Research Reports - White and gray matter contributions to executive function recovery after traumatic brain injury
Neurology. 2015 Apr 7;84(14):1394-401
Cristofori I(1), Zhong W(2), Chau A(2), Solomon J(2), Krueger F(2), Grafman J(2)
OBJECTIVE: We investigated the association between regional white and gray matter
volume loss and performance on executive functions (EFs) in patients with
penetrating traumatic brain injury (pTBI).
METHODS: We studied 164 pTBI patients and 43 healthy controls from the Vietnam
Head Injury Study. We acquired CT scans for pTBI patients and divided them
according to lesion localization (left and right prefrontal cortex [PFC]). We
administered EF tests (Verbal Fluency, Trail Making, Twenty Questions) and used
voxel-based lesion symptom mapping (VLSM) and group-based correlational and
multiple regression analyses to examine the relative influence of gray and white
matter lesions on EF recovery.
RESULTS: The VLSM analysis revealed that white and gray white matter lesions were
associated with impaired EFs. In the left PFC lesion group, damage to the PFC
gray matter, anterior corona radiata, and superior longitudinal fasciculus (SLF)
were most correlated with functional recovery. Verbal Fluency, which involves a
broad fronto-temporo-parietal network, was best predicted by SLF lesion volume.
Trail Making and Twenty Questions, which is associated with more focal left
frontal damage, was better predicted by PFC lesions.
CONCLUSIONS: Our results indicated that white matter volume loss can be a
superior predictor of recovery and a crucial factor driving clinical outcome in
functions involving a broad network such as Verbal Fluency. White matter damage
may place additional burden on recovery by deteriorating signal transmission
between cortical areas within a functional network.