Nummular headache is a primary headache disorder and therefore it has been moved from the Appendix to Chap. 4 in the ICHD-IIIβ [1]. Since defined by Pareja et al. in 2002 [30], more than 200 cases have been reported. This coin-shaped cephalalgia was first described as a chronic, mild–moderate, pressure-like pain that is felt exclusively in a circumscribed area with a diameter of 2–6 cm, in the absence of any underlying lesions of the head. Current diagnostic criteria are summarised in Table 12.2. Primary nummular headache is considered a rare entity, though its exact prevalence is uncertain. Nummular headache accounts for about 1 % of headaches attending a general neurology outpatient office and up to 5 % of headaches in a specialised clinic [31].

There is no specific treatment for primary nummular headache. Anti-epileptics have been tried in most reported patients, with gabapentin being effective in around half of cases [32]. Local botulinum toxin type A has been injected in a few patients and proved to be effective in some of them [33]. Local nerve blocks showed effectiveness in only one quarter of patients [31].

Hypnic headache is a rare, recurrent, sleep-related, primary headache disorder, which usually begins after 50 years of age. Pain tends to be bilateral and mild to moderate, develops only during sleep, and usually lasts from 15 to 180 min. Most cases are persistent, with daily or near daily headaches, but an episodic subform (on <15 days/month) has been described [1]. The exact pathophysiological mechanisms of hypnic headache have not been elucidated; a disturbance of the suprachiasmatic nucleus, as mammalian pacemaker, dysregulation of melatonin and a disorder of REM sleep have been some of the postulated mechanisms [34].

Several different treatments have been tried in hypnic headache. Lithium remains the most indicated treatment for hypnic headache [35]. Treatment should be started with low doses (300 mg) of lithium carbonate at bedtime, which can be increased up to 600 mg at bedtime if necessary. Lithium should be tapered after 3–4 months. If headache recurs during tapering, a longer duration therapy may be needed. Renal and thyroid function as well as serum lithium levels must be assessed periodically to avoid toxicity. Usual side effects include tremor, diarrhoea, increased thirst and polyuria and not infrequently make lithium poorly tolerated by hypnic headache patients, which are usually elderly people. Other agents that have been reported to effectively treat hypnic headache in small observational series include bedtime doses of caffeine (40–60 mg tablet, or as a cup of coffee), melatonin (2 mg), flunarizine (5 mg) or indomethacin (25–75 mg) [34–37]. Indomethacin appears to be more useful when attacks are strictly unilateral. Due to the poor tolerability of lithium and indomethacin and even though they seem to be the most efficacious preventive treatment for hypnic headache, we usually try first melatonin and flunarizine. In anecdotal reports, other drugs, such as topiramate, gabapentin, pregabalin, acetazolamide, pizotifen, acetylsalicylic acid, prednisone or verapamil have apparently been useful in preventing attack recurrence. Options, such as beta-blockers, tryciclic antidepressants, oxygen or subcutaneous sumatriptan have afforded no benefit [34].

New daily persistent headache is defined as persistent headache, daily from its onset which is clearly remembered. In the new ICHD-IIIβ it is clarified that the pain can be migraine-like or tension-type-like (Table 12.3). New daily persistent headache is unique in that the headache is daily from onset, typically occurring in individuals with no prior headache history. Patients with this disorder invariably recall and can accurately describe such an onset; if they cannot do so, another diagnosis should be made. New daily persistent headache has two clinical subforms: a self-limiting one that resolved within several months without therapy, in which an infectious origin has been hypothesised, and a refractory form that is resistant to aggressive treatment regimens [1].