TPC-Journal-V5-Issue2

274 sensory processing disorder (SPD) will be utilized in this article, since SPD is the most prevalent term used in recent years (Miller, Nielsen, Schoen, & Brett-Green, 2009). Similarly, we will use the term sensory processing to also encompass sensory integration, as they are often used interchangeably in the literature. Background The most commonly known senses are auditory (sound), olfactory (smell), tactile (touch), visual (sight) and gustatory (taste); two less known senses are proprioception and the vestibular sense (James et al., 2011; Katz, 2006; Withrow, 2007). Proprioception is a sense found in muscles, tendons and joints that deciphers bodily awareness and coordinated movements. The vestibular sense is located in the inner ear and provides sensory input regarding one’s balance and gravity. Sensory processing is a complex neurobiological process in which individuals’ seven senses perceive information or stimuli from the environment, sending data to the brain to interpret, process and respond to; the senses and brain are constantly engaged in a process of perceiving, interpreting, processing, and responding to environmental stimuli (Byrne, 2009; Katz, 2006; Miller et al., 2009; Parham & Mailloux, 2015; Walbam, 2013; Withrow, 2007). Sensory processing is a developmental process, and thus especially crucial in the children’s first 10 years of life (Ayres, 1979). In summary, a typically developing child may easily and accurately perceive and process environmental stimuli, yet this is not the case for all children. Sensory processing has been well studied in the occupational therapy profession during the last 50 years, beginning with the groundbreaking work of Dr. A. Jean Ayres, occupational therapist, psychologist and neuroscientist (Parham & Mailloux, 2015). During the last several decades Ayres and others discovered patterns of atypical sensory processing in children, which have collectively come to be labeled as SPD. “Sensory processing disorder is a heterogeneous condition that includes a variety of subtypes. Individuals with the disorder have impaired responses to, processing of, and/or organization of sensory information that effects [sic] participation in functional daily life routines and activities” (Miller et al., 2009, p. 1). Further, Parham and Mailloux (2015) described SPD as “patterns that emerge developmentally . . . and are thought to reflect subtle neural processing differences involving sensory and motor systems” (p. 266). Thus, children with SPD struggle with the neurobiological cycle of receiving, sending, processing and responding to stimuli, and they experience a severity that negatively impacts their daily functioning (Ayres, 1979; Davies & Gavin, 2007; Owen et al., 2013; Parham & Mailloux, 2015). As a result of skewed sensory processing, individuals with SPD may overreact or underreact to stimuli, perceiving stimuli to much greater or lesser degrees than peers (Byrne, 2009; Dunn, 1997, 2001; James et al., 2011; Katz, 2006; Miller et al., 2007; Walbam, 2013; Withrow, 2007). For example, a crowded indoor playground could be loud to one child, but frightening or even physically painful for a child with auditory sensitivities. While a typical child may get dizzy from spinning around, a child with an underdeveloped vestibular system may rarely become dizzy and seek spinning to feel soothed. Although children with SPD may have neurological similarities, SPD is a highly individualistic disorder that presents differently in each child and can be described by corresponding subtypes (Dunn, 1997, 2001; James et al., 2011; Murphy, 2011; Walbam, 2013; Withrow, 2007). While there is consensus on an overarching definition for SPD, there is not a consistent nosology for describing the subtypes (Miller et al., 2009). Proposed nosologies of SPD subtypes typically include hyposensitivity, hypersensitivity and sensory-seeking subtypes (Ayres, 1979; Dunn, 1997, 2001; Interdisciplinary Council on Developmental and Learning Disorders, 2012; James et al., 2011; Katz, 2006; Miller et al., 2007; Walbam, 2013; Zero to Three, National Center for Infants, Toddlers and Families, 2005).