What is Sensory Processing Disorder?


It took months of reading, researching, and asking questions before I could finally wrap my head around what SPD is. Here’s the most simple definition: SPD is a complex neurological disorder that affects the way sensations are experienced and processed. SPD exists when sensory signals don’t get organized into appropriate responses and, as a result, a child’s daily routine and activities are disrupted (Miller 2006).

Ok, but what does this actually mean? And how does it affect my child’s life? How does it affect my parenting style?

Kids with SPD are sensitive to and often misinterpret information they are getting from their eight, yes eight!, senses.

We all know the five senses: sight, hearing, taste, smell, and touch. There are also three additional senses, the “hidden” senses, that most of us aren’t familiar with: proprioception, vestibular, and interoception. These sensory systems are important to understand in the context of sensory issues, especially the proprioceptive and vestibular senses.

Our proprioceptive sense comes from receptors in our joints, muscles, and bones that give us body awareness and provide information about how we are moving.

If a child has poor proprioception, he may:

  • Hold crayons or pencils too tight or too loose
  • Walk on his tiptoes
  • Have poor balance
  • Be “accident prone”
  • Seek out movements like crashing, bumping, and jumping
  • Have trouble following instructions for physical movement

The vestibular sense is our movement and balance. It’s the first sense to fully develop in utero and has the most influence on our daily lives. Our vestibular sense answers two basic questions: Which way is up? and Where am I going? It helps us keep our balance, coordinate movements of our head with our eyes, use both sides of our body at the same time, feel the direction and speed of movement, and remain upright against the pull of gravity. When there is dysfunction with vestibular processing, the other sensory systems will also be affected.

A child with vestibular dysfunction may:

  • Appear clumsy
  • Have poor postural control (e.g., sitting slumped over or even falling off a chair)
  • Have poor eye-hand and eye-foot coordination
  • Dislike being tilted backwards
  • Be very “cautious” with movement
  • Be terrified or have no fear of heights
  • Become overly dizzy with the slightest spin or not get dizzy at all despite excessive spinning
  • Have speech delays
  • Experience emotional insecurity

Children with SPD tend to have dysfunctional processing of both the proprioceptive and vestibular sensory systems, two sensory systems that are vital to feeling secure and having a good sense of self.

Interoception, the least known of all the sensory systems, is a sense that helps you feel and understand what's going on inside your body. Am I hot? Cold? Do I have to go to the bathroom? Am I hungry? Thirsty? Am I full? What exactly am I feeling? These are all questions that interoception answers.

Most of us have efficient interoception so answering these questions comes naturally. Kids with SPD often have difficulty knowing and feeling what's going on inside their bodies, which makes answering these questions difficult and causes problems ranging from poor self-regulation and frequent meltdowns to delayed potty training and frequent bed-wetting.

A child with poor interoception may:

  • Become too hot or too cold, or vice versa
  • Have difficulty in extreme temperatures or going from hot to cold like a heated house to cold outdoors
  • Have severe mood swings
  • Be unable to regulate arousal level- may fluctuate between being hyper and lethargic
  • Have difficulty regulating heart rate
  • Be unable to regulate thirst- always thirsty or never thirsty
  • Be unable to regulate hunger- eats all the time or hardly eats
  • Have difficulty potty training
  • Have frequent bed wetting
  • Have frequent constipation or diarrhea

Most of us have never given a second thought to how we process information from our senses because it happens automatically and seamlessly, hence the confusion about what sensory processing disorder is and how it affects children.

When you start to think about what it might be like if you tried to grip a pencil but couldn't feel how much pressure you needed in order to hold it, or if you were hanging upside down and had no idea where your body was in space, or if you couldn't tell when you had to go to the bathroom, you start to understand the importance of sensory processing and how sensory processing affects children.