Dynamic imaging in mild traumatic brain injury: support for the theory of medial temporal vulnerability.
OBJECTIVE
To determine whether patients with mild traumatic brain injury (TBI) and persistent postconcussive symptoms have evidence of temporal lobe injury on dynamic imaging.


METHODS
Case series.


METHODS
An academic medical center.


METHODS
Twenty patients with a clinical diagnosis of mild TBI and persistent postconcussive symptoms were referred for neuropsychologic evaluation and dynamic imaging. Fifteen (75%) had normal magnetic resonance imaging (MRI) and/or computed tomography (CT) scans at the time of injury.


METHODS
Neuropsychologic testing, positron-emission tomography (PET), and single-photon emission-computed tomography (SPECT).


METHODS
Temporal lobe findings on static imaging (MRI, CT) and dynamic imaging (PET, SPECT); neuropsychologic test findings on measures of verbal and visual memory.


RESULTS
Testing documented neurobehavioral deficits in 19 patients (95%). Dynamic imaging documented abnormal findings in 18 patients (90%). Fifteen patients (75%) had temporal lobe abnormalities on PET and SPECT (primarily in medial temporal regions); abnormal findings were bilateral in 10 patients (50%) and unilateral in 5 (25%). Six patients (30%) had frontal abnormalities, and 8 (40%) had nonfrontotemporal abnormalities. Correlations between neuropsychologic testing and dynamic imaging could be established but not consistently across the whole group.


CONCLUSIONS
Patients with mild TBI and persistent postconcussive symptoms have a high incidence of temporal lobe injury (presumably involving the hippocampus and related structures), which may explain the frequent finding of memory disorders in this population. The abnormal temporal lobe findings on PET and SPECT in humans may be analogous to the neuropathologic evidence of medial temporal injury provided by animal studies after mild TBI.
Umile
Eric M
EM
Department of Rehabilitation Medicine, University of Pennsylvania Medical Center, Philadelphia, PA, USA.
Sandel
M Elizabeth
ME
Alavi
Abass
A
Terry
Charles M
CM
Plotkin
Rosette C
RC
D000328:Adult; D000818:Animals; D001924:Brain Concussion / Q000175:diagnosis* / Q000209:etiology; D001930:Brain Injuries / Q000150:complications* / Q000175:diagnosis*; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging / Q000592:standards; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis* / Q000209:etiology; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000592:standards; D011379:Prognosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013702:Temporal Lobe / Q000293:injuries*; D013997:Time Factors; D014055:Tomography, Emission-Computed / Q000592:standards; D015899:Tomography, Emission-Computed, Single-Photon / Q000592:standards; D014057:Tomography, X-Ray Computed / Q000592:standards; D014474:Unconsciousness / Q000209:etiology