Definition and Overview
Hemicrania continua is a one-sided headache that is closely related to trigeminal autonomic cephalalgias, and is characterized by pain that continues uninterrupted on one side. Pain appears fixed to one side, left or right, and usually does not change sides.
Normally, mild to moderate baseline pain persists, and then a more severe exacerbation period appears on top of it. The exacerbation phase is accompanied by ipsilateral autonomic symptoms. Absolute response to indomethacin is the key to diagnosis.
symptoms
pain pattern
- Persistent underlying pain on one side: Uninterrupted, one-sided headache
- Exacerbating stage: More severe pain appears on top of the underlying pain for tens of minutes to several days.
- Pain location: fixed on one side of the forehead, around the eye, or temporal area
Autonomic symptoms (ipsilateral)
During the worsening phase of pain, ipsilateral conjunctival injection, tearing, nasal congestion or runny nose, ptosis, and miosis appear. In one clinical study, approximately 68% of patients showed a distinct paroxysmal exacerbation phase, and complaints of restlessness (agitation) were common during the exacerbation phase.
diagnosis
The diagnosis of persistent hemicrania is a clinical diagnosis according to the International Classification of Headache Disorders, Third Edition (ICHD-3) criteria. Diagnostic criteria include unilateral headache lasting more than 3 months, ipsilateral autonomic symptoms or restlessness, and complete response to therapeutic doses of indomethacin.
It is characterized by the fact that absolute response to indomethacin itself is included in the diagnostic criteria. The diagnosis is confirmed when pain completely disappears after indomethacin test administration. Because it is a unilateral fixed headache, it is recommended to rule out secondary causes with a brain MRI.
treatment
indomethacin
Indomethacin is the first-line treatment and serves both diagnosis and treatment. Maintain the lowest dose that completely controls pain.
Side Effect Management
Indomethacin is a non-steroidal anti-inflammatory drug that has a risk of side effects such as gastrointestinal bleeding, stomach ulcers, and decreased renal function. When taking it for a long time, use a gastroprotective agent such as a proton pump inhibitor and check renal function periodically.
alternative drugs
When it is difficult to use indomethacin, other non-steroidal anti-inflammatory drugs, topiramate, melatonin, etc. are tried, but the consistency of effect is not as good as indomethacin.
Clinical implications
If ipsilateral autonomic symptoms are observed in a headache that persists and is fixed on one side, hemicrania continuum should be suspected and a trial of indomethacin should be considered. Because drug response determines diagnosis, appropriate dose and sufficient duration of testing are important.