Categorization
There are MANY primary and secondary causes of headache:

There are MANY causes of secondary intracranial headache:

Consider the SNNOOP10 mnemonic for headache red flags!
- S ystemic symptoms, including fever
- N eoplasm history
- N eurologic deficit
- O nset is sudden, abrupt
- O older age (onset >50 years)
- P ositional headache
- P attern change or recent onset of new headache
- P recipitated by sneezing, coughing
- P apilledema
- P rogressive headache
- P regnancy or puerperium
- P ainful eye, autonomic features
- P ost-traumatic onset
- P athology of immune system
- P ainkiller overuse
Evaluation
- Age, gender profession
- Duration of headache
- Location/ irradiation
- Intensity
- Qualitative characteristics
- What time of day does pain start and how long does it last
- What is the frequency of the headaches
- Triggering events, relieving and aggravating factors
- Related symptoms
- Medications and frequency of administration
HEADACHE with Systemic symptoms
- Many possibilities: fever, nuchal rigidity, altered mental status, photophobia, confusion, petechial rash, weight loss, etc.
Evaluation: Consider head CT, LP, blood cultures
DDx: bacterial meningitis, encephalitis, fungal meningitis, aseptic meningitis, autoimmune neurosarcoidosis, Behcet syndrome
Abrupt-onset HEADACHE
- Thunderclap headache that reaches maximal intensity within seconds to a minute
- Explosive and unexpected
- May have associated neurological deficits (e.g., hemiparesis, oculomotor deficits)
- Consider history of anticoagulant use or trauma, nausea, vomiting, or meningismus
Evaluation: Consider head CT, LP (xanthochromia?)
DDx: Subarachnoid hemorrhage, AVM rupture, aneurysm rupture, reversible cerebral vasoconstriction syndrome
Positional headache
- Headache with upright or sitting position
- Resolves with recumbency
- May be associated with tinnitus, vertigo, dizziness, nuchal rigidity/pain, unsteady gait, diaphoresis, anorexia, etc.
Evaluation: Consider MRI brain/spine, LP
DDx: Spontaneous hypotension headache, post-LP CSF leak, CSF shunt malfunction, cervicogenic, Chiari I malformation
HEADACHE Aggravated by coughing/sneezing
- Aggravated by valsalva, cough or bending over
- May be associated with nausea, vomiting, fever, worsening/progressive headache, focal neurological deficits, papilledema, new-onset seizures, fatigue, or cognitive dysfunction
Evaluation: Consider MRI brain (vs head CT), LP
DDx: Primary intracranial tumors, metastasis, abscesses, chronic subdural hematoma, ICP
New-onset headache in older patient
- Patients over 50 years or age
- May be associated with fever, fatigue, weight loss, jaw claudication, diplopia, or transient monocular vision loss
Evaluation: Consider temporal artery biopsy, head CT, color doppler ultrasound
DDx: Giant cell arteritis, trigeminal neuralgia, acute herpes zoster, post herpetic neuralgia
headache with Blurry vision
- Blurry vision has many forms: diplopia, vision loss, etc.
- May be associated with nausea, loss of coordination and balance, headaches upon waking early in the morning, or unilateral blurry vision/seeing halos
Evaluation: Consider fundoscopy, head CT, LP (elevated opening pressure?)
DDx: Pseudotumor cerebri, hydrocephalus, tumor, acute hypertension, glaucoma, cavernous sinus thrombosis
headache with Painful eye
- May have associated autonomic features (e.g., lacrimation, miosis, ptosis, rhinorrhea), conjunctival injection, vision loss, seeing halos
Evaluation: Consider fundoscopy, MRI brain
DDx: Optic neuritis, glaucoma, cluster headache, migraine, trigeminal autonomic cephalgia, Cavernous sinus thrombosis, draining AVM
Post-traumatic headache
- Any recent trauma or injury?
- May have associated confusion, loss of consciousness, memory loss, acute worsening
Evaluation: head CT vs MRI brain
DDx: Concussion syndrome, TBI
headache with Acute neck pain
- May have associated Horner’s syndrome or focal deficits
Evaluation: Consider CTA, MRA, Doppler
DDx: Cervical artery dissection (carotid dissection, vertebral artery dissection)
headache in the immunosuppressed patient
- May have associated low CD-4 count, photophobia, pain with eye movement, altered mental status, confusion, or focal deficits
Evaluation: head CT, MRI brain, LP
DDx: Cryptococcal meningitis, toxoplasmosis, JC virus, acute HIV encephalitis
headache in Pregnancy / postpartum
- Concerning features would include new onset, throbbing, diffuse (holocephalic), constant, blurry vision, photophobia, scotoma, diplopia, hemianopsia, focal deficits
Evaluation: BP, Cr, fundoscopy, MRI brain or CT head
DDx: Preeclampsia with severe features (includes HA), cerebral venous thrombosis, stroke
Case 1
24yo woman with history of IV drug use is admitted with shortness of breath and lower extremity edema. Overnight, she develops new onset headache and associated confusion.
- What are the red flags?
- What’s your DDx?
- What would you do next?
Case 2
45yo woman presents with sudden onset severe headache, 2 episodes of vomiting, and photophobia without neurological deficit. 10 days ago, she was evaluated for these exact symptoms and underwent non-contrast head CT (unremarkable) followed by an LP (also unremarkable). She then saw a neurologist in follow-up who subsequently diagnosed her with reversible cranial vasoconstriction syndrome (RCVS).
- What is your next step?
Case 3
24yo woman with homozygous factor V Leiden presents with sudden onset headaches after recently starting OCP.
- What is likely cause of her headache?
- What are the red flags?
- In what other patients would you be concerned about this presentation?
Blog post based on Med-Peds Forum talk by Cecilia Paasche, PGY1, and Tabitha N’dungu, PGY1