J. Bleiberg et al., CONSISTENCY OF WITHIN-DAY AND ACROSS-DAY PERFORMANCE AFTER MILD BRAININJURY, Neuropsychiatry, neuropsychology, and behavioral neurology, 10(4), 1997, pp. 247-253
The objective of this study was to determine whether inconsistent and
erratic within-day and across-day performance is a symptom of mild to
moderate traumatic brain injury (TBI), and to determine whether impair
ed consistency of performance can coexist, in the same patient, with i
ntact or ''normal'' performance on single administrations of neuropsyc
hological and other cognitive tests. The design was a matched-pair stu
dy in which a computerized cognitive test battery was administered 30
times over 4 days to all subjects. Performance patterns between TBI an
d control subjects were compared. Subjects also received traditional n
europsychological testing. The setting was a rehabilitation hospital o
utpatient department. The subjects were 12 adult volunteers, six with
documented TBI and six with no history of TBI, neurologic illness, or
injury. Control subjects showed consistent improvement of performance
over days 1 to 4, whereas subjects with TBI showed erratic and inconsi
stent performance across days. In addition to inconsistent performance
, some subjects with TBI showed worsening performance across days. The
main outcome measures were performance on the Automated Neuropsycholo
gical Assessment Metrics (ANAM) battery and performance on traditional
neuropsychological tests. Some patients with TBI in the study who hav
e normal initial performance on traditional clinical neuropsychologica
l tests and newly developed computerized cognitive tests show abnormal
ities of sustained performance. Such abnormalities are most apparent w
hen performance is observed over multiple days, and are characterized
by erratic and inconsistent across-day performance. Inconsistent perfo
rmance was observed even in those subjects with TBI whose initial perf
ormance was equal to or better than that of the control subjects. Defi
cits in dynamic performance may explain why some patients with TBI who
have excellent neuropsychological test performance nonetheless compla
in of functional decrement from premorbid ability.