8 Sensory Systems
Sensory Processing Disorder
What is sensory processing disorder (SPD)?
When there is disruption or hindering in the ability to detect, organize, and/or create an adaptive response to sensations, sensory processing skills become inefficient resulting in sensory processing disorders (SPD). Everyone has sensory preferences, but individuals with SPD experience greater challenges participating in daily life. Individuals with SPD may misinterpret everyday sensory input, feel bombarded by stimuli, they may seek out sensation or movement, or they may not feel sensory input that others feel. This can lead to difficulties with managing behaviors and emotions, academic failure, motor clumsiness, difficulty attending or completing tasks, and/or poor social skills; as well as, self-stimming behaviors like hand flapping, jumping, rocking, etc. Signs of SPD look different depending on what sensory systems are being affected and how they are being misinterpreted. Therapists use this information to identify an individual's SPD subtype or category that best fits their processing challenges.
Subtypes of SPD
Sensory Modulation Disorders
Sensory modulation is our ability to respond appropriately to the sensory stimuli. This means remaining an appropriate level of arousal, an alert and relaxed state, when we are taking in the sensations around us. Sensory modulation disorders happens when one is unable to maintain the right level of alertness when responding to the sensory environment. An alert but relaxed state is needed in order to function optimally in daily life. Children with sensory modulation disorders are often described as sensitive, hyper, or lethargic depending on their ability to modulate incoming stimuli.
SENSORY OVER-RESPONSIVITY
Individuals with sensory over-responsivity are more sensitive to sensory stimulation than most people. Their bodies feel sensation too easily or too intensely. They might feel as if they are being constantly
bombarded with information. Consequently, these people often have a "fight or flight" response to sensation e.g. being touched unexpectedly or loud noise. They often try to avoid or minimize sensations, e.g., withdraw from being touched, or cover their ears to avoid loud sounds. If a person is severely over-responsive, they may “freeze” up, in which they are shut down and are not able to take in any sensation.
SENSORY UNDER-RESPONSIVITY
Individuals who are under-responsive to sensory stimuli are unaware of sensory stimuli meaning they do not feel it. They may have a delayed response to sensory input and/or respond with less intensity. Often these individuals are quiet and passive, disregarding or not responding to stimuli of the usual intensity available in their sensory environment. They may appear withdrawn, difficult to engage and or self-absorbed because they do not detect the sensory input in their environment.
SENSORY CRAVING
Individuals are often actively seeking or craving sensory stimulation and seem to never be satisfied with their sensory input. Individuals with this pattern have a seeming insatiable desire for sensory input. They tend to be constantly moving, crashing, bumping, and/or jumping. They may “need” to touch everything and not understand personal space. A key factor for sensory craving is that when the individual receives more input, it does not regulate them (reduce their arousal); in fact, true sensory craving disorders become more disorganized with additional sensation.
Sensory-Based Motor Disorders
Sensory-based motor disorders describes a condition in which a child is struggling with motor skills, like balance, gross motor, fine motor, coordination, and the the performance of skilled, non-habitual and/or habitual motor tasks that is stemming from sensory processing deficit related to movement. These disorders are often a result of either tactile, proprioceptive, and/or vestibular processing challenges. This foundation issue is different from neuro-motor disorders in which there is a specific structural/anatomical, biochemical, or electrical abnormality in the brain, spinal cord, or nerves (i.e. Cerebral Palsy, seizure disorders, gene or chromosomal abnormalities, etc.)
DYSPRAXIA
Individuals with dyspraxia have trouble processing sensory information properly, resulting in problems planning and carrying out new motor actions. They may have difficulty in one or more of the following:
1) forming a goal or idea, 2) planning a sequence of actions or 3) performing new motor tasks 4) interpreting feedback from their motor action. These individuals are clumsy, awkward, and accident prone. They may break toys, have poor skill in ball activities or other sports, or have trouble with fine motor activities. They may prefer sedentary activities or try to hide their motor planning problem with verbalization or with fantasy play.
POSTURAL DISORDER
Individuals with postural disorder have difficulty stabilizing his/her body during movement or at rest in order to meet the demands of the environment. They lack the perception of where their body is positioned and tend to have poorly developed movement patterns that depend on core stability. They may appear weak and/or have poor endurance to sustain certain positions and tend to compensate by leaning on things or will constantly move/change body positions. They often do not have the body control to maintain a good standing or sitting position. When postural control is good, the person can reach, push, pull, etc. and has good resistance against force.
Sensory Discrimination Disorders
Sensory discrimination refers to the process in which specific qualities of sensory stimuli are perceived and meaning attributed to them. It is accurately understanding what is seen, heard, felt, tasted, or smelled. Individuals with sensory discrimination disorder (SDD) have difficulty determining characteristics of sensory stimuli resulting in a poor ability to interpret or give meaning to specific qualities of stimuli. They may take extra time to process important aspects of sensory stimuli, appear awkward in gross and fine motor activities, and/or inattentive to people and objects in the environment. SDD can affect all eight senses including:
AUDITORY DD
Difficulty interpreting characteristics of sensory stimuli that is heard
VISUAL DD
Difficulty determining/interpreting characteristics of sensory stimuli that is seen
TACTILE DD
Difficulty determining/interpreting characteristics of sensory stimuli that is felt on the skin or interpreting higher level visual/spatial characteristics of touch (includes stereognosis and graphesthesia disorders)
PROPRIOCEPTIVE DD
Difficulty determining/interpreting characteristics of sensory stimuli experienced through use of the muscles and joints
VESTIBULAR DD
Difficulty interpreting characteristics of sensory stimuli, experienced through movement of the body through space or against gravity
GUSTATORY DD
Difficulty determining/interpreting characteristics of sensory stimuli that is tasted
OLFACTION DD
Difficulty determining/interpreting characteristics of sensory stimuli that is smelled
INTEROCEPTION DD
Difficulty interpreting stimulation from internal organs (may not feel need to use the toilet or may have frequent somatic complaints such as stomach aches)
Reference: (2017). Subtypes of SPD. STAR Institute. Retrieved from https://www.spdstar.org/basic/subtypes-of-spd