10.1.4 Sleep apnoea headache

Description:
Morning headache, usually bilateral and with a duration of less than four hours, caused by sleep apnoea. The disorder resolves with successful treatment of the sleep apnoea.

Diagnostic criteria:
A. Headache present on awakening after sleep and fulfilling criterion C
B. Sleep apnoea (apnoea-hypopnoea index ≥5) has been diagnosed1
C. Evidence of causation demonstrated by at least two of the following:

    1. headache has developed in temporal relation to the onset of sleep apnoea
    2. either or both of the following:

      a) headache has worsened in parallel with worsening of sleep apnoea
      b) headache has significantly improved or remitted in parallel with improvement in or resolution of sleep apnoea

    3. headache has at least one of the following three characteristics:

      a) recurs on >15 days per month
      b) all of the following:

        i. bilateral location
        ii. pressing quality
        iii. not accompanied by nausea, photophobia or phonophobia

      c) resolves within 4 hr

D. Not better accounted for by another ICHD-3 diagnosis.

Note:
1. The apnoea-hypopnoea index is calculated by dividing the number of apnoeic events by the number of hours of sleep (5-15/hr = mild; 15-30/hr = moderate; >30/hr = severe).

Comments:
10.1.4 Sleep apnoea headache seems to be less frequent and of longer duration than previously assumed. A definitive diagnosis requires overnight polysomnography. Although morning headache is significantly more common in patients with sleep apnoea than in the general population, headache present upon awakening is a non-specific symptom which occurs in a variety of primary and secondary headache disorders, in sleep-related respiratory disorders other than sleep apnoea (eg, Pickwickian syndrome, chronic obstructive pulmonary disorder), and in other primary sleep disorders such as periodic leg movements of sleep.

It is unclear whether the mechanism of 10.1.4 Sleep apnoea headache is related to hypoxia, hypercapnia or disturbance in sleep.