ABSTRACT
Introduction 439 Executive function 441 Research findings 442 Developmental considerations 443
Recovery following ABI in childhood 445 Commencement of rehabilitation=intervention 447 Models of intervention 447 Direct approach 448 Behavioral compensation 448 Behavior modification strategies 448 Environmental modifications and supports 449 Educational=instructional support 449
Applications of strategies for executive dysfunction 450 Cognitive interventions 450 Attentional control 450 Sustained attention 451 Response inhibition 451 Planning=goal setting 452 Cognitive flexibility 455
Social=behavioral interventions 456 Role of educating caregivers 458 Works in progress 459 Development of intervention techniques in our laboratory 459
How to bring intervention techniques into an educational setting=context 460 Conclusion 461 References 462
Following traumatic brain injury (TBI), thousands of young lives are lost or permanent disability is sustained (Adelson et al., 2003; Goldstein & Levin, 1987; Jennett, 1996; Kraus, 1987, 1995; Mazurek, 1994). Although the pattern of sequelae
for injury sustained in adulthood is now outlined with some certainty (Levine, 1988; Pruneti, Cantini, & Baracchini-Muratorio, 1988), knowledge pertaining to adults is not reliably generalizable to the pediatric population (Anderson & Moore, 1995; Jennett & Teasdale, 1981; Levine, 1988; Levin, Benton, & Grossman, 1982). In fact, there is increasing evidence that the young child’s brain may be particularly vulnerable to early trauma and a number of explanations have been proposed to account for this vulnerability. Physiologically, the child’s brain is incompletely developed. In comparison to adults, the child’s skull is more flexible, neck control is poor, and the head is proportionally larger, leading to less focal damage, but greater diffuse injury and interruption to cerebral development (Hudpeth & Primram, 1990). With regard to cognitive and developmental factors, children possess fewer well-consolidated skills than adults as they are just beginning to accumulate skills and knowledge, therefore, have fewer established skills. Future acquisition of these skills may be compromised, depending on the nature and severity of the cerebral damage (Dennis, 1989). The most common type of TBI in children and adolescents is closed head injury,
which accounts for almost 90% of all head injuries. In closed head injury, the brain oscillates within the skull and neuronal pathways may stretch or sever within the brain or brainstem (Davis & Vogel, 1995). Pathological consequences include diffuse injury to the white matter of the brain, as well as the stretching and shearing of nerve fibers, axons, and tracts throughout the brain (diffuse axonal injury) in areas, including the frontal lobes, temporal lobes, corpus callosum, fornix, cerebellum, and ascending and descending brainstem pathways (Adams, Graham, Murray, & Scott, 1982; Levine, 1988; Mattson & Levin, 1990; Stuss & Gow, 1992). When this widespread damage occurs in a brain that is still developing, the predictability of outcome is more difficult (Pruneti et al., 1988), with such diffuse damage impacting on processes such as neuronal myelination and frontal lobe maturation (Hudpeth & Primram, 1990; Thatcher, 1991). While neuronal proliferation and synaptogenesis in the frontal cortex reaches a peak between 1 and 2 years of age, the frontal lobes and their functions continue to emerge throughout adolescence and young adulthood. These aspects of brain development have been linked to the establishment of higher order skills such as information processing, planning, social cognition, self-regulation, and executive skills (Adolfs, 2003; Cicerone & Tupper, 1990; Milner & Petrides, 1984; Stuss & Gow, 1992; Walsh, 1978). Disruption to the maturation of these functions may cause permanent impairment of established skills and reduce the child’s potential to acquire new skills (Beaulieu, 2002; Dennis, 1989), often resulting in dysfunctional behaviors and poor relationships. Over the past decade, advances have been made in rehabilitation practices to
obtain the best outcome for the individual following brain injury. Mazaux and Richer (1998) distinguished three phases of rehabilitation. The first takes place during coma and during arousal states, with the primary aim of providing sensory stimulation. The second phase facilitates recovery of impairments and compensates for difficulties in areas including cognition and behavior. The third phase includes outpatient therapy, with the aim of acquiring independence in physical, social, and domestic areas, to re-enter the community successfully. While the rehabilitation given and the therapy outcome varies depending on the participant’s age and nature of impairment (Chen, Heinemann, Bode, Granger, & Mallinson, 2004; Dumas, Haley, Ludlow, & Rabin,
Executive functions and
2002), the importance of the family-professional collaboration and the use of a multidisciplinary rehabilitation service are key factors in enhancing successful functional outcomes (Barnes, 1999; Hostler, 1999; Semlyen, Summers, & Barnes, 1998; Swaine, Pless, Friedman, & Montes, 2000). The aim of this chapter is to define executive function (EF), to outline the nature of
EF impairments following acquired brain injury (ABI) using a developmental perspective, to discuss postinjury recovery processes, the commencement of rehabilitation and models of intervention. The few available evaluative intervention studies will be outlined, with focus directed to the important role of caregivers, particularly in the educational context.
