Clinical Characteristics and Pathophysiology of Post-Traumatic Headache

To better understand the clinical characteristics and complex pathophysiological events that constitute persistent post-traumatic headache (PPTH) and to identify possible calcitonin gene-related peptide (CGRP) hypersensitivity in PPTH patients.

The present project will embark upon identifying novel PTH-specific biomarkers by incorporating a plethora of scientific approaches. First, clinical biomarkers will be assessed by deep phenotyping of clinical characteristics and associated comorbidities using a semi-structured interview and multiple validated questionnaires. Second, biochemical biomarkers will be determined by plasma levels measurements of blood markers for headache hypersensitivity and neuronal/axonal damage. Third, imaging biomarkers will be established by magnetic resonance imaging (MRI) to assess structural and functional changes in the brain. Lastly, molecular biomarkers will be identified by examining whether intravenous infusion of calcitonin gene-related peptide (CGRP) provokes headache attacks mimicking the usual headache phenotype in subjects with PTH. This would determine whether PTH patients exhibit hypersensitivity to CGRP (molecular biomarker) and advance our understanding of the complex pathophysiological events that constitute the headache phenotypes in PTH sufferers.

100 patients with PPTH and 100 healthy controls will undergo a deep phenotyping of clinical characteristics and associated comorbidities. This is followed by a single MRI-session for all subjects. Lastly, the 30 patients with PPTH will participate in a randomized, double-blind, placebo-controlled, 2-way crossover study. These patients will be allocated to receive intravenous infusion of CGRP or placebo (isotonic saline) over 20 minutes on 2 study days.

30 patients with PPTH will be allocated to receive intravenous infusion of 1.5 µg/min calcitonin-gene related peptide over 20 minutes Other Name: CGRP

30 patients with PPTH wil be allocated to receive 40 mL Placebo (isotonic saline) over 20 minutes. Other Name: Isotonic Saline

A randomized clinical trial with a double-blinded, randomized, placebo-controlled crossover design. 30 PPTH patients will be included. All participants will receive continuous intravenous infusion of 1.5 µg/min CGRP over 20 min. The following variables will be recorded before, during and after infusion (every 10 min over 60 min): headache intensity on a verbal rating scale from 0 to 10 and headache characteristics. At 90 min, participants will be discharged and instructed to fill out a headache diary for 24 hours from start of infusion.

A randomized clinical trial with a double-blinded, randomized, placebo-controlled crossover design. 30 PPTH patients will be included. All participants will receive continuous intravenous infusion of 40 mL placebo (isotonic saline) over 20 min. The following variables will be recorded before, during and after infusion (every 10 min over 60 min): headache intensity on a verbal rating scale from 0 to 10 and headache characteristics. At 90 min, participants will be discharged and instructed to fill out a headache diary for 24 hours from start of infusion.

Headache characteristics will be assessed using Headache Under-Response to Treatment Index (HURT-Index) questionnaire. The total score ranges from 0 to 24 with a higher score indicating a lower effectiveness of intervention against headache.

Cognitive function will be assessed using Montreal Cognitive Assessment (MoCA) questionnaire. The total score ranges from 0 to 30 points. The MoCA is divided into 7 subscores: visuospatial/executive (5 points); naming (3 points); memory (5 points for delayed recall); attention (6 points); language (3 points); abstraction (2 points); and orientation (6 points). One point is added if the subject has ≤12 years of education. A total of 30 points may be given. A score ≤25 indicates some degree of cognitive impairment.

Depression will be assessed using Hospital Anxiety and Depression Scale (HADS) questionnaire. The total score ranges from 0-21. A score of 0-7 points is regarded as being in the normal range. A score of 8-10 points is suggestive of a depressive state (borderline abnormal). A score of 11-21 points indicates a probable presence of a depressive state (abnormal).

Anxiety will be assessed using Hospital Anxiety and Depression Scale (HADS) questionnaire. The total score ranges from 0-21. A score of 0-7 points is regarded as being in the normal range. A score of 8-10 points is suggestive of a state of anxiety (borderline abnormal). A score of 11-21 points indicates a probable presence of an anxiety disorder (abnormal).

Allodynia will be assessed using Allodynia Symptom Checklist (ASC-12) questionnaire. The total score ranges from 0-24 points. A score of 0-2 suggests no allodynia. A score of 3-5 suggests mild allodynia. A score of 6-8 suggests moderate allodynia. A score of 9 or more suggests severe allodynia.

Post-traumatic stress disorder will be assessed using Harvard Trauma Questionnaire (HTQ). The total score ranges from 16-64. The total score is divided with 16 and a clinical cut-off score of 2.5 is set to be indicative of PTSD.

Quality of Sleep will be assessed using Pittsburgh Sleep Quality Index (PSQ-I). The measure consists of 19 individual items, creating 7 components that produce one global score. The total PSQ-I score ranges from 0 to 21 with lower scores indicating a healthier sleep quality.

Muscle tenderness will be assessed using Total Tenderness Score (TTS). The total score ranges from 0-48 with higher scores indicating a higher degree of muscle tenderness.

The number and location of white matter lesions will be assessed using T2-weighted Fluid-Attenuated Inversion Recovery.

Brain network functional connectivity will be assessed using blood oxygen level-dependent functional magnetic resonance imaging.

Migraine-like features are defined as headache fulfilling at least two of the following four characteristics: Unilateral location Pulsating quality Moderate or severe pain intensity Aggravation by or causing avoidance of routine physical activity (e.g. walking or climbing stairs) And during headache at least one of the following must be fulfilled: Nausea and/or vomiting Photophobia and phonophobia Headache mimicking the usual exacerbated headache with migraine-like features If the participant fulfills these criteria at baseline, then incidence of exacerbated headache with migraine-like features is defined as: - An increase in headache intensity combined with an increase in the degree nausea and/or photophobia and phonophobia (based on a mild / moderate / severe scale)

Headache area under the curve is defined as headache intensity x duration up to 12 h after CGRP infusion

Time to maximum headache score on CGRP day compared to placebo day will be assessed using a headache questionnaire

Inclusion Criteria for PPTH patients: 18-65 years of age Subject has PPTH in accordance with the diagnostic criteria of the International Headache Society (IHS) Concussion (mild traumatic brain injury) occured > 12 months ago Subject, who are fertile women, must be on safe contraceptives Exclusion Criteria for PPTH patients: Pre-trauma existing primary headache disorder (maximum 1 day/per month with tension-type headache) and medication-overuse headache > 1 episode with a sustained concussion Whiplash Pregnant or lactating women Cardiovascular disease of any kind Hypertension on the experimental day Hypotension on the experimental day Pre-trauma existing psychiatric disorder of any kind - unless well-regulated Any anamnestic or clinical signs of any kind deemed relevant for the study by the physician examining the subject Any MRI contraindication and a wish of not being informed about unexpected MRI changes