Neuropsychological Evaluation in Children with Epilepsy

Lisa D. Stanford

Julie M. Miller

Epilepsy occurs in approximately 4.3 to 9.3 per 1,000 children and is the most common neurological condition in childhood (1,2). The course of epilepsy in children is highly diverse and dependent upon age of onset, duration of seizures, type of seizure (e.g., absence, complex partial, generalized tonic-clonic, status-epilepticus), response to/effect of antiepileptic drugs (AEDs), etiology (e.g., idiopathic, tumors, head trauma, genetics), and comorbid conditions (e.g., autism, cerebral palsy). The deleterious impact of frequent seizure activity on the developing brain has been previously well established, and has been shown to entail a range of disruption in skill development across cognitive functioning, academic achievement, adaptive skill acquisition, memory and learning, and behavior (3,4,5,6,7,8). The increased risks, the complexities, and the variable impact of the disorder on social, cognitive, and behavioral development present a unique challenge for pediatric neurologists, pediatricians, school personnel, and child psychiatrists, who have to address the needs of these children as they begin their education. Subsequently, the need for systematic and comprehensive evaluation of a school-aged child’s functioning is critical in determining appropriate treatment plans and educational intervention. Neuropsychological evaluation has been established as a useful tool for the pre- and postsurgical evaluation of the child with epilepsy and has been advocated as an essential component of the workup of any child with epilepsy, regardless of the intended treatment approach (9). In pediatric epilepsy, understanding a child’s cognitive functioning, learning ability, and behavior in the context of neuropsychiatric issues is increasingly defining the role of the pediatric neuropsychologist. This collaboration becomes essential in managing the neurobiologically complicated picture of children presenting with epilepsy and comorbid conditions, such as attention-deficit hyperactivity disorder (ADHD), developmental delay, autism, learning disabilities (LDs), anxiety, and depression. Additionally, developmental issues along with medical, genetic, environmental, behavioral, and sociocultural influences have become increasingly important in the treatment and accommodation of school-aged children, especially with the impetus caused by federal legislation mandating public schools to provide services and programs for all handicapped children. The federally funded disability category, other
health impairment (OHI), which is most commonly used to determine the unique educational needs of children with epilepsy, further increased the necessity for those treating and educating children who have sustained some central nervous system (CNS) dysfunction to understand the impact of epilepsy on learning and development.

The pediatric neuropsychological evaluation that also contains components of assessing academic achievement, psychosocial factors, and emotional functioning in the context of cognitive functioning (e.g., memory, language, attention, motor skills, visual perception) in children with epilepsy offers a unique solution to understanding and interpreting individual differences in cognitive profiles to make treatment decisions that are transferable to the educational environment (10). A child’s pattern of cognitive functioning is compared with the normative or expected pattern of performance on measures of cognitive ability and academic achievement within contextual circumstances (e.g., family dynamics, comorbid disturbance of mood or affect, individual differences in learning) and then examined within the framework of a child’s need for school accommodations and placement.

Purposes of the Neuropsychological Evaluation

There are several reasons why a neuropsychological evaluation might be needed or requested in children with epilepsy. The first is differential diagnosis. Often, parents present with a unifying but vague concern regarding poor academic progress in their child that the medical professional knows may be attributable to a multitude of factors. The increased availability of neuroimaging, electroencephalograms (EEGs), and other neuroradiologic tests has de-emphasized the role of differential diagnosis for the pediatric neuropsychologist. However, a child may occasionally present with atypical behavioral outbursts, subtle learning problems, lapses of attention, and “soft” neurological signs that have not yet been diagnosed as less obvious types of epilepsy (i.e., absence seizures). The evaluation allows for categorization of a child’s level of ability, and aids in the determination of whether a child may be able to respond to treatment and, if so, what type of treatment might be most appropriate given a child’s ability and information processing style. Additionally, if the diagnosis of epilepsy has been made and the child is being treated with AEDs, the neuropsychological evaluation may assist in ruling out other comorbid conditions (e.g., perinatal or developmental issues, LD, substance abuse), determining the individual pattern of strengths and weaknesses, and identifying the efficacy of a particular medication on learning and cognition. Finally, the neuropsychological evaluation offers unique and individualized educational recommendations that are readily translatable to the school environment.

Children with epilepsy have to contend with numerous challenges associated with adjusting to a chronical neurologic disorder, but those who have co-occurring cognitive processing issues are more likely to feel overwhelmed and frustrated. In addition, emotional and interpersonal adjustment difficulties in children with epilepsy are commonly seen in combination with cognitive deficits, and a neuropsychological evaluation may help the teacher, family members, and therapists understand why a child is having a difficult time interpersonally and how this subsequently affects his or her learning.

General Considerations in Assessing Children with Epilepsy

The neuropathology of epilepsy in infants and children is substantially different from that in adults. For example, neurological injury in adults affects brain areas after the individual has reached maturity with regard to cognitive and behavioral functioning. In children, however, early CNS dysfunction not only disrupts previously acquired skills but may also disrupt the normal development
of abilities that are yet to emerge. Additionally, the timing of the neurological insult will affect the nature and long-term outcome of epilepsy to a greater extent in children than in adults. Epilepsy that develops very early in life (i.e., infancy) can result in the disruption of programmed cell migration patterns (11), while onset of seizures during the child’s first few years of life, when the brain is still developing, may affect myelination of fiber tracts (12). These are just examples of ways in which the timing of onset of epilepsy in the developing child is a critical aspect for understanding the neuropsychological consequences on the child’s functioning, which may not necessarily be a consideration in adult neuropsychology evaluations.

Neuropsychological evaluation of the child with epilepsy presents a unique challenge to the pediatric neuropsychologist (13). Specifically, in addition to the need to establish proper rapport, the essential component of any evaluative process, the child with epilepsy requires assurance of a safe environment that is free of environmental obstructions in case of seizure activity. It is essential for the clinician to consider the intrusive effects of seizures during testing, as well as the impact of antiepileptic medication on test performance. Additionally, the clinician should have prior knowledge of the child’s typical seizure presentation so that the clinician can be vigilant for potential seizure activity during the evaluation. Finally, it is essential that the test battery be modified to accommodate any specific needs of the epileptic child, such as impaired language skills or hemiparesis, or other cognitive functions disrupted by the impact of seizures.

Factors that Influence Testing

Although the selection of test measures to be used in neuropsychological assessments largely depends on the nature of the referral question and presenting problems, it is also influenced by several factors that are discussed in this section. These include the child’s age, mental capacity and developmental ability, culture and ethnicity, and any medical or physical conditions that may impact test results. These factors are also critical when interpreting data from testing.

The Age and Developmental Level of the Child

There has not been a comprehensive neuropsychological evaluation developed for infants and very young children (14), although several developmental tests have been used to assess global functions such as language development, motor skills, and atypical behaviors. They have also been recent development of domain specific batteries for young children, but the particulars of these neurodevelopmental evaluations are beyond the scope of this chapter. However, testing is influenced by the obvious issue that infants and very young children tend to be relatively inconsistent in their approach to structured tasks, which results in difficulty in reliably assessing their cognitive abilities. In general, there is a low correlation with regard to future skill levels and test scores obtained during infancy and early childhood. The exception to this is for children whose scores fall in the extremely high or low range of ability (15,16). Therefore, it is important to be cautious when making inferences on measures used in infants and toddlers. Another limitation in using neuropsychological evaluations with very young children is their developmental immaturity with most of the areas assessed in neuropsychological examinations such as language, memory, and problem solving, which do not develop until well into late childhood, and some do not reach their most mature levels until adolescence (17). Therefore, some of the deficits that the child may possess may not manifest at a young age, and instead appear later when they are in an environment when those skills are required (e.g., school).

Culture and Ethnicity

Every neuropsychological test is influenced by cultural factors, with some more than others (18). Picture vocabulary tests are
highly culturally loaded, as identification of most of the objects requires an understanding of the objects in their linguistic terms. Conversely, matrix tests and digit span tests are not as culturally loaded but still require some knowledge of specific language symbols. It is not likely that measures can ever be created without any influence from an individual’s learning or cultural experience. Therefore, it is essential to evaluate several cultural factors that may impact test results before making any interpretations of the data. Sattler, 2001 (18) emphasizes the following factors: (a) the child and family’s degree of acculturation, (b) their cultural and religious beliefs about epilepsy and the associated disability, (c) the family structure and intrafamily relationships, (d) their attitudes toward medical and mental health professionals and treatment, and (e) their ability to communicate. The ability to understand and express thoughts, ideas, feelings, and behaviors seems to be the most salient and likely issue that might lead to questioning of the validity of the data, that is, the child’s ability to understand the task demands of the evaluation, as well as his or her ability to convey the correct response, and will greatly influence the test scores.

Physical and Medical Conditions

Cognitive dysfunction and epilepsy co-occur in several different ways. These include disruption in the course of a clinical epileptic event (ictal deficits), after the epileptic event (postictal deficits), transitory dysfunction as a result of epileptiform discharges, persistent deficits, deficits associated with atypical lateralization (reorganization of neural circuitry), and nonspecific effects of epilepsy (e.g., side effects of AEDs, sleep disruption, fluctuating attention), and specific cognitive deficits associated with focal lesions. The effects of AEDs on cognitive functioning in adults have been previously well established, but are still largely under investigation in children. Children in the midst of neurodevelopment are particularly at risk for the adverse cognitive side effects of AEDs, with the most commonly affected areas across the life span being attention, vigilance, memory, and mental and motor processing speed (4). Although the purpose of administering AEDs is to inhibit undesired discharges within particular areas of the brain, there is also a tendency for preferred brain functions to be inhibited as well. Therefore, a child on antiepileptic medication at the time of testing is influenced not only by the underlying neurophysiologic disturbance itself but also the effect of antiepileptic medication.

All of these conditions of cognitive dysfunction associated with intractable epilepsy may occur during the course of neuropsychological assessment. Each circumstance has a unique impact on a child’s functioning and is associated with different patterns of functioning on neuropsychological tests. The review of the extensive literature as to the specific deficit patterns associated with each of these events is beyond the scope of this chapter. However, the reader is referred to Lishman, 1987 (19), Bennett, 1992 (20), and Baron et al. 1995 (13). Despite these important considerations, the comprehensive neuropsychological evaluation is composed of multiple critical domains including cognitive, behavioral, and emotional functioning, which are required to provide an in-depth understanding of the child’s abilities to function optimally in his or her home, school, and community.

Components of a Neuropsychological Evaluation

There are several domains to be considered when comprehensively assessing the neuropsychological functioning of a child with epilepsy. This includes gaining substantial information pertaining to the child’s developmental history, onset of seizures, treatment, academic achievement record, and teacher’s observations, with an extensive assessment of intellectual functioning, academic achievement, memory, language, visuospatial and visuomotor functions, motor functioning, executive functioning and attention, and behavioral and emotional functioning.

Clinical Interview

Because of their cognitive limitations and lack of self-awareness, children, unlike adults, are not self-referred into clinics. More often, they are referred, owing to concerns by their parents, teachers, or medical professionals, who serve as multiple informants in this regard. Obtaining information from multiple sources will allow an assessment of the consistency and contradictions in the nature and severity of presenting problems to be made. Obtaining information from different informants will also reflect whether the symptoms persist across settings and the role that environmental factors may contribute to the problem behaviors. Interviews with the informants should include questions regarding when the symptoms associated with epilepsy began, the child’s achievement of developmental milestones, additional medical history, the family’s psychiatric and medical history, and the child’s academic, behavioral, social, emotional, and cognitive functioning. Additional information can also be obtained from medical records (i.e., medications, neuroimaging), previous testing records, and school files.

General Intelligence

There is no agreed-upon definition of intelligence. Nonetheless, there are three areas that have consistently appeared in the literature as the main components of this construct. These include (a) the ability to adjust or adapt to the environment, (b) the ability to learn, and (c) the ability to engage in higher-order thinking, such as reasoning, problem solving, and decision making (18). Intelligence quotient (IQ) tests provide a broad assessment of cognitive abilities that can be used to compare a child’s relative standing with that of his or her same-aged peers. In children, tests of intellectual functioning generally tap more fluid, rather than crystallized, types of intellectual abilities (21). Several examples of IQ tests for children include, but are not limited to, the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) (22), Stanford-Binet Test of Intelligence-Fifth Edition (SB-V) (23), and Kaufman Assessment Battery for Children (K-ABC) (24). There are also other measures developed to assess the intelligence of a child with special limitations such as little or no phrase speech (lack of language) or English as a second language (i.e., Leiter International Performance Scale—Revised [25]; Test of Nonverbal Intelligence—Third Edition [26] or, for younger children, Wechsler Preschool and Primary Scale of Intelligence—Third Edition [WPPSI-III] [27]).

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