Cluster headache

Cluster headaches are a particularly painful form of recurrent headache considered the most common trigeminal autonomic cephalalgias ¹. This is also known by a variety of different names, for example: paroxysmal nocturnal cephalgia, histamine headache (also known as Horton Headache), cranial autonomic syndrome³

Epidemiology

Cluster headaches are fairly uncommon affecting 0.06 to 0.4% of the population ¹. Men are more often affected (M:F 3:1) ¹. 

Clinical presentation

Cluster headaches are characterised by severe unilateral anterior or lateral headache (frontal, orbital or temporal) ¹. Headaches typically last from a quarter of an hour to a few hours (45 to 60 minutes is typical) and are associated with ipsilateral autonomic signs ^1,2:

• cutaneous: sweating, swelling
• orbital: conjunctival injection, miosis, ptosis, lacrimation
• nasal: congestion and rhinorrhea

They are clustered temporally and often described as having a 'clockwork' recurrence, occurring anywhere from many times a day to every second day ¹.

Radiographic features

The main role of imaging in patients with cluster headaches is to exclude other causes of a severe headache (see differential diagnosis below). SPECT, PET, MRI (functional MRI and voxel-based morphometry)  have been used in a research setting to attempt to elucidate the underlying pathophysiology of cluster headaches and other trigeminal autonomic cephalalgias ². 

Treatment and prognosis

A detailed discussion of the treatment of cluster headaches is beyond the scope of this article, however, generally, treatment strategies can be divided into: 

1. acute management
2. preventative management
3. interventional procedures

Acute management

Acute management focuses on triptans (e.g. sumatriptan - subcutaneous or intranasal, zolmitriptan - oral) and inhaled oxygen ¹. 

Preventative management

A variety of drugs have been shown to reduce the frequency of attacks, including verapamil, lithium, valproic acid, and topiramate ¹. 

Interventional procedures 

A variety of interventions are used in medically refractory cases or patients in whom medical therapy is not tolerated. Procedures include ¹: 

• ablative procedures on the trigeminal nerve (e.g. glycerol rhizotomy, trigeminal section, radiosurgery
• trigeminal microvascular decompression
• deep brain stimulation (hypothalamus)
• occipital nerve stimulation or greater occipital nerve injection

Differential diagnosis

Once the typical episodic and recurrent nature of the headaches becomes apparent and the stereotyped pattern of signs and symptoms evident the diagnosis can usually be made with a high degree of certainty. Initially, however, many other causes of a severe headache may be thought of as possible aetiologies, including: 

• reversible cerebral vasoconstriction syndrome
• subarachnoid haemorrhage
• migraine
• structural lesions (e.g. tumours or haemorrhages)