neuropsychological impairments on the cantab test battery

Cogniţie, Creier, Comportament / Cognition, Brain, Behavior Copyright © 2007 Romanian Association for Cognitive Science. All rights reserved. ISSN: 1224-8398 Volume XI, No. 3 (September), 539 - 552

NEUROPSYCHOLOGICAL IMPAIRMENTS ON THE CANTAB TEST BATTERY: CASE REPORTS OF

CHILDREN WITH FRONTAL AND TEMPORAL LOBE EPILEPSY

Steluţa PALADE * 1 , Ileana BENGA 1 ' 2 1 Clinic of Pediatric Neurology, Cluj Napoca, Romania

2 University of Medicine and Pharmacy “Iuliu Haţieganu”, Department of Pediatric Neurology, Cluj Napoca, Romania

ABSTRACT

Frontal and temporal lobe epilepsy in children has been less studied compared to that seen in adults. Children with epilepsy are at significant risk for cognitive impairment. Computerized batteries can record aspects of performance that are difficult for psychometrists to achieve with traditional tests. There has been recent interest in applying computerized technology to neuropsychological assessments, especially in epilepsy. We tested two children, one with frontal lobe epilepsy (three assessments) and one with temporal lobe epilepsy (two assessments) and compared their results between assessments. The cognitive evaluation included the Cambridge Neuropsychological Automated Testing Battery (CANTAB) and also IQ measured with Raven Progressive Matrices test. Two different patterns of cognitive functioning were obtained. Performance was different on some CANTAB tasks: lower in frontal and temporal tasks for the child with frontal epilepsy and with more specific deficits for the child with temporal lobe epilepsy. The cases studied revealed differences in cognitive function between assessments; the neuropathological substrate was also discussed. The findings highlight the benefit of using neuropsychological tests rather than general intellectual outcome alone, to obtain a better distinction of the specific cognitive weaknesses associated with epilepsy in children.

KEYWORDS: frontal and temporal lobe epilepsy, CANTAB, children, memory.

* Corresponding author: E-mail: [email protected]

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INTRODUCTION Epilepsy in childhood is a common clinical problem with frequent

associated social and learning burdens. Intellectual disability is a major contributor to the psychosocial comorbidity in childhood epilepsy (Nolan et al., 2003). The psychological and cognitive consequences of epilepsy can have a major impact on the social and academic adjustment of patients with epilepsy. The learning difficulties (in mathematics, reading, spelling and writing) found in 1/3 of epileptic children are frequently the consequence of specific cognitive disabilities rather than a disorder of global intellectual function although the distribution of intelligence quotient (IQ) scores of children with epilepsy is skewed toward lower values (Chaix et al., 2006). Various factors are considered likely to induce cognitive disabilities: the age of onset, period of time since onset, the type of epilepsy, the nature and frequency of the seizures, and the effects of antiepileptic treatment. Moreover, interictal EEG discharges are implicated in transient neuropsychological disturbance and may contribute to the cognitive problems of some children with epilepsy (Binnie, 2003).

The question of whether certain types of epilepsy and their underlying etiologies are characterized by a specific profile of cognitive strengths and weaknesses is of interest for diagnosis and treatment of children with epilepsy (Jokeit & Schacher, 2005). Epilepsy is not a unitary disease entity and refers to symptoms of paroxysmal disturbance of brain activity. Seizure onset zone, seizure frequency, seizure duration, and seizure semiology may vary considerably between and within patients. Considerable efforts have been undertaken to develop a common taxonomy of epilepsy (Benga, 2003). The fundamental dichotomy between generalized and focal or localization-related epilepsies is well accepted and useful in diagnostic and treatment. In contrast the sub-classification of symptomatic, cryptogenic and idiopathic epilepsies cannot be considered as definite (Jokeit & Schacher, 2005).

We’ll present some characteristics of symptomatic focal epilepsies. The “International Classification of Epilepsies” suggests four main localization-related epilepsies: temporal lobe epilepsies, frontal lobe epilepsies, parietal lobe epilepsies and occipital lobe epilepsies. There are no specific causes or etiologies of these epilepsies with the exception of hippocampal sclerosis. There is widespread agreement that temporal lobe epilepsies associated with hippocampal sclerosis represent a highly prevalent discrete syndrome.

Temporal lobe epilepsy is the most frequent focal epilepsy. Although the semiology of temporal lobe epilepsy has been studied in detail in adults, relatively few studies have examined temporal lobe epilepsy in infants and children (Ray & Kotagal, 2005). The leading cognitive symptoms are impairments of episodic memory due to structural lesions of the hippocampal formation.

Frontal lobe epilepsy is the second most frequent localization-related epilepsy. The initial symptomatology of frontal lobe seizures depends on the location of the epileptogenic zone. The complexity and diversity of frontal lobe

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functions are reflected by the variability of symptoms found in frontal lobe seizures and by the variability of related neuropsychological deficits (reduced attention span and psychomotor speed) (Exner, Boucsein, & Lange, 2002; Helmstaedter, Kemper, & Elger, 1996). Age at onset of frontal lobe epilepsy may considerably influence the presence of specific frontal deficits (Upton & Thompson., 1997).

Neurocognitive profiles are often difficult to circumscribe, maybe due to the fact that, during development, both reduction of learning potential and greater functional plasticity are at work, in opposite directions. Cognitive impairments, when present, might be permanent, transient, state-dependent, or due to a developmental delay. Also, test-retest reliability is rather low, often showing a trend towards deterioration (Benga, Visu-Petra, Palade, & Benga, 2007).

Results of neuropsychological diagnostics rarely aid in pinpointing the specific type of epilepsy and underlying etiology in a certain patient. Knowledge about the type of epilepsy and the underlying pathology provides vital information for neuropsychologists regarding evaluation of the nature of the deficits as either transient or chronic, in estimating probability of functional recovery, in providing therapeutic recommendations and in guiding decisions regarding treatment options ( Cormack et al., 2007; Jokeit & Schacher, 2005; Benga, 2003).

METHODS

Participants and methods

At the time of testing no norms for children were available for the Romanian population on the CANTAB battery and as the tests are considered relatively “culture – free” we used the appropriate normative data provided in the CANTAB manual (test results were normalized to z score to allow direct comparation between tests; a z score of ≤ /2/ is generally considered significantly different from normal).

We have tested 2 children with epilepsy (frontal lobe epilepsy, temporal lobe epilepsy), from different ages (11 years old and respectively 16 years old). Children were seen in Clinic of Pediatric Neurology, Cluj Napoca between 2005- 2006 for neuropsychological assessment as part of their medical evaluations. To appreciate the impact of neuropathology on cognitive functioning we included a measure of IQ. The child with temporal lobe epilepsy was assessed two times (in April, 2006 and July 2006), with six tests from CANTAB (Psychomotor Screening, Pattern Recognition, Spatial Recognition Memory, Delayed Matched to Sample, Paired Associates Learning, Spatial Memory Span). The child with frontal lobe epilepsy was evaluated three times (in April 2005, January 2006 and September 2006; tests used: Psychomotor screening, Pattern Recognition, Spatial Recognition Memory, Delayed Matched to Sample, Paired Associates Learning, Spatial Memory Span, Spatial Working Memory, Stocking of Cambridge, Big/Little Circle, Intra/Extradimensional Set-Shifting, Rapid Visual Information Processing, Reaction Time. All medical data from the neurological evaluation were obtained.

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Neuropsychological tasks

The children were evaluated using tasks from CANTAB – Cambridge Automated Testing Battery, a computerized battery valid for the assessment of frontal, temporal and striatal functions (Sahakian et al., 1988). The CANTAB battery requires no verbal responses and was administrated on a computer with touch-screen monitor. The following neuropsychological tasks were used:

Psychomotor Screening (MOT) This is a simple reaction time task that measures psychomotor speed and

fine motor accuracy. A series of crosses is shown in different locations on the screen. After a demonstration of the correct way to point, using the forefinger of the dominant hand, the subject must touch the crosses in turn.

Pattern Recognition (PRM) CANTAB employs a delayed match-to-sample paradigm to measure

recognition memory for visual patterns. Accuracy and response latency are recorded. The percentage of correct responses across blocks involving recognition of abstract visual patterns represents the subject’s pattern-recognition score. The subject is presented with series of 12 visual patterns, one at a time, in the centre of the screen. These patterns are designed so that they cannot easily be given verbal labels. In the recognition phase, the subject is required to choose between a pattern they have already seen and a novel pattern. In this phase, the test patterns are presented in the reverse order to the original order of presentation. The sub-test is repeated with a new set of 12 patterns to be remembered.

Spatial Recognition Memory (SRM) SRM is a test of spatial recognition memory in a forced-choice paradigm.

This test is primarily sensitive to dysfunction in the frontal lobe, and relatively insensitive to temporal lobe damage according to the authors. The percentage of correct trials on trials requiring the child to recognize targeted spatial locations represents the spatial-recognition score.

A white square is shown on the screen in various locations. In the presentation phase, a white square is shown on the screen in five different locations. Each appearance of a square marks a location on the screen which the subject must later remember. In the recognition phase, the square reappears in the same five locations as in the presentation phase, in reverse order. On each appearance, it is paired with an identical distractor square in a location not used in the presentation phase. The subject must touch the square in the location that has appeared before, whilst ignoring the distractor. This represents one block. This block is repeated three more times, each time with five new locations.

Delayed Matching to Sample (DMS) DMS is a test of simultaneous and delayed matching to sample. This test is

primarily sensitive to damage in the medial temporal lobe area, with some input from the frontal lobes.

The subject is shown a complex visual pattern and then, after a brief delay, four patterns. Each pattern is made up of four sub-elements, each of a different

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colour. One of the choice patterns is identical to the sample, one is a novel distractor pattern, one has the shape of the sample and the colours of the distractor, and the fourth has the colours of the sample and the shape of the distractor. To discourage strategies based on encoding single quadrants, all four choice patterns have one quadrant in common with the sample. The subject is instructed to touch the pattern that matches the sample. In some trials the sample and the choice patterns are shown simultaneously, whereas in others a delay (of 0, 4, or 12 seconds) is introduced between covering the sample pattern and showing the choice patterns. If the first choice is incorrect, the subject must make a second choice, and so on, until a correct choice is made.

Paired Associates Learning (PAL) PAL assesses episodic memory and learning (sensitive to changes in

medial temporal lobe functioning). The outcome measures for the PAL test may be divided into the following groups: errors, trials, memory scores, stages completed. The clinical mode of PAL has eight stages, which a subject must complete in order from 1 to 8 patterns.

For each stage, boxes are displayed on the screen. All are opened in a randomized order. One or more of them will contain a pattern. The patterns shown in the boxes are then displayed in the middle of the screen, one at a time, and the subject must touch the box where the pattern was originally located.

Each stage may have up to 10 trials in total (the first presentation of all the shapes, then up to 9 repeat presentations). If the subject makes an error, the patterns are represented to remind the subject of their locations. When the subject gets all the locations correct, they proceed to the next stage. If the subject cannot complete a stage correctly, the test terminates.

Spatial Memory Span task (SSP) This task, based on the Corsi block task, measures memory for a spatial

sequence. The maximum sequence length (which defines the length of the child’s nonverbal memory span) that can be achieved is nine.

A pattern of white boxes is shown on the screen. Some of the boxes change in colour, one by one, in a variable sequence. In the clinical mode, at the end of the presentation of each sequence, a tone indicates that the subject should touch each of the boxes coloured by the computer - in the same order as they were originally presented. In the reverse mode the tone indicates that the subject should touch each of the boxes coloured by the computer - in the reverse order to the order in which they were originally presented. In both modes, the number of boxes in the sequence is increased from a level of 2 at the start of the test to a final level of 9. There are three possible sequences at each level, but as soon as the subject passes a sequence at each level they will immediately progress to the next level, not necessarily performing all three sequences at each level. If all three sequences at any level are completed unsuccessfully, the test terminates. The sequence and colour used change from sequence to sequence to minimize interference.

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Spatial Working Memory task (SWM) This self-ordered searching task measures working memory for spatial

stimuli and requires use of mnemonic information to work towards a goal. The task increases in difficulty such that the participant ultimately completes 40 trials: four trials each with two items, three items, four items, six items, and eight items. The number of errors at each difficulty level and a strategy score are recorded. PET imaging studies indicate that this task activates both the dorsal and ventral prefrontal regions (Luciana & Nelson, 1998).

The test begins with a number of coloured squares (boxes) being shown on the screen. The aim of this test is that, by process of elimination, the subject should find one blue ‘token’ in each of a number of boxes and use them to fill up an empty column on the right hand side of the screen. The number of boxes is gradually increased from three to eight boxes. The colour and position of the boxes used are changed from trial to trial to discourage the use of stereotyped search strategies.

The subject must touch each box in turn until one opens with a blue token inside (a search). When a blue token has been found, the subject has to place it in the right column (‘home’) by touching the right-hand side of the screen. Touching any box in which a blue token has already been found is an error. The subject decides the order in which the boxes are searched. The computer determines the number of empty boxes that must be visited (discounting errors).

Stockings of Cambridge (SOC) This task measures spatial planning and behavioral inhibition (Shallice,

1982). Two conditions are administered: a planning condition and a visuomotor condition that requires no planning. The measurement of the selection and execution latencies in the yoked condition provides baseline estimates of motor initiation and execution times (Veale, Sahakian, Owen & Marks, 1996). These movement times are then used to derive measures of planning times. Two variables were computed within each of four levels of problem difficulty (two-, three-, four-, and five-move problems): the average number of moves to complete each set, and the planning time before problem initiation. SOC is a test of spatial planning and spatial working memory, which gives a measure of frontal lobe function.

The subject is shown two displays containing three coloured balls. The displays are presented in such a way that they can easily be perceived as stacks of coloured balls held in stockings or socks suspended from a beam. The subject must use the balls in the lower display to copy the pattern shown in the upper display. The balls may be moved one at a time by touching the required ball, then touching the position to which it should be moved. The time taken to complete the pattern and the number of moves required are taken as measures of the subject’s planning ability.

Big/Little Circle (BLC) BLC is primarily a training/screening test to prepare the subject for the

Intra-Extra Dimensional Set Shifting (IED) test, and so should usually be given before the IED test. BLC is a simple test of attention. This visual discrimination test is designed to train a subject to follow a simple rule and reverse a rule.

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The subject is presented with a series of pairs of circles, one large and one small. The subject is instructed first to touch the small circle and then, after 20 trials, to touch the larger circle for a further 20 trials.

Intradimensional/Extradimensional Set-Shifting task This task measures discrimination and reversal learning under conditions

that require the subject to shift attention to changing patterns of visual stimuli. The task encompasses nine stages, and the highest stage reached by an individual child is recorded. Additionally, two stages are of particular interest: stage 6 which requires participants to make a withincategory (intradimensional) shift, and stage 8 which requires participants to make a between-category (extradimensional) shift. To compare children’s performance at each of these two stages the number of trials to reach criterion and the number of errors at each stage were calculated. Variables coded for each subject include the stage reached, the trials to criterion, and the number of error scores for each completed stage.

Rapid Visual Information Processing (RVP) This test is sensitive to dysfunction in the parietal and frontal lobe areas of

the brain and is also a sensitive measure of general performance. RVP is a test of visual sustained attention.

A white box appears in the centre of the computer screen, inside which digits, from 2 to 9, appear in a pseudo-random order, at the rate of 100 digits per minute. The test is in two parts; a ‘warm-up’ practice stage which lasts for two minutes and is not scored, and a test stage which lasts for three minutes. Subjects are requested to detect target sequences of digits (for example, 2-4-6, 3-5-7, 4-6-8) and to register responses using the press pad. Target sequences occur at the rate of 16 every 2 minutes.

Reaction Time (RTI) This task is designed to measure the subject’s speed of response to a visual

target where the stimulus is either predictable (simple reaction time) or unpredictable (choice reaction time).

A yellow spot appears on the screen. The task for the clinical mode of RTI is divided into five stages, each successive stage having increasingly complex response requirements. In the first stage, the subject simply has to touch the screen when a yellow spot appears in the centre of the screen, neither touching too soon nor too late. Once the subject has achieved 5 out of 6 correct, or completed a maximum of 18 attempts, the second stage, which is the choice reaction task, is introduced.

In the second stage, the yellow spot may now appear in any one of five locations. Again, the subject is trained to a criterion of 5 out of 6 correct, with a maximum of 40 attempts. If the subject fails to achieve the criterion on this stage, the test terminates. Successful subjects are then introduced to the press pad. In the third stage, the subject is required to hold down the press pad button until the yellow spot appears in the centre of the screen, but does not have to touch the screen. In the fourth stage, the subject is required to hold down the press pad button until the yellow spot appears in the centre of the screen, and then must touch

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the screen where the spot appears. This is the first of the two assessed stages. In the fifth and final stage, the choice reaction task is again introduced, and by this stage the subject has been trained to hold down the press pad button until the spot appears, then release the press pad button and touch the position on the screen where the spot was presented.

Other psychological tests Raven’s Standard Progressive Matrices test was used for establishing IQ

scores. This is a test of observation skills and clear-thinking ability. It offers insight about someone’s capacity to observe, solve problems, and learn. The test has a total of 60 items presented in 5 sets (A–E), with 12 items per set, with items within a set becoming increasing difficult, requiring ever greater cognitive capacity to encode and analyze information. In each test item, a candidate is asked to identify the missing segment required to complete a larger pattern. All items are presented in black ink on a white background.

Statistical analysis was performed using SPSS 8.0 for Windows. The performance of children was compared, for each of the computerized measures, with the appropriate normative data (stratified by age) provided in the CANTAB manual. This comparison is provided automatically by the software included in the CANTAB battery. RESULTS

Case report 1 (temporal epilepsy)

A 16 year old boy was admitted for the first time when he was 12 years old with suspected epileptic seizure. He presented 3 morpheic seizures in a period of 2 weeks (oral automatisms, respiratory dysfunction, difficult to awake, with duration under 1 minute). Computer tomography was normal. The treatment was initiated with Carbamazepine. For a period of 2 years he was free of seizures. At 14 he presented diurnal seizures: activity stopping, stereotyped short answers to all questions, staring and sometimes producing motor automatisms with a duration under 1 minute. With increase in doses of Carbamazepine for 1 year he was free of seizures. At 15 years, he again had seizures (5 seizures/ 6 month). In April 2006, a week before admission, he had 2 seizures at school (he stood up, walked in the class without answering to the teacher questions). There was no family history of epilepsy. Personal history: born at term, Apgar score = 2, hypoxia; normal psychomotor development. On admission, the neurological examination revealed no abnormal findings. The electroencephalogram analysis revealed temporal epileptic discharges. He underwent a neuropsychological assessment (CANTAB battery and Raven Progressive Matrices Test). The final diagnostic was temporal epilepsy (based on semiology of seizures, EEG, MRI).

In July 2006 he was admitted again for persistence of seizures. In 3 months he presented 5 seizures/ week, and accused memory dysfunction and learning difficulties. Magnetic resonance imaging revealed hippocampal sclerosis.

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CANTAB Parameters

SS

P

SS

P

SS

P

PA

L

PA

L

PA

L

PA

L

PA

L

PA

L

PA

L

DM

S

DM

S

SR

M

SR

M

PR

M

PR

M

MO

T

Z S

CO

RE

2

1

0

-1

-2

-3

-4

Assessment

1

2

Figure 1. Graphic representation of CANTAB results (case 1: temporal epilepsy)

Note: z scores for MOT: Psychomotor Screening; PRM: Pattern Recognition; SRM: Spatial Recognition Memory; DMS: Delayed Matched to Sample; PAL: Paired Associates Learning; SSP: Spatial Memory Span at the two assessment sessions.

Neuropsychological data demonstrated a low intelligence score (I.Q. score

85 - Raven’s Standard Progressive Matrices test) relative to normative standards; also he scored below normal levels of functioning on the test of simultaneous matching to sample (DMS), (z score-1,83) and above average on the spatial memory recognition task (SRM) (z score 0,15) and on the memory for spatial sequences task (SSP) (z score = 0.21) at the first assessment, on April 2006. The second assessment, on July 2006 (after 3 months, with increase of seizure frequencies at 5 seizures/week) revealed the same I.Q. score (I.Q. score 85, Raven’s Standard Progressive Matrices test). At the same session, on the paired associates learning (PAL) task, compared to the previous asssesment, there was a higher number of errors (z score = 1.37), a similar number of stages completed (6), and an increased of number of trials (19), as we can see in Fig. 1.

Case report 2 (frontal epilepsy)

We evaluated an 11 ½ years old girl admitted for the first time when she was 7 ½ years old for epilepsy, complex partial seizures (deviation of the head and eyes on the left side). The treatment was initiated with Carbamazepine. For a period of 2 ½ years she was free of seizures. At 10 years she again had seizures, with a new semiology (feels cold, stares, arms up), with a duration up to 10 seconds. Magnetic resonance imaging (MRI) was normal (2005). Carbamazepine

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was associated with Depakine, but secondary effects appeared (nausea, vomiting), so it was replaced with Phenobarbital and Rivotril. Under this treatment the control of seizures was obtained for one year. At 11 years she again started to have seizures, both nocturnal and diurnal (gastrointestinal sensations, sudden fears, arms lifting, staring, motor automatisms), 5-8 seizures/day. She also had behavioral difficulties such as irritability, inattention and obsessive-compulsive behaviors. In April 2006, magnetic resonance imaging (MRI) revealed gliosis and focal displasia in the frontal superior gyrus. Her treatment was with Carbamazepine and Topamax; more therapeutical schemas were changed (number of seizures increased until of 50 seizures/day). Frequency of seizures diminished (1/2 seizures/week) until September 2006, when she had another medical evaluation in our hospital, after neurosurgical assessment. There was no family history of epilepsy. Personal history: born at term, Apgar score 9, normal psychomotor development. On admission, neurological examination revealed no abnormal findings. The electroencephalogram study showed diffuse, irritative epileptic discharges. She underwent a neuropsychological assessment (with CANTAB battery and Raven’s Standard Progressive Matrices test). The final diagnostic was frontal epilepsy (based on semiology of seizures, EEG, MRI).

Figure 2. Graphic representation of results (case 2: frontal epilepsy) Note: z scores for MOT: Psychomotor Screening; PRM: Pattern Recognition; SRM: Spatial Recognition Memory; DMS: Delayed Matched to Sample; PAL: Paired Associates Learning; SSP: Spatial Memory Span; SWM: Spatial Working Memory; SOC: Stocking of Cambridge; BLC: Big/Little Circle; IED: Intra/Extradimensional Set-Shifting; RVP: Rapid Visual Information Processing; RTI: Reaction Time at the three assessment sessions.

CANTAB Parameters

RVP

RTI

RTI

RTI

RTI

IED

IED

BLC

SO

C

SO

C

SW

M

SW

M

SSP

PAL

PAL

PAL

PAL

DM

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SR

M

PR

M

MO

T

Z S

CO

RE

2

1

0

-1

-2

-3

-4

Assessment

1

2

3

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Neuropsychological data revealed a low intelligence score (I.Q. score 82 –

first assessment; I.Q. score 85 – second assessment and I.Q. score 90 – third assessment with Raven’s Standard Progressive Matrices test), relative to normative standards; she also scored below normal levels of functioning (as we can see in fig. 2), on the test of delayed matching to sample (DMS) (z score = - 1.07); the number of correct percent on pattern and spatial recognition memory (PRM/SRM) task was above average, but the latencies were high (z score = - 1.55); also the mean of subsequent thinking time on spatial planning was high (SOC) (standard score z = - 9.31); paired associate learning (PAL) task revealed the most pronounced deficit with high number of errors (z score = - 3.95). Between the first and the second assessment we could observe the performance within the same limits; between the second and the third assessment we could observe an improvement in performance on the task of paired associate learning (PAL), and reaction time (RTI). The length of the child’s nonverbal memory span (SSP task) remained lower (z score -1,61) as we can see in Fig.2. DISCUSSION

Temporal lobe epilepsy is the most prevalent type of focal epilepsy in both children and adults. The disorder varies greatly with regard to etiology, age of onset, seizure type, severity and duration. The main underlying causes are medial sclerosis, neoplasms, vascular disease and neuro-developmental disorders. Mesial temporal epilepsy is the most frequently encountered form of temporal lobe epilepsy (Sauerwein, Gallagher, & Lassonde, 2005). The syndrome is characterized by early onset, a history of recurrent febrile seizures and unilateral hippocampal sclerosis, which can be visualized by magnetic resonance imaging (Engel, 1996).

Although epilepsy is primarily a childhood disorder, neuropsychological studies in children have only recently started to emerge. The findings indicate that children with temporal lobe epilepsy present deficits that are similar in many aspects to those observed in adults. Furthermore, the children are at risk of developing learning disabilities and behavior problems that can be related to temporal lobe dysfunction (Sauerwein et al., 2005; Nolan et al., 2003; Chaix et al., 2006). Age of onset appears to be the most reliable predictor of long term cognitive outcome. Converging evidence suggests that early onset is associated with greater and more widespread cognitive impairment. However, although children with later onset and uncomplicated temporal lobe epilepsy may have normal intelligence, many tend to have learning disabilities (Sauerwein et al., 2005). Simple focal seizures, starting at school age are generally not associated with a decline in intellectual functioning. In contrast, seizures starting in infancy risk interfering with mental development at a time of maximal vulnerability.

Memory impairment is the most proeminent symptom of temporal lobe epilepsy in adults (Helmstaedter, 2005) and children (Helmstaedter & Elger, 2000).

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Language dysfunction is another characteristic feature of temporal lobe epilepsy (Janszky et al., 2005).

Although deficits in executive functions are the hallmark of frontal lobe dysfunction, several studies have shown that children and adults with temporal lobe epilepsy may present impairments that are similar to, although less severe than those seen in patients with frontal lobe epilepsy (Hernandez et al., 2003; Sauerwein et al., 2005; Benga et al., 2007).

Frontal lobe epilepsy is one of the most complicated and least understood forms of epilepsy (Sinclair, Wheatley, & Snyder, 2004). Children with frontal lobe epilepsy have deficits in executive functions, working memory and also difficulties in behavioral adjustment (Hernandez et al., 2003).

Our results in the case study of a child with temporal lobe epilepsy revealed a low global functioning and a performance bellow normal levels of functioning in memory and new learning (PAL). The children accused difficulties in his academic tasks (specially in the ability to retain new information). We know that the natural evolution and prognosis of temporal lobe epilepsies in children is extremely variable and factors such as age at onset, frequency of seizures, history of episodes of status and the presence, and type of an underlying lesion may influence both the control of seizure and cognitive outcome. Evidence suggests that progressive behavioral changes occur, particularly increasing memory deficit, over time. In everyday clinical practice systematic neuropsychological testing of patients with nonidiopathic focal epilepsy can certainly yield invaluable information on their cognitive profile and on the specific domains necessitating rehabilitative measures.

Frontal lobe epilepsy is one of the most complicated and least understood forms of epilepsy (Sinclair et al., 2004). Children with frontal lobe epilepsy have deficits in executive functions, working memory and also difficulties in behavioral adjustment (Hernandez et al., 2003). Performance on executive function tests is primarily viewed as reflective of frontal lobe dysfunction. Frontal lobe epilepsy in childhood is a distinct epilepsy syndrome with characteristic features. The condition is often misdiagnosed as a sleep disorder or psychiatric problem and seizures are difficult to control (Sinclair et al., 2004).

In our case studies, it is interesting to examine neuropsychological and behavioral changes with time. In the first assessment, her global functioning was below normal, with specific deficits on DMS task, PAL and SOC. Between first and second assessments (April 2005, January 2006), the performance was within the same limits. At the third assessment (September 2006), performance was better than before, with normalized functioning in performance at visual memory and learning, latencies and attention functions (number of seizures were diminished from 50 seizures/day to 1/ 2 seizures/week). This suggests that improvement of neurocognitive functions followed improvement of seizures control. It is also interesting to remark obsessive thoughts and compulsive behaviors which appeared in this period.

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CONCLUSIONS

The findings highlight the benefit of using neuropsychological tests rather than general intellectual outcome alone in order to obtain a better distinction of the specific cognitive weaknesses associated with epilepsy in children. The results of this study can be helpful in understanding and treating the educational and behavioral problems which appear in children with epilepsy. What can be concluded is that in everyday practice the need for neuropsychological testing must be raised in the initial evaluation of every child with epilepsy.

ACKNOWLEDGEMENTS This research was supported by a VIASAN grant for neuroscience, S2PED/2004-2006. REFERENCES Benga, I. (2003). Epilepsia şi crizele neepileptice. Cluj Napoca: Editura Medicalã

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