Abnormalities of the Attentional Network Following Traumatic Brain Injury in Pediatric Patients: A fMRI Study (S42.002)

OBJECTIVE: To assess abnormalities of functional MRI (fMRI) activity during a sustained attention task in pediatric patients with traumatic brain injury (TBI). BACKGROUND: Attentional deficits, which are commonly assessed by the Continuous Performance Test (CPT), are a significant consequence of pediatric TBI. DESIGN/METHODS: FMRI scans were acquired from 16 pediatric TBI patients (mean age=14.6 years; mean time from TBI=1.8 years, range=0.04-7.5 years) and 7 healthy controls (mean age=10.8) during Conners’ CPT administration (inter-stimulus interval=1, 2, 4 s). Patients underwent the Wechsler Intelligence Scale for Children (WISC-IV) evaluation. FMRI data were analyzed using SPM8. During second level analysis, we assessed: 1) average fMRI activity during the CPT; 2) increased activity with increasing task difficulty (“load” effect) in controls and TBI patients, separately; and 3) comparison of fMRI activity between controls and patients. RESULTS: In both groups, significant activations during the CPT task were found in the right somatosensory cortex, supplementary motor area and middle cingulate cortex. Controls also activated right parietal regions and the left middle frontal gyrus (MFG), while patients experienced a broader pattern of activations, including the bilateral insulae, left cerebellum, and right MFG. Compared with controls, patients had significantly increased activity in occipital and frontal areas. With increasing task difficulty (“load effect”) both groups had increased fMRI activity in the bilateral middle occipital gyrus. During this condition, compared to TBI patients, controls also had an increased recruitment of the middle occipital gyrus as well as temporal and parietal regions. Patients having better scores at WISC test showed a reduced activity of the anterior cingulate cortex during the CPT task, and higher activity of frontal regions during the “load” condition. CONCLUSIONS: Pediatric TBI patients experience an inability to optimize the recruitment of the attentional network, which might contribute to explain the attentional deficits frequently observed in this condition. Study Supported by: