NEUROPSYCHOLOGICAL SIGNIFICANCE OF AREAS OF HIGH SIGNAL INTENSITY ON BRAIN MRIS OF CHILDREN WITH NEUROFIBROMATOSIS

Of children with neurofibromatosis (NF), 40% hare a cognitive or learn ing impairment. Approximately 60% also have anomalous areas of high si gnal intensity on T-2-weighted brain MRIs. The association of these hy perintensities and neuropsychological status is not fully understood. We administered a battery of neuropsychological tests and a standard c linical MRI to determine the impact of hyperintensity presence, number , and location on cognitive status in 84 children (8 to 16 years) with NF type 1. These children underwent standard clinical MRI using a GE 1.5-tesla scanner (except one child who was examined with a 1.0-tesla scanner). We conducted three types of analyses: Hyperintensity presenc e or absence. -Scores of children with (55%) and without hyperintensit ies (45%) were compared using t tests. No statistically significant di fferences between groups in intellectual functioning or any neuropsych ological variable were found. Number of hyperintensities -The number o f hyperintensity locations per child ranged from one to five (mean = 2 .22), Pearson correlations revealed no significant association between the number of hyperintensities and neuropsychological performance. Lo cation of hyperintensities -In four of the five locations studied, no statistically significant differences were found between scores of chi ldren with a hyperintensity in an area and those with one elsewhere. H owever, mean scores for IQ, Memory, Motor, Distractibility, and Attent ion domains for children with hyperintensities in the thalamus were si gnificantly lower than scores for those with hyperintensities elsewher e. These results suggest that the simple presence or absence of hyperi ntensities, or their total number, is not as important as their anatom ic location for detecting their relationship with neuropsychological s tatus. Taking location into account, hyperintensities in the cerebral hemispheres, basal ganglia, brainstem, or cerebellum seem to have no i mpact on neuropsychological functioning, whereas hyperintensities in t he thalamus do.