Background and Objectives.—Although chronic daily headache, mainly transformed migraine, is an important reason for consultation in headache clinics, its actual prevalence is unknown. This study analyzes the prevalence of the different types of chronic daily headache in an unselected population. Methods.—A questionnaire exploring headache frequency was distributed to 2252 unselected subjects. Those having headache 10 or more days per month were given a headache diary and were seen by a neurologist who classified their headaches. The varieties of chronic daily headache were classified according to the second revision of IHS criteria proposed by Silberstein et al published in Neurology 1996;47:871. Results.—The questionnaire was returned by 1883 subjects (83.5%). One hundred thirty‐five admitted to headache 10 or more days per month. Chronic daily headache criteria were fulfilled by 89 individuals (4.7%). Eighty were women. Forty‐two (47.2% of subjects with chronic daily headache and 2.2% of all subjects) had chronic tension‐type headache. Analgesic overuse was found in 8 (17%). Transformed migraine was diagnosed in 45 (50.6% of subjects with chronic daily headache and 2.4% of all subjects). Fourteen (31.1%) individuals with this form of chronic daily headache overused ergots or analgesics. The remaining 2 cases in this series met the criteria of new daily persistent headache. No one was diagnosed as having hemicrania continua. Conclusions.—Almost 5% of the general population (9% of women) suffers from chronic daily headache, the proportion of chronic tension‐type headache and transformed migraine being quite similar. Less than one third overuse analgesics. The prevalence of chronic daily headache subtypes shown here differs from data obtained from headache clinics, emphasizing that caution is needed in extrapolating data from specialized units to the general population.

The nosology of migraine premonitory (PS) and resolution (RS) symptoms was studied in 100 migraineurs consulting their general physician. They were asked to fill in, for three attacks, a PS and RS questionnaire. 'True' PS/RS were those experienced the day before (or the day after) the headache had started only if they were not present in a questionnaire completed in a pain-free period. True PS and RS were experienced by 84% and 80%, respectively, of subjects for the first attack. The mean and range (per patient) of PS were 6.8 and 0-21 and of RS 4.7 and 0-15. Anxiety, phonophobia, irritability, unhappiness and yawning were the commonest PS, whereas asthenia, tiredness, somnolence and concentration difficulties were the most common RS. Gender, age and Migraine Disability Assessment scores did not influence PS and RS. Both PS and RS were more frequent in migraine with aura subjects. Patients on preventatives showed a decreased frequency of PS and, to a lesser degree, of RS. Severity of headache was associated with a higher frequency of RS. Individual RS and especially PS were quite consistent after three attacks. Almost two-thirds of the symptoms were noticed in at least two out of three attacks, while more than a half of PS and more than a quarter of RS repeated in three out of three attacks. In conclusion, around 80% of unselected migraineurs experience RS and PS. Migraine with aura and severe pain are risk factors for experiencing PS and RS, while preventatives were protective, especially for PS.

In the general population, CDH reduced all QoL aspects studied with the SF-36. This reduction in QoL was most marked in subjects with analgesic overuse. QoL was affected more by the chronicity than by the intensity of pain.

Daily or near-daily headache is a widespread problem in clinical practice. The general term of chronic daily headache (CDH) encompasses those primary headaches presenting more than 15 days per month and lasting more than 4 hours per day. CDH includes transformed migraine (TM), chronic tension-type headache (CTTH), new daily persistent headache (NDPH), and hemicrania continua (HC). Around 40% of patients attending a specialized headache clinic meet CDH diagnostic criteria, of which 80% are women. In these clinics about 60% of patients suffer from TM, 20% from CTTH, and 20% meet NDPH criteria. Most, some 80%, overuse symptomatic medications. One should be very cautious on extrapolating these numbers to the general population. CDH prevalence in the general population seems to be around 4% to 5% (up to 8% to 9% for women). Regarding the prevalence of CDH subtypes, NDPH is rare (0.1%), whereas the prevalence of TM (1.5% to 2%) and CTTH (2.5% to 3%) is clearly higher. In contrast to data from specialized clinics, only around a quarter of CDH subjects in the general population overuse analgesics; the prevalence of CDH subjects with analgesic overuse being 1.1% to 1.9% of the general population. Most of these patients with analgesic overuse are TM patients.

It has been suggested that folate metabolism could be involved in migraine pathogenesis. We analysed the 5',10'-methylenetetrahydrofolate reductase (MTHFR) genotypic distribution in a large migraine sample. We genotyped 230 migraine patients (152 migraine without aura (MO) and 78 migraine with aura (MA)) and 204 nonheadache controls. The incidence of TT homozygosis for migraine in general (12%), MO (9%) and MA (18%) did not significantly differ from that found in healthy controls (13%). Differences were significant when the frequency of TT homozygosis between MA and MO (P = 0.03, OR = 2.34, 95% CI = 1.04-5.26) was compared. There was a tendency for a higher frequency of the MTHFR T allele in the MA group (42%) as compared to MO (29%) and controls (36%). These differences were significant only in the case of MA vs. MO (P = 0.006, OR = 1.75, 95% CI = 1.15-2.65). These results could indicate that the MTHFR C677T polymorphism, causing mild hyperhomocystinaemia, might be a genetic risk factor for experiencing aura among migraineurs. Overall, however, there was no association between migraine and the C677T MTHFR polymorphism.