Individual case analysis of processing speed difficulties in children with and without traumatic brain injury

Two studies were conducted to determine the frequency of processing speed difficulties relative to estimates of other problem-solving abilities in children with and without traumatic brain injury (TBI). The two samples consisted of 213 normally functioning school-age children and 65 TBI children and 19 trauma controls. All children were administered the WISC-III/IV Vocabulary, Block Design, and Coding subtests. The frequency of children in each sample having a Coding subtest score of 3 or 4 scale points below the Vocabulary or Block Design score (whichever one was lower) was calculated. Using a 3-point scale difference, the presence of processing speed deficits relative to other cognitive abilities in the school sample was low (5.2%), and was equivalent to that demonstrated by trauma controls (5.3%). However, in the TBI sample, 18 out of 65 TBI patients (27.7%) showed this same pattern. Using a 4-point discrepancy scale, 3.3% of normal children and 16.9% of TBI children showed this pattern. The frequency of this pattern increased with severity of TBI, using two different but related classification systems. These preliminary findings require cross validation in a larger sample before definite conclusions can be reached.