Overview of Sensory Defensiveness and Sensory Dysregulation
by Leslie E. Packer, PhD
Last updated February 2009
In the course of normal development, the brain integrates and organizes sensory input from the environment. The sensory inputs consist of sound, sight, touch, movement, body awareness, and the pull of gravity. These sensory integrative experiences form the building blocks for children’s more complex learning as they mature. But what happens if the normal sensory integration processes that occur with maturation are delayed or disordered? What happens then?
Dr. A. Jean Ayres is generally credited with developing both a theory of sensory integration dysfunction and therapeutic interventions for children suffering from it. Of particular importance here, her work emphasizes the importance of three of the senses: tactile, vestibular, and proprioceptive:
The tactile (touch) system provides information on light touch, pain, temperature, and pressure. If a child suffers from dysfunction in the tactile system, he may experience light touch or a gentle hug as intense or aversive, he may find certain kinds of fabrics or clothing irritating, may refuse to eat foods of a particular texture, and may avoid touching or handling certain kinds of objects. We say that a child is “tactile defensive” when he or she is extremely sensitive to light touch. When touched, it is as if the brain is flooded with an overload of sensory input that it cannot process, and the child’s response may be disorganized and emotional. How often do we attempt to gently refocus a distracted child with a light touch on the shoulder? How often have we seen a child who seems to be having an exaggerated pain response to something that we know was “just minor?” Perhaps we think that the child is just a “drama queen” or attempting to get our attention, but could it be that they are really perceiving the sensory input differently than we do?
The vestibular system involves structures within the inner ear (the semi-circular canals) that detect movement and changes in the position of your head. If you were to close your eyes for a moment and tilt your head, you would know that your head is tilted even without having the visual input because your vestibular system provides that information. If a child’s vestibular system doesn’t develop or integrate normally, she may be hypersensitive to vestibular stimulation and have fearful reactions to ordinary childhood activities such as swinging on swings, going down slides, etc. She may also experience difficulty walking on or negotiating nonlevel surfaces such as hills or stairs. Children with this kind of hypersensitive vestibular system often appear clumsy, but not all clumsy children have hypersensitive vestibular systems, and not all children with vestibular dysfunction are hypersensitive. Some are under- or hyposensitive. Children with hyposensitive vestibular systems often engage in what appears to be sensation-seeking behaviors. They may whirl around like a dervish, jump, and/or spin.
The proprioceptive system provides feedback from your muscles, joints, and tendons that enables you to know your body’s position in space. If there is a disturbance in the proprioceptive system, the child may be clumsy, fall, seem to maintain abnormal body postures, have difficulty manipulating small objects, and and may resist trying different movements. If you’ve ever watched a student’s grip on a writing instrument and noticed how abnormally tight the grip was, you may have been seeing an indication of this kind of problem (although there might be other explanations for the problem).
When we talk about sensory processing difficulties or sensory integration dysfunction, we are talking about some disturbance in the child’s ability to process sensory input. It could be a disturbance in just one of the sensory systems, or it could involve two or more systems.
While this brief overview has focused on three systems (tactile, vestibular, and proprioceptive), parents and teachers need to keep in mind that the child can have sensory defensiveness in any of the sensory systems. For example, some children will find certain sounds intolerable (such as the bell signaling change of periods, or noises in the hallway), while other children may find particular smells or tastes intolerable. Any kind of sensory defensiveness can make it difficult for the child to function normally in a school setting or to engage in normal social activities with peers.
If a child appears significantly impaired by sensory-related issues, parents may wish to arrange for an assessment by a qualified occupational therapist. If sensory-related issues are affecting school functioning, parents may wish to ask the school district to arrange for a school-based OT evaluation, keeping in mind that the scope and purpose of a school-based OT assessment are generally somewhat different than an OT assessment arranged for privately.
As is often my advice, let your child’s behavior guide you. If your child seems to have significant trouble handling what should be “normal” parts of their childhood — if they avoid situations that their peers would enjoy, if they avoid too many foods or textures, if they avoid playground equipment out of fear, if they seem to experience normal voice volumes as “too loud” — then you may want to consider an OT assessment.
SOME SIGNS OF SENSORY PROCESSING DIFFICULTIES
Some signs of sensory processing difficulties include:
- Overly sensitive to touch, movement, sights
- Inability to habituate to sounds and fear with unexpected noises
- Easily distracted
- Holding hands over ears in complex environment
- Avoids tastes, smells, or textures normally tolerated by children that age
- Activity level that is unusually high or unusually low
- Impulsive, lacking in self-control
- Inability to unwind or calm self
- Poor self-concept
- Social and/or emotional problems
- Physical clumsiness or apparent carelessness
- Hesitation going up or down stairs
- Difficulty making transitions from one situation to another
- Holding on to walls, furniture, people, or objects, even in familiar settings
- Delays in speech, language, or motor skills
- Delays in academic achievement
- Seeks out movement activities, but poor endurance and tires quickly
The signs and symptoms are somewhat dependent on developmental age. A number of web sites have more detailed checklists available. See the the SPD Foundation’s checklist by age group for one such checklist.
HOW IS SENSORY PROCESSING DISORDER DIAGNOSED?
Sensory Processing Disorder (SPD) is not yet recognized in the DSM (diagnostic manual), and efforts by its advocates to have it included in the DSM-V have produced only partial success to date. As of December 2008, the DSM-V Committee wrote to the SPD Foundation that the committee needed “a significant number of additional studies” before SPD would be recognized as a distinct disorder and not, perhaps, as a subtype of Autism or ADHD. Whether sufficient reports and evidence can be provided in time remains to be seen. There have been a few preliminary small studies suggesting that SPD may occur by itself (i.e., in the absence of any other disorders), but SPD usually occurs with other disorders. The SPD Foundation provides information and research on proposed subtypes of SPD.
Having SPD recognized as a subtype of Autism or ADHD would not be a terrible thing for some children, but would not help children who have SPD comorbid with other disorders or who might have SPD without any other disorder.
At the present time, then, there are no firm set of criteria for diagnosing SPD, although there are a number of checklists and scales that a qualified occupational therapist may use as part of an assessment. Parents need to remember that diagnosis requires more than just parents going over a checklist and saying, “Wow, that is really describing my child.” A checklist can be a good starting point for pursuing professional assessments that can rule out or indicate other medical or neurological conditions that need to be addressed or treated.
SENSORY PROCESSING AND OTHER DISORDERS
When I attended a workshop on sensory integration therapy years ago and the presenter started describing the symptoms, I had to ask her how what she was describing was different from Attention Deficit Hyperactivity Disorder (ADHD), because some of the core symptoms for sensory integration dysfunction being describing included impulsivity, hyperactivity, distractibility, and fine motor problems.
ADHD and sensory SPD are not identical, even though there’s a lot of similarity or overlap, she replied. Children with SPD might be unusually sensitive or over-responsive to touch or certain kinds of sensory experiences, and they might be extremely uncomfortable with certain types of fabrics, she explained. Well, my son had those problems, too — I used to have to cut all the tags out of the back of his shirts, he still is uncomfortable stand wearing shirts with button holes, and we totally gave up on him wearing socks for over five years because he had to keep pulling them up and the seams drove him crazy. And my husband still has sensory issues about clothing and won’t wear certain fabrics because he “can’t stand” how they feel against his skin. But I thought that was part of their Tourette’s Syndrome and Obsessive-Compulsive Disorder (OCD). Now I was beginning to wonder whether what a lot of us had attributed to OCD might be this “other thing” — sensory processing dysfunction.
By the end of the workshop, it still seemed that there was tremendous overlap between what the presenter was calling SPD and my son’s and husband’s ADHD-TS-OCD.
As I started reading more on the topic of sensory integration years ago, I learned that sensory issues seemed to be discussed a lot in certain parent groups: parents of children with ADHD, parents of autistic children, parents of children with Tourette’s Syndrome and/or OCD, and parents of children with Fragile X Syndrome, to name but some.
In the past few years, we now have research that actually confirms parents’ concerns and reports in terms of the the greater prevalence of difficulties associated with certain disorders, and the relationship between sensory processing difficulties and behavior or emotional regulation.
Sensory Issues in Obsessive-Compulsive Disorder and Tourette’s Syndrome
Sensory phenomena are a frequently-reported, but little understood, part of Tourette’s Syndrome, and to a lesser extent, Obsessive-Compulsive Disorder. The phenomena have been described as “urges,” “itches,” or “premonitory urges.”
Prado and her colleagues (2008) have reviewed the research on sensory phenomena in children with Tourette’s Syndrome (TS), OCD, and TS+OCD. There appears to be a subgroup of children with early-onset OCD who have a significant sensory phenomenon as part of their presentation. From their study, some of the experiences below sound very much like sensory processing issues or sensory defensiveness (sensory over-responsiveness):
Different Descriptions of Sensory Phenomena
|Tactile, visceral, and muscle-skeletal||Uncomfortable sensations in the skin, muscles-joints, or body, which come before or along with the repetitive behaviors. The individual may have to repeat certain behaviors until experiences a sense of relief from this uncomfortable sensation.|
|“Just-Right” experiences triggered by visual, auditory, or tactile sensations||A need for objects to look a certain way or “just-right.”
A need for objects or people to sound “just-right” or have the “just-right” pitch.
A need for touching people or objects until getting a “just-right” feeling in the hands or the body
|Feeling of incompleteness/need to feel “just right” (without triggering stimuli)||The individual may have an inner feeling and/or perception of discomfort that makes him/her do things until feeling relieved. He/she has an inner sense of not being “just-right” or feeling ”incomplete,” and he/she needs to repeat a behavior until feeling “just-right” or ”complete.”|
|Urge||No sensations of feeling, just an urge to perform the repetitive behaviors.|
|Energy||An energy that have to be released.|
|Urge||Need to perform repetitive behaviors not preceded by obsessions nor by any type of sensory phenomena.|
Hazen Reichert, et al. (2008) describe a subset of children with OCD who have a clinically significant intolerance or intrusive reexperiencing of ordinary sensory stimuli that drive compulsive behaviors. These children did not experience any intrusive thoughts that are characteristic of typical OCD. Unfortunately, although their study suggests sensory processing deficits, they did not obtain any direct measures.
To date, there has been no research that I’ve been able to find that examines whether individuals with TS or OCD really have any sensory processing deficits that would show up in testing when compared with normal controls, although some research has found thinning in the sensorimotor cortex of patients with TS. Thus, it is possible that the sensory phenomena described above may be related to sensory processing difficulties, but then again, they may not be. We need actual research to examine the possibility.
Sensory issues in autism spectrum disorders (ASD)
Tomchek and Dunn (2007) found that compared to normally developing 3 to 6 year-olds, 95% of children with autism spectrum disorders (ASD) displayed some level of sensory processing deficits, most notably in Underresponsive/Seeks Senation, Auditory Filtering and Tactile Senstivity. Their findings received confirmation from a study by Ashburner et al. (2008), who found that Underresponsive/Seeks Sensation and Auditory Filtering explained 47% of the variance in academic performance in a group of students with ASD who had average intelligence. Of particular significance, they found significant correlations between (1) auditory filtering and inattention to cognitive tasks, (2) tactile hypersensitivity and hyperactivity and inattention, and (3) movement sensitivity and oppositional behavior. A significant relationship between sensory processing and emotional and behavioral patterns was also reported by Baker, Lane, et al. (2008).
Sensory issues in Attention Deficit Hyperactivity Disorder
Huecker and Kinnealey (1998) reviewed available literature and conducted a retrospective chart review of 90 children with ADHD seen in OT clinics. They found (pdf) three major types of sensory processing deficits: developmental dyspraxis (68.9% of children), tactile defensiveness (82.2%), and poor anti-gravity control (81.1%). Dyspraxia is impaired motor planning or execution of skilled motor acts in the correct sequence.
Parush, Sohmer, et al. (2007) compared boys with ADHD with and without tactile defensiveness (TD) to normal controls on several measures of somatosensory functioning. Of note, boys in the ADHD+TD group exhibited significantly higher central somatosensory evoked potentials (SEP) amplitudes than did the ADHD-TD group, suggesting a central inhibitory mechanism is involved in tactile defensiveness.
Bröring, Rommelse, et al. (2008) found that girls with ADHD had higher levels of tactile defensiveness than normally developing peers or boys with ADHD; boys with ADHD and controls did not differ from each other. Siblings of ADHD had no tactile defensiveness, regardless of gender.
Sensory issues in Social Anxiety Disorder (Social Phobia)
Sensory processing sensitivity may also contribute to Social Anxiety Disorder (social phobia). Hofmann and Bitran (2007) found that sensitivity was highly correlated with harm avoidance and agoraphobic avoidance; patients wtih a generalized subtype of social anxiety disorder reported higher levels of sensory-processing sensitivity than individuals with a non-generalized subtype. Their higher sensitivty may help explain the development of greater avoidance.
Sensory issues and “rage attacks”
Cheng and Boggett-Carsjens (2005) suggest that children who have what I call “rage attacks” should be screened for sensory processing deficits that might contribute to dysregulated mood and increased risk of explosive outbursts.
Sensory issues, sleep problems, and behavior
Of particular interest to me, a study by Shochat et al. (2009) looked at the relationship between sensory hypersensitivity, sleep, and behavior in normal school children. Not surprisingly, they found a significant relationship among all three measures, but the relationship between sleep and behavior decreased when controlling for sensory processing. In other words, some of what many of us may have thought was the impact of sleep problems on behavior may be mediated by sensory processing difficulties that interfere with sleep. Tactile sensitivity was a significant predictor for sleep problems, while sensation seeking and tactile sensitivity were significant and moderately strong predictors for behavior.
The more data that accumulates, the more it seems clear that many children and teens with neurological disorders should be screened for sensory processing deficits if they are having behavioral problems.
THERAPY AND SCHOOL-BASED INTERVENTIONS
There is little doubt that occupational therapy has something to offer in terms of techniques that may help children normalize their sensory processing and improve behavior or academics, but which techniques actually work? Research on the effectiveness of different types of interventions has not yet produced many clear answers.
One of the more controversial issues involved whether “sensory integration therapy” is effective. Research attempting to validate its effectiveness produced equivocal results, due, in part, to design limitations. Some of the problems in evaluating research on its effectiveness are evident in a 2001 review by Hender and a 2004 policy statement about auditory integration training published by the American Speech-Language-Hearing Association. A review by Mulligan (2003), however, found that 4 out of 5 studies investigating the effectiveness of occupational therapy with a sensory integration approach reported “significant gains on outcome measures after intervention.” The most significant improvements were for gross and fine motor outcome measures. While those aspects of functioning are important, what we are looking for is evidence that the child is better able to tolerate normal sensory experiences, or improves in behavior or academic functioning.
One other reason that it is difficult to answer the question of “does sensory integration therapy” work, is because “sensory integration therapy” is not a manualized modality that can be strictly applied and replicated. It is, instead, a conceptual approach to working with children that is synonymous with “occupational therapy” in current usage. Lucy Miller (2003) provides an informative explanation of what questions we need to ask and why it is so difficult to find answers. In her article, she acknowledges that the question, “Is sensory-based OT an effective intervention?” could not be answered (at that time) by available empirical evidence.
What we can, and should be able to answer through adequately controlled research, however, is determine whether specific elements or techniques are of benefit. Before we spend our time, money, insurance benefits, and hope, shouldn’t we know whether there’s any likelihood of effectiveness? One classroom intervention that seems to have some reported usefulness is the use of weighted vests for some young school children with autism or ADHD. A survey of professional school-based occupational therapists found that weighted vests were reported to increase attention span, staying on task, and staying in the child’s seat. It is important to note that those were survey responses, however, and no actual objective data were provided to assess or support the therapists’ impressions or reports. In a recent review of the use weighted vests, Stephenson and Carter (2009) reviewed the available studies and concluded that that “… on balance, indications are that weighted vests are ineffective. There may be an arguable case for continued research on this intervention but weighted vests cannot be recommended for clinical application at this point.” Their review reminds us, once again, that we need objective data from designs that are adequately controlled.
While weighted vests produced equivocal results in terms of effectiveness, a small study on using therapy balls instead of chairs for students with ADHD indicated that it might be effective. Using an ABAB design with 3 students with ADHD, Schilling, Washington, et al. (2003) found improved in-seat behavior and writing legibility during the therapy ball phases. Schilling and Schwartz (2004) conducted the same experiment on young children with Autism Spectrum Disorder. As with the ADHD students, students with ASD showed substantial improved in engagement and in-seat behavior when participants were seated on therapy balls. In both studies, teachers and students expressed preference for the therapy balls. in light of demonstrated effectiveness in these small, but controlled, studies, the use of therapy balls as alternatives to regular seating warrants further exploration in school settings. One of the questions that needs to be addressed is what happens if the therapy balls are used over extended periods — do any benefits wear off or continue?
Many parents are already familiar with other types of strategies, such as the use of fidgets that allow children to decrease stress and channel excess energy into socially acceptable behaviors. Fidgets may help a student concentrate better.
Other programs, such as Astronaut Training (for vestibular, auditory, and visual systems), and the “How Does Your Engine Run?” program are based on sensory processing and arousal. Another approach that may be used as part of programming is a sensory diet — a planned and individualized set of activities throughout the day to control the sensory input the child receives. Allowing the child to chew gum or something crunchy may be part of a sensory diet, depending on the student’s needs. Once again, however, although these techniques are in use, there is little controlled research to demonstrate their effectiveness by typical scientific and clinical standards.