In long-term survivors of childhood and adolescent central nervous system (CNS) tumors, neuropsychological and psychosocial late effects of therapy occur in a milieu of numerous medical late complications (Anderson et al., 2001). With improvements in treatment and survival rates for these patients since the 1980s, most children and adolescents with CNS tumors currently diagnosed will become long-term survivors (Pollack, 1994). This is particularly true for children with medulloblastoma or low-grade astrocytoma. Therefore, concerns about late complications of therapy are increasingly important to survivors and their families. In addition to the late consequences of radiation therapy and chemotherapy, which are similar for all survivors of childhood cancer, the singular susceptibility of the brain and spinal cord to injury causes several late consequences unique to long-term survivors of CNS tumors.

Late complications may be due to the tumor, surgery, radiation therapy, chemotherapy, or the psychological trauma of dealing with a malignancy, and the late effects following CNS tumors include medical, psychological, neuropsychological, and psychosocial problems. Some late effects may be life threatening. In fact, long-term survivors of CNS tumors have an excess risk of mortality relative to survivors of other cancers (Mostow et al., 1991; Nicholson et al., 1994). In a large cohort study of childhood cancer survivors (Oeffinger et al., 2006), CNS tumor survivors were among the most likely to have chronic health conditions and multiple other chronic conditions; in addition, they often have functional impairments (Ness et al., 2005).

Introduction

Neuropsychology, broadly defined, is the study of brain–behavior relationships. The term was coined by William Osler in the early 1900s and gained wider appeal in the 1960s. The field was influenced by pioneers in neuroanatomy, neurology, and physiology, who began to explore the brain's functionality (Broca, 1865; Hughlings-Jackson, 1931; Lashley, 1950; Wernicke, 1874). Modern neuropsychology represents a blend of careful clinical observation grounded in the pioneering work of Alexandr Luria (1973), and a more actuarial approach that utilizes psychometric instruments to describe and quantify an individual's functioning (Halstead, 1947; Reitan, 1974). Neuropsychology has become a science of human behavior as it is influenced by brain functioning and by social, psychological, and cultural contexts.

Pediatric neuropsychologists are concerned with developmental issues and take into account the genetic, medical, environmental, behavioral, and sociocultural influences that impact the maturation of a child (Baron, 2004). The human nervous system is never static and development occurs across the lifespan. However, the rapidity of development in childhood and adolescence calls for a specific developmental focus when conducting evaluations with this age group.

At birth, infants have more than 100 billion neurons (Berger, 2005). In the first 2 years of life the brain undergoes a period termed transient exuberance when as many as 15 000 new connections are established per neuron (Thompson, 2000). Following this period of rapid growth, there is a period of rapid elimination of synapses called “pruning” that peaks in adolescence and is variable across different brain regions (Kolb & Wishaw, 2003).