Acute and longitudinal changes in motor cortex function following mild traumatic brain injury.
OBJECTIVE
To evaluate excitability and inhibition of the motor cortex acutely and longitudinally following mild traumatic brain injury (mTBI).


METHODS
A longitudinal paired case-control design was used to examine cortical excitability and inhibition in 15 adults who had sustained an mTBI (mean age = 20.8 ± 1.2 years) and 15 matched control participants (mean age = 21.1 ± 1.3 years).


METHODS
Participants visited the lab within 72 hours of injury and again at 1, 2, 4 and 8 weeks post-injury. During each visit, transcranial magnetic stimulation was used to examine resting motor threshold (RMT), motor evoked potential peak-to-peak amplitude (MEPamp) and cortical silent period (CSP) duration of the first dorsal interosseous muscle.


RESULTS
There were no differences between groups in RMT (p = 0.10) or MEPamp (p = 0.22) at 72 hours post-injury or across the 2-month testing period (p ≥ 0.68), indicating similar cortical excitability. However, the CSP duration was higher in individuals with mTBI, indicating greater intra-cortical inhibition compared with the control group at 72 hours post-injury (p = 0.03) and throughout the 2 months of recovery (p = 0.009).


CONCLUSIONS
mTBI appeared to have little effect on cortical excitability, but an acute and long-lasting effect on intra-cortical inhibition.
Department of Human Physiology, University of Oregon , Eugene, OR , USA.
Nick R
NR
Miller
Alia L
AL
Yasen
Logan F
LF
Maynard
Li-Shan
LS
Chou
David R
DR
Howell
Anita D
AD
Christie
D000328:Adult; D001143:Arousal / Q000502:physiology; D001930:Brain Injuries / Q000150:complications / Q000503:physiopathology* / Q000534:rehabilitation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009044:Motor Cortex / Q000293:injuries / Q000503:physiopathology*; D009483:Neuropsychological Tests; D011379:Prognosis; D011930:Reaction Time; D011795:Surveys and Questionnaires
Evoked potentials; mild traumatic brain injury; neurobehavioural