Headache Investigations

Investigations

Non-Contrast Computed Tomography (CT) Brain

• Consider if the patient has:
  • Sudden onset severe headache that reaches maximal severity within one hour.
  • Headache with ≥1 of the following red flags:
    • Increasing frequency or severity
    • Fever or neurological deficit
    • History of cancer or immunocompromise
    • Older age (>50 years) of onset
    • Post-traumatic onset
  • Headache with new onset or pattern during pregnancy or peripartum period
  • Headache with features of intracranial hypertension (e.g., papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva).

MRI Brain

• Consider if the patient:
  • Headache with features of intracranial hypertension (e.g., papilloedema, pulsatile tinnitus, visual symptoms worse on Valsalva).
  • Headache with features of intracranial hypotension (e.g., positional, worse when upright, better when lying down).
  • Headache with new onset or pattern during pregnancy or peripartum period.
  • Headache with one or more of the following red flags:
    • Increasing frequency or severity
    • Fever or neurological deficit
    • History of cancer or immunocompromise
    • Older age (>50 years) of onset, or post-traumatic onset.
  • New primary headache of suspected trigeminal autonomic origin.

Lumbar Puncture (LP)

• Order an LP after a negative CT without contrast:
  • If the patient has the worst headache of their life, or a ‘thunder-clap headache’ (SAH)
  • If the patient has a fever (brain abscess, meningitis, encephalitis)
  • If the patient has neck stiffness (SAH, meningitis)
  • If the patient is young, overweight, and female (sinus venous thrombosis, pseudotumor cerebri)
  • After negative CT when considering SAH, meningitis, pseudotumor cerebri.

Laboratory Tests

• Erythrocyte sedimentation rate, when considering giant cell arteritis
• ABG, when considering hypoxia or hypercapnia
• Carboxyhaemoglobin, when considering carbon monoxide poisoning
  • A pulse CO-oximeter may reveal elevated CO levels, but this test is not widely available.
• FBC and liver function tests are performed if pre-eclampsia is suspected. Urinalysis is also required in these patients.

Limit of Imaging

Limit of Imaging

SNOOP

• Systemic symptoms, illness, or condition (e.g., fever, weight loss, cancer, pregnancy, immunocompromised state including HIV)

• Neurologic symptoms or abnormal signs (e.g., confusion, impaired alertness or consciousness, papilledema, focal neurologic symptoms or signs, meningismus, or seizures)

• Onset is new (particularly for age >40 years) or sudden (e.g., “thunderclap”)

• Other associated conditions or features (e.g. head trauma, illicit drug use, or toxic exposure; headache awakens from sleep, is worse with Valsalva maneuvers, or is precipitated by cough, exertion, or sexual activity)

• Previous headache history with headache progression or change in attack frequency, severity, or clinical features.

Secondary Headache Source

• Impaired vision or seeing halos around light (glaucoma)

• Subacute angle closure glaucoma.

• Visual field defects (lesion of the optic pathway e.g. pituitary mass).

• Sudden, severe, unilateral vision loss (optic neuritis)

• Morning headache is nonspecific (primary headache syndrome, sleep apnea, chronic obstructive pulmonary disease, obesity hypoventilation syndrome)

• The presence of nausea, vomiting, worsening of headache with changes in body position (particularly bending over), an abnormal neurologic examination, and/or a significant change in prior headache pattern (tumor).

• Intermittent headaches with high blood pressure (pheochromocytoma).

MRI vs. CT

• Detecting edema

• Vascular lesions

• Intracranial pathology
  (posterior fossa)

• Available

• Urgent or Emergency care

• Concern for subarachnoid hemorrhage
  (thunderclap headache)