Effects of Brain Lesion Location and Size on Reading and Arithmetic after Childhood Traumatic Brain

1
Effects of Brain Lesion Location and Size on
Reading and Arithmetic after Childhood Traumatic
Brain Injury
Gerri Hanten,1 Mary Newsome,1 Xiaoqi Li,1 Jill
Hunter,2 Harvey Levin1 1Baylor College of
Medicine, Department of Physical Medicine and
Rehabilitation2Texas Childrens Hospital,
Department of Pediatric Neuroradiology
BACKGROUND Children with traumatic brain injury
(TBI) often show post-injury declines in reading
skills and other measures of academic achievement
(Ewing-Cobbs et al., 2006). In children with TBI,
diffuse disruption of white matter is common, as
are focal lesions of gray and white matter.
Studies in uninjured subjects indicate that
intactness of left temporo-parietal brain regions
correlates with reading ability and with
performance on reading, spelling, and rapid
naming tasks in uninjured children. However, the
degree to which reported deficits in reading and
math correspond to injury of specific brain
regions in children with TBI is unclear.
METHOD Participants. 36 children (mean
age13.7) with severe TBI (Glasgow Coma Scale
score3-8) were tested 3 months post-injury in a
prospective study of childhood TBI. No child had
previous TBI, neurologic or psychiatric disorder,
or evidence of child abuse. Academic measures.
Children completed subtests of the Woodcock
Johnson III (WJ) Tests of Achievement as part of
a larger study. The subtests included
Letter-Word Identification, a measure of single
word and letter decoding Passage Comprehension,
a measure of silent reading comprehension
Calculations, a measure of basic math skill and
Applied Problems, a measure of skill in solving
practical math problems. Brain Lesion Data All
children underwent MRI on a Philips 1.5 T Intera
whole body scanner, including coronal fluid-level
inversion recovery (FLAIR), sagittal 3D FFET1-
and T2-weighted sequences, and dual axial proton
density and T2 pulse sequences. Individual foci
of signal abnormality were marked on 5 mm
continuous T2-weighted FLAIR images by a
neuroradiologist, using picture archiving system
(PACS) software. Measurements were conducted
without reference to injury severity rating.
Areas of signal abnormality were initially
recorded in cm2, summed, and converted to volume
measures (area multiplied by 0.5 cm). We examined
frontal, temporal, and parietal lobes only, as
lesions in other regions were relatively rare.
RESULTS Relation of Lesion presence to academic
measures. We tested whether the mere presence a
lesion in a specific location accounted for
significant differences on the WJ tests in lesion
and without-lesion groups. Lesion groups were
inclusive, that is, each child with a lesion in
the region was included, regardless of lesions in
other regions. We found the presence of a
frontal lesion did not discriminate groups on any
WJ sub-test measure. However, presence of a left
frontal lesion had a significant effect on
applied problems, t(33)2.56, p0.01, and
calculations, t(32)2.12, p0.04, but not on the
reading measures. Presence of a lesion in the
temporal or parietal lobes did not predict poor
performance on any subtest measure. Relation of
lesion size to academic measures. To assess the
relation of lesion size to performance on the
WJ-III measures we calculated the Pearson
correlation coefficients between lesion size and
individual scores for the regions examined above.
After accounting for differences in lesion size
by area of interest, correlations among the size
of regional lesions and the WJ subtests revealed
that there was a significant relation between
size of lesion and performance on each of the
measures only for lesions in the parietal lobes
Passage comprehension r-0.52, p0.05 letter
word ID r-0.72, p0.003 applied problems
r-0.55, p0.04 calculations r-0.61, p0.02.
Practical Significance/Implications These
findings extend understanding of the relations
among academic outcome measures and measures of
neural structure integrity. Such findings
facilitate the anticipate academic problems, and
aid in the development of strategies for
intervention after childhood TBI, especially in
relation to specific skills.