Sensory Integration Education

Dr. Ellen McLaughlin, Ed.D., OTR/L, FAOTA, is an associate professor and Program Director, for the Occupational Therapy programme in Misericordia University. She presented a short course on "Theoretical and Neuroscience Foundations for Paediatric Interventions" at the AOTA conference in April. This presentation was evidence based and the information was synthesised succinctly which made it meaningful for clinicians. Dr. McLaughlin, kindly shared a snapshot of this short course for the benefit of our readers allowing us to disseminate information from this international conference.

As therapists we always strive to provide the best experiences for our clients so they can achieve their potential. Clearly specifying the theoretical and neurological principles that underlie some of our most common interventions helps us to move in that direction efficiently and effectively. In a recent editorial, The State of the Science in Sensory Integration (Pfeiffer, May-Benson & Bodison, 2018, p. 2) it was stated, “researchers should articulate the underlying mechanism for why the intervention…..is expected to enhance child participation… this would allow researchers to test the underlying theory of why the intervention is thought to be helpful, as well as the intervention’s effectiveness in supporting child participation.“

We can adapt this challenge about research to our activities as clinicians by:

- Ensuring that valid assessments have been conducted to confirm that the performance deficits seen are due to sensory processing difficulties.

- Articulating the specific principle that guides the intervention being used, with some understanding of the neurological processes of why the intervention is proposed to work.

Sensory Integration from a Broad Perspective

Principle: If we provide an enriching sensory environment, with active engagement & appropriate challenge and dosage, changes to the brain will occur (Lane & Schaaf, 2010).

There is a strong foundation of basic research that supports these claims (Lane & Schaaf, 2010), yet therapists must consider and specifically apply each of the elements in this principle.

Active involvement in an enriching Sensory Environment 

When providing multisensory or cross modal sensory interventions it is essential that these sensory elements be required components of the task. Strong task analysis skills with critical judgment must be applied here, as simple inclusion of a specific sensation may not be enough to elicit the change in the nervous system. Recent computational models of multisensory processing in the brainstem suggest that for sensory integration to advance during development, direct experience in coordinated sensory processing is necessary to surpass the brain’s tendency to have individual sensory inputs compete, rather than collaborate (Cuppini, Stein & Roland, 2018).

Appropriate challenge & dosage

To achieve this, it must be based on a valid, clear assessment, with interventions focused to include the specific sensory functions implicated, at the just right level, as one size does not fit all in respect to sensory integration interventions.

Deep Pressure

Key Neurological Areas: Low threshold Aβ Mechanoreceptors - Dorsal Horn - Dorsal Column Pathway - Reticular Formation - Vagal and Parasympathetic System - Sympathetic System - Cortical Awareness.

Principle: If you apply sustained, deep tactile input to the skin, it can produce an inhibited, relaxed state in the client, affecting such areas as mood, muscle tone, and autonomic function.

A common intervention for occupational therapists to employ is the use of deep pressure, often as a method to calm the nervous system through brushing, wrapping in blankets, and using compression devices or garments. When we use deep pressure to reduce a negative sensory tactile experience, such as tactile defensiveness, we are incorporating a process involving presynaptic inhibition.

In this case, activation of mechanoreceptors (by shaking your hand, rubbing or placing pressure on the skin) starts a process called presynaptic inhibition, whereby the pressure impulses conveyed along the dorsal column medial leminiscus pathway “fire back” at the dorsal horn area of the spinal cord to inhibit the nociceptive (pain, tickle, itch) sensations that are sent along the anterolateral nociceptive pathway, to lessen them. When deep pressure is instead used for a more generalized effect, other pathways are implicated and the focused neurological effect occurs higher up, in brain stem areas. These brain stem areas impact the reticular activating system which has a direct influence on increasing parasympathetic activity through increased vagal tone, and decreasing sympathetic response. The effect of deep pressure using a pressure vest after a stressor was applied, resulted in outcomes such as lessening of arousal as measured by physiological parameters such as heart rate, respiration, electrodermal activity (Reynolds, Lane & Mullen, 2015). Champagne, Mullen, Dickson, & Krishnamurty (2015) confirm the physiological effects of deep pressure sensation in adults. More recently, Bestbier & Williams (2017) provided an account of significant results in a well-designed study conducted in a residential facility with 8 children with autism or severe intellectual disabilities over a period of three months.

Soothing Tactile Input

Key Neurological Areas: Unmyelinated C Tactile Afferents on Hairy Side of Skin - Mechanoreceptors-Dorsal Colum Pathway - Thalamus – Posterior Insular Cortex – Orbitofrontal Cortex.

Principle: If we utilize soothing social touch we can impact emotional regulation, and promote social responsiveness and connection.

Soothing social or pleasant touch is differentiated from discriminative touch or pressure touch. While it starts out on the same dorsal column pathway, the receptors are different, and the final processing areas in the brain are different.

It has been shown through physiological measures, behavioral responses and functional brain imaging that these C tactile primary afferents contribute to pleasant touch and provide an important sensory underpinning of social behavior (Liljencrantz & Olausson, 2014). For this type of touch, the emotional, sense of self/ body scheme, interoceptive and embodied cognition processes of the brain are most impacted. Clinicians working with mental health and trauma may be particularly interested in investigating evolving research in this area, as it indicates that activation of these fibers triggers oxytocin release, reducing physiological arousal, impacting positive affect and potentially inhibiting pain (Walker, Trotter, Swaney, Marshall, & Mcglone).

Movement Input

Key Neurological Areas: Oxygen consumption – improved inhibition evident via EEG – increased activation of anterior cingulate cortex and superior frontal gyrus – better executive functioning.

Principle: Movement increases blood flow to the brain, promoting attention, mental clarity and memory. Movement will assist children to focus.

Movement breaks, sensory pathways, advocating for recess time…all of these activities contribute to better attention, executive functioning and learning for our children. Studies with elementary and adolescent children have demonstrated this on a neurological level through viewing activity of the brain, as well as in academic outcome measures (Hillman, et al, 2014). The more consistency, enjoyment and intensity we can integrate into these movement activities, the better.

Proprioception  

Key Neurological Areas: Muscle spindle and golgi tendon sensory receptors – dorsal column pathways to conscious cortical and unconscious brainstem areas – hypothalamus, pituitary, adrenal areas.

Principle: If we activate proprioceptors in the context of meaningful occupation, we can increase awareness of body scheme, modulate arousal state and ultimately improve focus in purposeful activity.

One way that therapists often use proprioception is to help children modulate their arousal levels through oral motor stimulation, specifically chewing. Chewing is an effective stress-coping behavior. While evidence was not available to document the impact of this clinically with children, in a comparison of nursing students who were randomly assigned to a 2-week mint gum chewing experience, or a control group the gum chewers were found to have significantly better scores on measures of anxiety and mood (Yu, Chen, Liu, & Zhou, 2013). Geriatric research also shows us that there is a clear association between geriatric loss of teeth and loss of the ability to chew with cognitive decline and dementia (Azuma, Zhou, Niwa, & Kubo, 2017).

It all starts when the muscle spindle embedded in the muscle and the golgi tendon organ located on the tendon, which are sensory receptors, detect muscle and tendon lengthening and shortening. These impulses are sent through conscious pathways to our cortex for awareness, and through unconscious pathways to our brainstem for cranial nerve input from chewing. Chewing suppresses the hyperactivity of the hypothalamus-pituitary-adrenal (HPA) axis which then can have a positive effect on, stress related hippocampus cognitive deficits.

Interoception

Key Neurological Areas: Visceral organs or muscles - small diameter C or A fibers – spinothalamic tract or vagus and glossopharyngeal cranial nerves and the solitary tract– insula – cingulate cortex.

Principle: If we optimize our ability to detect and process interoceptive signals we can influence sensory and emotional regulation supporting daily behaviors.

Interoception is the sensing and awareness of our internal body signals, including those that help us maintain homeostasis, i.e. hunger, thirst, urination, sleep, and those that reflect emotions such as anxiety, excitement, and calm. It includes any bodily information that is sent by either small diameter C or A fibers through lamina I and the spinothalamic tract to the insula and cingulate cortex (Craig, 2002), and to vagus and glossopharyngeal cranial nerves and the solitary tract (Critchley and Harrison, 2013). Mahler (2017) provides a multitude of interventions addressing distress tolerance and recommending mindfulness skills to improve interoceptive awareness and provide increased self-control for better occupational performance, particularly for children with autism spectrum disorder. Payne, Levine, and Crane-Godreau, address interoception difficulties and interventions associated with trauma.

Interoceptive feelings are regulated by the brain’s insular cortex. Today’s scientists are now identifying connections between an under or over-functioning insular cortex with ASD, OCD, PTSD, ADHD, anxiety, BPD, etc.

It is often our intent to improve sensory processing and integration and to modulate arousal and emotional regulation levels, as these are neurological foundations essential for the social interaction, attention and environmental interactions that are embedded in the performance demands of every child’s day. When we carefully consider the theoretical and neurological principles that support our interventions we increase our chances of providing the best therapeutic outcomes possible.