Learning Disabilities and Language Function in Epilepsy

PATTERNS OF ACADEMIC ACHIEVEMENTParadiso et al. (1994) conducted the only cluster ana-lytic investigation of learning disability subtypes in epi-lepsy (1). Study subjects were well-characterized pa-tients with chronic and intractable temporal lobe epi-lepsy. Selection criteria included WAIS-R Full Scale IQ,>79; age 18 years or older; at least 12 years of education;no magnetic resonance imaging (MRI) findings otherthan atrophy; left hemisphere dominant for speech; andunilateral temporal lobe epilepsy. Mean (standard devia-tion) demographic and clinical characteristics werechronologic age of 31.9 years (9.5 years); gender (56male/61 female subjects); education, 13.1 years (2.4years); age at onset, 13.0 years (11.2 years); laterality oftemporal lobe epilepsy, 59 left, 58 right; and full-scaleIQ, 92.0 (9.9).Wide Range Achievement Test–Revised (WRAT-R)Reading, Spelling, and Arithmetic subtests were the de-pendent measures. Statistical procedures were as fol-lows: (a) the initial cluster structure solution was deter-mined using complete linkage hierarchical technique, (b)the internal validity (reliability) of the initial solutionwas tested with additional analytic techniques using bothWard’s procedure and one-stage iterative partitioningtechniques, and (c) the external validity was then exam-ined by investigating the neuropsychological and clinicalpredictors of the identified clusters.Six clusters were identified: average academicachievement (36% of sample), high average achievement(12%), moderate reading/spelling underachievement(21%), marked reading/spelling (8%), arithmetic under-achievement (10%), and reading/arithmetic under-achievement (13%). The mean WRAT-R scaled scoresfor these clusters are provided in Table 1. Overall, ad-equate academic achievement was evident in 48% of thesample, whereas various patterns of underachievementwere evident in 52%.INTERICTAL LANGUAGE FUNCTION INCHILDREN AND ADULTS WITH EPILEPSYLanguage batteriesThis summary highlights a few investigations of lan-guage function in epilepsy. Davey and Thompson (2)conducted an early investigation of language function in60 patients with chronic epilepsy. Patients were assessedwith the ITPA and the BMUS and reported that a largeproportion, >30% in some instances, exhibited impairedlanguage performance. Impairments were more wide-spread in receptive functions compared with expressivelanguage abilities and reading. Interestingly, Davey andThompson found that previous caregivers and education-al systems had largely overlooked language problems inthat none of the subjects had undergone recent evalua-tions or speech therapy. Predictors of language abnor-mality were identified, but laterality of focus was notsignificant.Hermann et al. (3) examined a series of patients withunilateral temporal lobe epilepsy using a standard lan-guage battery including tests of naming, repetition, flu-ency, spelling, and aural and reading comprehension. Ascan be seen in Table 2, patients with left temporal lobeepilepsy generally performed significantly worse thanright temporal lobe patients across most scales. The dif-ferences were significant in naming, repetition, and sev-eral tests of comprehension, consistent with Davey andThompson’s observations. It also is of interest that theright temporal lobe epilepsy group scored higher than the50th percentile on only one scale, suggesting that lan-guage problems may be evident in temporal lobe epi-lepsy more generally, but are exacerbated in left tempo-ral lobe epilepsy.