What predicts citation counts and translational impact in headache research? A machine learning analysis.

BACKGROUND: We aimed to develop the first machine learning models to predict citation counts and the translational impact, defined as inclusion in guidelines or policy documents, of headache research, and assess which factors are most predictive. METHODS: Bibliometric data and the titles, abstracts, and keywords from 8600 publications in three headache-oriented journals from their inception to 31 December 2017 were used. A series of machine learning models were implemented to predict three classes of 5-year citation count intervals (0-5, 6-14 and, >14 citations); and the translational impact of a publication. Models were evaluated out-of-sample with area under the receiver operating characteristics curve (AUC). RESULTS: The top performing gradient boosting model predicted correct citation count class with an out-of-sample AUC of 0.81. Bibliometric data such as page count, number of references, first and last author citation counts and h-index were among the most important predictors. Prediction of translational impact worked optimally when including both bibliometric data and information from the title, abstract and keywords, reaching an out-of-sample AUC of 0.71 for the top performing random forest model. CONCLUSION: Citation counts are best predicted by bibliometric data, while models incorporating both bibliometric data and publication content identifies the translational impact of headache research.

Consensus recommendations on the role of nurses in headache care: A European e-Delphi study.

BACKGROUND: Nurses work at headache centres throughout Europe, and their care for migraine patients is acknowledged. However, the specific roles and tasks of nursing vary, and a unified understanding is lacking, posing challenges to knowledge sharing and research. OBJECTIVES: Using an e-Delphi study method, the objective is to obtain healthcare professional headache experts' opinions on nursing-specific roles and tasks and combine this into consensus statements for nurse recommendations for migraine treatment. METHODS: A three-round questionnaire study was conducted with nurses and neurologists from 18 specialised headache centres in 10 countries. In round 1, statements were compiled from a systematic examination of existing literature and expert opinions. In rounds 2 and 3, the experts rated the importance of statements (from round 1) on a 5-point Likert scale. Statements were analysed using a content analysis method, and the consensus of pre-defined statements was evaluated with gradually increased predetermined criteria using descriptive statistics. RESULTS: Twenty-one experts, representing all 10 countries, participated. The predetermined consensus of ≥70% agreement was reached for 42 out of the initial 63 statements. These statements formed the final recommendations within two themes: "The nurses' roles and tasks in the clinical setting" and "The nurses' roles and tasks in educating patients and colleagues." The consensus level of statements was strong, with 40% receiving unanimous agreement (100%) and 97% achieving relatively high agreement (>80%). CONCLUSION: Nursing plays a vital role with diverse tasks in migraine care. This study offers practical recommendations and a framework for nurses, equipping them with a clinical tool to enhance care and promote a coordinated approach to migraine treatment.

Cognitive assessment during the phases of a spontaneous migraine: a prospective cohort study.

INTRODUCTION: Cognitive symptoms are reported commonly throughout all phases of a migraine; however, there is a paucity of objective cognitive profiling. Previous studies have been limited by practice effect, and variable populations. METHODS: Participants completed 1 month of daily testing with a computerised cognitive battery involving a simple reaction (SRT), choice reaction (CRT) and a working memory test (WM). Results were correlated with their diary to identify interictal scores, and scores during each phase of a migraine, and non-migraine headache days. RESULTS: A total of 16 patients with episodic migraine participated. During the headache phase of a migraine, responses to SRT, CRT and WM tasks were significantly slower and less accurate than interictally. During the postdrome, WM task performance was slower and less accurate. Non-migraine headache days were not associated with significant change. CONCLUSION: The headache and postdromal phase of a migraine day was associated with objective evidence of cognitive dysfunction in patients with episodic migraine.

Does pain self-efficacy predict, moderate or mediate outcomes in people with chronic headache; an exploratory analysis of the CHESS trial.

BACKGROUND: Chronic headache disorders are disabling. The CHESS trial studied the effects of a short non-pharmacological intervention of education with self-management support for people affected by migraine and/or tension type headache for at least 15 days per month for at least three months. There were no statistically significant effects on the Headache Impact Test-6 (HIT-6) at 12-months. However, we observed improvement in pain self-efficacy questionnaire (PSEQ) and short-term HIT-6. We explored the impact of the CHESS intervention on PSEQ, and subsequently, on the HIT-6 and chronic headache quality of life questionnaire (CH-QLQ) at four, eighth and 12 months. METHODS: We included all 736 participants from the CHESS trial. We used simple linear regression models to explore the change of HIT-6 and CH-QLQ with treatment and PSEQ at baseline (predictor analysis), and the interaction between treatment and baseline PSEQ (moderator analysis). We considered the change of PSEQ from baseline to four months as a mediator in the mediation analysis. RESULTS: Baseline PSEQ neither predicted nor moderated outcomes. The prediction effect on change of HIT-6 from baseline to 12 months was 0.01 (95% CI, -0.03 to 0.04) and the interaction (moderation) effect was -0.07 (95% CI, -0.15 to 0.002). However, the change of PSEQ from baseline to 4-month mediated the HIT-6 (baseline to 8-, and 12-month) and all components of CH-QLQ (baseline to 8-, and 12-month). The CHESS intervention improved the mediated variable, PSEQ, by 2.34 (95% CI, 0.484 to 4.187) units and this corresponds to an increase of 0.21 (95% CI, 0.03 to 0.45) units in HIT-6 at 12-months. The largest mediated effect was observed on the CH-QLQ Emotional Function, an increase of 1.12 (95% CI, 0.22 to 2.20). CONCLUSIONS: PSEQ was not an effective predictor of outcome. However, change of short-term PSEQ mediated all outcomes, albeit minimally. Future behavioural therapy for chronic headache may need to consider how to achieve larger, and more sustained increases level of self-efficacy than that achieved within the CHESS trial. TRIAL REGISTRATION: ISRCTN79708100.

The short-term effects of CGRP monoclonal antibodies on bone turnover: A prospective cohort study.

BACKGROUND: Calcitonin gene-related peptide monoclonal antibodies (CGRP mAb) are an effective treatment of migraine however may have possible off-target effects. Pre-clinical studies implicate CGRP in several aspects of bone turnover and homeostasis. The clinical effect of CGRP mAb on bone turnover is not known, however. METHODS: Between June 2021 and July 2022, a multi-centre prospective cohort study was undertaken with eligible patients undergoing paired testing of the validated bone turnover markers procollagen type I N-terminal propeptide (P1NP) and serum C-terminal telopeptide of type I collagen (CTX) prior to and at least three months following administration of a CGRP mAb. RESULTS: A total of 45 patients with a mean age of 41.8 (SD 11.9) were included in the final analysis, all of whom received a ligand-targeting CGRP mAb. Administration of a CGRP mAb was associated with a statistically significant increase in P1NP from 44.5 microg/L to 51.5 microg/L (p = 0.004), but no significant change in CTX. CONCLUSION: In otherwise homeostatic conditions, short-term administration of a CGRP mAb is associated with increased P1NP, a bone formation marker but not with increased CTX, a bone resorption marker. Further study is required to validate these findings over longer time periods, in a larger cohort, and in pre-existing states of increased calcium stress and bone-turnover.

Chronic Migraine Epidemiology and Outcomes - International (CaMEO-I) Study: Methods and multi-country baseline findings for diagnosis rates and care.

BACKGROUND: The Chronic Migraine Epidemiology and Outcomes-International study provides insight into people with migraine in multiple countries. METHODS: This cross-sectional, observational, web-based cohort study was conducted in Canada, France, Germany, Japan, United Kingdom, and United States. An initial Screening Module survey solicited general healthcare information from a representative sample and identified participants with migraine based on modified International Classification of Headache Disorders-3 criteria; those with migraine completed a detailed survey based on validated migraine-specific assessments. RESULTS: Among 90,613 people who correctly completed the screening surveys, 76,121 respondents did not meet the criteria for migraine, while 14,492 did. Among respondents with migraine, mean age ranged from 40 to 42 years. The median number of monthly headache days ranged from 2.33 to 3.33 across countries, while the proportion of respondents with moderate-to-severe disability (measured by Migraine Disability Assessment) ranged from 30% (Japan) to 52% (Germany). The proportion of respondents with ≥15 monthly headache days ranged from 5.4% (France) to 9.5% (Japan). Fewer than half of respondents with migraine in each country reported having received a migraine diagnosis. CONCLUSION: These results demonstrated high rates of migraine-related disability and underdiagnosis of migraine across six countries. This study will characterize country-level burden, treatment patterns, and geographical differences in care.

The prevalence of headache disorders in Postural Tachycardia Syndrome: A systematic review and meta-analysis of the literature.

BACKGROUND: Headache is a common presentation of postural tachycardia syndrome, yet robust prevalence data is lacking. OBJECTIVES: To undertake a systematic review and meta-analysis to estimate the prevalence of headache disorders in postural tachycardia syndrome, and to explore the potential shared pathophysiological mechanisms that underpin these conditions as well as treatment options. METHODS: Three databases were searched for publications evaluating prevalence of migraine (primary outcome) and general and orthostatic headache (secondary outcomes) in patients with postural tachycardia syndrome. Two independent reviewers selected studies and extracted data. A random-effects meta-analysis calculated the pooled prevalence of migraine in postural tachycardia syndrome. A narrative literature review explored the pathophysiology and treatment options for concurrent headache disorders and postural tachycardia syndrome. RESULTS: Twenty-three articles met inclusion criteria. Estimated pooled prevalence of migraine in postural tachycardia syndrome was 36.8% (95% CI 2.9-70.7%). Various shared pathophysiological pathways for these conditions, as well as proposed treatment strategies, were identified.Limitations: Heterogeneity of study design, populations, and methodology for identifying headache disorders and postural tachycardia syndrome limited the generalisability of results. CONCLUSIONS: Migraine is a commonly reported comorbidity in POTS, however the true prevalence cannot be determined from the current literature. Further studies are required to assess this comorbidity and investigate the underlying mechanisms, as well as identify effective treatment strategies.

Efficacy of galcanezumab in patients with migraine and history of failure to 3-4 preventive medication categories: subgroup analysis from CONQUER study.

BACKGROUND: Chronic migraine (CM) and episodic migraine (EM) are associated with substantial headache-related disability, poor quality of life and global societal burden. In this subgroup analysis from the CONQUER study, we report efficacy outcomes from a pre-specified analysis of galcanezumab versus placebo in patients with CM or EM and 3-4 prior preventive medication category failures due to inadequate efficacy (after at least 2 months at maximum tolerated dose), or safety or tolerability reasons. The patient population is of particular interest due to evidence of decreased quality of life and increased economic burden among patients with migraine that is inadequately managed and is of interest to decision-makers globally. METHODS: Key outcomes included overall mean change from baseline in monthly migraine headache days and proportions of patients achieving ≥30% (CM), ≥50%, and ≥ 75% reduction (response rates) in monthly migraine headache days across Months 1-3. Patient functioning and disability were evaluated at Month 3. RESULTS: Of the 462 randomized patients, 186 (40.3%) had a history of 3-4 preventive category failures. Galcanezumab versus placebo resulted in significantly (P ≤ .001) larger overall mean reduction in monthly migraine headache days (total: - 5.49 versus - 1.03; CM: - 6.70 versus - 1.56; EM: - 3.64 versus - 0.65). Similarly, the ≥50% response rate was significantly (P ≤ .001) higher with galcanezumab versus placebo (total: 41.0 versus 12.7; CM: 41.5 versus 8.4; EM: 41.1 versus 16.5). In the CM group, the ≥30% response rate was significantly higher in the galcanezumab group than the placebo group (CM, 57.5 versus 19.8, P ≤ .0001) as was the ≥75% response rate (13.3 versus 2.6, P ≤ .05). Galcanezumab also resulted in significant (P < .0001) improvements in patient functioning and reductions in disability. CONCLUSIONS: Galcanezumab was effective in a difficult-to-treat population of patients with CM or EM who had failed 3-4 prior preventive medication categories. TRIAL REGISTRATION: CONQUER. Clinicaltrials.gov identifier: NCT03559257 .

Inflammatory complications of CGRP monoclonal antibodies: a case series.

BACKGROUND: Calcitonin gene-related peptide (CGRP) is expressed throughout the body and is a known mediator of migraine, exerting this biological effect through activation of trigeminovascular, meningeal and associated neuronal pathways located in close proximity to the central nervous system. Monoclonal antibodies (mAb) targeting the CGRP pathway are an effective new preventive treatment for migraine, with a generally favourable adverse event profile. Pre-clinical evidence supports an anti-inflammatory/immunoregulatory role for CGRP in other organ systems, and therefore inhibition of the normal action of this peptide may promote a pro-inflammatory response. CASES: We present a case series of eight patients with new or significantly worsened inflammatory pathology in close temporal association with the commencement of CGRP mAb therapy. CONCLUSION: This case series provides novel insights on the potential molecular mechanisms and side-effects of CGRP antagonism in migraine and supports clinical vigilance in patient care going forward.

Chronic Headache Education and Self-management Study (CHESS) - a mixed method feasibility study to inform the design of a randomised controlled trial.

BACKGROUND: Self-management support programmes are effective in a range of chronic conditions however there is limited evidence for their use in the treatment of chronic headaches. The aim of this study was to test the feasibility of four key aspects of a planned, future evaluative trial of a new education and self-management intervention for people with chronic headache: 1) recruiting people with chronic headache from primary care; 2) a telephone interview for the classification of chronic headaches; 3) the education and self-management intervention itself; and 4) the most appropriate patient reported outcomes (PROMS). METHODS: Participants were identified and recruited from general practices in the West Midlands of the UK. We developed a nurse-led chronic headache classification interview and assessed agreement with an interview with headache specialists. We developed and tested a group based education and self-management intervention to assess training and delivery receipt using observation, facilitator, and participant feedback. We explored the acceptability and relevance of PROMs using postal questionnaires, interviews and a smartphone app. RESULTS: Fourteen practices took part in the study and participant recruitment equated to 1.0/1000 registered patients. Challenges to recruitment were identified. We did 107 paired headache classification interviews. The level of agreement between nurse and doctor interviews was very good. We piloted the intervention in four groups with 18 participants. Qualitative feedback from participants and facilitators helped refine the intervention including shortening the overall intervention and increasing the facilitator training time. Participants completed 131 baseline questionnaires, measurement data quality, reliability and validity for headache-specific and generic measures was acceptable. CONCLUSION: This study indicated that recruiting people with chronic headache from primary care is feasible but challenging, our headache classification interview is fit for purpose, our study intervention is viable, and that our choice of outcome measures is acceptable to participants in a future randomised controlled trial (RCT). TRIAL REGISTRATION: ISRCTN, ISRCTN79708100. Registered 16th December 2015, http://www.isrctn.com/ISRCTN79708100.

OnabotulinumtoxinA for hemicrania continua: open label experience in 9 patients.

BACKGROUND: Hemicrania continua is a strictly unilateral, continuous headache, typically mild to moderate in severity, with severe exacerbations commonly accompanied by cranial autonomic features and migrainous symptoms. It is exquisitely responsive to Indomethacin. However, some patients cannot tolerate treatment, often due to gastrointestinal side effects. Therapeutic alternatives are limited and controlled evidence lacking. METHODS: We present our experience of nine patients treated with OnabotulinumtoxinA for hemicrania continua. All patients were injected using the PREEMPT (Phase 3 REsearch Evaluating Migraine Prophylaxis Therapy) protocol for migraine. RESULTS: Five of nine patients demonstrated a 50% or more reduction in moderate to severe headache days with OnabotulinumtoxinA with a median reduction in moderate to severe headache days of 80%. Patient estimate of response was 80% or more in five subjects. The median and mean duration of response in the five responders was 11 and 12 weeks (range 6-20 weeks). Improvements were also seen in headache-associated disability CONCLUSIONS: OnabotulinumtoxinA adds a potential option to the limited therapeutic alternatives available in hemicrania continua.

SUNCT, SUNA and trigeminal neuralgia: different disorders or variants of the same disorder?

PURPOSE OF REVIEW: Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), short-lasting unilateral neuralgiform headache attacks with autonomic symptoms (SUNA) and trigeminal neuralgia are considered different disorders, thus grouped in separate sections of the International Classification of Headache Disorders 3 beta. However, the clinical, radiological and therapeutic overlap between SUNCT, SUNA, and trigeminal neuralgia has challenged this traditional view. This review summarizes the available clinical and pathophysiological evidence on whether SUNCT, SUNA and trigeminal neuralgia should be considered separate entities or variants of the same disorder. RECENT FINDINGS: Data on the clinical phenotype and effective management strategies in SUNCT and SUNA syndromes have shown striking similarities with trigeminal neuralgia. Moreover, studies exploring radiological findings supported the hypothesis of common aetiological and pathophysiological basis between SUNCT/SUNA and trigeminal neuralgia. However, a limitation of most studies is that they have included small samples of patients and therefore any conclusions need to be drawn cautiously. SUMMARY: Despite being considered distinct conditions, emerging clinical and radiological evidence supports a broader nosological concept of SUNCT, SUNA, and trigeminal neuralgia. These conditions may constitute a continuum of the same disorder, rather than separate clinical entities. Further evidence is required to shed light on this nosological issue, given its potential impact on clinical practice and further research studies in this area.

Migraine is underdiagnosed and undertreated.

Migraine is a common neurovascular disorder characterised by attacks of head pain that are typically unilateral and often described as severe and throbbing in association with nausea and sensitivity to sensory input, i.e. light, sound and head movement. The headaches typically last 4-72 hours, up to 31% of migraineurs have aura on some occasions. Migraine is commonly episodic. With an increasing intake of painkillers, patients often complain of an escalation of migraine attacks or a transformation to a chronic daily background pain with exacerbations. Acute painkiller use, both prescription and OTC, should be enquired about in all cases and medication overuse headache suspected and managed if patients are taking any acute painkiller excessively. Migraineurs should be encouraged to have regular habits. Regular sleep, exercise, meals, work habits and relaxation will be rewarded by a reduction in headache frequency. NICE guidelines recommend adopting the stepped-down approach to management. They suggest a combination of a triptan, NSAID or paracetamol, and an anti-emetic taken as early as possible during the headache. The decision to commence a preventative agent should depend on a combination of attack frequency, duration and severity, as well as response to abortive therapy and patient preference.

SUNCT and SUNA: medical and surgical treatments.

Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA) are rare and often disabling primary headache disorders. Their management can be challenging. The abortive therapies are not generally useful as the attacks are relatively short lasting. A myriad of pharmacological preventive treatments have been tried in single case reports or small series in an open-label fashion. Lamotrigine, as an oral preventive treatment, and lidocaine, as an intravenous transitional treatment, seem to be the most effective therapies. For medically intractable chronic forms of SUNCT and SUNA, several surgical approaches have been tried. These include ablative procedures involving the trigeminal nerve or the Gasserian ganglion, microvascular decompression of the trigeminal nerve, and neurostimulation techniques. This review provides an overview of the current pharmacological and surgical options for SUNCT and SUNA syndromes.

The red ear syndrome.

Red Ear Syndrome (RES) is a very rare disorder, with approximately 100 published cases in the medical literature. Red ear (RE) episodes are characterised by unilateral or bilateral attacks of paroxysmal burning sensations and reddening of the external ear. The duration of these episodes ranges from a few seconds to several hours. The attacks occur with a frequency ranging from several a day to a few per year. Episodes can occur spontaneously or be triggered, most frequently by rubbing or touching the ear, heat or cold, chewing, brushing of the hair, neck movements or exertion. Early-onset idiopathic RES seems to be associated with migraine, whereas late-onset idiopathic forms have been reported in association with trigeminal autonomic cephalalgias (TACs). Secondary forms of RES occur with upper cervical spine disorders or temporo-mandibular joint dysfunction. RES is regarded refractory to medical treatments, although some migraine preventative treatments have shown moderate benefit mainly in patients with migraine-related attacks. The pathophysiology of RES is still unclear but several hypotheses involving peripheral or central nervous system mechanisms have been proposed.

Managing patients with cluster headache in primary care.

Cluster headache is a strictly unilateral headache that occurs in association with cranial autonomic features. Although it can begin at any age, the most common age of onset is in the third or fourth decade of life. The diagnosis is purely clinical and it is therefore crucial to take a good history looking for its distinctive features. Although cluster attacks are unilateral, they may alternate sides. Pain is excruciating and located mainly around the orbital and temporal regions though any part of the head may be affected. Attacks have an abrupt onset and offset and usually last around 45-90 minutes but can range from 15 minutes to three hours. Attack frequency generally varies from one every other day to three a day, although the International Headache Society criteria state there may be up to eight attacks a day. The key feature of cluster headache is the presence of at least one cranial autonomic symptom during an attack. Alcohol, physical exertion, warm environments, sleep and the smell of volatile substances can all trigger acute attacks. The majority of patients will have episodic cluster headache with recurrent bouts separated by remission periods of more than a month. The remaining 10-20% have chronic cluster headache and no significant remission periods over the course of a year. Specialist advice should be sought at first presentation for confirmation of diagnosis, development of a plan for managing current and future cluster bouts and where first-line treatments fail.

Supportive Self-Management Program for People With Chronic Headaches and Migraine: A Randomized Controlled Trial and Economic Evaluation.

BACKGROUND AND OBJECTIVES: Chronic headache disorders are a major cause of pain and disability. Education and supportive self-management approaches could reduce the burden of headache disability. We tested the effectiveness of a group educational and supportive self-management program for people living with chronic headaches. METHODS: This was a pragmatic randomized controlled trial. Participants were aged 18 years or older with chronic migraine or chronic tension-type headache, with or without medication overuse headache. We primarily recruited from general practices. Participants were assigned to either a 2-day group education and self-management program, a one-to-one nurse interview, and telephone support or to usual care plus relaxation material. The primary outcome was headache related-quality of life using the Headache Impact Test (HIT)-6 at 12 months. The primary analysis used intention-to-treat principles for participants with migraine and both baseline and 12-month HIT-6 data. RESULTS: Between April 2017 and March 2019, we randomized 736 participants. Because only 9 participants just had tension-type headache, our main analyses were on the 727 participants with migraine. Of them, 376 were allocated to the self-management intervention and 351 to usual care. Data from 586 (81%) participants were analyzed for primary outcome. There was no between-group difference in HIT-6 (adjusted mean difference = -0.3, 95% CI -1.23 to 0.67) or headache days (0.9, 95% CI -0.29 to 2.05) at 12 months. The Chronic Headache Education and Self-management Study intervention generated incremental adjusted costs of £268 (95% CI, £176-£377) (USD383 [95% CI USD252-USD539]) and incremental adjusted quality-adjusted life years (QALYs) of 0.031 (95% CI -0.005 to 0.063). The incremental cost-effectiveness ratio was £8,617 (USD12,322) per QALY gained. DISCUSSION: These findings conclusively show a lack of benefit for quality of life or monthly headache days from a brief group education and supportive self-management program for people living with chronic migraine or chronic tension-type headache with episodic migraine. TRIAL REGISTRATION INFORMATION: Registered on the International Standard Randomized Controlled Trial Number registry, ISRCTN79708100 16th December 2015 doi.org/10.1186/ISRCTN79708100. The first enrollment was April 24, 2017. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that a brief group education and self-management program does not increase the probability of improvement in headache-related quality of life in people with chronic migraine.

Coexistence of hemiplegic migraine with SUNCT or SUNA: a case series.

BACKGROUND: Hemiplegic migraine (HM) is a rare subtype of migraine with aura that includes transient hemiparesis of different degrees. The dominantly inherited type, called familial hemiplegic migraine, along with the sporadic type, in which no family history of similar attacks exists, have been recently recognized by the revised International Classification of Headache Disorders (ICHD-2). Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA) are also very rare conditions that are classified as trigeminal autonomic cephalalgias. This report provides the first description of an association between HM and SUNCT/SUNA. CASES: Eight females and two males with both these disorders were identified between 2007 and 2010. CONCLUSION: The coexistence of such rare primary headache disorders is probably due to a common underlining mechanism, with a sodium channelopathy being an attractive potential candidate.

Bilateral paroxysmal cephalalgia: a novel indomethacin-responsive primary headache syndrome?

INTRODUCTION: Paroxysmal hemicrania (PH) is a primary headache disorder characterised by frequent, short-lasting, very severe, strictly unilateral attacks occurring in association with cranial autonomic features. A striking feature of this disorder is its clear response to indomethacin. CASE REPORT: In contrast to this stereotypic presentation, we describe a man with indomethacin-responsive headaches that have a temporal profile similar to that of PH but whose attacks have a bilateral distribution without associated cranial autonomic features. DISCUSSION: There have been several case reports of patients presenting with short-lasting, frequent, bilateral headaches responding to indomethacin, without cranial autonomic features. These cases have been described as representing bilateral PH although strict unilaterality of pain and cranial autonomic phenomena are cardinal features of PH. These cases may represent a novel indomethacin-responsive syndrome and therefore, for now, should be studied separately from PH until their pathophysiological basis is better understood.