When is a migraine not a migraine?

If a patient with migraine develops a thunderclap headache or experiences a change in aura, is the cause a migraine or does the patient have a secondary headache? Not recognizing a secondary headache in a patient who has migraine is a major pitfall in migraine diagnosis. Tips to aid accurate diagnosis were described by Professor Kathleen Digre, University of Utah, UT at Virtual Scottsdale Headache Symposium 2020.

Circumstances increasing the risk of secondary headache

The SNOOP mnemonic red flags aid diagnosis of secondary headache

Migraine may mimic secondary headaches and secondary headaches mimic migraine, said Professor Digre. Diagnosis of a secondary headache in a patient who has migraine requires experience in recognizing patients with conditions that increase their risk of a secondary headache and use of appropriate imaging.

She highlighted the importance of using the SNOOP mnemonic red flags for secondary headache when evaluating patients to determine whether:1

  • the patient has Systemic symptoms or a systemic illness
  • the patient has Neurologic symptoms
  • the Onset was fast
  • the patient is Older than 50 years of age
  • there is an identifiable Pattern (e.g. first headache or change, precipitants, postural link, pregnancy)

Thunderclap headache is associated with secondary headaches that affect blood vessels

In addition, certain headache types are more prone to secondary headache disorder. For example, thunderclap headache—a severe pain with an abrupt onset reaching a maximum within 1 minute and lasting more than 1 minute2—is associated with secondary headaches that affect blood vessels, said Professor Digre.

It is also important to pay attention to aura, added Professor Digre. A transient ischemic attack (TIA) may be associated with aura. However, in contrast to the aura of migraine, the aura of a TIA is a negative symptom with loss of vision rather than a positive phenomenon such as bright lights; and it is abrupt in onset, unilateral and static. The sensory symptoms of a TIA are also negative (i.e. numbness) in contrast to the positive paresthesias associated with migraine.3

A transient ischemic attack may be associated with negative aura


When is neuroimaging indicated?

The American College of Radiology’s (ACR) 2019 guidance on neuroimaging for headache is that patients with headaches consistent with migraine who have a normal neurologic examination do not need neuroimaging,4 said Professor Digre. A 2020 systematic review by Evans et al. supports this guidance but adds that there should be no atypical features or SNOOP red flags.5

Neuroimaging is not necessary for headaches consistent with migraine and if neurologic examination is normal

The ACR further advises that patients with thunderclap or trigeminal headache, chronic not-improving headache, optic disc edema and other red flags such as trauma and malignancy should be investigated with computed tomography and/or magnetic resonance imaging.4

Neuroimaging may also be considered for presumed migraine for:

  • unusual, prolonged, or persistent aura
  • increasing frequency, severity, or change in migraine clinical features
  • first or worst migraine
  • migraine with brainstem aura
  • confusional migraine
  • hemiplegic migraine
  • late‐life migrainous accompaniments
  • migraine aura without headache
  • side‐locked migraine
  • post-traumatic migraine5

Our correspondent’s highlights from the symposium are meant as a fair representation of the scientific content presented. The views and opinions expressed on this page do not necessarily reflect those of Lundbeck.

  1. Dodick DW, et al. Semin Neurol 2010;30:74–81.
  2. Classification Committee of The International Headache Society. Cephalalgia 2018;1:1–211.
  3. Vongvaivanich K, et al. Cephalalgia 2015;35:894–911.
  4. Whitehead MT, et al. J Am Coll Radiol 2019:16:S364–377.
  5. Evans R, et al. Headache 2020;60:318–36.
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