Diagnosing primary headache disorders: ‘Everything is migraine unless it isn’t’

Diagnosing primary headache disorders through a close examination of patient history 

Primary headache disorders classified by the 3rd edition of the International Classification of Headache Disorders (ICHD-3) include migraine, tension-type headache, and trigeminal autonomic cephalalgias (TACs).² Secondary headache is described as a new headache occurring in close temporal relation to another disorder known to cause headache, or fulfilling other criteria for causation by the underlying disorder.² To aid in diagnosing primary headache, Dr. O’Brien recommended using an algorithm that starts with close evaluation of patient history and a thorough clinical examination. In her opinion, obtaining a thorough history is key for diagnosing headache, and this should include the history of present illness (HPI) such as temporal pattern, location, description of the pain, associated features, and precipitating factors—as well as past medical history (PMH) including comorbid conditions. Dr. O’Brien also stressed the importance of interrogating family and social history including heritability and health/lifestyle changes, as well as a detailed physical examination with attention to extracranial structures.

Expensive testing and imaging may be unnecessary unless there are red flags

In terms of diagnostics for primary headache, Dr. O’Brien covered many options including cerebrospinal fluid (CSF) analysis, testing for inflammatory markers, head computed tomography (CT) to rule out acute stroke, and brain magnetic resonance imaging (MRI) for patients with abnormal neurological examination results. However, she stressed that unless ‘red flag’ signs and symptoms are identified through their use, expensive testing and imaging are often not required for an accurate diagnosis and can lead to confusion, miscommunication, and further unnecessary tests. 

Dr. O’Brien claimed that red flags can include an abnormal neurological exam or atypical or complex aura, and she finds a particular pneumonic to be helpful in identifying possible underlying pathological conditions that might require neuroimaging. The SNOOP pneumonic accounts for systemic signs/symptoms, secondary risk factors, neurological symptoms, onset, older age, positional, prior, papilledema, and precipitated by Valsalva.³ For Dr. O’Brien, SNOOP is a useful tool for differential diagnosis. 

Tips on diagnosing migraine

Though several primary headache disorders exist, Dr. O’Brien stressed that migraine accounts for 90% of headache complaints in the clinic. While reviewing the ICHD-3 diagnostic criteria for migraine with and without aura, Dr. O’Brien highlighted that predictors of migraine known as ‘PIN’ (photophobia, impairment/intensity, and nausea) provide a positive predictive value for migraine diagnosis of 93% if two out of three symptoms are present. She also noted that migraine headache in children and adolescents is more often bilateral and frontotemporal compared with what is seen in adults and can have other unique characteristics. In closing, Dr. O’Brien emphasized the importance of noticing changes in clinical clues, explaining a case study in which a patient with history of migraine with visual aura was later diagnosed with comorbid functional neurological disorder (FND) upon presenting new symptoms.

Toward efficient and accurate diagnosis of primary headache disorders

For Dr. O’Brien, the use of ICHD-3 criteria is key for accuracy in diagnosing headache disorders—however, she stressed that expensive testing and neuroimaging are not always required if there are no red flags. She highlighted that the scarcity of headache specialists around the world represents a huge unmet need and voiced her hope for more healthcare professionals to join her in improving the lives of patients living with headache.