Hemicrania continua

This code describes a rare, chronic, and persistent primary headache disorder characterized by continuous, unilateral head pain of moderate intensity, with superimposed exacerbations of severe pain. These exacerbations are typically accompanied by ipsilateral autonomic features (e.g., conjunctival injection, lacrimation, nasal congestion, ptosis) and/or restlessness or agitation. The hallmark of hemicrania continua is its absolute and complete response to indomethacin.

Use this code when documentation clearly indicates a diagnosis of hemicrania continua, often supported by a positive indomethacin trial. This diagnosis is typically made by a neurologist based on specific diagnostic criteria, including the continuous unilateral pain and the presence of associated autonomic symptoms during exacerbations.

• Ensure documentation specifies "hemicrania continua" and not another type of continuous headache.
• Distinguish from other trigeminal autonomic cephalalgias (TACs) like paroxysmal hemicrania or cluster headache, which have different pain patterns and treatment responses.
• This code is a primary headache diagnosis; do not use for secondary headaches.