Previously used term:
Headache not classifiable.
- Headache with characteristic features suggesting that it is a unique diagnostic entity
- Headache does not fulfil criteria for any of the headache disorders described above.
Several new headache entities have been described in the time between the first edition of The International Classification of Headache Disorders and this third edition. It is anticipated that there are more entities still to be described. Such headaches, until classified, can be coded as 14.1 Headache not elsewhere classified.