In preschool, children learn about the five senses- vision, hearing, smell, touch, and taste. But there are actually two more senses. Proprioception helps one know where the body is in space. MedicineNet.com states, “proprioception is the ability to sense stimuli arising within the body regarding position, motion, and equilibrium.” Vestibular provides information of head placement in space to gravity by way of semicircular canals in the middle ear.
Proprioceptive, vestibular, and tactile input are critical for sensory-motor development. An individual receives sensory information and integrates it with motor systems to manage head, torso and limbs in space against gravity for a specific task. Movement is learned. Experience is the sculptor of the brain to solidify connections. Individuals learn movement and postural adjustments through sensory feedback. Postural control is affected by vision, auditory, somatosensory, and vestibular input. Sensory feedback provides input with regard to success of postural adjustments to gravity or performance of functional tasks. For example, during feeding the baby uses vision to see the spoon and food, uses tactile to feel the spoon and grasp, and the tongue to taste food if it reaches the mouth. Sensory coupled with motor is critical for success and sensory feedback helps to guide corrections.
What happens if sensory information is not present, unclear or confusing when received by the individual?
Sensory Processing is the ability to synthesize, organize and process incoming sensory information and use it for purposeful activity, not necessarily motor. “Sensory Processing Disorders are impairments in detecting, modulating, interpreting or responding to sensory stimuli.” (Miller, Coll, Schoen 2007).
There are three main categories:
- Sensory modulation disorder
- Sensory-based motor disorder
- Sensory discrimination disorder
“Sensory modulation disorders are impairments in regulating the degree, intensity, and nature of the response to sensory input resulting in problems in daily routines.”(Miller 2006) Sensory-based motor disorders include postural disorder and dyspraxia (motor planning). Sensory discrimination disorders involve limitations in discriminating between stimuli in a certain sensory domain. For instance, someone with auditory discrimination issue may have difficulty hearing the difference in cap, cat or pack or in the teacher speaking and background noise.
In this article, the emphasis will be on sensory modulation and seating and mobility choices to positively impact on these issues. In other words, assist the client to self-regulate their response to stimuli in a healthy manner. There are three subtypes under sensory modulation including:
- Sensory over-responsivity
- Sensory under-responsivity
- Sensory craving
The easiest way to understand this is to consider sensory input with regard to threshold. Sensory input can come in different intensities. Some individuals have a low threshold to receive input earlier than the typical population. This could be true for only one sensation or several. Remember the senses- tactile, taste, smell, vision, hearing, vestibular, and proprioception.
An individual with low threshold tactile may find the tags on back of the shirt unbearable, or touch overwhelming.
He will do best with sustained, deeper touch rather than tickling or brushing lightly over skin. With regard to seating, seams in upholstery, as well as, fabric and medium choice may adversely affect the client. A smooth, breathable fabric (Dartec) may work better than rougher grain fabric, as will seat and back without seams on weight bearing areas for some clients. Medium choice, shape to seat & back, and side guards can provide continuous contact, reduce sliding on fabric, as well as provide cocooning to escape sensory overload.
Convaid’s tension adjustable with upholstery wrap or anatomical back could serve well here. Low threshold visual clients may do well with a canopy to shield them from excessive visual stimuli they cannot manage. Low Threshold Vestibular clients feel the slightest movements of the head with more intensity. If this client would need tilt due to poor postural control, it is best to limit the tilt to a few degrees and over time build tolerance to greater head excursion to reduce over-stimulation and fight or flight response (emotional melt downs).
An individual with a higher threshold for tactile or vestibular sensations will need more input to sense touch or movement-hence the term sensory seeker. The high threshold tactile may stomp about, appear clumsy, move excessively, and have poor awareness of personal space and safety. He may hug other children too hard. Convaid’s full torso chest vest and position cushion may provide needed deep tactile input. Seating that hugs the client by way of shape and medium can be helpful, as can dynamic backs that one can pound against to receive deep pressure input and better body awareness in space. This dynamic back (X:Panda by R82) can also help with the high threshold vestibular client, who needs much more input to know where head is in space to gravity. Oscillating back and forth with their trunk pounding against a back can supply that input. This input can then allow them to focus and calm for activities.
In conclusion, Sensory Processing Disorders affect a person’s ability to synthesize, organize, and process incoming sensory information and use it for purposeful activities. Sensory processing disorders affect 1 out of every 20 children (Ahn, Miller, Milberger, McIntosh 2004). It is imperative the seating team effectively evaluate and recommend equipment for this population that will aide in self-regulation.
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