Headache

Basics

Description

  • A discomfort in the head, scalp, or upper neck due to activation of pain-sensitive structures, including the meninges, cranial blood vessels, and pericranial muscles
  • Arises from activation of pain-sensitive intracranial and extracranial structures via multiple pathophysiologic mechanisms
  • Pain transmission pathways:
    • Trigeminal nerve (CN V)
    • Cervical nerves (C1–C3)
  • Pain modulation pathway:
    • Enhances or suppresses pain perception through interneuronal mechanisms
    • Descending control from the periaqueductal gray (PAG), rostral ventromedial medulla (RVM), and spinal cord modulates pain signals at the dorsal horn and trigeminal nucleus
  • Primary headache:
    • Disorder that occurs without an underlying structural cause
    • Caused by dysfunction in pain modulation pathway
  • Secondary headache:
    • Disorder caused by an identifiable underlying pathology affecting pain-sensitive structures
  • Headache accounts for 2–4% of all ED visits:
    • 95% have a benign etiology (lower in patients >50 yr)
    • Primary headaches account for ∼90% of presentations
    • More common in females (∼3:1 ratio), particularly for migraines
    • Recurrent ED visits for headache are common (∼15–30% return within 6 mo)
    • Life-threatening etiologies are rare and can be difficult to diagnose

Etiology

Primary Headache

  • Migraine:
    • Throbbing headache, nausea, photophobia, phonophobia
    • May have aura, vertigo, stroke-like symptoms
  • Tension-type headache:
    • Bilateral, nonpulsatile, band-like pressure
    • Mild to moderate intensity, not worsened by activity
    • Triggered by stress, poor posture, anxiety, eye strain, or uncorrected vision
  • Cluster headache:
    • Unilateral, severe pain with autonomic symptoms (tearing, nasal congestion)
    • Short duration, recurrent in clusters over weeks
    • Triggered by alcohol, strong emotions, altered sleep habits

Secondary Headache

  • Thrombosis/vascular:
    • Subarachnoid hemorrhage (severe, thunderclap, possible syncope)
    • Cerebral venous sinus thrombosis (CVST)
    • Cranial artery dissection (neck pain, stroke symptoms)
    • Hypertensive encephalopathy (altered mental status, severe diastolic HTN)
    • Cerebellar stroke
  • Intracranial (traction, pressure):
    • Mass lesions
    • Idiopathic intracranial hypertension
    • Obstructive hydrocephalus
    • Intracranial hemorrhage
    • Chiari malformation
  • Extracranial (compression):
    • Occipital neuralgia
    • Cervicogenic headache
    • Trigeminal neuralgia
    • Enlarged cervical lymph nodes
    • Carotid artery dissection
    • Vertebral artery dissection
  • Inflammation/infectious:
    • Meningismus is most commonly associated with inflammation of the meninges
    • Meningitis
    • Encephalitis
    • Temporal arteritis
    • Cerebral vasculitis
    • Acute intracranial hemorrhage-induced inflammation
    • Brain abscess
    • Lupus cerebritis
    • Postviral headache
  • CSF pressure dysregulation headaches:
    • Postlumbar puncture headache
    • Spontaneous intracranial hypotension (CSF leak)
  • Impaired vascular autoregulation/endothelial dysfunction:
    • Posterior reversible leukoencephalopathy syndrome (PRES)
    • Large vessel stroke (less common)
    • Hypertension
    • Reversible cerebral vasoconstriction syndrome (RCVS)
  • Toxic/metabolic:
    • Carbon monoxide
    • Medication side effects
    • Medication overuse/rebound
    • Hypoglycemia
    • Thyroid disorders
    • Pheochromocytoma
  • Ophthalmologic/otolaryngologic:
    • Acute angle closure glaucoma (nausea, eye pain, conjunctival injection, increased IOP)
    • Optic neuritis
    • Temporal neuritis
    • Dental or TMJ pain (referred headache)
    • Sinusitis
    • Mastoiditis
  • Traumatic
    • Posttraumatic/concussive headache (acute or chronic)
    • Chronic subdural hematoma

Pediatric Considerations

Serious causes of headache in children are rare but those who come to the ED for this complaint should all have follow-up with a pediatrician

Geriatric Considerations

Older patients with new headache have a higher likelihood of a serious etiology and should have more thorough evaluation with a low threshold for imaging

Pregnancy Considerations

In addition to all other causes of headaches, pregnant women (and recently postpartum women) are at increased risk for CVST, eclampsia, PRES, and RCVS

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