delay.
For example, a child with an under-responsive vestibular system may need extra input to his "motion sensor" in order to achieve a state of quiet alertness; to get this input, the child might fidget or run around, appearing ostensibly to be hyperactive, when in fact, he suffers from a sensory related disorder

# 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).
Children with lower sensitivity (hyposensitivity) 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 heightened sensitivity (hypersensitivity) 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 tolerate and integrate 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 (Biel and Peske, 2005). These may include selecting soft, tag-free clothing, avoiding fluorescent lighting, and providing ear plugs for "emergency" use (such as for fire drills).
Some occupational therapists also treat adults with this condition.

# Alternative views
Not everybody agrees with the notion that hypersensitive senses is necessarily a disorder. However, sensory integration dysfunction, sometimes called sensory processing disorder, is only diagnosed when the sensory behavior interferes significantly with learning, playing, and activities of daily living (ADL).
Sensory issues can be on a spectrum. Being annoyed and distracted by the sound of a noisy ventilation system or the scratchiness of a sweater is considered to be a typical sensory response. However, when a child is so strongly affected by background noise or tactile sensations that he totally withdraws, becomes hyperactive and impulsive, or lashes out as part of a primitive fight-or-flight response, the child's sensory issues are severe enough to warrant intervention.
In addition to experiencing hypersensitivity, a person can experience hyposensitivity (undersensitivity to sensory stimuli). One example of this is insensitivity to pain. A child with sensory integration dysfunction may giggle when given an injection or not even blink when receiving a second-degree burn.
There is no proof for the idea that hypersensitivity would necessarily be a result of sensory integration issues. However, there is anecdotal evidence that sensory integration therapy results in more typical sensory responses and sensory processing. For example, Temple Grandin has claimed that the deep pressure created by a cattle squeeze machine she used in her youth resulted in her being able to tolerate the affectionate hugs and touches she craved.
Additionally, 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.
It is possible Sensory Integration Dysfunction can be misdiagnosed, just as with any other disability. Some experts claim that occupational therapists and other professionals incorrectly apply this label to individuals with attention difficulties or who simply don't put forth any effort during assessments.
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 (although many, many school teachers, therapists, and administrators are unfamiliar with sensory integration dysfunction or don't believe in it, this sometimes happens. 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.
As part of the auditory evaluation, the student may be asked to listen to signals coming from either side of a pair of headphones and identify where they are coming from. If the student is bored or distracted, or confused by the oral directions given, the test may be inconclusive and may not isolate what the problem is. The assessor must consider sensory and language factors in evaluating the student's performance on the test. Diagnoses based on single tests are unreliable, and integrated assessment utilizing multiple sources of information is the preferred means of diagnosis.
Similarly, a child may be mistakenly labeled "ADHD" or "ADD" 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.
Children with FAS (Fetal Alcohol Syndrome) display many sensory integration problems.
While the diagnosis of sensory integration dysfunction is accepted widely among occupational therapists and also educators, these professionals have been criticized for overextending a model that attempts to explain emotional and behavioral problems that could be caused by other conditions.
Children who receive the diagnosis of sensory integration dysfunction should also be observed for signs of anxiety problems, ADHD, food intolerances, and behavioral disorders, as well as for autism. Genetic problems such as Fragile X syndrome should be looked into as well. Sensory integration dysfunction is not considered to be on the autism spectrum, and a child can receive a diagnosis of sensory integration dysfunction without any comorbid conditions.
Because comorbid conditions are common with sensory integration issues, it is important to investigate whether the child has other conditions as well which make him or her reactive, "touchy", or unpredictable, and manifest in a manner similar to that characterized by occupational therapists as sensory integration dysfunction.
The theory of SI points out that children learn through their senses. If a child seems to have difficulty processing sensory information, it makes sense to observe whether he or she is developmentally on track (in terms of social skills, fine motor skills, gross motor skills, language, etc.)
While the physical methods employed by occupational therapists as treatment for SID are often palliative (they make the child feel better--much as a nice massage or physical contact would make anyone feel better), it is important that children diagnosed with sensory integration dysfunction be observed closely so that any other conditions will not be overlooked.
SI therapy is not "one size fits all." According to SI theory, children with sensory integration issues have their own unique set of sensory responses that need to be addressed. What is calming and focusing for one child may be overstimulating for another, and vice versa. The child's unique set of sensory responses must be considered when designing a sensory diet.
Some adults identify themselves as having sensory integration dysfunction; that is, they report that their hypersensitivity, hyposensitivity, and related sensory processing issues, such as poor self-regulation, continue to cause significant interference in their daily lives at home, at work, and at school.
Alternatively, there is evidence to suggest that some gifted children also have an increased tendency toward hypersensitivity (e.g., finding all shirt tags unbearable), which may be correlated with their greater intellectual proclivity toward perceiving the world in unconventional ways.