Sensory processing disorder or SPD is a neurological disorder causing difficulties with taking in, processing, and responding to sensory information about the environment and from within the own body (visual, auditory, tactile, olfaction, gustatory, vestibular, and proprioception).
For those identified as having SPD, sensory information may be sensed and perceived in a way that is different from most other people. Unlike blindness or deafness, sensory information can be received by people with SPD, the difference is that information is often registered, interpreted and processed differently by the brain. The result can be unusual ways of responding or behaving, finding things harder to do. Difficulties may typically present as difficulties planning and organizing, problems with doing the activities of everyday life (self care, work and leisure activities), and for some with extreme sensitivity, sensory input may result in extreme avoidance of activities, agitation, distress, fear or confusion.
SPD is often associated with a range of neurological, psychiatric, behavioral and language disorders.
There is no known cure; however, there are many treatments available.[Initially the term traditionally used for children and adults with sensory processing difficulties was Sensory Integration Dysfunction (SID).
A new nosology has been proposed by Lucy J. Miller, Ph.D., OTR and colleagues. The new terms are meant to increase understanding between Occupational Therapists and other professionals who frequently encounter SID and physicians and other health professionals who approach sensory integration dysfunction 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 Dysfunction is now 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 affecting postural control challenges and/or dyspraxia.
Type III - Sensory Discrimination Disorder (SDD). Sensory discrimination or incorrect processing of sensory information. Incorrect processing of visual or auditory input, for example, may be seen in inattentiveness, disorganization, and 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 over-responsivity 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.
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 Patricia Wilbarger.
The sensory diet is a schedule of daily activities that gives the child the sensory fuel their 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.
Relationship to other disorders
Autistic spectrum disorders and difficulties of sensory processing
Sensory processing disorder is a common comorbidity with autism spectrum disorders. Although responses to sensory stimuli are more common and prominent in autistic children and adults, there is no good evidence that sensory symptoms differentiate autism from other developmental disorders.Differences are greater for under-responsivity (for example, walking into things) than for over-responsivity (for example, distress from loud noises) or for 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
Other disorders
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".
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 aphasia. 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
Researchers have described a treatable inherited sensory overstimulation disorder that meets diagnostic criteria for both attention deficit disorder and sensory integration dysfunction.
Sensory integration therapy
Main article: Sensory integration therapy
Several therapies have been developed to treat SID. 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.[16] Although replicable treatments have been described and valid outcome measures are known, gaps exist in knowledge related to sensory integration dysfunction and therapy.[17] Empirical support is limited, therefore systematic evaluation is needed if these interventions are used.[18]
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).
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 (Urwin and Ballinger 2005) for a range of presentations seen in adult clients including for those with Autism and Asperger's Syndrome, as well as adults with dyspraxia and some mental health difficulties (Brown, Shankar and Smith 2009) [20] that therapists suggest may arise from the difficulties adults with sensory processing difficulties encounter trying to negotiate the challenges and demands of engaging in everyday life(Brown, Shankar and Smith 2006).[21]
Snoezelen Rooms
Some individuals with sensory processing disorder may benefit from spending time in Snoezelen environments. Snoezelen rooms may consist of several elements that can both energize and relax users. These elements include anything from various lighting effects and areas of darkness, to tactile bins and vibrating surfaces, as well as scents and sounds. The individual enters the room with opportunity for free exploration. He or she is given time to seek out the sensory experiences that appeal to his or her unique sensory system. This process can help regulate the sensory system.[22]
Alternative views
Not all professionals agree with the notion that hypersensitive or hyposensitve senses necessarily constitute 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 located 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. 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 empirical evidence that hypersensitivity results from sensory integration issues. There is anecdotal evidence that sensory integration therapy results in more typical sensory responses and sensory processing. For example, Temple Grandin has reported that the deep pressure, or proprioceptive input, created by a cattle squeeze machine she used in her youth resulted in her being able to interact in her environment.
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 speculated that SID 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.
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 may also have signs of anxiety problems, ADHD, food intolerances, and behavioral disorders, as well as for autism, and may have genetic problems such as Fragile X syndrome. 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, a child may have 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. A child who seems to have difficulty processing sensory information, may not be developmentally on track (in terms of social skills, fine motor skills, gross motor skills, language, etc.)
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. Treatment often depends on the child's unique set of sensory responses.
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.
