Sensory Integration Education

Shánna Louwrens is a South African paediatric occupational therapist with 9 years of clinical experience. After completing her undergraduate degree at the University of Pretoria in 2011, she went on to obtain her certification in Ayres Sensory Integration (ASI), Neurodevelopmental Therapy (NDT), and her Master of Occupational Therapy degree. She is currently working at a school for children with cerebral palsy, as well as in the private sector.

Shánna began her occupational therapy journey in a semi-rural clinic in Johannesburg. Although she always had a keen interest in paediatrics, it was working in this setting that her passion for CP was ignited. Whilst completing her ASI training, she realised that several children with CP also had some of the challenges seen in children with sensory integration (SI) disorders, including low arousal or sensitivity to touch and noise. She hypothesised that these difficulties were contributing to their functional limitations. Subsequently, she began using the principles of ASI when treating these children. The improvements in their arousal, participation and even their motor skills reinforced her belief that SI intervention has an important role to play in this diagnostic group. The paucity of evidence-based research to support what she saw in the clinic inspired her to examine the sensory modulation piece in CP. Shánna has had the privilege of presenting her research at ESIC and ISIC in 2019.

Introduction

Cerebral palsy, the most prevalent childhood disability, is a sensorimotor disorder occurring after insult to the developing brain (Bax et al., 2005). Historically, the focus has been on motor impairments but advances in neuroimaging studies highlight that both motor and sensory areas contribute to the impairments associated with CP (Scheck et al., 2012). Interestingly, a study done by Hoon et al. (2009) found that in some cases sensory impairments have a more significant impact on function.

Children with CP are typically classified according to their predominant motor patterns, which are related to specific areas of damage within the central nervous system (CNS). Ataxic, dyskinetic and spastic CP are the most described subtypes in the literature (SCPE, 2000). Often the spastic subtype is further divided into quadriplegia, diplegia and hemiplegia depending on the area of the body affected. The processing of incoming sensory information also occurs in distinct areas in the CNS; however, less is known about the unique sensory deficits in the different subtypes.

Occupational therapists have been studying sensory modulation in different clinical populations for over 30 years. Sensory modulation disorders (SMD) occur in about 5% of the population (Ahn et al.,2004), but this prevalence is considerably higher in children with disabilities. While the exact prevalence in CP is unknown, recent studies indicate that children with CP present with significant vestibular, visual, and multisensory processing difficulties (Pavão & Rocha, 2017). Despite this, sensory modulation is not routinely assessed or treated in children with CP. Furthermore, motor interventions continue to be the gold-standard of intervention, with little research into sensory-based interventions (Novak et al., 2020).

Trends show that distinct sensory modulation patterns (SMP) occur in different conditions (Cheung & Siu, 2009). Specific patterns have also been observed among the CP subtypes. Blanche and Nakasuji (2001) explored some differences in Understanding Sensory Integration in Diverse Populations (p345-364). However, these are founded by clinical reasoning and not sound empirical evidence. It is important to determine whether distinctive patterns exist in different groups as this can have implications for diagnosis, assessment, and intervention.

Aim, Methodology and Data Analysis

To bridge the gap in the literature, a quantitative, comparativedescriptive study was conducted in 5 special needs schools in Johannesburg, South Africa. The study aimed to (i) determine the most prevalent SMP in children with CP, and (ii) determine whether differences occurred between the subtypes. The Sensory Profile 2 (SP2) was used to measure sensory modulation in 154 children with CP, aged 5-15 years old. All the children were classified as functioning on a Gross Motor Function Classification System (GMFCS) level I, II or III, and therefore, were able to walk to some degree. Nonwalkers and those with additional comorbidities were excluded from the study.

The “more” and “less” bands of the SP2 were combined and labelled as the “not like” band. The percentage of children scoring in the “not like” band was calculated for each subtype and then compared statistically. Sensory modulation disorders were identified in a subtype when 50% or more of the children in that subtype scored in the “not like” band. Although the behavioural sections were analysed, the focus of this paper will be on the quadrant and sensory system data.

Study Findings and Discussion

In the sample of 154 children, 61 had spastic diplegia (40%), 49 had spastic hemiplegia (32%), 21 had ataxia (14%), 21 had dyskinesia, and 2 children had spastic quadriplegia (1%). Children with spastic quadriplegia were excluded from the comparative study because of the small sample size. These children tend to have severe motor impairments, and therefore, did not meet the GMFCS inclusion criteria.

The prevalent quadrant and sensory system patterns are illustrated in figure 1 and 2. Registration was the most frequent pattern in all the subtypes. A closer analysis of the sensory systems revealed a high prevalence of vestibular and proprioceptive difficulties across the groups. Since most of the questions in the SP2 relate to high threshold behaviours, we can assume that children with CP tend to be under-reactive in these systems. Motor impairments, which are characteristic of this condition, could impact on how these children receive, process, and use vestibular-proprioceptive information. Although to a lesser degree, avoiding patterns were also common in most of the subtypes. Children who avoid sensory experiences may not receive the sensory information that they need to develop different skills. Therefore, the influence of both under-reactivity and over-reactivity should be considered in this population.

Figure 1. The prevalence of quadrant patterns in the ataxic (AT), dyskinetic (DY), spastic diplegic (SD) and spastic hemiplegic (SH) subtypes

When comparing the different subtypes, some clinical differences were noticeable. The ataxic and dyskinetic subtypes had a high prevalence of all four quadrant patterns, as well as difficulties in most of the sensory domains. In contrast, the spastic subtypes had more specific patterns. The generalised pattern observed in the movement disorders may be related to the involvement of the thalamus and cerebellum, which are considered to play an important role in modulation (Bundy & Lane, 2020). Overall, the spastic disorders were less seeking than the movement disorders, which corresponds with the literature describing children with spasticity as being more passive (Blanche et al., 1995).

Figure 2. The prevalence of sensory patterns in the different subtypes of CP

The study found that children with spastic diplegia had prominent registration, proprioceptive and vestibular difficulties, with a generally lower prevalence of all other patterns. The clustering of movement systems could be associated with their GMFCS level, whereby most children in this subtype require additional support to walk. While tactile modulation difficulties were less common, they frequently have discrimination difficulties in clinical practice. This could be because they use their hands to mobilise.

Both low threshold patterns were highly prevalent in the spastic hemiplegic subtype. In particular, they presented with tactile and visual modulation difficulties. Over-reactivity, especially tactile defensiveness, is associated with emotional and attentional difficulties (Miller et al., 2007). These SMP could explain, at least in part, the attention and behavioural problems often observed in this subtype. In comparison to other subtypes, children with spastic hemiplegia had a lower prevalence of registration, vestibular, and proprioceptive difficulties. The fact that they have a more functional side and are generally more skilled walkers may aid their ability to register and process these inputs.

A statistically significant difference (Fishers Exact test, p=0.000) was identified between the subtypes in the proprioceptive system. Additional differences were observed between unique subtype pairs. The spastic diplegic subtype had more registration (Z-test, p=0.027) and proprioceptive (Z-test, p=0.000) difficulties than the hemiplegic subtype. The registration and proprioceptive differences are probably related to the differences in motor functioning. 

Study Implications For Sensory Integration

This study provides strong evidence that children with CP have extensive SMD. Furthermore, there is preliminary evidence that different subtypes of CP present with different SMP. The different patterns may be related to differences in the neuroanatomical pathology and associated fallout.

Clinicians rely on accurate reports and observations of specific behaviours to identify SMD in children. Because the motor and sensory pathways are intricately linked, it makes it challenging to distinguish between motor and sensory behaviours in CP. For example, is the child withdrawing from a loud noise because of over-reactivity or because of a retained reflex?

It is important to appreciate that motor patterns influence the quantity, duration, intensity, and type of incoming sensory information. This, in turn, may affect the child’s ability to register, regulate and appropriately respond to everyday sensory experiences. Similarly, SMD could result in dysfunctional patterns that affect motor functioning. The type of play occupations that the child engages in, as well as their home and school environment, are other factors which may contribute to SMD in CP.

The findings of this study have implications, not only for occupational therapists but for all clinicians working in the field of CP. Even if SI is not the primary approach, it is imperative to assess and understand the child’s unique SMP and how this influences arousal, behaviour, and motor skills. For example, an under-reactive child may not respond to traditional NDT therapy which requires handling, positioning, and movement. Likewise, an overly sensitive child may need to self-regulate and organise their nervous systems to tolerate handling or splinting. 

Sensory integration intervention aims to enhance body scheme, sensory modulation, and praxis by presenting sensory opportunities in a collaborative and child-directed manner (Bundy & Lane,2020). Whilst acknowledging that children with CP may need additional support, these outcomes are still possible. Children with CP are used to being handled and moved; therefore, their experience of the world is more passive.

Therapy may begin by providing opportunities to experience novel, intense, and self-directed sensations. Do they know what it feels like to somersault or spin around? Have they experienced the feeling of playing in mud or sand? The clinician may also want to consider adapting the equipment, the environment or therapeutic handling to facilitate the child’s ability to actively participate in meaningful sensory experiences.

The sensory piece has gained greater attention in the literature, especially recently, and in some cases may contribute to or even outweigh the motor impairments in CP (Blanche & Nakasuji, 2001). Current neuroscience acknowledges the role of enhancing sensory experiences early on in development to support reorganisation in the CNS (Guzetta et al., 2007). SI clinicians are pivotal in the assessment and treatment of sensory processing in children with CP.

References

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Blanche EI, Nakasuji B. Sensory integration and the child with cerebral palsy. Understanding the nature of sensory integration with diverse populations: Therapy Skill Builders; 2001. p. 347-84.

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