Sensory-based interventions with adult and adolescent trauma survivors An integrative review of the occupational therapy literature

Purpose – An emerging evidence base, and increased awareness of the effects of trauma on the body, advocates a sensory-based approach to treatment with posttraumatic stress and complex trauma survivors. This paper aims to identify, analyse and summarise the empirical evidence for the sensory-based interventions, which occupationaltherapistsareusinginthetreatmentofadultandadolescenttraumasurvivors. Design/methodology/approach – An integrative review of the literature was undertaken. Both empirical and conceptual papers were included. An inductive approach and constant comparative method were used to understandandsynthesise the research. Findings – The literature search yielded 18 papers describing the types of sensory-based interventions used, sensory processing (SP) patterns and the context and evidence for sensory-based occupational therapy practice with trauma survivors. Nine of the studies were empirical and nine were conceptual and review papers. Themes identi ﬁ ed included: atypical SP patterns; type of sensory-based intervention used with traumasurvivors; andtransdisciplinarytreatment programmescan reducethesymptoms of trauma. Practical implications – Sensory-based interventions with adult and adolescent trauma survivors are emerging as promising areas of practice and research in the literature. Although empirical data is limited, the sensory needs of the body in processing trauma experiences is becoming more recognised and are supported by the atypical SP patterns identi ﬁ ed in survivors. A sensory-based, transdisciplinary approach to treatment hasthepotentialto be effective intreating thetraumasurvivor. Originality/value – With a skill base in sensory integration and occupational analysis, occupational therapists have much to offer the ﬁ eld of trauma studies. This review begins to address the gap in the literature, recommending more rigorous controlled outcome research with larger sample sizes, person-centred studies focussing on the trauma survivor ’ s perspective and continuing professional development and mentorship foroccupational therapistsworkingwith this population.


Introduction
There is a compelling evidence base to demonstrate that traumatic experiences are relatively common occurrences among clinical and general populations (Smith et al., 2016) and are associated with a number of persistent mental health difficulties including posttraumatic stress disorder (PTSD), complex posttraumatic stress disorder (CPTSD), major depressive disorders, anxiety disorders and psychosis (APA, 2013;Maercker et al., 2018;van der Kolk, 2005), as well as physical illness, disease and disability (Felitti and Anda, 2010).
A traumatic incident may be a single event or may result from repeated exposure to events the individual experiences as threatening bodily harm or death to the self or another (Maercker et al., 2018). Complex trauma or CPTSD often begins early in life and involves the child's caregiving system (Buxton and Turnbull, 2018). It is different from single event trauma in that it may include prolonged physical, emotional, and sexual abuse, as well as profound neglect, all of which interrupt normal development, secure attachment, leading to changes in the developing brain that persist into adulthood (Ogden et al., 2006;van der Kolk, 2005). However, it is the overwhelming nature of trauma that elicits survival responses from the brain and nervous system and, if recurrent, these survival or fight/flight and freeze responses will adversely affect the development of affective, physiological and cognitive functions, as well as self-regulatory and relational capacities in the survivor (Clark et al., 2015;van der Kolk, 2005van der Kolk, , 2018. The reasons why the effects of trauma on an individual can be so extensive still remain inconclusive. As a response to traumatic experience, especially in early life, unregulated bodily experiences replay themselves endlessly and are believed to be experienced in the body as somatic sensation (Ogden et al., 2006;Fisher, 2006Fisher, , 2018van der Kolk, 2005van der Kolk, , 2015van der Kolk, , 2018Koomar, 2009). This is of particular relevance for persons who experienced trauma in early life, as the brain has not developed its narrative capacity at this stage to support conscious memory processing (van der Kolk, 2005Kolk, , 2015. Thus, when a trauma survivor experiences triggering events or sensations in the body, overwhelming physiological and emotional responses that occurred during the original traumatising event may reoccur, compromising the person's occupational participation, performance and potential Koomar, 2009).
The importance of the body and adopting a sensory approach to addressing the symptoms of trauma have been advocated by healthcare researchers and professionals, as worthy avenues for exploration in the nascent field of trauma treatment (Champagne and Stromberg, 2004;Koomar, 2009;Ogden et al., 2006;van der Kolk, 2015;Warner et al., 2013). Given that most of the therapeutic modalities to date focus on drug or talking therapy (Hetrick et al., 2010;van der Kolk, 2018), the body's role in processing traumatic experience via the senses has been largely left out of treatment initiatives (Ogden et al., 2006;Fisher, 2006;van der Kolk, 2018).
Sensory approaches and sensory-based interventions, although still emerging through the trauma-informed framework (WHO, 2017;, have become part of the international effort for the reduction in seclusion and restraint in mental health services (Champagne and Stromberg, 2004;WHO, 2017). Sensory-based interventions address an individual's sensory system in a therapeutic manner to create change and enable adaptation to one's physical environment  and have been used in occupational therapy with children with behavioural issues and complex trauma histories (Fraser et al., 2017;Koomar, 2009). While the evidence for the use of sensory approaches in both adult mental health (Sutton et al., 2013;Machingura and Lloyd, 2017), and in the treatment of children with complex trauma (Koomar, 2009) is growing in governance, policy and practice, the specific needs of adult and adolescent trauma survivors has received less attention. In IJOT 48,1 consideration of the high prevalence of childhood trauma in mental health service users (APA, 2013;Gorey and Leslie, 1997;Rossiter et al., 2015;) and the evidence evolving in the field of trauma studies indicating the pivotal role of the sensate body in treatment (Clark et al., 2015;van der Kolk, 2015van der Kolk, , 2018Fisher, 2006Fisher, , 2018, it seems appropriate to include the unique needs of the adult and adolescent trauma survivor in this enquiry.
This review intends to determine the evidence for and the extent to which sensory-based interventions are being practiced in occupational therapy with adult and adolescent trauma survivors.
The research questions for this study include: RQ1. What sensory-based interventions are occupational therapists utilising with adult and adolescent trauma survivors?
RQ2. What is the empirical evidence to support the use of sensory-based interventions with adult and adolescent trauma survivors in occupational therapy?

Methods
An integrative literature review approach was chosen to allow for the inclusion of both empirical and conceptual literature. This approach enables the summarising of appraised research from diverse contexts in an area of emerging occupational therapy practice (Whittemore and Knafl, 2005). This enables a more comprehensive and holistic understanding of the phenomenon (Whittemore and Knafl, 2005). The paucity of research in this area did not lend itself to other systematic meta-analysis. The stages of an integrative review, which we followed are outlined by Whittemore and Knafl (2005) and include: clearly identifying the problem, purpose or phenomenon, conducting a thorough systematic literature search, evaluating, analysing and presenting the synthesised findings and limitations of the studies selected, with conclusions.

Literature search strategy
A literature search was conducted in Medline in Ebsco, EMBASE and AMED, PsychINFO, CINAHL, Scopus and the Cochrane Library. These databases were selected as they cover the majority of peer-reviewed allied health literature. Reference lists of included papers were reviewed for additional studies and citations searched for more recent studies (Whittemore and Knafl, 2005). Boolean phrases were used. The initial list of terms was added to iteratively as new search terms or keywords were identified. These are highlighted in Figure 1. Articles published between January 1995 and June 2019 were considered, given the growing body of research on trauma and sensory-based interventions within this time frame.
The titles and abstracts of all articles from database searches were screened using the inclusion or exclusion criteria. Duplicates were removed. Full-text articles were sought when further information was required to make a selection decision. Any uncertainty was resolved by having the article reviewed by both authors and consensus was reached by discussion. This was the case for one article. Reference lists and citations of included papers were also reviewed to identify any further relevant papers. The remaining papers were examined in detail. The process of identifying studies from search to inclusion is shown in Figure 2. Because of the limited empirical research available it was decided to include conceptual papers and sensory processing (SP) studies with adult trauma survivors.

Analysis
The purpose of each research study, including a description of the interventions, study design, outcome measures and analysis was extracted from the data. Following this, the core findings and limitations for each study were established. Data extracted from the conceptual papers reviewed included type, purpose, conclusive findings and recommendation. Data was extracted and summarised from both the research studies and conceptual papers. The articles were critically appraised using the McMaster University guidelines and appraisal forms for quantitative and qualitative research (Law et al., 1998a(Law et al., , 1998b. Table I identifies and defines key terms for the purposes of this review. To better understand the literature available, key commonalities and differences were summarised using an inductive approach: allowing the themes to be constructed based on the literature rather than using a predetermined set of criteria (Goddard and Melville, 2004). Data was sorted into categories and grouped into themes using a constant comparative method (Maykut and Morehouse, 1994). Themes observed were defined, named and extrapolated to produce three key themes.

Results
The initial search yielded 519 papers, with a total of 18 studies in the final review, including nine empirical studies and nine conceptual papers ( Figure 2). Variations existed in study design, setting and geographical location. The results of the studies reviewed are summarised in Tables II and III. Eight of the nine conceptual papers reviewed originated from the USA, compared with five of the nine empirical papers reviewed. The remaining studies and one conceptual paper originated from Canada (n = 2), Israel (n = 2) and Italy (n = 1). One of the total number of papers included an adolescent population with an age range of 12-22 years

Key search terms including Boolean operators
Initial terms: trauma, traumatic stress, sensorybased interventions, occupational therapy

Inclusion Criteria
Includes or describes a sensory-based y intervention, , technique, occupation, q , p , modality, or a sensory y, y approach AND Occupational therapy p py participation AND Persons aged 12 years g y & older with a history y of complex trauma p and/or a diagnosis of g PTSD.

Exclusion Criteria
Does not include a contribution from occupational therapy.
Focus on children, , autism, intellectual , disability, brain injury, y, j y, dementia or trauma as emergency room g y admission.
IJOT 48,1 (Warner et al., 2014). One paper (Fraser et al., 2017), carried out a review on both children and adolescent populations and was, therefore, included, as data specific to adolescents could be extracted. The total population across the studies was n = 686 and the age range for this group was 13-71 years. In the research which specifically and empirically assessed sensory processing skills, there were n = 457 participants (Engel-Yeger et al., 2013;Engel-Yeger et al., 2015;Serafini et al., 2016), with one of these studies (n = 1) also including a sensory-based treatment approach and psychotherapy intervention . Sole Occupational Therapy intervention accounted for n = 4 study participants (Kimball et al., 2018). N= 10 participants took part in a sensory integration (SI) treatment as an adjunct to psychotherapy treatment and n = 10 adolescents participated in a Records excluded with reason (n = 437) x Population included children x Trauma relating to brain injury or orthopaedic injury x Did not relate to the research question x Did not include an occupational therapy contribution Full-text articles assessed for eligibility (n = 25) Full-text articles excluded, with reason (n = 7) x Sensory-based intervention as a preventative approach to developing combat x non-peer reviewed (n = 1) x Occupation with no reference to sensory components of activity (n = 1) x Did not include an occupational therapy contribution (n = 4) Empirical studies (n = 9) Conceptual papers and reviews (n = 9) Total articles included in integrative review including conceptual papers (n = 18) stress (n = 1) Source: Moher et al. (2009) Sensory-based interventions sensory motor arousal regulation treatment (SMART) with a control of n = 21 participants receiving psychotherapy treatment as usual (TAU). N = 215 participants were involved in transdisciplinary treatment programmes in total. The majority of participants in the papers reviewed took part in the four studies assessing SP skills (Engel-Yeger et al., 2013;Engel-Yeger et al., 2015;Serafini et al., 2016).

Conceptual papers and reviews
The nine conceptual papers retrieved support a trauma-informed, sensory approach within a recovery-orientated context for the treatment of complex trauma and PTSD Champagne and Stromberg, 2004;Fraser et al., 2017;Herold et al., 2016;Holland et al., 2018;Warner et al., 2013). Seven of the studies included a discussion of the commitment to study trauma, trauma-informed care and the establishing of best practices to address trauma consequences Champagne and Stromberg, 2004;Fraser et al., 2017;Holland et al., 2018;. These have led to an important policy change, including seclusion/restraint reduction initiatives with access to occupational therapy (Champagne and Koomar, 2011;Champagne and Stromberg, 2004;Holland et al., 2018;. One of the notable strengths of sensory approaches emphasised in all of the conceptual papers reviewed reiterates how sensory-based interventions target intense physical manifestations of traumatic sequelae and offer a different therapeutic experience to that of conventional psychopharmacological treatment approaches. These intense physical  Ayres (2005Ayres ( /1979, which address the sensory experiences of an individual to optimise well-being and function; aim to assist persons more effectively regulate their emotional and physiological arousal (Machingura and Lloyd, 2017;Sutton et al., 2013) Sensory-based interventions Address the sensory system therapeutically to create change and/or enable adaptation to one's environment, including sensory modalities and sensorimotor activities Warner et al., 2013;Sutton et al., 2013) Sensory modalities Intervention involving specific techniques, occupation or equipment including, for example, yoga, art making, gardening, sound therapy, massage and weighted blankets ) Sensorimotor activities Promote the ability of the body to process and integrate information through movement and sensation including grounding techniques (Ogden et al., 2006;Clark et al., 2015) Sensory integration The ability of the nervous system to take in information, organise it and act with the environment effectively (Ayres, 2005(Ayres, /1979. Also, known as Ayres SI Sensory processing The ability to take in information through the senses (touch, movement/balance, hearing smell, taste and vision) interpret and make a meaningful response Miller and Lane, 2000) Sensory discrimination The ability to take in information from one's physical environment and gain perceptual awareness (Ayres, 2005(Ayres, /1979 Sensory modulation The neurological regulation of response to sensory stimuli; the central nervous systems capacity to balance and organise sensory inputs that arise both within an individual's sensory apparatus and those that arise external to the body (Sutton et al., 2013), which determine how to respond to environmental demands (Miller and Lane, 2000) and engage in meaningful roles, and occupations (Koomar, 2009;    IJOT 48,1 manifestations, often leading to overwhelm and difficulty with emotional or affect regulation, interfere with the individual's ability to attend simultaneously to cognitive, emotional and behavioural functions. This appears to be the driving force for the exploration of new treatment initiatives across the literature with recommendations for a sensory-based approach to trauma intervention based on SI theory in occupational therapy (Warner et al., 2013). In the absence of any firm evidence base, this quest, coupled with the reduction of reported seclusion/restraint incidents Champagne and Stromberg, 2004;Warner et al., 2013), appear to have led to an advocation for sensory-based approaches in the conceptual literature. While some researchers acknowledge the need for ongoing professional development and training for occupational therapists in relation to trauma-informed care and sensory-based interventions Champagne et al., 2010;Fraser et al., 2017) other authors, (Herold et al., 2016) draw attention to possible avenues for intervention with trauma survivors, for example, aquatic therapy. All the papers conclude that more research is required (Champagne and Stromberg, 2004;Champagne et al., 2010;Fraser et al., 2017;Herold et al., 2016;Holland et al., 2018;Warner et al., 2013). Interestingly, none of the conceptual papers reviewed addressed the needs or wishes of the trauma survivor from their perspective, yet all advocate person-centred, trauma-informed practice. One paper discussed a collaborative transdisciplinary person-centred programme for young adult women;

Reference and country Purpose of study Study design Conclusion
Warner et al.
The USA motor approaches to the treatment of affect and behavioural dysregulation traumatised adolescents in residential care, within a sensory integrative frame of reference (Ayres, 1972(Ayres, , 2005 rationale for the SMART programme for traumatised adolescents in residential care introduction of SM strategies and SMART preliminary initiatives Require empirical evidence as data to support claims of the effectiveness of SMART is scant and correlational Recommend occupational therapy SI interventions, staff training and support and service planning  Table III.

Sensory-based interventions
however, it did not expand on how person-centredness was measured or perceived by the participants (Holland et al., 2018).

Qualitative and quantitative studies
Three key themes were identified from the research studies reviewed: (1) atypical SP patterns; (2) type of sensory-based intervention with trauma survivors; and (3) transdisciplinary treatment programmes can reduce the symptoms of trauma.
Atypical sensory processing patterns A sensory profile describes a person's SP patterns. Measured in four quadrants: sensory sensitivity, sensory avoidance, low registration and sensory seeking, the validated adolescent/adult sensory profile (AASP) (Brown and Dunn, 2002) was used in all the studies reviewed on this theme. The studies reviewed to shed light on the diversity and the commonalities of this theme. Four papers were retrieved, specifically relating to SP patterns and trauma in adults. Three papers focussed on posttraumatic stress (PTS) (Engel-Yeger et al., 2013;Engel-Yeger et al., 2015; and the fourth on bipolar and unipolar disorders and traumatic childhood experiences (Serafini et al., 2016). All studies highlighted atypical SP patterns, mainly expressed in sensory sensitivity, sensory avoidance and low registration as compared to the AASP normal range values (Engel-Yeger et al., 2013;Engel-Yeger et al., 2015;Serafini et al., 2016). A lower tendency for sensory seeking behaviours, was evident in three studies. In contrast, , using a single case study design and focussing on a sensory-based intervention, found no difference in sensory seeking behaviour, compared to the AASP normal range values. Engel-Yeger et al. (2013, 2015 and Serafini et al. (2016) co-authored three papers. Both primary studies included the same experimental study design with a control group (Engel-Yeger et al., 2013, 2015. Differences between the PTS group and control were manifested in all five sensory modalities (taste, vestibular, visual, touch and auditory) and activity level, with a higher number of significant differences found in the vestibular modality (movement), touch modality and most notably the auditory modality (Engel-Yeger et al., 2013). In addition, Engel-Yeger et al. (2015) looked at close personal relational intimacy fears in individuals with PTS symptoms and found that fear of intimacy was significantly predicted by both PTS symptoms (p # 0.01) and low registration (p # 0.001). However, it is not clear how the researchers recruited their participants for the 2013 study, and no standardised tool was used in either study to ascertain previous traumatic experiences. Consideration given to life in a war zone over the past 60 years, would have revealed the control participants' exposure to some degree of traumatic stress in Israel, in their lifetime. There is, however, no discussion on this issue. Serafini et al. (2016) investigated traumatic childhood experiences and their relationship with SP patterns, alexithymia and quality of life among patients with unipolar and bipolar disorders. They found that in both unipolar and bipolar groups lower registration of sensory input, as well as hypersensitivity (sensory sensitivity and avoidance patterns) correlated with enhanced childhood traumatic events. While both groups scored higher in physical neglect in childhood, bipolar subjects showed more emotional neglect and abuse, and physical neglect and this was statistically significant (p < 0.001) (Serafini et al., 2016). The researchers also found that alexithymia played no role in differentiating unipolar and IJOT 48,1 bipolar groups nor predicting quality of life. Critically, the study design did not include a control group and, although the sample size was large, there were more unipolar subjects in the comparative analysis. In contrast to the other four studies reviewed, Serafini et al. (2016) did assess for other treatment regimens, including psychoactive medication, and required that subjects had been stable for at least six months prior to participating in the study.

Type of sensory-based intervention with trauma survivors
The literature shared several sensory-based interventions and techniques in addition to the "sensory room"; a therapeutic multimodal, sensory environment, which has been advocated for in much of the mental health research (Champagne and Stromberg, 2004;Holland et al., 2018;Warner et al., 2013). Holland et al. (2018) described the sensory component of a trauma treatment programme for young adult women who had experienced chronic childhood trauma. The "sensory room" and sensory-based interventions, including a customised "sensory kit" to help regulate overwhelming sensory and emotional stimuli, formed an integral part of the transdisciplinary treatment. Although the "sensory kit" was not discussed, the use of weighted blankets and tactile equipment were incorporated into other sensory activities and occupations, which included yoga, cooking and art-making. Individual sensory treatment programmes where developed and informed by a sensory profiling assessment (AASP: Brown and Dunn, 2002). Kimball et al. (2018) described a specific sensory treatment protocol, the "Wilbarger Therapressure Programme" (WTP), which for the purposes of this study involved the participants applying very deep touch pressure to their skin through using a special Therapressure TM brush and firm joint compression. Serving as their own controls for the single-subject design methodology, two of the four participants, all with a self-reported diagnosis of PTSD, showed positive change on all outcome ratings, increased occupational performance and modulation of salivary cortisol levels (Kimball et al., 2018). The treatment period was two weeks duration only and there was no follow-up on participants. Although with two out of the four participants showing positive improvements, the WTP warrants further investigation.  carried out an in-depth case study describing sensory processing patterns (SPPs), occupational engagement issues with occupational therapy assessment and intervention through the sensory modulation programme (SMP, Champagne, 2008a). The 1-1 SMP emphasises both the therapeutic use of self as an occupational therapy practitioner and person-centred practice initiatives. Champagne describes SPP, sensory modulation (SM) and sensory discrimination (SD) through a three-stage therapeutic process model for working with people experiencing disorders emerging from traumatic experience. Occupational therapy interventions and the SMP initially focussed on stabilisation and creating safety, rather than working specifically with trauma experiences. These stabilisation measures, which include sensory-based techniques and interventions have been described as "preparatory" in nature, creating the conditions within which to support clients participating in meaningful and purposeful life activities Parker et al., 2007). Champagne (2011a) provides the most explicit example of sensory-based treatment including sensorimotor activities, grounding techniques, integrative therapies such as aromatherapy and sensory diets in the practice of occupational therapy. However, though promising, there remains limited evidence to support the generalisability of SMP as part of routine clinical practice, given the single case study design.

Sensory-based interventions
Similarly, Kaiser et al. (2010) developed a SI protocoled treatment programme in conjunction with psychotherapy as a treatment for complex traumatic stress. Using vestibular, visual and auditory input as a "bottom -up" or body-informed approach to addressing the symptoms of adults with a history of complex trauma, Kaiser and colleagues found significant changes in total scores of self-perception and affect/impulse regulation (p < 0.05). The assessor was blind, although the intervention was administered by the first author, introducing significant bias. This small study, while preliminary and observational, supports clinical exploration using SI with adult populations. A 20 per cent attrition rate was noted in this small study, and the reasons for this are not adequately addressed in this instance. The studies reviewed varied in the type of sensory-based intervention or technique used including preparatory, purposeful and occupation-based activities Kaiser et al., 2010;Kimball et al., 2018), which may form part of a transdisciplinary treatment programme (Holland et al., 2018;Parker et al., 2007;Warner et al., 2014).  (2004), Holland et al., 2018 andWarner et al. (2014) have all advocated a sensory-based trauma-informed framework for practice, with both transdisciplinary and 1-1 occupational therapy intervention. While descriptions of 1-1 sensory-based interventions for survivors of complex trauma are scarce in occupational therapy literature, three studies reflect a transdisciplinary approach, which included occupational therapists and led to a reduction in traumatic stress symptoms for those studied.
Programmatic interventions such as the SMART programme for traumatised adolescents in residential care (Warner et al., 2014), the women recovering from abuse programme (WRAP, Parker et al., 2007) and the programme for traumatic stress recovery [posttraumatic stress recovery programme (PTSR)] in adults with PTS (Harper et al., 2006) all include a sensorimotor approach and a trauma-informed transdisciplinary model of working, with the SMART further emphasising the SI occupational therapy contribution to the programme.
Both WRAP and the PTSR included group work as the main vehicle for programme delivery, and the PTSR and SMART included additional individualised 1-1 occupational therapy, including SM and sensorimotor activity involving the sensory room. The WRAP, (Parker et al., 2007), was the only qualitative study found to investigate the experience of female trauma survivors following intervention. Only seven participants completed the interviews from a potential 57 participants. The authors did suggest that an outbreak of the SARS virus may have been one of the reasons for the low participation rate. Three key findings deepen the understanding of the trauma recovery process among the participating women, according to the researchers; these findings involve breaking trauma-based patterns, undergoing therapy and the healing journey as a continuous process. Parker et al. (2007) advocate a relational empowerment-based model as a foundation for serving the mechanisms of change, as some of the self-care and grounding activities explored during the programme were continuously used by participants to enable them to "manage and cope" on what they described as their healing journey.
The PTSR programme based on the sanctuary model (Bloom, 1997) includes sensory components as support for affect-regulation and coping with relationships and everyday life (Bloom, 2006). Using a mixed method, pre-and post-test design, Harper et al. (2006) found a significant improvement in self-care, relationships and communication, coping with feelings IJOT 48,1 and spirituality following programme completion. However, these improvements were not maintained following discharge. Warner et al. (2014), building on the SMART intervention model and methodology (Warner et al., 2013), compared once weekly SMART intervention with TAU psychotherapy among an adolescent sample. Using standardised measures and a pre-and post-test assessment at six months, the results suggested the benefits of using SMART in addressing sensory issues and the symptoms of anxious and depressed mood in adolescents. Although the study sample was small and the results are preliminary, the SMART shows a promising alternative sensory approach to traditional trauma therapy with this population.
In a descriptive paper and using a case vignette, Holland et al. (2018) describe a trauma treatment programme, which includes a person-centred, strengths-based approach, underpinned by the attachment, regulation and competency (ARC) model. As mentioned earlier, this transdisciplinary programme includes a large sensory component based on the initiatives described by . While the single case vignette is helpful in illustrating perceived gains of the programme, there is no empirical data to support or quantify these claims.

Discussion
Sensory approaches and sensory-based interventions have a growing presence in the mental health literature, and occupational therapists are emerging as potentially key players in this field of practice (Scanlan and Novak, 2015). For survivors of trauma, interventions which address the body on a sensory level and support self-regulation, can affect an individual's engagement and participation in occupations . This review has explored the emerging evidence in occupational therapy for sensory-based intervention with the adult and adolescent trauma survivor. The three themes identified support the understanding of some of the factors contributing to sensory-based occupational therapy and identify those interventions currently practised with these groups.
Much of the empirical research reviewed tends to focus on symptom management as an outcome measure of treatment efficacy Kaiser et al., 2010;Warner et al., 2014). This process of symptom categorisation, mostly using the diagnostic and statistical manual of mental disorders (DSM; APA, 2013) criteria, is not without its problems (Whalley Hammell, 2007) and raises methodological issues when outcomes are based on the diagnostics and measurement of symptoms using instruments arising from debated criteria that do not include a complex trauma framework (van der Kolk et al., 2009;Maercker et al., 2018). All but one study (Parker et al., 2007) used DSM criteria for diagnostics and outcome measurement, with one study using participant-reported diagnosis of PTSD as the criterion (Kimball et al., 2018). Therefore, the findings of studies based on these criteria Engel-Yeger, 2013, 2015Harper et al., 2006;Kaiser et al., 2010;Serafini et al., 2016;Warner et al., 2014) must be carefully considered. In addition, the use of non-standardised measurement tools such as those used by  reduces the rigour of a study. Considering the work of Harper et al. (2006) and validation of the Canadian Occupational Performance Measure (COPM, Law et al., 2005) in a PTS programme, the outcomes for two of the studies Kimball et al., 2018) might have been more persuasive had such an instrument been adopted.
Given such fundamental issues with the trauma research, for the first time since 1979, the two main international mental health diagnostic systems the DSM and the international classification of diseases  are no longer in broad agreement over what types of PTSD exist, and the presentation of symptoms that are seen with PTSD. Now, the muchdebated "complex trauma" (van der Kolk et al., 2009) has been given the official diagnostic Sensory-based interventions recognition of CPTSD by the ICD-11 (Buxton and Turnbull, 2018). For a body of research to become evidence informed, there needs to be some continuity and clarity around both the concepts, the contexts within which the research is conducted and the outcome measures used. It would appear that diagnostics will continue to be an issue for both researcher and clinician for some time to come.

Implications for practice
The relative scarcity of sensory-based trauma intervention studies in occupational therapy can be observed from the limited empirical and published studies available. However, we do know that trauma-informed sensory-based service initiatives (Champagne and Stromberg, 2004;Holland et al., 2018;Stoller et al., 2012;Moore, 2010;Martin, 2015), sensory-based trauma therapy for children (Fraser et al., 2017) and non-sensory specific interventions and occupations for adult trauma survivors (Snedden, 2012;Precin, 2011) are part of the wider occupational therapy process (Lopez, 2011). As a component of a SMP, other sensory-based interventions such as aquatic activities, horticulture, art making and sensory-enhanced yoga may be both effective and age-appropriate methods of application with adolescent and adult trauma survivors (Harper et al., 2006;Herold et al., 2016;Holland et al., 2018;Martin, 2015;Parker et al., 2007;Re et al., 2014;Stoller et al., 2012). However, the studies in this review do not distinguish between SI interventions, the core sensory components of an occupation or the active engagement in a meaningful occupation, as the therapeutic vehicle leading to functional change for the trauma survivor. The actual mechanisms or processes that lead to change lack clarity. Future research focussing on all of these areas and addressing the relational aspect of the therapeutic encounter is warranted with trauma survivors if an understanding of the mechanisms for change is to be reached. Studies focussing on collaborative transdisciplinary initiatives within a trauma-informed framework support the occupational therapy role in development and sustainment of these programmes, as emphasised in the SMART programme (Warner et al., 2014). Although the study sample was small and the results are preliminary, the SMART shows a promising alternative sensory approach to traditional trauma therapy for this population. More rigorous controlled outcome research with a larger sample size is required (Warner et al., 2014).
A transdisciplinary approach, is not only desirable and essential to trauma-informed practice, but may also be the very foundation for the success and efficacy of an intervention (Martin, 2015). It is recommended that sensory-based treatments form part of a transdisciplinary assessment and treatment process (Fraser et al., 2017;Parker et al., 2007;Harper et al., 2006) for the trauma survivor and be a component of trauma-informed healthcare services . The complex nature of trauma and its effects on an individual survivor or community may mirror the complexity required in approaching treatment and predicting outcomes for this population. A diverse and trauma educated skillset is required  and each discipline can support another in further developing their expertise when collaboration is established and valued (Williams, 2017).
This collaboration extends its reach to all individuals who form part of a trauma-informed framework. It is, however, ironic that despite much discussion and policy change favouring a person-centred approach to healthcare there still remains a clear lack of qualitative studies from the trauma survivor's perspective. Parker et al. (2007) drew attention to the importance of ongoing support for the trauma survivor. This was the only study to emphasise how the successful use of coping skills, following exposure to trauma, can build resiliency and promote post-traumatic growth (Underleider, 2003). Both have been identified as key desirable outcomes in the treatment of trauma (Pfeiffer et al., 2014;Snedden, 2012). Studies have suggested that without continued community support and a trauma-informed approach to IJOT 48,1 recovery, the benefits of resource-intensive trauma treatment programmes may not be effectively retained in the long term (Felitti and Anda, 2010;Harper et al., 2006Harper et al., , 2008Parker et al., 2007). Parker et al. (2007) shed light on this potential, which lies beyond the amelioration of traumatic stress symptoms. However, the WRAP (Parker et al., 2007) and the PTSR (Harper et al., 2006) are both observational studies, share methodological drawbacks with no controls and high attrition rates; evaluation of these programmes remains inconclusive. Despite this, providing ongoing community therapeutic support, including a spiritual/meaning-making component (Harper et al., 2006;Parker et al., 2007), may be areas worthy of exploration by occupational therapy. These are themes which resonate with the profession's inherent philosophy and practice (Harper et al., 2006(Harper et al., , 2008. Occupational therapy resources, such as the Canadian model of occupational performance and engagement (Townsend and Polatajko, 2007), which are person-centred and inclusive of a "spiritual meaning making" component may provide the supportive framework upon which to base investigation and practice in the future. However, this complex phenomenon requires sensitive exploration as increased awareness of trauma brings its own personal challenges for clinicians. As Koomar (2009, p. 3) acknowledges: [. . .] it is a highly courageous act to open to the pain and vulnerability that comes with holding the trauma of another person, as well as to reflect on personal childhood pain that may emerge.
Other factors, which may influence outcomes are provided in the SP studies reviewed, which shared a corroboration on SPPs typical of most trauma survivors studied. However, , in a single case study design, did not find a lower tendency for sensory seeking, contrary to the other three studies reviewed (Engel-Yeger et al., 2013, 2015Serafini et al., 2016). The lower tendency of sensory seeking patterns associated with trauma survivors in the research may be related to exaggerated emotional responses including pathological fear and unrealistic negative perceptions of one's environment leading to stimulation avoidance or withdrawal (Foa et al., 1999;Engel-Yeger et al., 2015). The single participant in Champagne's (2011a) study was a practising nurse and actively involved in the therapeutic processes of occupational therapy and psychotherapy. It is unclear if active social participation or work circumstances influenced SPPs, given that the productivity levels of the other studies participants were not reported. Furthermore, occupational therapists are required to be aware that the survival mechanisms that are inherent in the SPPs identified with the trauma survivor, may help individuals ensure a sense of personal safety and participation in daily life. According to Engel-Yeger et al. (2015), emotional responses such as shame, despair and hopelessness may accentuate fears of personal intimacy for the trauma survivor and this, in turn, may complicate the therapeutic relationship and any trauma treatment programme.
However, what is clearly lacking in the occupational therapy literature is high-quality empirical support for sensory-based interventions and occupations. Sample size needs to be larger, studies more longitudinal and comparative to other treatments. This research would not be without its challenges though because of the heterogeneity of the sensory-based interventions and occupations; it is difficult to compare, for example, the WTP (Kimball et al., 2018), with the sensory learning programme (SLP) (Kaiser et al., 2010), with sensory occupations such as art-making, yoga and cooking (Holland et al., 2018). There also needs to be clarity regarding the nature and extent of trauma experienced by survivors (Serafini et al., 2016;Kimball et al., 2018;Van der Kolk et al., 2009), the influence of SPPs (Engel-Yeger et al., 2013, 2015Serafini et al., 2016; and the sensory-based treatments most appropriate for the different stages of the recovery process Kaiser et al., 2010). Indeed, specific sensory-based interventions have been shown to support the preparatory phases in trauma treatment by assisting in creating a sense of safety or stability Sensory-based interventions for the survivor Champagne and Koomar, 2011;Machingura and Lloyd, 2017) and may also be used throughout the trauma processing phase (Harper et al., 2006;Van der Kolk, 2005;Warner et al., 2014) and the ongoing life journey (Parker et al., 2007). More clarity on what sensory-based interventions are most appropriate for which group of trauma survivors and when to use the same is, therefore, warranted. The interchangeable use of terms such a sensory approach, sensorimotor approach, SI approach, sensory-based approach and sensory disorders appear throughout the research reviewed. This led to some confusion for the reader. Three papers Fraser et al., 2017), clearly and distinctively defined the sensory terms used. For future research purposes, and as a profession, occupational therapy may do well to clarify the terminology used and to standardise applied definitions (Fraser et al., 2017;Rodger et al., 2012). This might help support the profession in identifying its unique role in this practice area.

Strengths and limitations
The purpose of this integrative review was to gather and present the holistic evidence, including expert opinion in the field. However, the limited number of published empirical studies, reviews and interventions evaluated in the English language and confined to occupational therapy, restricted discussion in respect of comparison and analysis of available data and led to the dominance of some author names. A study across all the professions who use sensory-based approaches and interventions, including, for example, nursing and social work, may have yielded more information generally, but would have restricted the enquiry into occupational therapy. Furthermore, the heterogeneity of the studies and interventions presented here are a drawback to this integrative review. Notwithstanding these limitations, all the studies evaluated reported positive results, with a greater emphasis on transdisciplinary treatment than on individualised SI treatment by occupational therapists. This review can assist in policy development, and also in the critical assessment of daily practice, and the educational needs of occupational therapists . However, it is too limited in scope to provide a thorough systematic analysis of the empirical research available.

Conclusion
The high prevalence of trauma in adult and adolescent mental health populations, and the extensive effects of trauma on the body, indicate a need for new approaches to treatment. There is emerging evidence in support of a sensory-based approach to treatment with these groups, with individualised sensory-based assessment and treatment as part of a transdisciplinary programme, as it has the potential to demonstrate effective outcomes. Although occupational therapy research is limited at this time, with a skillset in occupational analysis and a background in SI practice the profession of occupational therapy is in a pivotal position in the evolving trauma-informed recovery movement. However, clarification and standardisation of the terms used to describe sensory-based interventions within the profession are necessary. Further training in the field of trauma studies and mentorship may be required by therapists, before claiming an active role in the development of key policy, research and services for persons with a history of trauma.