Dr Keith Hopcroft continues our series of fascinating but often unrecognised conditions
The case
A 60-year-old lady attends with a story of a headache that is present ‘24/7' and has been going on for weeks. Though constant, there are exacerbations when she says the pain is unbearable. She's tried a variety of over-the-counter analgesics to no avail.
The persistence of the headache makes you think of tension or analgesic headache, though you ensure her temporal arteries are not palpable or swollen. But, on further questioning, two features of the history perplex you. One is that the pain affects only one side of her head. The other is that the exacerbations are accompanied by a watering eye and nasal blockage. Further questioning and examination bears no fruit – and the patient is desperate for help.
The diagnosis
This lady has hemicrania continua (HC). The cause of this remains obscure. It is described as rare, though the current view is that it is more common than previously believed, often being misdiagnosed.
Most cases will end up referred to neurologists or headache clinics and, even then, the diagnosis may be overlooked.
The patient is likely to have an MRI scan – normal in HC – to rule out rare intracranial pathology causing similar symptoms.
Typical features
HC causes a moderate unilateral headache with episodes that may become severe – and during which ‘cluster-type' phenomena may occur, such as conjunctival injection, eye watering, rhinorrhoea, nasal congestion, pupillary constriction or ptosis. The textbook definition requires the headache to have continued for at least three months. It is much more common in women and has no obvious triggers.
The differential includes migraine, cluster headache, temporomandibular joint pain and atypical facial pain.
Treatment
This condition has an idiosyncratic response to indomethacin. In fact, some authorities view complete resolution of the symptoms with this treatment as diagnostic.
Indomethacin needs to be continued indefinitely, although some cases do eventually resolve.
Issues for the GP
Unilateral headache or facial pain has a wide differential but the clue here is the persistence of the symptoms. The distress caused and the diagnostic uncertainty will result in a low threshold for referral – but it is worth trying indomethacin first.
Take home point
Consider hemicrania continua in perplexing and significant unilateral headache in women – a trial of indomethacin may clinch the diagnosis.
Hemicrania continua
