RESUMEN
BACKGROUND AND PURPOSE: It is estimated that 18-30% of concussion sufferers experience symptoms lasting more than 1 month, known as persistent post-concussion symptoms (PPCS). Symptoms can be debilitating, and include headache, dizziness, nausea, problems with memory and concentration, sleep and mood disruption, and exercise intolerance. Previous studies have used quantitative susceptibility mapping (QSM) to show altered tissue susceptibility levels in adults acutely following concussion, however this finding has yet to be investigated in participants with PPCS. MATERIALS AND METHODS: In this exploratory case-controlled study, we measured tissue susceptibility using quantitative susceptibility mapping (QSM) in 24 participants with PPCS following mild traumatic brain injury (mTBI) and 23 healthy controls with no history of concussion. We compute tissue susceptibility for seven white matter tracts and three deep grey matter regions and compare tissue susceptibility between groups using ANCOVA models controlling for age and sex. We also assess the relationship between regional tissue susceptibility and symptoms. RESULTS: There were no significant differences between tissue susceptibility in participants with PPCS compared to control subjects in any of the evaluated regions. However, we show lower tissue susceptibility across four white matter tracts was generally associated with worse symptoms in the PPCS group. Specifically, we saw relationships between white matter susceptibility and headache (p=0.006), time since injury (p=0.03), depressive symptoms (p=0.021) and daytime fatigue (p=0.01) in participants with PPCS. CONCLUSIONS: These results provide evidence in support of persistent changes in the brain months-to-years following injury and highlight the need to further understand the pathophysiology of PPCS, to determine effective prevention and treatment options. ABBREVIATIONS: ATR: Anterior Thalamic Radiation; Caud: Caudate; CCB: Corpus Callosum Body; CCG: Corpus Callosum Genus; CCS: Corpus Callosum Splenium; CH: Cingulum; DHI: Dizziness Handicap Inventory; ESS: Epworth Sleepiness Scale; FM: Forceps Minor; FSS: Fatigue Severity Scale; GAD: Generalized Anxiety Disorder; HIT-6: Headache Impact Test 6; IFOF: Inferior Fronto-Occipital Fasciculus; ILF: Inferior Longitudinal Fasciculus; mTBI: mild traumatic brain injury; Pal: Pallidum; PPCS: Persistent Post-Concussive Symptoms; PCSC: Postconcussional Syndrone Checklist; PHQ: Patient Health Questionnaire; Put: Putamen; RPQ: Rivermead Post Concussion Symptoms Questionnaire; SLF: Superior Longitudinal Fasciculus; QSM: Quantitative Susceptibility Mapping.