Thalamic subfield iron accumulation after acute mild traumatic brain injury as a marker of future post‐traumatic headache intensity

Abstract

The thalamus plays a pivotal role in the pathomechanism of pain and headache, yet the role of the thalamus in post-traumatic headache (PTH) attributed to mild traumatic brain injury (mTBI) remains unclear. To explore alterations in thalamic subfield volume and iron accumulation in individuals with PTH relative to healthy controls (HC). 107 participants underwent multimodal T1-weighted and T2* brain magnetic resonance imaging. Using a clinic-based observational study, thalamic subfield volume and thalamic iron accumulation were explored in 52 individuals with acute PTH (mean age=41.3; SD=13.5), imaged on average 24 days post mTBI, and compared to 55 HC (mean age=38.3; SD=11.7) without history of mTBI or migraine. mTBI symptoms and headache characteristics were assessed at baseline (0–59 days post-mTBI) (n=52) and 3-months later (n=46) using the Symptom Evaluation of the Sports Concussion Assessment Tool (SCAT-5) and a detailed headache history questionnaire. Relative to HC, individuals with acute PTH had significantly less volume in the lateral geniculate nucleus (mean LGN volume: PTH=254.1, SD=43.4 vs HC=278.2, SD= 39.8; p=0.003) as well as more iron deposition in the left LGN (PTH: T2* signal=38.6, SD=6.5 vs HC: T2*signal=45.3, SD=2.3; p=0.048). and. Correlations in individuals with PTH revealed a positive relationship between left LGN T2* iron deposition and SCAT-5 symptom severity score at baseline (r=−0.29, p= 0.019) and maximum headache intensity at 3-months follow-up (r= −0.47, p= 0.002). Relative to healthy controls, individuals with acute PTH had less volume and higher iron deposition in the left LGN. Higher iron deposition in the left LGN might reflect mTBI severity and poor headache recovery.