Functional Magnetic Resonance Imaging of Post-Traumatic Headache: A Systematic Review.

Purpose of review: To evaluate existing functional magnetic resonance imaging (fMRI) studies on post-traumatic headache (PTH) following traumatic brain injury (TBI).

Recent findings: We conducted a systematic search of PubMed and Embase databases from inception to February 1, 2024. Eligible fMRI studies were required to include adult participants diagnosed with acute or persistent PTH post-TBI in accordance with any edition of the International Classification of Headache Disorders. We identified five eligible fMRI studies: two on acute PTH and three on persistent PTH. These studies assessed resting-state functional connectivity involving comparisons with one or more of the following groups: people with migraine, those with mild TBI but no PTH, and healthy controls. In acute PTH, studies focused exclusively on functional connectivity between the periaqueductal gray or hypothalamus and other brain regions. In persistent PTH, evidence of altered functional connectivity was identified primarily within cingulate, sensorimotor, and visual regions, indicating a hypersensitivity to sensory stimuli in PTH. Despite these insights, the fMRI data remains sparse and is limited by inconsistent results and small samples. The paucity of fMRI studies on PTH limits our understanding of its neurobiological basis. The available evidence suggests that alterations in functional connectivity occur within brain areas involved in emotional and sensory discriminative aspects of pain processing. However, inconsistent results and small sample sizes underscore a critical need for larger, more rigorous fMRI studies. Future studies should also consider using task-based fMRI to investigate possible hypersensitivity to different sensory stimuli in PTH after TBI.