Sensory Integration

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Introduction

Sensory integration, or sensory processing, is the organisation of sensation for use. It refers to the ability of our brain to recognise and respond to signals sent by our sensory system. Our senses include hearing, vision, smell, taste, touch, proprioception, interoception, and our vestibular system - which provides information about movement, changing head position and gravity.

Sensory integration plays an important role in a child's development. This includes their ability to develop and maintain social-emotional relationships, as well as develop motor skills, cognitive skills, adaptive skills, and others. Children can be hypo- or hyper-sensitive to sensory inputs. When children have difficulty processing and responding to sensory information, their ability to participate in daily activities, school activities, etc. can be affected.

Sensory integration (SI) has been described by Amy Stephens (director of Lifelong Learning) as a framework of reference to be used across the multidisciplinary team and as both an intervention and approach. The end point of SI, Amy further explains, is to allow the individual to identify what they need from their environment, and how they can manipulate their environment for what they need.

This article provides a brief overview of sensory integration and offers recommendations for sensory integration therapy for children with cerebral palsy when sensory processing challenges are present. Optionally, read Sensory Integration Therapy in Paediatric Rehabilitation to learn more about the development, conditions treated, and the role of the Occupational Therapist.

Senses

While our five senses of touch, vision, hearing, smell and taste are commonly known, there are other senses which inform us about our bodies and the world they inhabit.

Both the five well-known senses as well as the other less known senses can be grouped into three areas namely:

1. Exteroception - Sensation from outside the body: Making use of the five common senses.
2. Proprioception - Sensation about body position and movement.
3. Interoception - Sensation from inside the body which is perceived through organs and viscera.

Following is a brief description of the systems most commonly addressed and utilised in a therapeutic environment.

Somatosensory system

The somatosensory system comprises of touch and proprioception.

One of the most important functions of this system is praxis: being able to plan and execute tasks.

1. Touch / Tactile System

Cutaneous Receptors

The tactile system is the sense of touch. It is the sense which allows for the perception, organisation and integration of information through receptors on our skin.

Information is received from receptor cells in the skin:

• Cutaneous receptors provide information about light touch, pressure, vibration, temperature, and pain
• Mechanoreceptors detect touch:
  • Hair follicles: affect touch perception
  • Pacinian corpuscles: sense vibrations and enable discrimination between smooth and rough surfaces / textures
  • Meissner corpuscles: sensitive to light touch, including a light tickle - they detect vibration and fine, discriminative touch
  • Merkel complexes: detect skin indentation and provide information on texture, curvature, and shape - they are activated by the applied pressure and location of objects we interact with
  • Ruffini corpuscles: detect stretch, as well as movement and finger position
  • C-fibre low threshold mechanoreceptors (LTM) respond to “pleasant” and “effective” mechanical stimuli like gentle stroking and brushing and small changes in skin temperature

• Thermoreceptors detect changes in temperature

These receptors relay information to different areas of the brain, namely the primary sensory cortex and the secondary somatosensory cortex.

Further somatosensory-vestibular-visual integration of information occurs in regions such as the vestibuli nuclei, thalamus and cortex.

The tactile system has multiple functions which range from the simple reflex withdrawal, to complex integration with other senses.Information received by the primary motor cortex is important for object manipulation and grasp, while information going to the secondary somatosensory region is involved in linking present and past sensations, needed in motor planning (a component of praxis). Tactile information is important in this process in regard to feedforward processing and prediction of movement .

2. Proprioception

Proprioception (kinaesthesia) helps us to move. Proprioception refers to information arising from skin, muscles, joints, ligaments, and bones. It allows us to perceive the location, movement, and actions of our body.Moreover, the sense of effort, the sense of force and the sense of heaviness are all involved in proprioception.

• When we change position or move our limbs, the tissues (e.g. skin, muscle, tendons, etc.) surrounding the moving joint are deformed
• It has been suggested that muscle spindles "play the major role in kinaesthesia"
• The skin receptors provide additional information
• It is also suggested that Golgi tendon organs contribute to proprioception

Proprioception

3. Vestibular System

The vestibular system provides information about movement, gravity, and changing head position. It contains two receptor types:

The semicircular canals - Detects angular movement of the head.

The Otolith organs - Detects linear movement of the head and the pull of gravity.

The vestibular system is linked to many regions and structures of the brain including the cerebellum, cranial nerves and even the cortex. This means that it plays a role in many functions of the brain and behaviors.

One important function is arousal regulation. Rapid or unpredictable acceleration is associated with increased alertness, while slow, rhythmical movement is associated with calming and drowsiness.

Neck and trunk musculature, important for head and postural control, is affected by vestibular input via the vestibulospinal tract. The refining of postural control is also affected by vestibular information coming to the cerebellum via the brainstem. Lane et al. (2019) highlighted the contribution the vestibular system has as a bilateral system, linking deficits in vestibular information to poor equilibrium reactions.

Cranial nerves receiving vestibular information via the longitudinal fasciculus aids eye and head movements. This information provides stability to an individuals surroundings even when the person is moving.

Connections to the visual and proprioceptive systems means that the vestibular information contributes towards anticipatory motor actions and plans.

In summary the vestibular system:

• Affects arousal regulation
• Affects postural control
• Facilitates balance and equilibrium responses
• Affects bilateral co-ordination
• Aids in maintaining a stable visual field (helps to stabilise our eyes when we are moving)
• Aids in spatial perception (telling us where we are in space and if the objects around us are moving or stationary)

Vestibular System

To learn more about the peripheral vestibular system, please click here.

4. Hearing / Auditory System

• The auditory system processes sound in the environment
• Auditory receptors in the inner ear identify various sound stimuli (e.g. loud / soft, far / near)
• These sound stimuli are then processed by the central nervous system to determine an appropriate response
  • for example, in situations where safety is a concern (e.g. a fire alarm goes off), we recognise the sound and act accordingly)
• Posture control can be influenced by sound frequency

5. Visual System

• Our visual system helps us see and perceive the environment around us
• It identifies sights and understands what the eyes see
• Visual inspection is also important in maintaining body balance as it helps position the body in space

Visual System

6. Smell / Olfactory System

• Our olfactory system allows us to distinguish various odours in the environment
• The three olfactory functions include:
  • Protection from environmental hazards - identifying safe or potentially dangerous situations (e.g. the smell of smoke)
  • Nutrition - Contributing to our appetite drive and food intake regulation.
  • Social behaviour - Human sweat, detected by our olfactory system is a powerful chemo-communicator and plays a role in fostering relationships. Smell is also involved in emotional regulation

It is important to note that the olfactory system is closely linked to the limbic system, which is responsible for emotions, behaviours and memories.

Sense of Smell

7. Taste / Gustatory System

• Our gustatory system distinguishes four tastes: sweet, sour, salty, and bitter
• It is closely associated with the olfactory system
• It allows us to identify desirable foods that are pleasant to us, as well as those that are potentially undesirable, such as a bitter dish

Tongue and Taste Buds

8. Interoception

Interoception is "the sense involved in the detection of internal regulation, such as heart rate, respiration, hunger, and digestion". Through interoception, we can distinguish our body's internal sensations.

Sensory Integration

Sensory integration or sensory processing "is the potential to develop adequate motor and behavioural reactions to stimulus." -- Ayres

The input from the senses is received, organised and interpreted to create a reaction appropriate to the stimuli received. This is also called sensory processing.

In 1960 Ayres proposed that:

1. Learning takes place as a function of reward and reinforcement.
2. One learns what one does.
3. Learning takes place because there is a purpose for it's taking place.

Ayres further proposed that development of the body scheme, development of posture and motor tasks, and even academic skills all needed the input of sensory information. In further regard, she emphasised how the sensory systems develop in relation to and because of one another.

Sensory integration theory places emphasis on "the active, dynamic sensory-motor processes that support movement as well as interaction within social and physical environments."

A great guide to Sensory Integration and Sensory Process terms can be found in the STAR Institute Sensory Integration & Processing Jargon Guide.

Sensory Integration / Processing Challenges

Sensory integration dysfunction is a problem in the ability to ‘‘organise sensory information for use.’’ -- Ayres

Sensory function is essential for motor ability, social skills, and various behaviours. Adequate sensory integration allows for the foundation of adaptive behaviour. Disruption in modulation, discrimination or integration of sensory input can create a cascading effect that impacts all levels of sensory processing. This can include motor, social and behavioural components (impairments and activity level of the ICF framework). This disruption can translate to problems with participation at home, school, and in the community.

In general, sensory integration dysfunction may cause an individual to have difficulty with the following:

• Initiating or sustaining peer interactions
• Developing relationships
• Participating in activities of daily living
• Regulating arousal behaviours
• Language development

Sensory integration processing deficits may cause an individual to:

• Respond to stimulation more quickly
• Respond to stimulation more intensely
• Respond to stimulation for longer than individuals who do not have difficulty with sensory integration processing

Examples:

• Extreme responses to stimuli, including noise in a classroom, odours in a restaurant, the touch of clothing, or the movement of playground equipment.
• The "fight, flight or freeze" behavioural responses, such as aggression, withdrawal, or preoccupation with the expectation of sensory input.
• Severe difficulty forming and maintaining peer relationships.
• Extreme efforts to control events in the environment by over-reliance on routines.
• Behaviour regulation problems like temper tantrums, outbursts, hitting, kicking, biting, or spitting.
• Profound withdrawal from the group.
• Slow to respond to sensation, requiring "more intense stimuli to respond to the demands of the situation".

Sensory Deficits and Cerebral Palsy

Children with cerebral palsy often have deficits in one or more sensory systems, including proprioception, tactile sensation, and visual perception. They can also have impairments in processing and modulating multisensory information which then affects their activity level, muscle tone, proprioception and emotional responses.

This can affect their functional activities, especially bilateral arm activities, such as eating, playing, dressing, and showering. A child with cerebral palsy and sensory processing difficulties might react to sensory stimuli in the following ways.

• Hyper-responsiveness to tactile input:
  • Does not like to be touched
  • Avoids activities that involve getting messy
  • Resists light touch
  • Avoids certain types of clothing
• Hypo-responsiveness to tactile input:
  • Lacks the ability to localise touch or respond when touched
  • Places items in their mouth
  • May have a preference for activities or situations which involve brushing their hair, touching or hugging
  • May fail to recognise when their hands or face are messy
  • Enjoys activities involving vibration
• Hyper-responsiveness to proprioceptive input:
  • Cries when they are in weight-bearing positions or when their joints are moved.
  • Chooses not to move or engage in activities.

• Hypo-responsiveness to proprioceptive input:
  • Bites or chews on non-food objects.
  • Engages in pinching or hitting others or themself.
  • Has difficulty changing body posture to match activity demands.
  • May have low, high, or variable muscle tone, which impacts the processing of proprioceptive information.
• Hyper-responsiveness to vestibular input:
  • Overreacts when moved in space.
  • Becomes fearful of bouncing or swinging.
  • Dislikes sudden or quick movements.
• Hypo-responsiveness to vestibular input:
  • Enjoys being moved and rocked passively.
  • Seeks opportunities to fall without regard to safety.
  • Likes excessive spinning, swinging, and active movements.

With children who are diagnosed with CP it is important to consider how they express or demonstrate their responsiveness to stimuli. A child may be able uses words to tell you when they like or don't like something, but a non-verbal child may communicate differently, especially when they are catagorised at a low GMFCS functioning level. A child may use sounds to communicate interest or level of alertness. Often a child who is overstimulated may become louder, but may also become quiet and inattentive as a form of 'shutdown'.

Also look for indicators such as tone change - do they get stiffer when they engage in the input? Or do their movements change, e.g. in a child with dyskinesia they may have movements which increase in amplitude. Or a child may fix certain joints such as hips or knees or demonstrate greater 'posturing'. Other indicators include drooling (an increase in arousal in any system may increase this), or a change in visual attention within the activity.

Sensory Integration Therapy

Sensory integration therapy (SIT) is done by trained occupational therapists, physiotherapists and even speech therapists, depending on the country and training required.

The "hallmark" of SIT is that it is performed in the context of play, including activities which the children enjoy and that ensures that the activities are their own reward.

SIT targets seven sensations: auditory, visual, gustatory (taste), olfactory (smell), somatosensory (proprioception and touch), vestibular, and interoception. It is suggested that SIT directly improves attentional, emotional, motor, communication, and/or social difficulties.

Pyramid of Learning

The Pyramid of Learning is an illustration that depicts the foundational skills needed by a child and the skills which then 'build on top' of these. The base needs to be adequately addressed for successful development of the ascending tiers. This is know as the bottom-up approach.

The goals of SIT is:

1. To facilitate a child's daily functioning.
2. To elicit a child's adaptive response in the form of an appropriate reaction to environmental or situational requirements.

Key Principles of the Sensory Integrative Approach

The Just Right Challenge - Activities performed offer a challenge, but are always orientated for success.

The Adaptive Response - The individual or child will adapt their behaviour with new and useful strategies in response to the therapeutic challenge.

Active Engagement - The individual/ child will actively participate in the environment and challenge developed by the therapist.

Child Directed - The therapist constantly observes behaviour and behavioural cues in the session. The cues provide leads to creating enticing and sensory-rich activities. The therapist follows the lead and suggestions of the individual/child.

General recommendations

Some recommendations when applying SIT is:

• Establish clear goals
• Ensure the child's physical safety
• Prepare the child before starting an activity (safety, posture, muscle tone)
• Promote sensory-enriched activities when appropriate (reduce sensory input when needed)
• Collaborate with the child on activity choice and maximise the child's success
• Guide self-organisation and support optimal arousal
• Build a therapeutic alliance through positive and supportive relationships
• Provide a "just-right" challenge
• Determine the activity's intensity and duration
• Promote positive experiences and respect a child's preferences
• Integrate into daily routine (like chores and art)
• Incorporate every movement into play

Other considerations related to Cerebral Palsy and SIT within an Occupational therapists perspective:

• The most important focus should be the occupations identified by the child and family. Note that occupation as defined in the therapeutic realm is anything which occupies one time in a meaningful way.
• Consider multiple hypotheses in the occupational analysis for the sensory difficulty.
• Make use of psychometrically sound outcome measures.
• Set specific and measurable goals focused on the occupations and participation levels.
• Involve the family and suggest changes to tasks and environment
• Clearly explain the state of the evidence to the family, for an informed choice.

The SI environment

Every environment a child resides in is appropriate for SIT, including schools, homes, yards, and playgrounds. However, sensory rooms tend to be utilised most frequently for treatment. Ensuring a child's physical safety is essential. Clinicians must carefully observe a child's reactions and pay attention to signs the child is becoming overwhelmed. If the child does become overwhelmed, the clinician should take prompt action and proactively change the situation.

Equipment: A sensory room should include at least three inventories of working materials for each sensation:

• tactile: sand, foam, various textures
• proprioception: ball pool / pit, therapy ball, heavy blanket
• vestibular: platform swing, bolster swing, net swing, tilt board, trampoline, ramp
• hearing: water (fountains, faucets, waves, and waterfalls), music (radio, instruments, chimes), instruments (drums, piano, guitar, keyboards and tambourines)
• visual: neon, patterned and florescent papers, coloured, strung, flashing, holiday and strobe lights, wind socks, wind-up toys, activity boxes and age-appropriate mobiles
• smell: air fresheners (lavender, potpourri and sachets), candles, lotions, powders, perfumes, flowers, plants, breads, cookies, stews, bacon, onions
• taste: fruits, milk-based items, hot and cold items, candies, cheese

Note: When introducing foods or liquids it is important to be aware of any allergies or food sensitivities. In addition, any loss of or impaired sensation must be screened for as well as a safe swallow. Children with CP often have sensory deficits or struggle with swallowing which makes them vulnerable to choking and aspiration, which could then lead to chest infections.

Activities

The following activities are examples of how elements of SI can be used to help treat sensory deficits depending on the sensory profile of the child.

It is important to consider:

a) What state the child is currently in, so as to determine which activities are required to bring the child into a regulated state.

b) Which activities would be stimulating to a child's system, thus increasing arousal and which would be inhibitory and thus depressing to a child's system.

1. Tactile Activities

• Functional play with a sensory board and different tactile materials.
• Playing with different brushes, drawing with soap crayons or chalk on the body, and erasing with various textures
• Engaging in different play activities with Play-Doh, like hiding small objects in the Play-Doh or creating a tactile bin for finger exploration
• Exploring kitchen activities, such as mixing, tasting, smelling, and washing vegetables
• Preparing a tactile bag (i.e. using a zipper bag filled with conditioner cream and food colours with small beans or toys hidden inside)
• Creating sensory balloons (e.g. balloons filled up with materials like cereals, flowers, sand, etc.)
• Making a tactile board using a piece of wood, tissue, and different materials

2. Proprioceptive Activities

• Engaging in playground activities
• Participating in gross motor activities
• Encouraging imitations of various movements
• Weight-bearing activities, such as crawling and push-ups
• Resistance activities like pushing and pulling

3. Vestibular Stimulation Activities

• Spinning, rocking, climbing, sliding, riding toys, walking, running
• Standing on one foot, progressing to standing on one foot with eyes closed
• Throwing a ball
• Shaking head or turning head from left to right at a rapid pace
• Bouncing on a bed, ball or parent’s knees
• Swinging in a blanket, swing, or on a rope

Safe-for-most strategies

The following strategies can be used for almost any sensory profile. They are used to regulate a child, in other words, bring them into the 'just-right' state for learning and engagement:

1. Linear vestibular - Slow back and forth movement. For example on a swing or hammock.
2. Deep pressure - A hug offered by another (co-regulation), swaddling in a blanket etc.
3. Low frequency vibration - Examples are a massage cushion or even driving in a car. For babies it can be seen as holding them close and letting them feel the vibration of your chest as you talk to them. This vibration generally spans between a sound you can hear and something you can feel in your body. It is of low pitch, not high buzzing.
4. Proprioception - Active movement of muscles. This is any movement against resistance or gravity. Often a favourite for children is crawling through a spandex tunnel (offering a resistance against limb movement). Active play incorporating whole body movement is another example.

To use SI or not to use SI

• Before incorporating Sensory Integration Therapy (SIT) into a rehabilitation plan, it is important to understand that there is a limited research evidence base for SIT, "with few positive outcomes and some null or negative outcomes" - when looking at the literature.
• If the parents and therapists decide to use sensory integration therapy, they should establish clear, functional outcomes as the baseline before starting with therapy. This should be accompanied by parent, teacher and team member education. After 8-10 weeks the outcome measures should be completed again to determine if the intervention is effective.
• A 2013 systematic review, updated in 2020, concluded that sensory integration is a "red light therapy" with regards to cerebral palsy and is considered and ineffective treatment. Therapists are advised to have open discussions with the family regarding "green light therapy" which has been shown to be effective and evidence-based.
• It is important to note that since 2013, more research studies have been conducted regarding the assessment of sensory deficits and sensory integration therapy with children with cerebral palsy, especially as an adjunct to other conventional therapy.
  • For instance a 2021 study showed that sensory integration therapy in combination with conventional physiotherapy exercises were more effective than just conventional therapy and exercises in improving gross motor function in children with cerebral palsy.

Resources

• What is Sensory Integration?
• Warutkar VB, Krishna Kovela R. Review of Sensory Integration Therapy for Children With Cerebral Palsy. Cureus. 2022 Oct 26;14(10):e30714.
• Case-Smith J, Weaver LL, Fristad MA. A systematic review of sensory processing interventions for children with autism spectrum disorders. Autism. 2015 Feb;19(2):133-48.
• Awalludin, ZA. Sensory Integration and Functional Movement: A Guide to Optimal Development in Early Childhood. 4th International Conference on Arts Language and Culture (ICALC 2019)
• Tracking Sensory Development