Pathophysiology

One of the trigeminal autonomic cephalalgias. The pathophysiology is poorly understood. Dysregulated firing of the trigeminal nerve is thought to play a role.

Epidemiology

Prevalence: < 1%

Risk factors:

• Male (4:1)
• Family history (weak)
• Smoking (controversial)

Classic presenting complaint

Episodes of:

• severe unilateral headache and face pain: centred around orbit and temporal area
• ipsilateral autonomic features: ptosis, mioisis, crying, rhinorrhea, conjunctival erythema
• restlessness

Timing of episodes:

• each episode lasts 15 mins – 3 hours (usually around an hour)
• episodes occur up to 8 per day
• episodes usually occur daily for ~ 2 months before subsiding
  • NB: in the chronic form of cluster headache, there is no remission between waves of attacks

Symptoms

During an attack:

• severe unilateral headache
• with ipsilateral autonomic features
• with agitation
• occurring 1 – 8x / day on every day for several weeks

Between attacks

• Normal

On examination

During an attack:

• Restlessness & agitation
• Signs ipsilateral to the headache:
  • Ptosis
  • Miosis (constricted pupil)
  • Conjunctival injection (erythema)
  • Rhinorrhea
  • Sweating

Between attacks:

• Normal

Clinical approach & differential

As with all headache syndromes the clinical approach is to exclude dangerous secondary causes for the headache before making a diagnosis of a primary headache disorder. Although the clinical syndrome of classic cluster headache is very typical, it should be born in mind that primary cluster headache is rare and can be mimicked by a structural lesion. The approach to headache is reviewed here. Thus, neuro-imaging is often recommended if there is any diagnostic uncertainty.

ICHD-3 diagnostic criteria:

• >5 attacks
• Attacks: severe unilateral pain 15 – 180 minutes (when untreated)
• 1 of:
  • Ipsilateral autonomic features
  • Restlessness / agitation
• Attacks occur 0.5 – 8 x / day
• No diagnosis that fits better

Differential diagnosis

• Secondary causes of headache
• Primary headache syndromes
  • Trigeminal autonomic cephalalgias:
    • Paroxysmal hemicrania
    • SUNA
    • SUNCT
  • Trigeminal neuralgia

Treatments

There are 2 aspects to treatment:

• Treating acute attacks
• Preventing future attacks

Treating acute attacks

Options:

• 100% oxygen
• Triptan (e.g. sumatriptan, zolmitriptan)
  • NB nasal absorption is delayed on the side of the headache so intranasal triptans should be adminitered contralaterally
• Options for refractory headaches:
  • IV dihydroergotamine
  • Oral ergotamine

Prevention

Principles:

• Treatment should be started immediately to prevent attacks during the ~2 month cluster period
• Treatment should be withdrawn slowly after the cluster period has finished
• Verapamil is the mainstay of therapy but can be combined with anti-migraine drugs
• In drug-refractory and chronic cluster headache, there is a role for non-pharmacological therapy

Options:

• Pharmacological
  • Verapamil
  • Oral steroids (short-course)
  • Anti-migraine drugs: pizotifen, topiramate, valproate
• Non-pharmacological
  • Greater occipital nerve block
  • Vagal nerve stimulation

Prognosis

Cluster headache is not curable. The aim of treatment is to reduce the frequency of attacks within a ~ 2 month period. It causes significant psychiatric morbidity.