Secondary Headache Red Flags
Secondary Headache Red Flags
What You'll Learn
- SNNOOP10 mnemonic (Do 2019): Systemic symptoms; Systemic disease (Neoplasm, HIV); Neurologic signs/symptoms; Onset sudden (thunderclap); Older age (>50); Pattern change/Progressive; Positional; Precipitated by Valsalva; Papilledema; Painful eye with autonomic features; Posttraumatic onset; Pathology of the immune system (HIV); Painkiller overuse/new drug at onset
- Thunderclap headache: SAH until proven otherwise; non-contrast CT approaches 100% sensitivity within 6 hours when read by an expert neuroradiologist on a modern multidetector scanner in a neurologically intact patient (Perry 2011); LP for xanthochromia if CT negative or if clinical suspicion persists despite a negative CT
- IIH: papilledema + elevated OP (>25 cm H2O) + normal MRI; acetazolamide first-line (IIHTT: 500 mg BID); MRI brain with venography (or CT/CTV when MRI unavailable) is required to exclude CVT and structural causes before LP-based IIH diagnosis
- SIH: orthostatic headache, diffuse pachymeningeal enhancement, brain sagging — “SEEPS” mnemonic; epidural blood patch if conservative measures fail
- Post-traumatic: new headache within 7 days of trauma; persistent if >3 months; treat based on phenotype it resembles
- Pregnancy/postpartum: always exclude CVT, preeclampsia, RCVS, PRES, pituitary apoplexy
- New headache >50 yr: GCA, mass lesion, or subdural hematoma until proven otherwise — ESR + CRP + temporal artery biopsy (≥1–2 cm); jaw claudication = strongest predictor
HighYield Pearls
- SNNOOP10 red flags: Systemic symptoms/disease (fever, HIV, cancer) + Neurologic signs + Onset sudden (thunderclap, <1 min to peak) + Older age (>50) + Pattern change/Progressive/Positional/Precipitated by Valsalva/Papilledema/Painful eye + autonomic/Posttraumatic/Pathology immune/Painkiller overuse
- Thunderclap = "worst headache of life" peaks within 60 sec → non-contrast CT FIRST (near-100% sensitive within 6 hr), then LP for xanthochromia if CT negative; DDx: SAH > RCVS > CVT > carotid/vertebral dissection > pituitary apoplexy > SIH > PRES
- GCA: age >50 + new HA + jaw claudication + scalp tenderness + vision change (AION/amaurosis) → ESR + CRP urgent; temporal artery US (halo sign) or biopsy; START HIGH-DOSE STEROIDS IMMEDIATELY — don’t wait for biopsy (prevents blindness); tocilizumab steroid-sparing
- IIH (pseudotumor): young obese woman + HA + transient visual obscurations + pulsatile tinnitus + papilledema; LP OP >25 cm H2O with normal CSF; MRI/MRV: empty sella, posterior globe flattening, optic nerve tortuosity, transverse sinus stenosis; treat weight loss + acetazolamide; optic nerve sheath fenestration or shunt if vision threatened
- Spontaneous intracranial hypotension (CSF leak): orthostatic HA (worse upright, better supine); MRI — pachymeningeal enhancement + brain sag + tonsillar descent + subdural collections; epidural blood patch; CT myelogram to localize leak
- Pituitary apoplexy: sudden severe HA + ophthalmoplegia (CN III/IV/VI) + visual loss (chiasm) + altered consciousness + adrenal insufficiency → IV hydrocortisone STAT; transsphenoidal decompression if vision compromised
- RCVS: recurrent thunderclap HA over days–weeks ± seizures/stroke; precipitants — vasoactive drugs (cocaine, SSRIs, cannabis, sympathomimetics), postpartum, surgery; "string of beads"/segmental vasoconstriction on CTA/MRA resolves ≤12 wk; nimodipine; STEROIDS WORSEN
- PRES: HA + visual changes + seizures + altered mental status; vasogenic edema parieto-occipital on FLAIR (bilateral, symmetric); triggers HTN, eclampsia, calcineurin inhibitors, chemo; treat trigger — usually reversible
- CVT: subacute HA + papilledema + focal deficit/seizures; OCP/pregnancy/postpartum/thrombophilia; CTV or MRV ("empty delta sign"); anticoagulate even with hemorrhagic infarct
- Meningitis/encephalitis: fever + meningismus + altered mental status — LP after CT if focal signs/papilledema; empiric antibiotics + acyclovir; dexamethasone before/with first dose for suspected bacterial meningitis
🔍 Quick ReferenceRed-flag pattern · Imaging / workup · Specific syndromes
Red-flag headache pattern
- Thunderclap, "worst headache of my life," peaks <60 sec → SAH / RCVS / dissection / CVT / pituitary apoplexy
- Orthostatic HA (worse upright, better supine) → spontaneous intracranial hypotension (CSF leak)
- Worse with bending / Valsalva / cough → raised ICP, posterior fossa mass, Chiari, IIH
- Woke from sleep / worse in AM → raised ICP (mass, hydrocephalus)
- Progressive over weeks → tumor, CVT, abscess, chronic SDH
- Fever + neck stiffness → meningitis/encephalitis
- Jaw claudication + scalp tenderness + vision change → giant cell arteritis
- Pulsatile tinnitus + obesity + transient visual obscurations → IIH
- First/worst headache >50 yr → GCA, mass, SDH until proven otherwise
- Postpartum thunderclap → RCVS > CVT > eclampsia/PRES
- Post-trauma HA → subdural, dissection, post-traumatic HA
- Sex/exertion-triggered thunderclap → RCVS (also primary cough/exertional HA after exclusion)
- Pregnancy + HA → eclampsia, CVT, RCVS, PRES, pituitary apoplexy
- HIV / cancer / immunosuppression + new HA → opportunistic CNS infection, lymphoma, metastases
Imaging / workup
- Non-contrast CT first for thunderclap → near-100% sensitive for SAH within 6 hr
- LP if CT negative → xanthochromia detectable by 12 hr post-bleed
- CTA neck/head → arterial dissection, RCVS, aneurysm
- MRV / CTV; "empty delta sign" on contrast CT → cerebral venous sinus thrombosis
- "String of beads" segmental vasoconstriction on CTA/MRA, resolves ≤12 wk → RCVS
- Halo sign on temporal artery ultrasound → GCA
- ESR >50 + CRP elevated → GCA (urgent)
- FLAIR vasogenic edema parieto-occipital (bilateral, symmetric) → PRES
- Empty sella + posterior globe flattening + optic nerve tortuosity + transverse sinus stenosis → IIH
- Diffuse pachymeningeal enhancement + brain sag + tonsillar descent → spontaneous intracranial hypotension
- SAH location clue → convexity/cortical = RCVS, amyloid, CVT cortical vein; basal cisterns = aneurysmal; perimesencephalic = benign nonaneurysmal
- Biconcave (crescent) hyperdensity crossing sutures → subdural hematoma
- Biconvex (lentiform) hyperdensity, doesn’t cross sutures → epidural hematoma (middle meningeal artery)
Specific syndromes / pearls
- Giant cell arteritis → age >50, ESR >50, jaw claudication, AION, halo sign US — START STEROIDS, don’t wait for biopsy; tocilizumab steroid-sparing
- IIH (pseudotumor cerebri) → young obese woman + papilledema + OP >25 + acetazolamide + weight loss; optic nerve sheath fenestration if vision threatened
- Spontaneous intracranial hypotension → orthostatic HA + brain sag + pachymeningeal enhancement + epidural blood patch
- Pituitary apoplexy → sudden HA + ophthalmoplegia + visual loss + adrenal crisis — hydrocortisone STAT + transsphenoidal decompression
- Trigeminal neuralgia → V2/V3 paroxysms triggered by light touch/chewing; image to exclude MS, posterior fossa lesion, neurovascular conflict (SCA loop); carbamazepine/oxcarbazepine first-line; microvascular decompression if refractory
- Thunderclap differential → SAH / RCVS / CVT / dissection / pituitary apoplexy / spontaneous low CSF / PRES
- Postpartum thunderclap differential → RCVS > CVT > eclampsia / PRES
- Nummular headache → coin-shaped, fixed, focal scalp pain (small well-circumscribed area)
- New daily persistent headache (NDPH) → exclude secondary causes first (CVT, low CSF, GCA) before labeling primary
Red Flag Assessment — SNNOOP10 (Do 2019)
SNNOOP10 Mnemonic
- S — Systemic symptoms: fever, weight loss, night sweats
- S — Systemic disease: known neoplasm, HIV, immunosuppression
- N — Neurologic signs/symptoms: focal deficits, altered consciousness, seizures, meningismus
- N — Neoplasm history: brain metastases, leptomeningeal disease (subsumed under systemic disease)
- O — Onset sudden: thunderclap headache (<1 min to peak intensity)
- O — Older age: new or progressive headache >50 yr → GCA, mass lesion, subdural hematoma
- P — Pattern change / Progressive: escalating frequency or severity, new headache type
- P — Positional: orthostatic (SIH) or recumbent-worse (elevated ICP)
- P — Precipitated by Valsalva: cough, exertion, sex → posterior fossa lesion, Chiari, IIH
- P — Papilledema: IIH, CVT, mass lesion
- P — Painful eye with autonomic features: cluster, dissection, cavernous sinus pathology, acute angle-closure glaucoma
- P — Posttraumatic onset: headache within 7 days of trauma; subdural, post-traumatic headache
- P — Pathology of the immune system (HIV): opportunistic CNS infection, primary CNS lymphoma
- P — Painkiller overuse / new drug at onset: medication overuse headache; vasoactive or other inciting agent
Red Flags → Diagnosis → Workup
| Red Flag | Suspected Diagnosis | Workup |
|---|---|---|
| Thunderclap onset (<1 min) | SAH, CVT, RCVS, dissection | CT head → LP → CTA/MRA |
| Fever + meningismus | Meningitis/encephalitis | LP (emergent), blood cultures |
| Papilledema | IIH, mass lesion, CVT | MRI + MRV → LP with OP |
| New onset >50 yr | GCA, mass, SDH | ESR, CRP, MRI brain, temporal artery biopsy |
| Worse with Valsalva | Chiari, posterior fossa mass, IIH | MRI brain + craniocervical junction |
| Positional (orthostatic) | SIH | MRI brain with gadolinium → spine MRI/CT myelogram |
| Progressive over weeks | Mass lesion, chronic SDH, CVT | MRI brain with contrast + MRV |
| Pregnancy/postpartum | CVT, preeclampsia, RCVS, PRES | MRI/MRV, BP monitoring, urine protein |
| Immunocompromised | CNS infection, lymphoma, PML | MRI brain, LP (cytology, cultures, PCR) |
| Systemic cancer + new headache | Brain metastases, leptomeningeal disease | MRI brain with contrast, LP cytology |
💎 Board Pearl
- Any “worst headache of my life” or headache reaching peak intensity in <1 minute = thunderclap → must rule out SAH regardless of other features
Continue reading — sign in
The full note has more clinical pearls, tables, and board-focused tips. Free account, no fee.