Sensory Processing Disorder
Sensory processing disorder (SPD) - or sometimes dysfunction in sensory integration (DSI) - describes when a person's nervous system has difficulty in taking in, integrating and making use of sensory information.
What is sensory processing or sensory integration?
In most people the senses - touch, hearing, vision, taste and smell as well as movement and body position - occur automatically, without having to think about them. The nervous system supplies information about these sensations to the brain, where the information is used to understand what is going on within the body and the world around us. These normally develop more fully during childhood. How the brain processes and uses this information is referred to as sensory integration. There are several stages in sensory processing:
The ability to process this information affects how we learn, do everyday activities and develop relationships with others.
What is sensory processing disorder?
If the brain has a problem in processing and using the sensory information provided, where it does not organise the sensory signals in a useful or accurate way, it can affect the ability to learn as well the development of behaviour, social and motor skills. This is referred to as sensory processing disorder (SPD), or sometimes dysfunction in sensory integration (DSI) or Sensory Integration Dysfunction (SID). This is an umbrella term that refers to a number of neurological disabilities.
There are varying levels of SPD. In some people only one of the senses such as touch or sight are involved, but in others the disorder involves several senses. In addition, the person may under-respond or over-respond to the signals, and to varying degrees. One person may find the feeling of certain types of clothing material unbearable, but another person may not react at all to pain or the sensation of hot or cold. A person with SPD may lose balance easily when walking or be accident-prone. Or he or she may reject food based on how it looks, may not be able to tell if the food is too spicy, salty or sweet, or may not be able to tell the difference between the taste of lemons or soap. Some people have a need for sensations and may seem to be in constant overdrive.
SPD is divided into three main categories of disorder:
- Sensory modulation disorder (type 1) - involves difficulty in grading or regulating responses to sensory input; this category includes sensory over- and under-responsiveness and sensory seeking.
- Sensory discrimination disorder (type 2) - when a person has difficulty interpreting specific characteristics such as intensity, speed, timing and duration of sensory input.
- Sensory-based motor disorder (type 3) - subdivided into dyspraxia -problems with sequencing, organisation and motor planning - and postural disorder such as distorted balance and core stability.