Confirm the Diagnosis First: Secondary-Headache Red Flags Before You Inject

Screening for secondary headache red flags is not an optional refinement on therapeutic neurotoxin practice. It is the part of the workflow that determines whether a patient gets a diagnosis or gets an injection, and it is the only part where getting it wrong can cost someone their life rather than their money.

Remember that we always evaluate headaches. If a patient comes to you carrying a diagnosis of migraine from a neurologist or a primary care physician, and they have had the appropriate workup, then we can go to treatment. What we do not do is treat a headache we have not confirmed, because other things cause headaches: vascular anomalies including aneurysms, structural lesions both benign and malignant, and inflammatory conditions that are not migraine at all. Injecting a neurotoxin is not a substitute for a workup.

This article exists because an aesthetic practice is a structurally dangerous place for an undiagnosed secondary headache to arrive. We are configured to say yes. We convert consultations, we schedule quickly, and we are used to treating on the patient's account of the problem. Every one of those habits is correct in aesthetics and wrong here.

Use a published framework, not a personal list

I could give you my list. So could every experienced injector, and every list would be slightly different and none would be auditable. Use a published one instead.

The SNNOOP10 list, developed by an international group and published in Neurology, is the most usable framework for a non-neurologist. It replaced older, shorter mnemonics with a systematic screen of red and orange flags, each tied to the secondary conditions it raises (Do TP, Remmers A, Schytz HW, et al. Red and orange flags for secondary headaches in clinical practice: SNNOOP10 list. Neurology. 2019;92(3):134–144).

The fifteen flags, and what each is pointing at:

1. Systemic symptoms including fever — bacterial or viral meningitis, encephalitis, brain abscess; also vasculitis, rheumatic and other inflammatory disease
2. Neoplasm in history — intracranial metastasis
3. Neurologic deficit, including decreased consciousness — intracranial haemorrhage, ischaemic stroke, mass lesion, infection
4. Onset that is sudden or abrupt (thunderclap) — subarachnoid haemorrhage above all, plus cerebral venous thrombosis, intracranial hypotension, reversible cerebral vasoconstriction syndrome
5. Older age (onset after 65) — a markedly higher base rate of serious secondary causes, including giant cell arteritis and stroke
6. Pattern change, or recent onset of a new headache — cerebral venous thrombosis, tumour, metastasis
7. Positional headache — intracranial hypotension, usually from a spinal CSF leak
8. Precipitated by sneezing, coughing or exercise (Valsalva) — Chiari malformation type 1 and posterior fossa lesions
9. Papilledema — raised intracranial pressure, intracranial mass
10. Progressive headache and atypical presentation — cerebral venous thrombosis, evolving mass lesion
11. Pregnancy or puerperium — hypertensive disorders, pituitary apoplexy, venous thrombosis
12. Painful eye with autonomic features — orbital, parasellar and posterior fossa pathology, carotid dissection
13. Post-traumatic onset — haemorrhage, dissection, post-traumatic headache
14. Pathology of the immune system, such as HIV — opportunistic infection, lymphoma
15. Painkiller overuse, or a new drug at headache onset — medication-overuse headache, or drug-induced headache

Print it. Put it in the intake. Screening every new headache patient against the list systematically is the point — the authors' own conclusion is that using it "will presumably increase the likelihood of detecting a secondary cause."

Be honest about what the framework is and is not

The same paper is candid that the evidence underneath red flags is thinner than their ubiquity suggests. Most red flags derive from clinical experience and case series, which establishes sensitivity but leaves specificity and predictive value largely unknown. The authors call for large prospective studies and note that a validated screening tool does not yet exist. They also state plainly that "it is not possible to detect every secondary headache with standard neuroimaging or laboratory tests."

So this is a screen that raises your index of suspicion. It is not a rule-out, and a clean SNNOOP10 does not convert an unconfirmed headache into a confirmed migraine. It only tells you that nothing has jumped out at a clinician who is not the one responsible for the diagnosis.

The flags most likely to reach an aesthetic practice, and the numbers behind them

Some of these fifteen will essentially never present to you. Others will, and it is worth knowing the arithmetic so you can weigh them properly.

Thunderclap onset

ICHD-3 defines thunderclap headache as a high-intensity headache reaching maximum intensity in under a minute. Both elements are required — abruptness and severity — so not every acute headache qualifies.

In a large multicentre emergency-department cohort of 2,131 patients with acute headache peaking within an hour and no neurologic deficits, subarachnoid haemorrhage was identified in 6.2%. A separate prospective study identified SAH in 25% of 148 thunderclap episodes, and in half of those cases the headache was the only symptom. The term sentinel headache describes an attack occurring before aneurysmal rupture, and a systematic review put its incidence before SAH at 10–43% (Do TP et al., 2019).

This is exactly the "vascular anomaly, aneurysm" category, and it is the reason a history question about the worst and most sudden headache of a patient's life belongs in your intake regardless of how chronic the current pattern is.

Pattern change or recent onset

This is the flag most relevant to a practice that sees chronic headache patients, and its numbers are sobering. In a prospective population-based study of 100 adults with recent-onset new headache or a change in pattern of an existing headache, intracranial lesions were found in 21%, and 62% of those patients had a normal neurologic examination (Do TP et al., 2019).

Read that twice. A normal neuro exam in a patient whose headache pattern has recently changed is not reassurance. Two-thirds of the ones with a lesion examined normally.

In a series of thirty patients diagnosed with cerebral venous thrombosis, 40% had headache as their only symptom, and the diagnosis in that isolated-headache group was delayed by roughly twice as long.

Neoplasm in history

The risk of finding a brain tumour in a headache patient with no history of neoplasm is under 0.1%. In a patient with a cancer history, it is a different problem entirely: in one study of oncology patients presenting with a newly developed headache, 32% of 68 had intracranial metastases; in a similar study, 54% of 54 did. The paper's recommendation is unambiguous — every oncology patient with a newly developed headache should undergo MRI.

Accompanying features that raise the concern further: emesis, headache duration of ten weeks or less, an atypical headache pattern, pulsating quality with moderate-to-severe intensity, gait instability, and an extensor plantar response.

Papilledema

A high proportion of patients found to have papilledema have serious underlying pathology, and in a retrospective series of 74 paediatric patients with primary brain tumours, 38% presented with papilledema. The counterweight is that papilledema is over-called: in a prospective study of 34 paediatric patients initially suspected of having it, only two actually did — the rest had pseudo-papilledema or a normal variant, and optic nerve head drusen has been mistaken for it in adults.

Practical reading: if you cannot perform and interpret fundoscopy confidently, the correct move is not to guess. It is to refer for an examination by someone who can.

Positional headache

A headache that comes on within seconds of standing and resolves quickly on lying flat suggests low CSF pressure. Spontaneous intracranial hypotension has an annual incidence of about 5 per 100,000 and is usually caused by a spinal-level CSF leak. Two traps: the orthostatic character can fade in chronic cases, and many migraine patients report worsening with physical activity, which mimics it — the discriminator is that migraine worsening is not expected to resolve on lying down.

Valsalva-precipitated headache

Secondary cough headache is associated with Chiari malformation type 1 in 40% of cases, and posterior fossa lesions account for roughly a further 15%. Ask the question. It takes four seconds and almost nobody asks it.

Age, pregnancy and immune status

Onset after 65 raises the base rate substantially — one record review found a serious secondary cause in 15% of patients aged 65 and over presenting with headache, versus 1.6% in a younger group. Pregnancy and the puerperium carry elevated risk from hypertensive disorders (roughly half of secondary headaches in that population) and pituitary adenoma or apoplexy. Immunosuppression changes the differential toward infection and lymphoma.

Mapping Dr. Croley's three categories onto the framework

In teaching this I describe three things that must be excluded before a headache becomes a treatment plan, and each maps onto the framework above.

Vascular anomalies, including aneurysms. Screened by thunderclap onset, sentinel headache history, neurologic deficit, and the age and pregnancy flags. The sentinel headache is the one worth asking about by name, because a patient will not volunteer "I had one appalling headache eight months ago that went away."

Structural changes — benign or malignant masses within the brain. Screened by neoplasm history, papilledema, pattern change or recent onset, progressive course, and neurologic deficit. The 21% figure above is the one that should govern your threshold.

Inflammatory conditions outside migraine. Screened by systemic symptoms and fever, older age, and immune-system pathology. Giant cell arteritis in the over-65 patient is the classic miss in a practice that sees a lot of foreheads and temples.

The examination you can realistically do — and its limits

You are not being asked to run a neurology clinic. You are being asked to do a competent screen and to know its edges.

What is reasonable in an aesthetic or therapeutic injection practice: a structured red-flag history taken against a written list; blood pressure; a basic cranial nerve and gross motor screen; assessment of neck stiffness; palpation for temporal artery tenderness in an older patient; and fundoscopy if — and only if — you perform it competently.

What is not reasonable: deciding on the basis of that screen that a patient who has never been worked up does not need one. The screen tells you when to escalate urgently. It does not confer a diagnosis. The diagnosis comes from a clinician with the training and the imaging to make it, and your role is to insist that it exists before you open a vial.

Note also that a normal examination carries far less reassurance here than injectors expect — the 62% figure above is the reason.

The patient who was controlled and stops being controlled

This is the scenario I most want injectors to have a rule for, because it looks like a treatment problem and behaves like a diagnostic one.

You have a patient doing well. Their headaches are much better as long as they are getting their neurotoxin. Then one cycle, they are not. The frequency climbs, or the character shifts, or the location moves, or a new symptom appears.

The reflex in an aesthetic practice is to treat that as inadequate dosing — go up, add sites, shorten the interval. Do not start there. If they were controlled and they are no longer controlled, that is the point at which we consider sending them back for further evaluation, imaging, or workup from their neurologist.

This is SNNOOP10 flag number six operating inside an established diagnosis. Pattern change in a previously stable headache patient is exactly the presentation the framework is built to catch, and the fact that the patient already carries a migraine diagnosis does not immunise them against developing something else. A patient can have chronic migraine and an aneurysm. The first diagnosis is not protective.

Build it into your protocol as an explicit stopping rule: a documented change in headache pattern, character, location or associated symptoms triggers a referral before it triggers a dose change.

What "refer" should mean, concretely

Referral in this setting is not one action, it is three, and the triage matters.

Emergency, same day. Thunderclap onset. New neurologic deficit or decreased consciousness. Headache with fever and neck stiffness. Papilledema with visual symptoms. Post-traumatic headache with deterioration. These go to an emergency department, not into next week's clinic list.

Urgent, days. New or changed pattern in a patient over 65. New headache in a patient with a cancer history. Progressive headache. Positional or Valsalva-triggered headache. New headache in pregnancy or in an immunocompromised patient. These need evaluation and usually imaging, ahead of any injection.

Routine, before treatment. An unconfirmed diagnosis with no active red flags. The patient is not in danger this week, but they are also not a candidate until somebody qualified has made the diagnosis and documented the workup.

In all three, say the reason out loud and write it down. "I am not treating today because your headache pattern has changed and that needs to be evaluated first" is a sentence patients accept far more readily than injectors expect.

Document the negative screen

If you screened and found nothing, that is a clinical finding and it belongs in the record. Note the framework you used, the flags you asked about, the examination you performed, the diagnosis and workup you relied on and who made it, and the date. A blank space in the chart is indistinguishable from never having asked.

For a related piece on recognising a different kind of emergency at the chairside, see Empire's review of whether Botox can cause blindness.

This screening framework reflects Dr. Chris Croley's clinical practice as taught in Empire Medical Training's hands-on curriculum, supplemented by the published SNNOOP10 list and its supporting data. Screening is not diagnosis. This article is educational and is not a substitute for training or for evaluation by a clinician qualified to diagnose headache disorders.

Related guides in this cluster

Part of Therapeutic Neurotoxin: Chronic Migraine.

Clinical GuideChronic Migraine On-Label Criteria: Deciding Which Patients Actually QualifyChronic migraine criteria decide who you can treat on-label. The label wording, the ICHD-3 definition, the diary, and the documentation Clinical GuideThe PREEMPT Protocol: Why Fixed-Site, Fixed-Dose Was the Trial Design, and What It Means in PracticeThe PREEMPT protocol is fixed-site, fixed-dose for a reason. What the trial design was, why the label is rigid, and where tailoring is Clinical GuideMigraine Treatment Outcome Measures vs Aesthetic Endpoints: Two Assessment FrameworksMigraine treatment outcome measures are disease burden, not movement. The four domains to record, the responder thresholds to pick, and