Post-traumatic headache phenotypes and clinical characteristics

Background/Aim: Post-traumatic headache often resembles migraine or tension-type headache, but distinct phenotype and clinical characteristics necessitate further delineation. We aimed to characterize the clinical phenotype, headache patterns, associated features and comorbidities, medication patterns and functional impact of post-traumatic headache in an adult population following mild traumatic brain injury. Methods: This is a cross-sectional analysis of a cohort of adults with post-traumatic headache after mild traumatic brain injury, by any mechanism, evaluated by a neurologist at an outpatient specialized concussion and headache center in Ontario, Canada between February 2021 and October 2023. Data were collected through standardized pre- and during-visit questionnaires. Descriptive statistics are presented. Results: Among 405 patients assessed by a neurologist for post-traumatic headache, median time since injury was 37 days (IQR: 13–126). Most patients reported headache 26 + days per month (292, 72.1%). Headache was continuous in 114 (28.1%), whereas in 215 (53.1%) it lasted hours to days. Headache location was unilateral in 174 (43.0%) and bilateral in 159 (39.3%). Headache quality was described as pulsating/throbbing in 260 (64.2%). The median severity was 7/10 (IQR 5–8). Aggravation by routine physical activity was reported in 287 (70.9%), nausea/vomiting in 279 (69.0%), photophobia in 358 (88.4%) and phonophobia in 337 (83.2%). There was no positional preference for 147 patients (36.3%), while 216 (53.3%) preferred lying down/reclined. Acute medication use frequency was reported as 3 + days per week in 218 (53.8%) and daily in 143 (35.3%). Within this cohort, 201 (49.6%) endorsed one or more psychiatric comorbidities. Only 66 (16.3%) had returned to full work/school attendance, while 169 (41.7%) were completely off usual occupational activities post-injury. One hundred seventy-eight (44.0%) reported pending litigation or insurance claims related to their injury, and/or having a work-related injury. Among the 183 (45.2%) who had undergone neuroimaging, 160 (87.9%) studies were reportedly normal, while there were 13 (7.1%) incidental findings and eight (4.3%) injury-related. Discussion: While select migraine features such as photophobia, phonophobia and worsening with routine physical activity are common in post-traumatic headache, there are also distinct features, including daily or near daily headache of long duration. The latter may suggest early sensitization in post-traumatic headache. There is an associated high risk of medication overuse headache, given frequent administration of acute medications, as well as high rates of psychiatric comorbidities and functional impairment. Future studies should aim to further delineate the longitudinal clinical, pathophysiological, and treatment response differences between post-traumatic headache and primary migraine.