Health-related quality of life in childhood hydrocephalus

Transcription

1 J Neurosurg Pediatrics 8: , 8: , 2011 Comparison of Hydrocephalus Outcome Questionnaire scores to neuropsychological test performance in school-aged children Clinical article Abhaya V. Kulkarni, M.D., Ph.D., 1 Ruth Donnelly, Ph.D., 2 and Iffat Shams, M.B.B.S., M.P.H. 1 Divisions of 1 Neurosurgery and 2 Psychology, The Hospital for Sick Children, University of Toronto, Ontario, Canada Object. The Hydrocephalus Outcome Questionnaire (HOQ) is an established means of measuring quality of life, but the cognitive component of this questionnaire has never been formally compared with gold-standard neuropsychological test scores. The authors hypothesized that the HOQ Cognitive Health score would demonstrate a relatively strong correlation with neuropsychological test scores, whereas much weaker correlations would be seen for HOQ Physical and Social-Emotional Health scores. Methods. A cross-sectional study of children with long-standing hydrocephalus presenting to The Hospital for Sick Children s Neurosurgery Clinic was performed between July 2006 and September Participating children and families completed the HOQ and a battery of 21 standard neuropsychological tests and questionnaires. Pearson correlation analysis was then performed. Results. A total of 83 patients (81% participation) was accrued; the mean age was 11.5 ± 3.4 years (mean ± SD) at the time of assessment. The mean age at hydrocephalus treatment was 1.3 ± 2.6 years. The mean overall HOQ score was 0.69 ± The HOQ Cognitive score had a moderate or strong correlation with 19 (90%) of 21 neuropsychological test scores, much more so than the HOQ Social-Emotional score (5 moderate or strong correlations, 24%) and the HOQ Physical score (1 moderate correlation, 5%). For 19 neuropsychological tests (90%), the HOQ Cognitive score had a stronger correlation than the other scores. The HOQ Cognitive score had particularly strong correlations with the Verbal IQ, List Learning, Behavior Problems, and Metacognitive Abilities components. Conclusions. Data from a wide-ranging representative sample of children with long-standing hydrocephalus provide added evidence of the validity of the HOQ Cognitive score and the overall domain structure of the HOQ itself. (DOI: / PEDS1179) Key Words pediatric hydrocephalus health outcome quality of life neuropsychology Health-related quality of life in childhood hydrocephalus is now recognized as an important outcome to consider. We have previously developed the HOQ, which has provided a simple, reliable, and valid way in which to measure HRQL in children with hydrocephalus. 17,18 Our group and others have since used the HOQ in several research studies of HRQL. 3,14 16,19,20,22 Within the spectrum of HRQL, cognition is seen Abbreviations used in this paper: HOQ = Hydrocephalus Outcome Questionnaire; HRQL = health-related quality of life; WAIS- III = Wechsler Adult Intelligence Scale Third Edition; WISC-IV = Wechsler Intelligence Scale for Children Fourth Edition; WPPSI-III = Wechsler Preschool and Primary Scale of Intelligence Third Edition; WRAT-3 = Wide Range Achievement Test Third Edition. as a particularly relevant component for children with hydrocephalus. The HOQ includes a cognitive health component, for example, consisting of 12 questions. The gold standard for objectively measuring cognitive performance has long been through the use of neuropsychological tests, including traditional IQ testing and other specific tests. We embarked on a study to assess detailed objective neuropsychological performance in a diverse group of children with treated hydrocephalus, and we compared these results to those obtained from the more subjective parent responses to questions from the HOQ. We hypothesized that, although there might be areas for which the HOQ scores mirror neuropsychological test results, there would probably also be areas for which these measures would provide unique information. We hypoth- 396 J Neurosurg: Pediatrics / Volume 8 / October 2011

2 Neuropsychological outcome in children with hydrocephalus esized that the HOQ Cognitive Health score in particular would demonstrate the strongest correlation with the neuropsychological tests, whereas much weaker correlations would be seen for HOQ Physical and Social-Emotional Health scores. The HOQ Cognitive score questions mainly revolve around parents appraisal of their child s learning, memory, and elements of the Executive Function component such as organization and attention. If our hypotheses were correct, then that would add confidence to the validity of the HOQ Cognitive score and the proposed domain structure of the HOQ itself. Methods We recruited a consecutive sample of children between the ages of 5 and 18 years, in whom hydrocephalus had been diagnosed and treated at least 6 months earlier, from the neurosurgery outpatient clinic of The Hospital for Sick Children, Toronto, between July 2006 and September These children had to have adequate skills in English to complete testing, as evidenced by at least 2 years of English schooling. Children who had undergone either a neuropsychological or psychological-educational assessment within 1 year prior to participating in this study were excluded, because this could have resulted in artificially inflated scores. This protocol was approved by the hospital s research ethics board, and written consent and assent were obtained from all participating families. Assessment of HRQL The child s primary caregiver was asked to complete the HOQ. The HOQ is a 51-item questionnaire with proven reliability and validity in measuring health outcome in children with hydrocephalus. 17,18 We have previously shown good correlations between the HOQ and several independent measures of health, 17 including the WRAT s Reading subtest, 29 Strengths and Difficulties Questionnaires, 12,13 and Functional Independence Measure for Children, 21 but we have not compared HOQ results to performance on neuropsychological tests. The HOQ provides scores of Overall Health, Physical Health, Cognitive Health, and Social-Emotional Health, all of which range from 0 (worse outcome) to 1.0 (better outcome). Previous work has suggested that, to be clinically meaningful, a difference in HOQ scores needs to be approximately on the order of 0.10 or greater, based on how parents perceive differences in health status. 14 Assessment of Neuropsychological Performance Children were given a battery of neuropsychological tests by a trained psychological assistant and supervised by an experienced pediatric neuropsychologist. The tests involved were the core tasks from a standard neuropsychological evaluation and were an intensive and comprehensive assessment of the child s cognitive functioning. These are listed in Table 1 and in the Appendix, and all are widely used and well-standardized instruments. The testing lasted approximately 5 hours and included tests of IQ, language, academics, memory, visual-motor and visual-spatial skills, and visual information processing speed. J Neurosurg: Pediatrics / Volume 8 / October 2011 We chose tests from the clinical test battery given to children with hydrocephalus who are referred to the Psychology division from the Neurosurgery division at The Hospital for Sick Children. These tests had to either encompass the entire age range of this study (5 18 years), or they had to have upward or downward extensions with similar formats and comparable outcome measures. A few words are in order here to explain the intelligence testing scores. We used different Wechsler intelligence tests depending on the age of the child: the WPPSI-III; 27 the WISC-IV; 25 and the WAIS-III. 24 However, to have comparable scores among these 3 tests, we used 3 measures from each Wechsler test: the Verbal IQ Index score, the Nonverbal IQ Index score, and the Processing Speed IQ Index score. Each index score is summed over several subtests within each domain of verbal and nonverbal intellectual abilities and processing speed. We did not use the Working Memory Index scores from the WAIS-III and the WISC-IV because there is no comparable index score on the WPPSI-III and also because the WAIS-III Working Memory score includes a mental arithmetic subtest, and there is no similar subtest as part of the WISC- IV Working Memory score. Most of the tests that we used have more than 1 outcome score. We selected the specific scores a priori that we thought best reflected the child s performance in the particular area of interest. The full names of the tests and the particular score or scores that we used from each test can be found in the Appendix. For the first 18 scores in this listing, higher values indicate stronger performance by the child. The last 3 scores listed are the results from 2 different parent questionnaires, and higher scores indicate more problems in the areas queried. One score is from a behavioral questionnaire, 1 in which parents answered questions relating to their child s possible difficulties in areas such as anxiety, depression, social problems, attention problems, and aggression. The other 2 scores are from an Executive Function questionnaire, 11 in which parents answered questions about their child s everyday functioning in areas such as control of behaviors (behavioral regulation score), and planning, organizing, self-monitoring, and paying attention (metacognitive abilities score). Statistical Analysis The Pearson correlation was used to assess the association between the 3 HOQ subscores (Cognitive, Physical, and Social-Emotional) and each test of neuropsychological function. Similar to the suggestion by Cohen 4 and others, 6 we defined a strong correlation as > 0.5, moderate as , and weak/negligible as < We hypothesized that HOQ Cognitive Health scores would have mostly strong or moderate correlation with any of the first 18 measures of neuropsychological function listed above, whereas the HOQ Physical and Social- Emotional Health scores would demonstrate mostly weak/ negligible correlation. For the last 3 measures listed, higher scores indicate poorer performance in these areas. Because a higher score on the HOQ indicates better outcome, we expected a relatively strong negative correlation between the Be- 397

3 A. V. Kulkarni, R. Donnelly, and I. Shams TABLE 1: Neuropsychological testing results Test* Patient Scores Test Population Scores HOQ Cognitive Score Pearson Correlation w/ HOQ Physical Score HOQ Social-Emotional Score Verbal IQ index 93 ± ± Nonverbal IQ index 87 ± ± Processing Speed IQ index 84 ± ± PPVT 96 ± ± EOWPVT 95 ± ± Ambiguous Sentences 8 ± 4 10 ± Oral Comprehension 99 ± ± Letter-Word ID 91 ± ± Calculation 83 ± ± Passage Comprehension 85 ± ± Stories Delayed 9 ± 4 10 ± Faces Delayed 9 ± 4 10 ± Design Memory 7 ± 3 10 ± Sentence Memory 10 ± 3 10 ± List Learning 44 ± ± List Memory Delayed 1 ± 1 0 ± Beery VMI 83 ± ± Spatial Relations 92 ± ± Behavior Problems 58 ± ± Behavioral Regulation 57 ± ± Metacognitive Abilities 62 ± ± * See Appendix for test details. Abbreviations: EOWPVT = Expressive One-Word Picture Vocabulary Test; PPVT = Peabody Picture Vocabulary Test; VMI = Visual-Motor Integration. Values in the 2nd and 3rd columns represent the mean ± SD for the patient and test populations, respectively. Strong correlations (> 0.5). havior Problems and the Social-Emotional HOQ scores. We hypothesized that the last 2 measures listed (Behavioral Regulation and Metacognitive Abilities) would have at least moderate negative correlations with both the HOQ Social-Emotional and Cognitive scores. These measures of executive function encompass such a broad range of loosely defined abilities (such as initiation, planning, organizing, attention, and self-monitoring) that it seems likely that both emotional and cognitive aspects of a child s functioning will be affected by strengths or weaknesses in these areas. All analyses were performed using the SPSS Advanced Statistics software package (version 17.0; SPSS, Inc.). Results A total of 103 patients and their families were approached to participate in this study, of whom 83 (81%) agreed to enroll. The most common reason for refusal to participate was lack of available time to complete the intensive neuropsychological testing. The characteristics of the participants are shown in Table 2. The school grade level of the children ranged from senior kindergarten to Grade 12. Five children had hydrocephalus secondary to a tumor, but none had received radiotherapy or chemotherapy. The mean HOQ scores were as follows: Overall Health (0.69 ± 0.21), Cognitive Health (0.57 ± 0.29), Physical Health (0.79 ± 0.19), and Social-Emotional Health (0.74 ± 0.19). The results of the 21 neuropsychological measures and their correlations with the HOQ scores are shown in Table 1. An in-depth analysis and discussion of the pattern of the neuropsychological test results is beyond the scope of this paper and will not be attempted here, but instead will be presented in a separate work. A summary of the strengths of correlations between the neuropsychological scores and HOQ scores is shown in Table 3. In general, the HOQ Cognitive score had a greater number of strong correlations than either the HOQ Physical or Social-Emotional scores. Also, for every test except Behavioral Regulation, the HOQ Cognitive score had a stronger correlation than the other scores. Discussion In a wide-ranging representative sample of children with long-standing, treated hydrocephalus, our study showed that the HOQ Cognitive score had a strong correlation with several tests of neuropsychological function. 398 J Neurosurg: Pediatrics / Volume 8 / October 2011

4 Neuropsychological outcome in children with hydrocephalus TABLE 2: Characteristics of 83 patients with long-standing hydrocephalus Characteristic Particularly strong correlations were shown with the Verbal IQ, List Learning, Behavior Problems, and Metacognitive Abilities components. We had previously shown a strong correlation (0.59, Pearson test) between the HOQ Cognitive score and the WRAT-3 29 in a sample of 90 children with hydrocephalus as part of the initial validation of the HOQ. 17 Only the Reading subtest of the WRAT-3 was used in that study, because it requires the least physical ability from the children (the other subtests, Arithmetic and Spelling, have a written component), and it had the highest test retest reliability (0.93) of all the subtests, along with excellent internal consistency (a = 0.91). 29 It was acknowledged, however, that the Reading subtest of the WRAT-3 was a limited test of cognition. This subtest from the WRAT-3 just requires the child to decode words, with no test of whether the words are understood, and is almost identical in form to the Letter-Word ID test we used in the current study. Therefore, we had yet to show that the HOQ Cognitive score was a valid measure of wider, more comprehensive aspects of cognition. That was the primary purpose of this study: to assess the validity of the HOQ Cognitive score by using a wide range of standardized neuropsychological tests, and to determine whether the HOQ Cognitive score provided information unique from the other HOQ subscores (Physical and Social-Emotional scores). Our results suggest that the HOQ Cognitive Health score is uniquely correlated with several well-established measures of cognition and is thus unique from HOQ Physical or Social-Emotional Health scores. It was not expected that the HOQ Cognitive Health J Neurosurg: Pediatrics / Volume 8 / October 2011 Value* mean age at assessment 11.5 ± 3.4 yrs mean age at 1st op for hydrocephalus 1.3 ± 2.6 yrs no. w/ ETV as primary procedure 9 (10.8) no. w/ cause of hydrocephalus posterior fossa cyst 14 (16.9) IVH due to prematurity 12 (14.5) aqueductal stenosis 11 (13.3) myelomeningocele 10 (12.0) trauma/spontaneous hemorrhage 6 (7.2) congenital communicating hydrocephalus 6 (7.2) tumor 5 (6.0) postinfectious 4 (4.8) other cyst 4 (4.8) other cause 11 (13.3) mean total days in hospital for initial treatment of hy ± 19.8 drocephalus mean total days in hospital for hydrocephalus compli ± 28.5 cations * The mean values are presented ± SD; the remaining values are expressed as the number of patients, with the percentage in parentheses. Abbreviations: ETV = endoscopic third ventriculostomy; IVH = intraventricular hemorrhage. TABLE 3: Summary of strengths of correlations between HOQ scores and neuropsychological tests Test Component Correlation (no. of tests, %) Strong Moderate Weak/Negligible HOQ Cognitive 4 (19) 15 (71) 2 (10) HOQ Physical 0 3 (14) 18 (86) HOQ Social-Emotional 1 (5) 4 (19) 16 (76) score would be very highly correlated with all or even most neuropsychological tests. After all, we know that when we report results from objective tests, we are comparing an individual child against comprehensive norms collected from large numbers of same-age or same-grade children. Therefore, when we say that, based on these objective results, a child is within the average range on a test in which the scores are normally distributed, we mean that the child falls within the middle 50% of a representative sample of children. However, when a parent completes the HOQ, they are asked to say how true each statement is for their child, with no comparison group specified. We do not know to what extent parent evaluations could be affected by extrinsic factors such as their general expectations for children who have hydrocephalus, or whether they think their child is really trying, even though they might have difficulty in some specific areas. We conceptualize the HOQ to be measuring aspects of quality of life, so we do not see it as a substitute for neuropsychological tests, which generally are tests of function. Because the HOQ measures the effect of function on quality of life, although the concepts being measured are related, they are complementary rather than redundant. Our study adds further confirmation of the validity of the HOQ structure and the HOQ Cognitive score in particular. Aside from showing the strong correlations of HOQ Cognitive score with neuropsychological tests, it is equally important that we have shown a much weaker correlation between almost all of these tests and the HOQ Physical and Social-Emotional scores. This suggests that these other scores are in fact measuring something unique and are not providing redundant, highly correlated information. This adds validity to the hypothesized domain structure of the HOQ. We envision the primary use of the HOQ as a research tool for the reliable measurement of quality of life outcome in children with hydrocephalus. Although we are now expanding its use to routine clinical monitoring of patients, its role in clinical management remains to be determined. As we gain more experience in the clinical setting, we hope the HOQ might be able to help identify patients who would benefit from more detailed neuropsychological testing. Again, we do not see the HOQ as a substitute for neuropsychological tests. We acknowledge several limitations in our work. First, despite this being one of the largest neuropsychological studies of children with hydrocephalus, our sample size remains relatively small. It is possible that, with more participants, we might have discovered stronger correlations in other areas. A second limitation is that ours is only a single-center experience. Further tests of validation in oth- 399

5 A. V. Kulkarni, R. Donnelly, and I. Shams er centers will be important to prove the reproducibility of our work. Conclusions In a wide-ranging representative sample of children with long-standing hydrocephalus, the HOQ Cognitive Health score demonstrated mostly strong and moderate correlations with a number of tests of neuropsychological function. The HOQ Physical and Social-Emotional Health scores demonstrated much weaker correlations. These data provide added evidence of the validity of the HOQ Cognitive score and the overall domain structure of the HOQ itself. Appendix Details of tests and scores used in this study. Verbal IQ index. For ages 5 years 5 years 11 months, WPPSI- III Verbal IQ score; for ages 6 years 15 years 11 months, WISC-IV Verbal Comprehension Index score; for ages 16 years, WAIS-III Verbal Comprehension Index score. Nonverbal IQ index. For ages 5 years 5 years 11 months, WPPSI-III Performance IQ score; for ages 6 years 15 years 11 months, WISC-IV Perceptual Reasoning Index score; for ages 16 years, WAIS-III Perceptual Organization Index score. Processing Speed IQ index. For ages 5 years 5 years 11 months, WPPSI-III Processing Speed score; for ages 6 years 15 years 11 months, WISC-IV Processing Speed Index score; for ages 16 years, WAIS-III Processing Speed Index score. PPVT. Peabody Picture Vocabulary Test Third Edition; 9 receptive language vocabulary test. EOWPVT. Expressive One-Word Picture Vocabulary Test Revised (2000 edition); 10 expressive language vocabulary test. Ambiguous Sentences. Subtest from the Test of Language Competence Expanded Edition; 28 higher-order language test. Oral Comprehension. Subtest from the Woodcock-Johnson III Tests of Achievement 30 (WJ-III); understanding orally presented sentences. Letter-Word ID. Subtest from the WJ-III; reading individual words. Calculation. Subtest from the WJ-III; test of math calculations. Passage Comprehension. Subtest from the WJ-III; understanding written sentences. Stories Delayed. For ages 5 years 15 years 11 months, Children s Memory Scale 5 (CMS), Stories subtest, 30-minute delayed testing; for ages 16 years, WMS-III: Wechsler Memory Scale, ed 3, 26 Stories subtest, 30-minute delayed testing. Memory for orally presented stories. Faces Delayed. For ages 5 years 15 years 11 months, CMS, Faces subtest, 30-minute delayed testing; for ages 16 years, WMS- III, Faces subtest, 30-minute delayed testing. Memory for pictures of faces. Design Memory. Subtest from the WRAML2: Wide Range Assessment of Memory and Learning, ed Memory for designs tested 10 seconds after presentation. Sentence Memory. Subtest from the WRAML2. Immediate memory for sentences presented orally. List Learning. For ages 5 years 15 years 11 months, California Verbal Learning Test Children s Version 7 (CVLT-C); for ages 16 years, California Verbal Learning Test 2 8 (CVLT-II). Memory for the list words recalled over all 5 oral presentations of the list. List Memory Delayed. For ages 5 years 15 years 11 months, CVLT-C; for ages 16 years, CVLT-II. Memory for list words freerecalled 20 minutes after last recall of the list. Beery VMI. The Beery-Buktenica Developmental Test of Visual-Motor Integration, ed 5. 2 Copying geometric shapes; visual mo tor skills. Spatial Relations. Subtest from the Woodcock-Johnson III Tests of Cognitive Abilities. 31 Ability to manipulate shapes mentally but with no visual-motor component. Behavior Problems. Child Behavior Checklist for Ages Behavioral questionnaire filled out by the parent; Total Problems score. Behavioral Regulation. Behavior Rating Inventory of Executive Function 11 (BRIEF); behavioral questionnaire filled out by the parent. Overall rating of child s ability to inhibit or shift behavior and to control emotions. Metacognitive Abilities. BRIEF; behavioral questionnaire filled out by the parent. Overall rating of the child s ability to initiate, to plan and organize, to self-monitor, and to pay attention. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Funding for this study was provided by the SickKids Foundation/Institute for Human Development, Canadian Institutes of Health Research, and the SickKids Research Institute. The funding organizations were completely independent of the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, and approval of the manuscript. Author contributions to the study and manuscript preparation include the following. Conception and design: all authors. Acquisition of data: all authors. Analysis and interpretation of data: Kulkarni, Donnelly. Drafting the article: Kulkarni, Donnelly. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Kulkarni. Statistical analysis: Kulkarni. Study supervision: Kulkarni. Acknowledgments The authors thank Margaret Wilkinson and Patricia Arseneau for their invaluable assistance in administering and scoring the neuropsychological tests. Ethical Approval Approval was obtained from the Institutional Review Board of The Hospital for Sick Children, Toronto. References 1. Achenbach TM: Child Behavior Checklist for Ages Burlington, VT: University of Vermont, Beery KE, Buktenica NA, Beery NA: The Beery-Buktenica Developmental Test of Visual-Motor Integration, ed 5. 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6 Neuropsychological outcome in children with hydrocephalus Third Edition (PPVT-III). Circle Pines, MN: American Guidance Service, Gardner MF: Expressive One-Word Picture Vocabulary Test Revised. Novato, CA: Academic Therapy Publications, Gioia GA, Isquith PK, Guy SC, Kenworthy L: Behavior Rating Inventory of Executive Function. Lutz, FL: Psychological Assessment Resources, Inc, Goodman R: The extended version of the Strengths and Difficulties Questionnaire as a guide to child psychiatric caseness and consequent burden. J Child Psychol Psychiatry 40: , Goodman R, Meltzer H, Bailey V: The Strengths and Difficulties Questionnaire: a pilot study on the validity of the self-report version. Eur Child Adolesc Psychiatry 7: , Kulkarni AV: Distribution-based and anchor-based approaches provided different interpretability estimates for the Hydrocephalus Outcome Questionnaire. J Clin Epidemiol 59: , Kulkarni AV, Cochrane DD, McNeely PD, Shams I: Comparing children s and parents perspectives of health outcome in paediatric hydrocephalus. Dev Med Child Neurol 50: , Kulkarni AV, Cochrane DD, McNeely PD, Shams I: Medical, social, and economic factors associated with health-related quality of life in Canadian children with hydrocephalus. J Pediatr 153: , Kulkarni AV, Drake JM, Rabin D, Dirks PB, Humphreys RP, Rutka JT: An instrument to measure the health status of children with hydrocephalus: The Hydrocephalus Outcome Questionnaire. J Neurosurg (2 Suppl Pediatrics) 101: , Kulkarni AV, Drake JM, Rabin D, Dirks PB, Humphreys RP, Rutka JT: Measuring the health status of children with hydrocephalus using a new outcome measure. J Neurosurg 101 (2 Suppl Pediatrics): , Kulkarni AV, Hui S, Shams I, Donnelly R: Quality of life in obstructive hydrocephalus: endoscopic third ventriculostomy compared to cerebrospinal fluid shunt. Childs Nerv Syst 26: 75 79, Kulkarni AV, Shams I: Quality of life in children with hydrocephalus: results from the Hospital for Sick Children, Toronto. J Neurosurg 107 (5 Suppl): , Msall ME, DiGaudio K, Rogers BT, LaForest S, Catanzaro NL, Campbell J, et al: The Functional Independence Measure for Children (WeeFIM). Conceptual basis and pilot use in children with developmental disabilities. Clin Pediatr (Phila) 33: , Platenkamp M, Hanlo PW, Fischer K, Gooskens RH: Outcome in pediatric hydrocephalus: a comparison between previously used outcome measures and the hydrocephalus outcome questionnaire. J Neurosurg 107 (1 Suppl):26 31, Sheslow D, Adams W: WRAML2: Wide Range Assessment of Memory and Learning, ed 2. Lutz, FL: Psychological Assessment Resources Inc, Wechsler D: WAIS-III: The Wechsler Adult Intelligence Scale, ed 3. San Antonio, TX: Psychological Corporation, Wechsler D: WISC-IV: Wechsler Intelligence Scale for Children, ed 4. San Antonio, TX: Psychological Corporation, Wechsler D: WMS-III: Wechsler Memory Scale, ed 3. San Antonio, TX: Psychological Corporation, Wechsler D: WPPSI-III: Wechsler Preschool and Primary Scale of Intelligence, ed 3. San Antonio, TX: Psychological Corporation, Wiig EH, Secord W: Test of Language Competence Expanded Edition. San Antonio, TX: Psychological Corporation, Wilkinson G: WRAT-3: Wide Range Achievement Test 3. Administration Manual. Wilmington, DE: Wide Range, Woodcock RW, McGrew KS, Mather N: Woodcock-Johnson III Tests of Achievement. Itasca, IL: Riverside Publishing, Woodcock RW, McGrew KS, Mather N: Woodcock-Johnson III Tests of Cognitive Abilities. Itasca, IL: Riverside Publishing, 2001 Manuscript submitted March 2, Accepted July 11, Address correspondence to: Abhaya V. Kulkarni, M.D., Ph.D., Division of Neurosurgery, The Hospital for Sick Children, University of Toronto, Room 1503, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada. abhaya.kulkarni@sickkids.ca. J Neurosurg: Pediatrics / Volume 8 / October