Sensory Integration-An overview
In-Service, April 4, 2006
Sensory Integration is a normal life function and process. Dr. A. Jean Ayers first defined sensory integration as "the neurological process that organizes sensation from one's own body and from the environment and makes it possible to use the body effectively within the environment." This is supposed to happen without any conscious effort at all on our part. When the systems do not function as they are supposed to, it is called sensory integration dysfunction (SID). This is a general term and the way it presents and affects the individual varies from person to person. Carol Kranowitz, in the revised version of The Out of Sync Child lists 3 main categories of SID.
When testing for sensory integration dysfunction, we look at the end product-the motor action, emotion, or behavior and start looking for patterns or clusters of symptoms. Having one or two "quirks" does not mean that there is dysfunction present. We do use standardized tests and questionnaires to help us put the pieces together. There is one test called the SIPT which stands for Sensory Integration and Praxis Tests. It is able to detect some but not all sensory processing dysfunction. It is a test of motor planning (praxis) and can detect sensory discrimination problems. It is not a test for sensory modulation dysfunction.
Treatment plans are highly individualized and are most successful when the family is able to carry over to the home environment strategies specifically selected and designed to treat the child's individual needs. In order for that to happen, it is important that you, the family know and understand the language that we use and the reason behind the "homework" or suggested activities for home. The suggestions that we give you are intended to carry over the work that the child has done in therapy to home, and increase the rate of change and improvement.
We will be defining a variety of terms and giving you a chance to experience some of what each of the sensory systems does and gain valuable insight into what you can do at home. We will start with a brief overview of the major types of sensory integration dysfunction. Then we will discuss the tactile, proprioceptive, vestibular, auditory, and visual systems in greater depth.
The Three Major Types or Classifications of SID
Modulation: is the brain's regulation of its own activity. Modulation involves matching the body's energy level and attention to the demands of the environment. It requires the brain to filter information and attend to certain information while disregarding other stimulation. When an individual over responds, under responds, or fluctuates in response to sensory input in a manner that is disproportional to that input, we say that the person has a sensory modulation disorder. The most common types of sensory modulation disorder are: tactile or sensory defensiveness, gravitational insecurity, aversive responses to movement, and poor sensory registration. Modulation is NOT always being "quiet and calm". For example being quiet, calm, and almost falling asleep at a loud basket ball game is not typical, just as a being excessively loud and rambunctious in a classroom or library setting is not typical. A well operating system with typically functioning modulation would be able to cheer loudly for their favorite basketball team and then immediately shift gears to be able to stand in line to order refreshments. An example of poor sensory modulation to the sense of touch would be to withdraw from and shout out as if in pain when getting foam soap on their hand.
Dyspraxia: The word praxis means Motor Planning, and dyspraxia means that there is a sensory based problem with motor planning. It is the ability of the brain to conceive, organize, and carry out a sequence of unfamiliar/novel or un-practiced actions. Motor planning is necessary to perform any coordinated movement - gross or fine motor. It requires the brain to recognize sensory information correctly, process it, and compare it to memory and to the desired outcome. It also involves planning the movement, executing it, and finally analyzing the performance in order to make adjustments to improve the next attempt. Eventually, the action becomes a habit and no longer requires so much of a conscious effort. A problem any where in this long sequence of events can be devastating to the final outcome and result in poorly coordinated movement, especially if the problem lies in the recognition and processing of the incoming sensory input.
Sensory Discrimination: is the ability to correctly register (or recognize) sensory input on a neurological level in order to use it functionally. When our sensory systems are functioning correctly (meaning they are registering and responding to incoming sensory input correctly) we are able to discriminate or know things about ourselves and the world around us without testing them out every time. For example, we know which way is up even if we are upside down, we can tell the difference between a penny and a quarter without looking at it, we can anticipate how much force to use when picking up an egg shell compared to a closed can of pop, and we can tell the difference between a safe touch and a threatening touch (feeling something crawling on your arm vs. a gentle pat on the arm). Sensory discrimination problems are nearly always the root cause of dyspraxia or poor motor coordination.
The Tactile System
I. Definition: The tactile system is the sensory system which layers our bodies and gives us information about physical objects surrounding us. It is the physical barrier between ourselves and the environment. The tactile receptors are found in the skin, and they serve the purposes of detecting and discriminating. This system is responsible for detecting and discriminating pressure, vibration, movement, temperature and pain. Once the tactile system takes in this information it is accountable for processing and organizing it to make a meaningful and accurate picture of the stimulus.
There are 2 components that make up the tactile sense:
1. Protective (defensive) system: As a protective system the tactile sense is expected to detect and alert the neurological system of danger. If on high alert mode, the tactile system may perceive many things as being dangerous even if they are not necessarily a threat. This protective sense may detect hot temperature, sharp objects, insect bites, or physical harm from another.
2. Discriminative system: The tactile system is also responsible for discriminating between various objects. The reliability of tactile discrimination is the highly reliant on adequate perceptual skills. It distinguishes that we are touching something and where on the body that it occurs. Tactile discrimination also tells us whether the touch is light or deep. Lastly the tactile discriminative system informs us of the size, shape, temperature, texture and density of the stimulus.
II. Dysfunction: Tactile system dysfunction occurs when there is inefficient processing in the central nervous system of sensations perceived through our skin. A child who is hyper-responsive (over responsive) has difficulty with touching and being touched by objects and people, especially when unexpected. A child with tactile system dysfunction may be unable to distinguish between dangerous and safe tactile sensations, and may misinterpret a friendly touch as being threatening.
Examples of Tactile system dysfunction:
1. An over responsive tactile system (tactile defensiveness) may look like the following:
2. An under responsive tactile system may look like the following:
3. Poor tactile discrimination may look like the following:
The Proprioceptive System
Proprioception is the unconscious awareness of body position. It tells us about the position of our body parts in relationship to each other and the environment. It allows us to have a knowledge of how much force and speed the muscle is required to generate in order to accomplish a specific movement which results in appropriately graded muscle control. The receptors are located in the muscle belly, tendons, ligaments, joint capsules, connective tissue, and the skin. An example of an intact proprioceptive system would be the ability to pick up an egg and place it on a plate without breaking it. The child must realize their position in relationship to the egg, create a plan to grasp the egg, carry out the motor plan, and then terminate the activity.
Dysfunction in proprioceptive processing is apparent through poor awareness of body and position. These children have difficulty grading movement and controlling motor patterns. They often press too hard or not hard enough on pencils and small objects. Sometimes movement is overshot or undershot. In the example of the egg, the child may break the egg when he picks it up, or place it too roughly on the plate causing it to break.
Children with proprioceptive dysfunction also have a poor sense of postural stability through their trunk. A strong stomach and back are required to have an upright posture and provide a stable base of support for the arms to function smoothly. These are necessary components for tasks such as balance and sequential movements. Without appropriate awareness of body position, motor patterns are difficult to create and carry out fluently. Many of these children appear to be "Klutzy", running into objects or pressing/pushing too hard.
A Child with Proprioceptive Dysfunction may demonstrate some of the following characteristics or behaviors:
The Vestibular System
I. Definition: The vestibular system is defined as the system that is located in the inner ear and tells us where our head/body is in relation to the earth. The primary function of this system is to register movement of the eyes, head, and neck and to respond to the pull of gravity. This system sends messages to the Central Nervous System about balance and movement, and helps us to generate muscle tone so that we can move smoothly and efficiently.
A: Some examples that can better explain the vestibular system is knowing whether you are moving or if you are standing still. Another example is knowing whether the objects in the room are motionless or moving. You are using your vestibualr system to help you to distinguish these differences.
II. Dysfunction: Dysfunction in the vestibular system is the result of inefficient processing in the brain, of sensations received through the inner ear. A child with vestibular dysfunction may have difficulty processing information about gravity, balance, and movement through space. Other areas affected by vestibular dysfunction can include muscle tone, bilateral coordination, praxis (motor planning), arousal state, vision, hearing, and emotional security.
A: The Over Responsive or Hypersensitive Child may demonstrate characteristics such as:
1. Showing an intolerance to movement:
2. Demonstrating Gravitational Insecurity:
B: The Under Responsive or Hyposensitive Child may demonstrate characteristics such as:
1. Showing little response to movement:
2. Demonstrating an increased tolerance for movement:
C. You may also see additional related characteristics in a child with Vestibular Dysfunction. They can include the following:
1. Poor postural control
3. Poor motor planning:
4. Is emotionally insecure:
The Auditory System
The auditory system is composed of the outer ear, inner ear, and the nerves and areas of the brain and is a complex system of hearing and processing sound. This system registers and responds to intensity (volume), frequency (high/low pitch), duration (time), and localization (direction) of the sounds in our environment.
The ability to hear and processes sound effects the child's ability to understand their position in space, body scheme, right side from left side in space, balance, posture, arousal, muscle tone, and emotional tone. The ability to process sound and to actively listen is directly related to the vestibular system due to the anatomical structure of the inner ear. When working together, the vestibular system and the auditory system give us the best picture of where our body is in space and what it is doing, functionally giving us a foundation for planning and executing motor plans.
Dysfunction occurs when a child becomes over sensitive to sound and is unable to tolerate normal daily sounds. For other children, dysfunction presents as under-sensitivity and they require or seek out intense sounds that interfere with daily tasks. This may also lead to speech and language problems.
The Child with Auditory System Dysfunction May Exhibit some of the following Characteristics or behaviors:
The Visual System:
The visual system is our window to the world. Its primary structure is the eyeball, but includes 6 muscles around each eye, the eye lid, nerves, and the primary reception area in the brain. It enables us to have a three dimensional picture of the world around us, identify sights, anticipate what is "coming at us", and allows us to prepare for a response.
The visual system is closely linked to our vestibular system. We use both our visual system and our vestibular system to give us our ability to balance. The two systems work closely together to give us good visual perception (an accurate mental representation of what we are seeing) and good visual motor skills (being able to coordinate our hands and eyes for work in space and for written work).
A. The over-sensitive/ over stimulated child may:
B. The Under-Responsive Child may:
Visual system problems can occur for many reasons and can be very complex. Therefore, it is very important to be sure that each child's vision is good. This goes far beyond screening to see if the child can see clearly (i.e. passing a typical school screening). Your therapist may suggest an eye exam by a developmental optometrist to look more specifically at all of the functions and necessary underlying skills of the visual system to rule out any non-sensory causes of visual system problems.
Doing a search for Sensory Integration will provide you with a wealth of information. There are many good web sites that have specific information related to individual questions. One place to start is the Sensory Integration International Web site: http://home.earthlink.net/~sensoryint/ . Another good website is www.sinetwork.org