Background: Post-traumatic headache (PTH) is a common symptom experienced by adolescents and adults who have sustained a mild traumatic brain injury (mTBI). To date, the pathogenesis embedded within the central nervous system (CNS) that underlies PTH in mTBI remains largely unknown. Neuroimaging studies have shown promise in terms of detecting changes in CNS structure between mTBI and control groups, reporting changes in regions such as the insula and temporal and cingulate cortices. The purpose of this study is to assess if changes in brain structure coincide with the persistence of headache symptoms by looking at two patient cohorts. It was predicted that unique changes in brain structure will appear in persons with and without post-traumatic headache relative to healthy controls.  

Methods: Patients diagnosed with mTBI (n=23,12-21 years old) were evaluated at 3-months post-concussion and separated into those recovered from headaches (R-PTH;n=10) and those with persistent headache (P-PTH;n=13). Patients were compared against a healthy control dataset (n=11). Participants completed the ImPACT concussion test and mTBI patients additionally completed a concussion questionnaire evaluating headache characteristics. Cortical thickness was evaluated using FreeSurfer at the p<0.01 level. White matter integrity and connectivity was evaluated using fractional anisotropy (FA) extracted from FSL's TBSS tool. Comparisons were performed between healthy controls and mTBI patients, as well as between R-PTH and P-PTH groups.

Results: Participants from the P-PTH group reported that their headaches impacted daily life to a moderate degree compared to the R-PTH group who reported no impact on daily. ImPACT data showed the P-PTH group reported higher mean concussion symptoms (26) compared to R-PTH (3) (t=-2.57,p=0.021). Relative to controls, cortical thickness in mTBI patients was significantly greater in the right superior frontal gyrus and inferior parietal lobule. In mTBI participants the right paracentral lobule exhibited both an increase and decrease in cortical thickness relative to controls. In the left hemisphere, controls had greater cortical thickness in the insula.  The P-PTH group showed greater cortical thickness in the superior parietal and pericalcarine cortex, and less thickness in the entorhinal when compared to R-PTH within the right hemisphere. In the left hemisphere, R-PTH showed greater cortical thickness in the precentral gyrus, superior parietal, and cingulate. DTI findings from the R-PTH group showed a trend suggesting a decrease in FA relative to controls in the anterior region of the corpus callosum.

Conclusion: The current findings indicate the presence of structural brain changes in patients with mTBI and headache regardless of symptom resolution. Unique group differences in cortical thickness suggest that the persistent of mTBI-related headache symptoms may have a distinct neurophysiological basis in regions involved in sensory integration and pain processing. Future research is targeted at understanding later time points and monitoring symptom resolution.

Evaluating changes in brain structure associated with persistent post-traumatic headache symptoms in a group of patients with mild traumatic brain injury