Paroxysmal hemicrania is characterized by multiple, brief, intense, daily focal head pain attacks. The pain is unilateral and always affects the same side. The pain is usually most severe in the auriculotemporal area, the forehead, and above or behind the ear. It may spread to involve the ipsilateral shoulder, arm, and neck. The pain is described as excruciating, throbbing, boring, or pulsating. Between attacks, the patient may have tenderness in the symptomatic area. During attacks, the patient usually sits quietly or may "curl up in bed," which contrasts with the usually increased restlessness and activity during attacks of cluster headache (Cittadini et al 2008). Some patients have interparoxysmal pain, so the differential diagnosis with hemicrania continua can be problematic as both are indomethacin-sensitive (Cittadini and Goadsby 2010). This may be the basis for a reported transition from hemicrania continua to paroxysmal hemicrania in single case report (Muller and Bekkelund 2011).
Paroxysmal hemicrania usually begins in adulthood. The mean age is 34 years, with a range of 6 to 81 years. Paroxysmal hemicrania has been reported in children (Kudrow and Kudrow 1989; Broeske et al 1993; Gladstein et al 1994; Moorjani and Rothner 2001; Talvik et al 2006; Vieira et al 2006; Tarantino et al 2011), and their symptoms are very much the same as those in adults (Blankenburg et al 2009). As in adults, the differential diagnosis with cluster headache can be troublesome (Solomon and Newman 1995). The author has seen a number of children between 4 and 12 years of age with typical indomethacin responses. In the author’s experience, the disorder settles in this age group after 2 to 3 years, and 1 patient has been reported with that behavior (Talvik et al 2009). The attack profile of paroxysmal hemicrania is highly characteristic. The frequency of attacks ranges from 2 to 30 per 24-hour period (Sjaastad et al 1980). Attacks usually last between 2 and 25 minutes and occasionally as long as 60 minutes. In a prospective study of 105 attacks, the mean duration was found to be 13 minutes, with a range of 3 to 46 minutes and a mean attack frequency of 14 in a 24-hour period (range 4 to 38) and even circadian distribution (Russell 1984). Nocturnal attacks associated with the REM phase of sleep have also been described (Kayed et al 1978).
Ipsilateral lacrimation is reported to occur in about 80% of attacks. When the lacrimation is bilateral, it is predominantly on the side of the pain (Antonaci and Sjaastad 1989). Conjunctival injection on the symptomatic side occurs during two thirds of attacks (Cittadini et al 2008). Some patients have ipsilateral eyelid edema and slight miosis. Photophobia may accompany some attacks, and increased forehead sweating, especially on the symptomatic side, is observed in a few patients. Photophobia, when present, is often unilateral to the side of the pain (Irimia et al 2008). Although not widely recognized, a sense of aural fullness is reported in paroxysmal hemicrania (Cittadini et al 2008), and may account for some patients reported not to have cranial autonomic features (Prakash et al 2013).
Three cases are documented of nonlateralized, short-lasting headache that responded to indomethacin, but these patients did not have cranial autonomic symptoms (Pollmann and Pfaffenrath 1986; Mulder and Spierings 2004; Bingel and Weiller 2005); one might consider this a different syndrome--perhaps paroxysmal cephalalgia (Matharu and Goadsby 2005). A case of short-lasting presentation with bilateral cranial autonomic features responding to indomethacin has also been reported (Evans 2008), as has a case with unilateral pain without apparent cranial autonomic features (Maggioni 2010). In the latter case, the description of the relevant negatives is incomplete, and the nosology of these entities is unclear.
Although the majority of attacks are sudden and spontaneous, approximately 10% may be precipitated mechanically, either by bending or by rotating the head (Antonaci and Sjaastad 1989). Attacks may also be provoked by external pressure against the transverse processes of C2, C3, C4, or the greater occipital nerve (Sjaastad et al 1982). The relationship between menstruation and paroxysmal hemicrania attacks is undetermined (Maggioni et al 2007; Maggioni 2011). Birth control pills do not seem to influence the attack frequency, and menopause has no reported effect. Unusual presentation with otalgia and a feeling of fullness in the ear has been reported (Boes et al 1998), as has extratrigeminal pain (Dodick 1998). A report from the Mayo Clinic suggests that the largest part of the phenotype can be seen without a response to indomethacin (Boes and Dodick 2002). The key features of the International Headache Society criteria are listed (Headache Classification Committee of The International Headache Society 2004). Cases of mixed trigeminal autonomic cephalalgias have been reported and underline the premise of ICHD-III that there is shared pathophysiology (Totzeck et al 2014).
The key features of the International Classification of Headache Disorders (ICHD), third edition beta criteria are listed below (Headache Classification Committee of the International Headache Society 2013).
Paroxysmal hemicrania has 2 key forms. The episodic form occurs during a period that lasts 7 days to 1 year and is separated by pain-free periods that last 1 month or more. The chronic form has attacks that occur for more than 1 year without remission or with remissions lasting less than 1 month.
To be diagnosed with paroxysmal hemicrania, patients must experience each of the following:
A. At least 20 attacks fulfilling criteria B through E
B. Severe, unilateral orbital, supraorbital, or temporal pain that lasts 2 to 30 minutes
C. Headache associated with at least 1 of the following symptoms or signs, ipsilateral to the pain:
E. Attacks are prevented absolutely by therapeutic doses of indomethacin1
F. Not better accounted for by another ICHD-3 diagnosis
The new criteria are very much like ICHD-II (Headache Classification Committee of The International Headache Society 2004), with the notable standardization of the cranial autonomic features amongst the Trigeminal Autonomic Cephalalgias (TAC) and the addition of the sense of aural fullness to all the TAC criteria (Goadsby 2012).