Posttraumatic Headache: Classification by Symptom-Based Clinical Profiles

Posttraumatic headache is a distinct headache type from migraine

PURPOSE OF REVIEW

Posttraumatic headache (PTH), a headache that develops within 7 days of a causative injury, is one of the most common secondary headaches, mostly attributed to mild traumatic brain injury (mTBI). Because presence of preinjury headache is a risk factor for developing PTH and PTH symptoms often resemble migraine or tension-type headache, the association between PTH and primary headaches has attracted attention from clinicians and scientists.

RECENT FINDINGS

Recent studies on epidemiological aspects, headache features, risk factors, imaging characteristics, and response to treatment, suggest overlapping features and distinct objective findings in PTH compared to migraine.

SUMMARY

We argue that PTH is distinct from migraine. Therefore, PTH epidemiology, pathophysiology, diagnosis, treatment, and prognosis should continue to be investigated separately from migraine.

Prevalence of and Risk Factors for Post-traumatic Headache in Civilian Patients After Mild Traumatic Brain Injury: A TRACK-TBI Study

OBJECTIVE

To ascertain the prevalence of and risk factors for post-traumatic headache (PTH) attributed to mild traumatic brain injury (mTBI).

PATIENTS AND METHODS

A prospective, longitudinal, multicenter cohort study of patients with mTBI and orthopedic trauma controls who were enrolled from February 26, 2014, to August 8, 2018. The baseline assessment was conducted as soon as possible following evaluation at the emergency department. Follow-ups were scheduled at 2 weeks, 3 months, 6 months, and 12 months postinjury. Eligible patients with mTBI included those 18 years of age or older who presented to the emergency department within 24 hours of head injury warranting evaluation by noncontrast head computed tomography scan. Acute PTH was considered present when a patient reported a headache score of greater than or equal to 2 on the Rivermead Post-concussion Questionnaire at 2 weeks postinjury (ie, headache is at least a mild problem compared with pre-injury). Persistent PTH was defined when a patient with acute PTH reported a Rivermead Post-concussion Questionnaire headache score of greater than or equal to 2 at the scheduled follow-up examinations.

RESULTS

Acute PTH was reported by 963 (60.4%) of 1594 patients with mTBI at 2 weeks postinjury. Among those with acute PTH, 439 (52.4%) of 837 patients reported persistent PTH at 3 months postinjury. This figure decreased over time and 278 (37.5%) of 742 patients continued to report persistent PTH at 6 months, whereas 187 (28.9%) of 646 patients did so as well at 12 months postinjury. Risk factors for acute PTH included younger age, female sex, fewer years of formal education, computed tomography-positive scans, alteration of consciousness, psychiatric history, and history of migraine. Risk factors for persistent PTH included female sex, fewer years of formal education, and history of migraine.

CONCLUSION

Post-traumatic headache is a prevalent sequela of mTBI that persists for at least 12 months in a considerable proportion of affected individuals. The attributable burden necessitates better patient follow-up, disease characterization, improved awareness of PTH in clinical practice, and identification of effective therapies.

Sensory hypersensitivities are associated with post-traumatic headache-related disability

OBJECTIVE

To examine whether sensory hypersensitivity contributes to headache-related disability in a secondary analysis of patients with post-traumatic headache.

BACKGROUND

Up to one-third of individuals with traumatic brain injuries report persistent headache 3 months post-injury. High rates of allodynia and photophobia have been observed in clinical studies and animal models of post-traumatic headache, but we do not fully understand how sensory amplifications impact post-traumatic headache-related disability.

METHODS

We identified a cross-sectional sample of patients from the American Registry for Migraine Research database with new or worsening headaches post-head injury from 2016 to 2020 and performed a secondary analysis of those data. We modeled the relationship between sensory sensitivity and Migraine Disability Assessment scores using questionnaires. Candidate variables included data collection features (study site and year), headache-related and general clinical features (headache frequency, migraine diagnosis, abuse history, sex, age, cognitive and affective symptom scores), and sensory symptoms (related to light, sound, and touch sensitivity).

RESULTS

The final sample included 193 patients (median age 46, IQR 22; 161/193, 83.4% female). Migraine Disability Assessment scores ranged from 0 to 260 (median 47, IQR 87). The final model included allodynia, hyperacusis, photosensitivity, headache days per month, abuse history, anxiety and depression, cognitive dysfunction, and age (R2  = 0.43). An increase of one point in allodynia score corresponded to a 3% increase in headache disability (95% CI: 0%-7%; p = 0.027), an increase of one-tenth of a point in the photosensitivity score corresponded to a 12% increase (95% CI: 3%-25%; p = 0.002), and an increase of one point in the hyperacusis score corresponded to a 2% increase (95% CI: 0%-4%; p = 0.016).

CONCLUSIONS

Increased photosensitivity, allodynia, and hyperacusis were associated with increased headache-related disability in this sample of patients with post-traumatic headache. Symptoms of sensory amplification likely contribute to post-traumatic headache-related disability and merit an ongoing investigation into their potential as disease markers and treatment targets.

Headache classification and automatic biomarker extraction from structural MRIs using deep learning

Data-driven machine-learning methods on neuroimaging (e.g. MRI) are of great interest for the investigation and classification of neurological diseases. However, traditional machine learning requires domain knowledge to delineate the brain regions first, followed by feature extraction from the regions. Compared with this semi-automated approach, recently developed deep learning methods have advantages since they do not require such prior knowledge; instead, deep learning methods can automatically find features that differentiate MRIs from different cohorts. In the present study, we developed a deep learning-based classification pipeline distinguishing brain MRIs of individuals with one of three types of headaches [migraine (n = 95), acute post-traumatic headache (n = 48) and persistent post-traumatic headache (n = 49)] from those of healthy controls (n = 532) and identified the brain regions that most contributed to each classification task. Our pipeline included: (i) data preprocessing; (ii) binary classification of healthy controls versus headache type using a 3D ResNet-18; and (iii) biomarker extraction from the trained 3D ResNet-18. During the classification at the second step of our pipeline, we resolved two common issues in deep learning methods, limited training data and imbalanced samples from different categories, by incorporating a large public data set and resampling among the headache cohorts. Our method achieved the following classification accuracies when tested on independent test sets: (i) migraine versus healthy controls-75% accuracy, 66.7% sensitivity and 83.3% specificity; (2) acute post-traumatic headache versus healthy controls-75% accuracy, 66.7% sensitivity and 83.3% specificity; and (3) persistent post-traumatic headache versus healthy controls-91.7% accuracy, 100% sensitivity and 83.3% specificity. The most significant biomarkers identified by the classifier for migraine were caudate, caudal anterior cingulate, superior frontal, thalamus and ventral diencephalon. For acute post-traumatic headache, lateral occipital, cuneus, lingual, pericalcarine and superior parietal regions were identified as most significant biomarkers. Finally, for persistent post-traumatic headache, the most significant biomarkers were cerebellum, middle temporal, inferior temporal, inferior parietal and superior parietal. In conclusion, our study shows that the deep learning methods can automatically detect aberrations in the brain regions associated with different headache types. It does not require any human knowledge as input which significantly reduces human effort. It uncovers the great potential of deep learning methods for classification and automatic extraction of brain imaging-based biomarkers for these headache types.

Post-traumatic Headache: Pharmacologic Management and Targeting CGRP Signaling

PURPOSE OF REVIEW

Post-traumatic headache is a common sequela of injury to the head and/or neck. Here, we review the current approach to pharmacologic management of post-traumatic headache and explore the therapeutic promise of targeting calcitonin gene-related peptide signaling to address unmet treatment needs.

RECENT FINDINGS

The scarcity of data from controlled trials has left clinicians to rely on mainly expert opinion for the pharmacologic management of post-traumatic headache. The current view is that a phenotype-guided approach should be used, in which patients are treated according to the primary headache phenotype that their clinical features resemble the most (e.g. migraine, tension-type headache). Moreover, incremental advances are being made in the field that aim to identify possible cellular and molecular drivers of headache persistence. Calcitonin gene-related peptide has emerged as a key drug target which, in turn, has prompted novel insights on the potential importance of early initiation of pharmacologic treatment following the onset of post-traumatic headache. This, in turn, might prevent subsequent persistence and chronification of headache.

Photophobia and allodynia in persistent post-traumatic headache are associated with higher disease burden

OBJECTIVE

To assess photophobia and allodynia in subjects with post-traumatic headache and examine how these sensory hypersensitivities associate with clinical measures of disease burden.

BACKGROUND

Post-traumatic headache is the most frequent and disabling long-term consequence of mild traumatic brain injury. There is evidence of sensory dysfunction in acute post-traumatic headache, and it is known from other headache conditions that sensory amplifications correlate with more severe disease. However, systematic studies in post-traumatic headache are surprisingly scarce.

METHODS

We tested light and tactile sensitivity, along with measures of disease burden, in 30 persistent post-traumatic headache subjects and 35 controls.

RESULTS

In all, 79% of post-traumatic headache subjects exhibited sensory hypersensitivity based on psychophysical assessment. Of those exhibiting hypersensitivity, 54% exhibited both light and tactile sensitivity. Finally, sensory thresholds were correlated across modalities, as well as with headache attack frequency.

CONCLUSIONS

In this study, post-traumatic headache subjects with both light and tactile sensitivity had significantly higher headache frequencies and lower sensitivity thresholds to both modalities, compared to those with single or no sensory hypersensitivity. This pattern suggests that hypersensitivity across multiple modalities may be functionally synergistic, reflect a higher disease burden, and may serve as candidate markers of disease.

Headache complexity (number of symptom features) differentiates post-traumatic from non-traumatic headaches

BACKGROUND

Post-traumatic headaches are a common sequela of mild traumatic brain injury (concussion). It is unclear whether or how these headaches differ phenotypically from primary headaches.

OBJECTIVE

Determine whether there is an overarching unobserved latent trait that drives the expression of observed features of post-traumatic headache and other headaches.

METHODS

Data from this post-hoc analysis come from the Warrior Strong Cohort Study conducted from 2010 through 2015. Approximately 25,000 soldiers were screened for concussion history at routine post-deployment health assessments. A random sample was invited to participate, enrolling 1567. Twelve observed headache phenotypic features were used to measure "headache complexity", the latent trait of clinical interest, using single factor confirmatory factor analysis. We compared headache complexity between groups and determined whether headache complexity predicted accessing medical care for headache.

RESULTS

Of 1094 soldiers with headaches, 198 were classified as having post-traumatic headache. These headaches were compared to those in the other soldiers (647 without concussion history and 249 with concussion history). Soldiers with post-traumatic headache had greater endorsement of all 12 headache features compared to the soldiers with non-concussive headaches. The confirmatory factor analysis showed good model fit (χ² (51) = 95.59, p = 0.0002, RMSEA = 0.03, comparative fit index = 0.99, and Tucker-Lewis index = 0.99), providing empirical support for the headache complexity construct. Soldier groups differed in their mean headache complexity level (p < 0.001) such that post-traumatic headache soldiers had greater headache complexity compared to non-concussed soldiers (standardized mean difference = 0.91, 95% confidence interval: 0.72-1.09, p < 0.001 and to concussed soldiers with coincidental headaches standardized mean difference = 0.75, 95% confidence interval: 0.53-0.96, p < 0.001). Increasing headache complexity predicted medical encounters for headache (odds ratio = 1.87, 95% confidence interval: 1.49-2.35, p < 0.001) and migraine (odds ratio = 3.74, 95% confidence interval: 2.33-5.98, p < 0.001) during the year following deployment.Conclusions and relevance: The current study provided support for a single latent trait, characterized by observed headache symptoms, that differentiates between concussive and non-concussive headaches and predicts use of medical care for headache. The single trait confirmatory factor analysis suggests that post-traumatic headaches differ from non-concussive headaches by severity more than kind, based on the symptoms assessed.ClinicalTrials.gov identifier NCT01847040.

Post-traumatic headache due to mild traumatic brain injury: Current knowledge and future directions

BACKGROUND/OBJECTIVE

Post-traumatic headache is one of the most common and persistent symptoms following mild traumatic brain injury. The objective of this narrative review is to provide an update on the diagnostic criteria, clinical presentation, epidemiology, pathophysiology, and treatment of post-traumatic headache, and to identify future research priorities.

METHODS

This is a narrative review of the literature regarding post-traumatic headache attributed to mild traumatic brain injury.

RESULTS

Onset of post-traumatic headache within 7 days of injury is the only evidence for a causal relationship between the injury and the headache included in the diagnostic criteria. Post-traumatic headache often resolves within the first few days of onset, whereas it persists for at least 3 months in 30-50%. The majority of insights into post-traumatic headache pathophysiology come from pre-clinical animal studies and human imaging studies, which implicate structural, functional, metabolic, and neuroinflammatory mechanisms for post-traumatic headache. There is a paucity of quality evidence for how to best treat post-traumatic headache.

CONCLUSIONS

Although meaningful progress has been made in the post-traumatic headache field, priorities for future research are numerous, including the optimization of diagnostic criteria, a greater understanding of post-traumatic headache pathophysiology, identifying mechanisms and predictors for post-traumatic headache persistence, and identifying safe, well-tolerated, effective therapies.

Interrelations between migraine-like headache and persistent post-traumatic headache attributed to mild traumatic brain injury: a prospective diary study

BACKGROUND

Persistent post-traumatic headache (PTH) is a common sequela of mild traumatic brain injury (TBI) and retrospective assessments have found a migraine-like phenotype to be very frequent. This has raised a discussion of shared underlying mechanisms and whether persistent PTH is simply trauma-triggered migraine.

METHODS

A 28-day prospective diary study with daily entries and acquisition of data on headache characteristics, associated symptoms, and acute medication use. A total of 64 patients with persistent PTH were enrolled from April 2019 to August 2019. Outcomes were the proportion of monthly headache days of any intensity that met the criteria for a migraine-like day or TTH-like day, as well as the corresponding figures for monthly headache days of moderate to severe intensity. Headache phenotypes were initially assigned based on diagnostic evaluation by semi-structured interview, whilst final headache phenotypes were assigned by diary review.

RESULTS

After diary review, we found that monthly headache days were exclusively migraine-like in 24 of 64 patients (38%) and exclusively TTH-like days in 8 of 64 patients (13%). Considering only monthly headache days of moderate to severe intensity, the corresponding figures were 35 of 64 patients (55%) for migraine-like days and 8 of 64 patients (13%) for TTH-like days. The following headache phenotypes were assigned based on diary review: chronic migraine-like (n = 47, 73%), combined episodic migraine-like and chronic TTH-like (n = 9, 13%), and 'pure' chronic TTH-like (n = 8, 13%).

CONCLUSIONS

A migraine-like phenotype is common in patients most adversely affected by persistent PTH, although some patients did have a pure chronic TTH-like phenotype. At minimum, these findings suggest that persistent PTH is - at least in some - not 'trauma-triggered migraine'.

Provider Training in the Management of Headache Following Concussion Clinical Recommendation: Promoting a Standardized Means for Efficient Patient Recovery and Timely Return to Duty

Background: Headache is a common symptom reported following concussion/mild traumatic brain injury. The Department of Defense's clinical recommendation (CR) describes guidance for primary care providers for the management of post-traumatic headache (PTH) in Service members.

Objective: The objective of this study is to examine the association between training on the CR with provider clinical practice, patient behaviors, and symptom recovery.

Methods: Participants were healthcare providers and two patient groups (one receiving care as usual [CAU] and another receiving care after provider training on PTH CR [CR+]). Providers were interviewed at three time points: (1) prior to CAU enrollment; (2) after CAU enrollment, but prior to training; and (3) after CR+ follow-up. Data from the second and third provider interview were used to evaluate a potential difference between provider practices pre- and post-training (n = 13). Patients were enrolled within 6 months of concussion. Patient outcomes (including neurobehavioral and headache symptoms) were assessed at three time-points: within 72 h (n = 35), at 1-week (n = 34) and at 1-month post-enrollment (n = 27).

Results: Most follow-up care reported by providers were recommended within 72 h of initial visit post-training vs. >1 week pre-training. Additionally, providers reported a greater number of visits based on patient symptoms after training than before. Post-training, most providers reported referring patients to higher level of care “as needed,” if not “very rarely,” compared to 25% reported referrals prior to training. At 1-week post-enrollment the CR+ patient group reported more frequent medical provider visits compared to the CAU group. This trend was reversed at the 1-month follow-up whereby more CAU reported seeing a medical provider compared to CR+. By 1-week post-enrollment, fewer patients in the CR+ group reported being referred to any other providers or specialists compared to the CAU group. No differences in patient outcomes by provider training was found.

Conclusion: The study results demonstrate the feasibility of training on the Management of Headache Following Concussion CR in order to change provider practices by promoting timely care, and promoting patient compliance as shown through improvement in follow-up visits and more monitoring within the primary care clinic.

Sensory hypersensitivities in those with persistent post-traumatic headache versus migraine

Background and Objective:

Symptoms of persistent post-traumatic headache (PPTH) most often resemble those of migraine, including the presence of photo-, phono-, and cutaneous hypersensitivities. The severity of these hypersensitivity symptoms in those with PPTH compared to those with migraine has yet to be fully elucidated. The objective of this study was to compare symptoms of sensory hypersensitivities between PPTH, migraine, and healthy controls (HCs). Further defining characteristics of PPTH and its similarities to migraine might assist with developing future diagnostic criteria for PPTH and provide insights into PPTH mechanisms.

Methods:

This analysis included 56 individuals with PPTH attributed to mild traumatic brain injury, 30 with migraine, and 36 HCs. To assess sensory hypersensitivities, all subjects completed the Allodynia Symptom Checklist-12, the Photosensitivity Assessment Questionnaire, and the Hyperacusis Questionnaire. Differences among groups were assessed using Fisher’s exact test, Kruskal–Wallis, or Mann–Whitney U test.

Results:

PPTH and migraine groups had greater severity of cutaneous, photo-, and phono-hypersensitivity symptoms compared to HCs. There were no statistically significant differences between the PPTH and migraine groups for cutaneous allodynia (median [first quartile, third quartile]; PPTH: 4.0 [2.0, 7.0]; migraine: 5.0 [3.0, 8.0]; p = 0.54) or photosensitivity severity (PPTH: 5.0 [2.0, 7.0]; migraine: 5.0 [2.0, 6.0]; p = 0.53). Those with PPTH had higher hyperacusis scores compared to those with migraine (PPTH: 23.0 [17.0, 31.0]; migraine: 13.5 [9.0, 24.0]; p = 0.001).

Conclusion:

Sensory hypersensitivity symptoms among individuals with PPTH are at least as severe as those experienced by people with migraine. Results further confirm symptom similarities between PPTH and migraine and could suggest that PPTH and migraine have a partially shared underlying pathophysiology.

Low plasma levels of calcitonin gene-related peptide in persistent post-traumatic headache attributed to mild traumatic brain injury

OBJECTIVE

To investigate the role of calcitonin gene-related peptide (CGRP) in persistent post-traumatic headache (PTH) attributed to mild traumatic brain injury (TBI).

METHODS

A total of 100 individuals with persistent PTH attributed to mild TBI and 100 age- and gender-matched healthy controls were enrolled between July 2018 and June 2019. Blood was drawn from the antecubital vein and subsequently analyzed using a validated radioimmunoassay for human CGRP. Measurements were performed on coded samples by a board-certified laboratory technician who was blind to clinical information.

RESULTS

CGRP plasma levels were lower in subjects with persistent PTH (mean, 75.8 pmol/L; SD, 26.4 pmol/L), compared with age- and gender-matched healthy controls (mean, 88.0 pmol/L; SD, 34.1 pmol/L) (p = 0.04). No correlation was found of CGRP plasma levels with monthly headache days (r = -0.11; p = 0.27), monthly migraine-like days (r = 0.15; p = 0.13), headache quality (r = -0.14; p = 0.15), or a chronic migraine-like headache phenotype (r = -0.02; p = 0.85).

CONCLUSIONS

CGRP plasma measurements are unlikely a feasible blood-based biomarker of persistent PTH. Future studies should assess whether CGRP plasma measurements can be used to predict development of persistent PTH.

Persistent post-traumatic headache: a migrainous loop or not? The preclinical evidence

Background

According to the International Classification of Headache Disorders 3, post-traumatic headache (PTH) attributed to traumatic brain injury (TBI) is a secondary headache reported to have developed within 7 days from head injury, regaining consciousness following the head injury, or discontinuation of medication(s) impairing the ability to sense or report headache following the head injury. It is one of the most common secondary headache disorders, and it is defined as persistent when it lasts more than 3 months.

Main body

Currently, due to the high prevalence of this disorder, several preclinical studies have been conducted using different animal models of mild TBI to reproduce conditions that engender PTH. Despite representing a simplification of a complex disorder and displaying different limitations concerning the human condition, animal models are still a mainstay to study in vivo the mechanisms of PTH and have provided valuable insight into the pathophysiology and possible treatment strategies. Different models reproduce different types of trauma and have been ideated in order to ensure maximal proximity to the human condition and optimal experimental reproducibility.

Conclusion

At present, despite its high prevalence, PTH is not entirely understood, and the differential contribution of pathophysiological mechanisms, also observed in other conditions like migraine, has to be clarified. Although facing limitations, animal models are needed to improve understanding of PTH. The knowledge of currently available models is necessary to all researchers who want to investigate PTH and contribute to unravel its mechanisms.

Increased severity of closed head injury or repetitive subconcussive head impacts enhances post-traumatic headache-like behaviors in a rat model

INTRODUCTION

Posttraumatic headache is one of the most common, debilitating, and difficult symptoms to manage after a traumatic head injury. The development of novel therapeutic approaches is nevertheless hampered by the paucity of preclinical models and poor understanding of the mechanisms underlying posttraumatic headache. To address these shortcomings, we previously characterized the development of posttraumatic headache-like pain behaviors in rats subjected to a single mild closed head injury using a 250 g weight drop. Here, we conducted a follow-up study to further extend the preclinical research toolbox for studying posttraumatic headache by exploring the development of headache-like pain behaviors in male rats subjected to a single, but more severe head trauma (450 g) as well as following repetitive, subconcussive head impacts (150 g). In addition, we tested whether these behaviors involve peripheral calcitonin gene-related peptide signaling by testing the effect of systemic treatment with an anti-calcitonin gene-related peptide monoclonal antibody (anti-calcitonin gene-related peptide mAb).

METHODS

Adult male Sprague Dawley rats (total n = 138) were subjected to diffuse closed head injury using a weight-drop device, or a sham procedure. Three injury paradigms were employed: A single hit, using 450 g or 150 g weight drop, and three successive 150 g weight drop events conducted 72 hours apart. Changes in open field activity and development of cephalic and extracephalic tactile pain hypersensitivity were assessed up to 42 days post head trauma. Systemic administration of the anti-calcitonin gene-related peptide mAb or its control IgG (30 mg/kg) began immediately after the 450 g injury or the third 150 g weight drop with additional doses given every 6 days subsequently.

RESULTS

Rats subjected to 450 g closed head injury displayed an acute decrease in rearing and increased thigmotaxis, together with cephalic tactile pain hypersensitivity that resolved by 6 weeks post-injury. Injured animals also displayed delayed and prolonged extracephalic tactile pain hypersensitivity that remained present at 6 weeks post-injury. Repetitive subconcussive head impacts using the 150 g weight drop, but not a single event, led to decreased vertical rearing as well as cephalic and extracephalic tactile pain hypersensitivity that resolved by 6 weeks post-injury. Early and prolonged anti-calcitonin gene-related peptide mAb treatment inhibited the development of the cephalic tactile pain hypersensitivity in both the severe and repetitive subconcussive head impact models.

CONCLUSIONS

Severe head injury gives rise to a prolonged state of cephalic and extracephalic tactile pain hypersensitivity. These pain behaviors also develop following repetitive, subconcussive head impacts. Extended cephalic tactile pain hypersensitivity following severe and repetitive mild closed head injury are ameliorated by early and prolonged anti-calcitonin gene-related peptide mAb treatment, suggesting a mechanism linked to calcitonin gene-related peptide signaling, potentially of trigeminal origin.

Different clinical phenotypes of persistent post-traumatic headache exhibit distinct sensory profiles

INTRODUCTION

Persistent post-traumatic headache remains a poorly understood clinical entity. Although there are currently no accepted therapies for persistent post-traumatic headache, its clinical symptoms, which primarily resemble those of migraine or tension-type headache, often serve to guide treatment. However, evidence-based justification for this treatment approach remains lacking given the paucity of knowledge regarding the characteristics of these two major persistent post-traumatic headache phenotypes and their etiology.

METHODS

We compared clinical features and quantitative sensory testing profiles between two distinct cohorts of persistent post-traumatic headache subjects that exhibited symptoms resembling either migraine (n = 15) or tension-type headache (n = 13), as well as to headache-free subjects that had suffered traumatic brain injury (n = 19), and to healthy controls (n = 10). We aimed to determine whether the two persistent post-traumatic headache subgroups could be discriminated based on additional clinical features, distinct quantitative sensory testing profiles, or the interaction of pain severity with the level of post-traumatic stress disorder.

RESULTS

Persistent post-traumatic headache subjects with migraine-like symptoms reported that bright light and focused attention aggravated their pain, while stress and nervousness were reported to aggravate the headache in subjects with tension-type headache-like symptoms. Quietness was better in alleviating migraine-like persistent post-traumatic headache, while anti-inflammatory medications provided better relief in tension-type headache-like persistent post-traumatic headache. The two persistent post-traumatic headache subgroups exhibited distinct quantitative sensory testing profiles with subjects exhibiting tension-type headache-like persistent post-traumatic headache displaying a more pronounced cephalic and extracephalic thermal hypoalgesia that was accompanied by cephalic mechanical hyperalgesia. While both persistent post-traumatic headache subgroups had high levels of post-traumatic stress disorder, there was a positive correlation with pain severity in subjects with tension-type headache-like symptoms, but a negative correlation in subjects with migraine-like symptoms.

CONCLUSIONS

Distinct persistent post-traumatic headache symptoms and quantitative sensory testing profiles may be linked to different etiologies, potentially involving various levels of neuropathic and inflammatory pain, and if confirmed in a larger cohort, could be used to further characterize and differentiate between persistent post-traumatic headache subgroups in studies aimed to improve treatment.

Persistent post-traumatic headache attributed to mild traumatic brain injury: Deep phenotyping and treatment patterns

Objective

To investigate clinical characteristics and treatment patterns in persistent post-traumatic headache attributed to mild traumatic brain injury.

Methods

A total of 100 individuals with persistent post-traumatic headache attributed to mild traumatic brain injury were enrolled between July 2018 and June 2019. Deep phenotyping was performed using a semi-structured interview while allodynia was assessed using the 12-item Allodynia Symptom Checklist.

Results

In 100 subjects with persistent post-traumatic headache, the mean headache frequency was 25.4 ± 7.1 days per month. The most common headache phenotype was chronic migraine-like headache (n = 61) followed by combined episodic migraine-like and tension-type-like headache (n = 29) while nine subjects reported “pure” chronic tension-type-like headache. The most frequent trigger factors were stress, lack of sleep, and bright lights. A history of preventive medication use was reported by 63 subjects, of which 79% reported failure of at least one preventive drug, while 19% reported failure of at least four preventive drugs. Cutaneous allodynia was absent in 54% of the subjects, mild in 23%, moderate in 17%, and severe in 6%.

Conclusions

The headache profile of individuals with persistent post-traumatic headache most often resembled a chronic migraine-like phenotype or a combined episodic migraine-like and tension-type-like headache phenotype. Migraine-specific preventive medications were largely reported to be ineffective. Therefore, there is a pressing need for pathophysiological insights and disease-specific therapies.

Enhanced post-traumatic headache-like behaviors and diminished contribution of peripheral CGRP in female rats following a mild closed head injury

INTRODUCTION

Females are thought to have increased risk of developing post-traumatic headache following a traumatic head injury or concussion. However, the processes underlying this susceptibility remain unclear. We previously demonstrated the development of post-traumatic headache-like pain behaviors in a male rat model of mild closed head injury, along with the ability of sumatriptan and an anti-calcitonin-gene-related peptide monoclonal antibody to ameliorate these behaviors. Here, we conducted a follow-up study to explore the development of post-traumatic headache-like behaviors and the effectiveness of these headache therapies in females subjected to the same head trauma protocol.

METHODS

Adult female Sprague Dawley rats were subjected to a mild closed head injury using a weight-drop device (n = 126), or to a sham procedure (n = 28). Characterization of headache and pain related behaviors included assessment of changes in cutaneous cephalic and extracephalic tactile pain sensitivity, using von Frey monofilaments. Sensitivity to headache/migraine triggers was tested by examining the effect of intraperitoneal administration of a low dose of glyceryl trinitrate (100 µg/kg). Treatments included acute systemic administration of sumatriptan (1 mg/kg) and repeated systemic administration of a mouse anti-calcitonin gene-related peptide monoclonal antibody (30 mg/kg). Serum levels of calcitonin gene-related peptide were measured at baseline and at various time points post head injury in new cohorts of females (n = 38) and males (n = 36).

RESULTS

Female rats subjected to a mild closed head injury developed cutaneous mechanical hyperalgesia, which was limited to the cephalic region and was resolved 4 weeks later. Cephalic pain hypersensitivity was ameliorated by treatment with sumatriptan but was resistant to an early and prolonged treatment with the anti-calcitonin gene-related peptide monoclonal antibody. Following the resolution of the head injury-evoked cephalic hypersensitivity, administration of glyceryl trinitrate produced a renewed and pronounced cephalic and extracephalic pain hypersensitivity that was inhibited by sumatriptan, but only partially by the anti-calcitonin gene-related peptide treatment. Calcitonin gene-related peptide serum levels were elevated in females but not in males at 7 days post head injury.

CONCLUSIONS

Development of post-traumatic headache-like pain behaviors following a mild closed head injury, and responsiveness to treatment in rats is sexually dimorphic. When compared to the data obtained from male rats in the previous study, female rats display a prolonged state of cephalic hyperalgesia, increased responsiveness to a headache trigger, and a poorer effectiveness of an early and prolonged anti-calcitonin gene-related peptide treatment. The increased risk of females to develop post-traumatic headache may be linked to enhanced responsiveness of peripheral and/or central pain pathways and a mechanism independent of peripheral calcitonin gene-related peptide signaling.

Posttraumatic vs nontraumatic headaches: A phenotypic analysis in a military population

OBJECTIVE

To describe and compare phenotypic features of posttraumatic headaches (PTH) and headaches unrelated to concussion.

METHODS

Participants are a random sample of recently deployed soldiers from the Warrior Strong cohort, consisting of soldiers with (n = 557) and without (n = 1,030) a history of a recent mild traumatic brain injury (mTBI; concussion). mTBI+ soldiers were subdivided as PTH+ (n = 230) and PTH- (n = 327). Headache classification was based on a detailed phenotypic questionnaire. Medical encounters for headache were documented for the year after deployment.

RESULTS

The findings here are limited to the soldiers with headaches, consisting of 94% of the mTBI+ soldiers and 76% of the mTBI- soldiers. Other than headache duration, all headache/migraine features were more common or more severe in the PTH+ group compared to the nonconcussed group (mTBI-) and compared to the concussed group with nontraumatic headaches (PTH-). Headaches were largely similar in the mTBI- and PTH- groups. The features most specific to PTH+ included allodynia, visual aura, sensory aura, daily headache, and continuous headache. Medical consultation for headache was most common in the PTH+ group (62%) vs the PTH- group (20%) or the mTBI- group (13%) (p < 0.008).

CONCLUSIONS

In this cohort of recently deployed soldiers, PTHs are more severe, frequent, and migraine-like and more often associated with medical consultation compared to headaches presumed unrelated to concussion. Future observational studies are needed to verify and characterize the PTH phenotype, which could be followed by treatment trials with appropriate and possibly novel outcomes for prespecified subgroups.

CLINICALTRIALSGOV IDENTIFIER

NCT01847040.

Structural and Functional Brain Alterations in Post-traumatic Headache Attributed to Mild Traumatic Brain Injury: A Narrative Review

Introduction: By definition, post-traumatic headache (PTH) attributed to mild traumatic brain injury (mTBI) is not associated with brain structural abnormalities that are seen on routine clinical inspection of brain images. However, subtle brain structural abnormalities, as well as functional abnormalities, detected via research imaging techniques yield insights into the pathophysiology of PTH. The objective of this manuscript is to summarize published findings regarding research imaging of the brain in PTH attributed to mTBI.

Methods:For this narrative review, PubMed was searched using the terms “post-traumatic headache” or “post-concussion headache” and “imaging” or “magnetic resonance imaging” or “research imaging” or “positron emission tomography”. Articles were chosen for inclusion based on their relevance to the topic.

Results: Ten articles were ultimately included within this review. The studies investigated white matter tract integrity and functional connectivity in acute PTH, structural measures, white matter tract integrity, cerebral blood flow, and functional connectivity in persistent PTH (PPTH), and proton spectroscopy in both acute and persistent PTH. The articles demonstrate that acute and persistent PTH are associated with abnormalities in brain structure, that acute and persistent PTH are also associated with abnormalities in brain function, that it might be possible to predict the persistence of PTH using brain imaging findings, and that there are differences in imaging findings when comparing PTH to healthy controls and when comparing PTH to migraine. Although it is not entirely clear if the imaging findings are directly attributable to PTH as opposed to the underlying TBI or other post-TBI symptoms, correlations between the imaging findings with headache frequency and headache resolution suggest a true relationship between the imaging findings and PTH.

Conclusions: PTH attributed to mTBI is associated with abnormalities in brain structure and function that can be detected via research imaging. Additional studies are needed to determine the specificity of the findings for PTH, to differentiate findings attributed to PTH from those attributed to the underlying TBI and coexistent post-TBI symptoms, and to determine the accuracy of imaging findings for predicting the development of PPTH.

Intact mast cell content during mild head injury is required for development of latent pain sensitization: implications for mechanisms underlying post-traumatic headache

Post-traumatic headache (PTH) is one of the most common, debilitating, and difficult symptoms to manage after a traumatic head injury. Although the mechanisms underlying PTH remain elusive, recent studies in rodent models suggest the potential involvement of calcitonin gene-related peptide (CGRP), a mediator of neurogenic inflammation, and the ensuing activation of meningeal mast cells (MCs), proalgesic resident immune cells that can lead to the activation of the headache pain pathway. Here, we investigated the relative contribution of MCs to the development of PTH-like pain behaviors in a model of mild closed-head injury (mCHI) in male rats. We initially tested the relative contribution of peripheral CGRP signaling to the activation of meningeal MCs after mCHI using a blocking anti-CGRP monoclonal antibody. We then used a prophylactic MC granule depletion approach to address the hypotheses that intact meningeal MC granule content is necessary for the development of PTH-related pain-like behaviors. The data suggest that after mCHI, ongoing activation of meningeal MCs is not mediated by peripheral CGRP signaling and does not contribute to the development of the mCHI-evoked cephalic mechanical pain hypersensitivity. Our data, however, also reveal that the development of latent sensitization, manifested as persistent hypersensitivity upon the recovery from mCHI-evoked acute cranial hyperalgesia to the headache trigger glyceryl trinitrate requires intact MC content during and immediately after mCHI. Collectively, our data implicate the acute activation of meningeal MCs as mediator of chronic pain hypersensitivity after a concussion or mCHI. Targeting MCs may be explored for early prophylactic treatment of PTH.