FFS: Cluster Headache

Cluster headache is the most prominent TAC and has been referred to as the “suicide headache” due to its extreme intensity.

The term “cluster headache” is often misused to describe migraines with cyclical attacks.

Management is similar to that of migraine, with triptans being first-line agents.

Epidemiology

• Prevalence: <1%
• Sex: More common in males

Pathophysiology

Cluster headache is classified as a neurovascular headache.

• Most accepted theory: Hypothalamic activation triggers the trigeminal-autonomic reflex, likely via a trigeminal-hypothalamic pathway.
• Stress (mental or physical) is a common precipitant.
• Rarely, structural lesions (e.g. pituitary tumours) may mimic or cause cluster headache.
• Some evidence suggests a familial or genetic component.

Clinical Features

1. Site

• Pain is centred around the orbit or temporal regions
• Strictly unilateral during each cluster period (side-shift occurs in ~15%)

2. Severity

• Typically severe, hence the term “suicide headache”
• Patients are often restless and may pace or rock

3. Duration

• Individual attacks last 15 minutes to 3 hours
• Contrasts with migraine which lasts >4 hours untreated

4. Frequency

• Attacks often occur nocturnally
• 1–8 attacks/day over 6–12 weeks
• Remission may last up to 12 months or longer

5. Autonomic Symptoms

• Unilateral autonomic dysfunction ipsilateral to the pain
• Due to parasympathetic hyperactivity and/or sympathetic impairment
• Involvement of the cavernous sinus plexus may lead to partial Horner’s syndrome

Associated features:

• Rhinorrhoea
• Lacrimation
• Conjunctival injection
• Ptosis
• Miosis
• Facial sweating

~3% of patients lack autonomic features

Chronic Cluster Headache

• Defined by no remission for ≥1 year or remission <1 month
• May be primary or evolve from episodic form (secondary chronic cluster)

Differential Diagnosis

Condition	Differentiating Features
Migraine	Longer duration, may swap sides, photophobia common
Paroxysmal hemicrania	Similar features, but shorter attacks; responds to indomethacin
Primary stabbing headache	Brief, ice-pick like pains
Trigeminal neuralgia	Shock-like pain, lacks autonomic symptoms
Giant cell arteritis	Consider in elderly with new unilateral headache

Investigations

No definitive diagnostic test — diagnosis is clinical and ideally confirmed by a neurologist.

Tests to exclude secondary causes:

• FBC
• ESR / CRP (especially for temporal arteritis)
• MRI Brain (with pituitary views) to exclude lesions near the sella turcica

Management

Neurologist involvement is essential.

Acute Treatment

1. Oxygen
   • 100% via CPAP-type mask or high-flow (15 L/min) with reservoir
   • Ineffective if <100% oxygen
   • Discontinue if no benefit in 20 minutes (risk of toxicity)
2. Triptans
   • Sumatriptan 6 mg SC or 20 mg intranasally
   • Rizatriptan 10 mg orally
   • Zolmitriptan 2.5 mg orally

Bridging Treatment

Used during initiation of preventive therapy:

• Prednisolone 50 mg/day for 5 days, taper by 12.5 mg every 3 days
• Naratriptan 2.5 mg orally BID for 1 week
• Greater occipital nerve block (e.g. methylprednisolone + bupivacaine or lignocaine)
  • May relieve symptoms for up to 3 months
  • Can be used as sole therapy for short cluster periods

Preventive Treatment

Start immediately post-diagnosis under neurologist supervision:

• Verapamil
• Topiramate
• Sodium valproate
• Gabapentin
• Melatonin (high-dose)

Refer to the Neurology Therapeutic Guidelines for detailed prescribing.

Neurosurgical Intervention

Consider in refractory, debilitating cases:

• Neuromodulation: Occipital nerve stimulation, deep brain stimulation (posterior inferior hypothalamus)
• Sphenopalatine stimulation

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Appendix 1

Schematic model showing most of the putative components in cluster headache pathogenesis.

• Pain afferents from the trigeminovascular system synapse on the trigeminocervical complex (TNC), and then project to the thalamus and lead to activation in cortical areas known to be involved in pain transmission.
• Either a direct influence of the hypothalamus or a reflex activation of the parasympathetic outflow from the superior salivatory nucleus (SSN) predominately through the pterygopalatine (sphenopalatine) ganglion, leads to the parasympathetic symptoms ipsilateral to the pain.
• A third-order sympathetic nerve lesion, thought to be caused by vascular changes in the cavernous sinus loggia with subsequent irritation of the local plexus of nerve fibers, results in a partial Horner’s syndrome.
• The key site in the CNS for triggering the pain and controlling the cycling aspects is in the posterior hypothalamic grey matter region.

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References

Publications

• Brazis PW, Masdeu JC, Biller J. Localization in Clinical Neurology. 8e 2021
• Fuller G. Neurological Examination Made Easy. 6e 2019

FOAMed

• Coni R. Cluster headache. LITFL
• Coni R. Headache classification. LITFL
• Coni R. Headache Essentials. LITFL