Types of Sensory Processing Disorders

The following information is excerpted and condensed from my book From Flapping to Function: A Parent's Guide to Autism and Hand Skills.

Types of Sensory Processing Disorders 

It has been my experience that most if not all children who have an autism spectrum disorder (ASD) also show one or more symptoms of  a Sensory Process Disorder (SPD). However, many children who have  SPD do not demonstrate the social  and communication challenges associated with autism.

Understanding SPD is complex because there are three primary diagnostic groups, and children may have more than one type. These three primary types are:
1) sensory modulation disorders (see 3 subtypes below)
2) sensory-based motor disorders and; (see 2 subtypes below)
3) sensory discrimination disorders 

In addition, there are the following subtypes, resulting in a total of six recognized sub-types of SPD. 

 1) Sensory Modulation Disorders 

• Sensory over-responding: These children are extra-sensitive to sensations, often picky eaters, and easily over-stimulated by sensations. They are sometimes called hyper-reactive or avoiders.
• Sensory under-responding: These children need a lot of stimulation to respond; for example, they can spin intensely without getting dizzy. They are sometimes called hypo-responsive, under-reactive, or seekers
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• Sensory craving: These children never seem to get enough stimulation, touching and chewing on everything. They may also be called seekers.

2) Sensory-Based Motor Disorders

• Postural disorders: These children show poor body awareness and low muscle tone; for example, they might slip out of a chair or lean their head on an arm while writing.
• Dyspraxia: These children have difficulty with motor control needed to perform tasks accurately (such as folding paper on a line).

3) Sensory Discrimination disorders: These children have difficulty interpreting sensations; for example, a child may keep stuffing more popcorn in her mouth, even though it is already full. 

 The Impact of Sensory Modulation Disorders on Individuals with Autism

Let’s look more closely at the first type of SPD called sensory modulation disorders and how it impacts individuals with autism. 

Many children with autism have challenges with sensory modulation. These children may be  described as having difficulty with self-regulation. Self-regulation is the ability to control one’s behavior, emotions, or thoughts and adapt to the demands of a situation. Children with a sensory modulation disorder may be impulsive, overly and easily stressed, difficult to soothe, or highly distractible. On the other extreme, they may seem lethargic, apathetic, or day-dreamy. Some children have behaviors associated with both seekers and avoiders! Most children with ASD have signs of sensory modulation disorders. Let’s take a closer look at the three subtypes of sensory modulation disorders.

• Sensory over-responding, or super-sensitive: Four-year-old George is easily overwhelmed by sounds, smells, movements, and things he sees, to the point where he frequently “shuts down” and cries. He hates to touch food, bubble bath, or fur, and often strips naked at home. George’s favorite “toys” are rocks and blocks of wood, which he lines up in the basement. Repetitive body movements—such as rocking, flapping his arms, or flicking objects—seem to calm him. George will give familiar people a “high five”—but it had better be a firm one. His mom calls him “the Naked Curious Avoider.” 

• Sensory under-responding: Ten-year-old Dorothy frequently daydreams and slumps in her chair at school. She finds it easier to do her homework while bouncing on a ball seat, listening to  music, and chewing gum. Even with all this sensory stimulation, Dorothy’s hand gets tired after writing a couple of sentences and she struggles to organize her sentences into a paragraph. 

• Sensory craving: Twelve-year-old twins, James and Errol, are home-schooled. They both love to make funny sounds, stand on their heads, and have pillow fights. Their parents converted the basement into a small gym with a suspended swing, trampoline, and crash pad made out of pillows on a mattress. James and Errol follow a schedule that includes weight lifting, jogging, cooking—the spicier the better, according to the boys—making bread, and creating pottery between their academic lessons and weekly visits to volunteer at a farm. These boys never seem to get enough stimulation.

Researchers have documented that sensory modulation disorders interfere with developing functional skills. Some of these children may have difficulty developing hand skills because they just don’t sit still long enough to learn and then practice them. For other children it takes extra effort just to sit upright and still long enough to connect two pop-it beads or insert a straw into a juice box. Both sensory “seekers” and “avoiders” frequently have fine motor delays because they lack experience and practice in common childhood activities, such as building with construction toys or cutting out paper dolls. 

Researchers disagree on which of the three types of sensory modulation disorders are most associated with autism. In fact, many children appear to fluctuate between hypersensitivity and hyposensitivity. 

Occupational therapists often use sensory-based strategies with children on the autism spectrum with the goal of  promoting engagement and self-regulation and decreasing what is called sensory defensiveness.  Sensory defensiveness describes strong sensitivities to touch, movement, or other sensations. Children who have sensory defensiveness are often described as “avoiders” because they try to escape from sensations that seem neutral or pleasant to most people, such as a kiss on the cheek. To them, the sensation seems unpleasant, perhaps even painful!

Strategies for Sensory Modulation Disorders

Occupational therapists often create sensory diets that may explore:

1)      Seating and positioning options 

2)      Use of weighted, vests, collars, lap bags or wrist weights

3)      Use of fidget tools

4)      Activities that provide deep pressure and movement sensory stimulation

Source: How Vibration Helps Children with Autism or Sensory Processing Disorders by RecyclingOT

The Impact of Sensory-Based Motor Disorders

Many children with autism have  one or both of the following type of SPD called a sensory-based motor disorder. 

1) Postural disorder

2) Dyspraxia 

These children often have low muscle tone so that it takes a lot of work to control their posture and movement. They  may  have decreased body awareness and appear clumsy. A child with poor body awareness might sit on top of, instead of next to, another child, have difficulty fitting his arm into a sleeve, or use so much force on a spoon that he splatters food on his clothing when scooping. Children with dyspraxia often do not stabilize (hold steady) materials when working (such as steadying the paper while writing). They may have delays in developing a hand preference or not develop one at all.  Also, they often avoid reaching from one side of the body to the other. 

 Strategies for Sensory-Based Motor Disorders 

Toy manufacturers know that children love multisensory games and products that engage all their senses. That is why some ring stackers and puzzles play music, baby toys may vibrate, markers may be scented, and some balls make giggly sounds when thrown. Multisensory like these appeal to more than one sense, and may help children better understand where objects are in relation to their bodies and how objects such as shapes relate to other objects such as shape sorters.  Many children find that multisensory and resistive activities help them to tolerate touch better so that they can engage in hand activities. Children with dyspraxia may also benefit from using

1)      Resistive activities that involve squeezing, pushing or pulling. This provides deep pressure sensory stimulation. Examples are- pushing Lego bricks together,  using a hole puncher or stapler, coloring over sandpaper squeezing a Hungry Harry ball.    

2)      Activities adapted to vibrate

3)      Activities with extra large, easy to manipulate parts such as stringing rings instead of beads.

4)      Simplified materials such as a shape sorter with only one or two shapes

5)       Repetitive activities that promote practice

      6)       “success only” activities

Source: Sensory-Motor Activities for Individuals with Autism by RecyclingOT

Sensory Discrimination Disorder

Sensory discrimination is the last of the SPD subtypes I describe in my book. It refers to abilities to differentiate various sensory stimuli such as temperatures, textures, and colors. 

Sensory discrimination disorders

·         Visual: Sense of sight

·         Auditory: Sense of hearing

·         Gustatory: Sense of taste

·         Olfactory: Sense of smell

·         Tactile: Sense of touch

·         Proprioception: Sense of position in space

·         Vestibular: Sense of balance

·         Interoception: sense of internal regulation

Children with sensory discrimination disorders often overreact to sensations they see, hear, taste, or feel. You have learned that this is called sensory defensiveness. Sensory defensiveness can impact any of the senses. However, it is the tactile sense that is most important for learning to grasp and manipulate objects. Children with tactile defensiveness (an overreaction to touch sensations) who have avoided early touch experiences, such as grasping a rattle, may be slow to learn about how objects differ in texture, size, weight, shape, or other attributes. These children may manipulate objects in an awkward and inefficient manner. 

Many of the same strategies that help children with sensory modulation challenges and/or sensory-based motor disorders also help children who are sensitive to touch and movement. These strategies include tummy positioning early in infancy, deep pressure and resistive activities, alternative seating, positioning, alternatives to messy play, and use of multisensory activities.