Presentation of a new instrument: the diagnostic headache diary

A new instrument, the Diagnostic Headache Diary, based on the operational diagnostic criteria of the International Headache Society (IHS), was tested in 61 migraine patients from a headache research clinic using the clinical diagnosis (IHS criteria) for comparison. All patients kept the diary for one to eight months. The clinical and diary diagnosis of migraine with and without aura was the same in, respectively, 72 and 87% of the patients. Nausea, photophobia and phonophobia tended to be more pronounced at the clinical interview. The diary identified 20 more cases of episodic tension-type headache and 15 fewer cases of chronic tension-type headache than the clinical interview. Two blinded observers always made the same IHS diagnoses when interpreting the diagnostic headache diary. A combination of a clinical interview and the diagnostic headache diary gives a qualitatively and quantitatively more precise diagnosis than a clinical interview alone.     

Lifetime prevalence and characteristics of recurrent primary headaches in a population-based sample of Swedish twins

OBJECTIVE: To examine the lifetime prevalence and other characteristics of recurrent primary headaches in twins. BACKGROUND: The twin model may provide insights into the role of genetic and environmental influences in headache disorders. However, assumptions as to whether twins are representative of the general population, and whether monozygotic and dizygotic twins are similar have rarely been addressed. METHODS: The study population consisted of a random sample of 17- to 82-year-old twins from the Swedish Twin Registry (n = 1329). Structured interviews on the telephone by lay personnel and the International Headache Society criteria were used for assessment and diagnosis of recurrent primary headaches. Prevalence data of the general population for migraine and tension-type headache was obtained from various published reports. RESULTS: A total of 372 subjects (29%) had ever had recurrent headaches. In total, 241 recurrent headache sufferers fulfilled the criteria for migraine or tension-type headache, and the lifetime prevalence was 7.1% for migraine without aura, 1.4% for migraine always with aura, 1.9% for migraine occasionally with aura, 9.4% for episodic tension-type headache, and 1.3% for chronic tension-type headache. The lifetime prevalence of all migraine and all tension-type headache, including another 84 subjects fulfilling all but one of the criteria for migraine or tension-type headache, was 13.8% and 13.5%, respectively. The corresponding prevalence risk for women was 2.4 (95% confidence interval [CI] 1.7, 3.4) and 1.5 (95% CI 1.1, 2.1), respectively. Zygosity was not a significant predictor for migraine. In tension-type headache, the prevalence risk for dizygotic twins and unlike-sexed twins as compared with monozygotic twins was 1.9 (95% CI: 1.2, 3.1) and 1.8 (95% CI: 1.1, 2.9), respectively. CONCLUSION: There is no twin-singleton or monozygotic-dizygotic difference for the risk of migraine. In tension-type headache, twins seem to have a lower risk than singletons, and this is especially true for monozygotic twins.     

Characteristics of headache in migraine without aura and episodic tension-type headache in the Turkish population according to the IHS classification

We evaluated the characteristics of headache in migraine without aura and episodic tension-type headache diagnosed according to the International Headache Society (IHS) Classification. Fifty migraine without aura and 50 tension-type headache patients were selected prospectively. Fifty-eight percent of migraineurs had pain of a pulsating quality; 88% had severe pain and 74% had unilateral pain; aggravation by routine physical activity was reported by 96%. Episodic tension-type headache was of a pressing quality in 52%, moderate in 40%, bilateral in 82% and aggravated by routine physical activity in 16%. Nausea and/or vomiting, photophobia and phonophobia were reported significantly more commonly in migraineurs than tension-type headache patients.     

Determinants of tension-type headache in children

The objective of this study was to study the prevalence, characteristics and predisposing factors of tension-type headache in children. An unselected population-based questionnaire study was carried out in 1409 Finnish schoolchildren aged 12 years. Of them, 1135 (81%) returned an acceptably completed questionnaire. The prevalence of episodic tension-type headache in children was 12% (138 of 1135). Children with episodic tension-type headache also often reported characteristics of pain typical for migraine. Children with frequent and persistent episodic tension-type headache reported stabbing and severe occipital pain, phonophobia and abdominal pain significantly more often than children with infrequent episodic tension-type headache. Neck-shoulder symptoms, symptoms of depression and oromandibular dysfunction were each independently associated with episodic tension-type headache. The father's occupation of a lower-level white-collar worker put the child at a four-fold risk for episodic tension-type headache. We conclude that episodic tension-type headache is as common as migraine in children. It can be associated with depression, oromandibular dysfunction and muscular stress. Especially children with frequent and persistent episodic tension-type headache report characteristics of pain typical for migraine.     

Kaplan Award 1998. Epidemiology of chronic daily headache in the general population

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.     

Outcome of juvenile headache in outpatients attending 23 Italian headache clinics. Italian Collaborative Study Group on Juvenile Headache (Società Italiana Neuropsichiatria Infantile [SINPI])

A multicenter 3-year follow-up study was carried out on young patients with headache referred to tertiary headache centers or pediatric clinics. Three years after the first examination in 1993, 442 (of an original sample of 719) young outpatients with headache (226 females and 216 males) were re-examined. The diagnostic criteria of the International Headache Society (IHS) and those modified for migraine without aura by Winner et al were applied at both the baseline evaluation and the 3-year re-examination. At the follow-up, 290 children still had headache, 101 were in clinical remission, and 51 had dropped out. Using the current diagnostic criteria, only 46.2% of patients having migraine without aura, 50% of those having migraine with aura, and 35.3% of those suffering from migraine disorders which do not fulfill IHS criteria for migraine received the same diagnosis at the time of follow-up. The percentage of patients receiving a diagnosis of migraine without aura rose significantly when new modified criteria were used (60.5%), whereas a drop in the frequency of migraine disorders not fulfilling IHS criteria was observed at follow-up, both in patients with the diagnosis of migraine without aura at the first examination (4.6%) and in patients with migraine not always fulfilling IHS criteria at the first examination (6.2%). Among all patients who received this latter diagnosis at the first examination, it was possible to make a diagnosis of migraine with aura at the follow-up in 8.8% of cases and that of migraine without aura in 26.5%. No significant variations in the frequency of either episodic tension-type headache or chronic tension-type headache were found, with the exception of a slight decrease in the percentage of tension-type headache which did not fulfill IHS criteria, but the difference between the first examination and the follow-up values does not reach the level of statistical significance (5% versus 12%). As far as the evolution of migraine is concerned, 17.4% of patients with migraine were headache-free at the 3-year follow-up. In tension-type headache, the percentage of patients who were headache-free was particularly high in those with the episodic form (32.9%) and in those suffering from tension-type headache not fulfilling IHS criteria (29.1%). The majority of patients who had been diagnosed as having unclassifiable headache at the first examination received a correct diagnosis at the follow-up with the exception of one patient. As observed in adult patients, variations in the headache characteristics were also observed in children and adolescents (that is, migraine with aura can change to migraine without aura, or the latter can transform into episodic tension-type headache or chronic tension-type headache can change into the episodic form). This follow-up study was aimed at reaching a better understanding of headache disturbances in children and adolescents, examining, in particular, variations of headache with time in this stage of life.     

Chronic daily headache. How should it be included in the IHS classification?

A number of patients attending specialty headache centers complain of very frequent, almost continuous or continuous headaches, which are usually grouped together under the term chronic daily headache , a category which does not appear in the International Headache Society (IHS) classification. On the basis of the IHS criteria, these patients can only be classified as having a chronic tension-type headache with the possible addition of migraine, if migrainous attacks are superimposed on the "background" headache. However, several studies have demonstrated that most patients with chronic daily headache originally suffered from migraine and that their migraine has transformed, in the course of time, into a chronic headache picture in which isolated migraine attacks may or may not persist. Despite some differences in the personal opinions of authors involved in the care of patients with chronic daily headache, some views seem to be generally accepted: (1) the great majority of chronic daily headaches are transformations of an original episodic migraine and cannot be included in the chronic tension-type headache category, (2) the current IHS classification does not allow many patients presenting with chronic daily headache to be classified correctly, (3) an important nosological category (transformed migraine) has emerged from all the studies on this subject, (4) it is impossible to diagnose transformed migraine merely by "photographing" the picture of single attacks. Although some theoretical problems remain unresolved, it seems to us that the next revision of the IHS classification can no longer ignore the existence of chronic daily headache.     

A Community-Based Prevalence :Study on Headache in Malaysia

This community study on headache in Malaysia was based on IHS diagnostic criteria and showed the last-year prevalence of migraine was 9.0%. Migraine with aura accounted for only 10.6% of the migrainous population. The last-year prevalence of tension headache was 26.5% (94.4% episodic, 5.6% chronic) and 28.2% for other types of headache. No case of cluster headache was found. Almost two thirds of the migraine subjects graded their headaches as severe, while almost 60% of the tension headache subjects and almost 70% of the other headache subjects graded their headaches as mild.
Overall, there was higher prevalence in females for migraine and tension headache, and in males for the other types of headache. The prevalence of headache was lower among those younger than 15 and older than 65 years of age. No significant differences were found in the prevalence of headache among the different racial groups nor among the urban versus the rural population.
All the headache types shared the same triggering factors suggesting that different physiological characteristics are responsible for the type of pain suffered. In the location of this community with its tropical climate, headache was attributed to sun exposure in 51.9% of the migraine subjects, 55.7% of the tension headache subjects, and 36.6% of the group with other headaches.     

Diagnosis of headache in childhood and adolescence: a study in 437 patients

We investigated whether the criteria for idiopathic headache published by the International Headache Society (IHS) are useful in childhood and adolescence and compared the diagnoses according to this classification with those of Vahlquist. We used a semi-structured questionnaire to examine a total of 437 children and adolescents referred consecutively to a headache outpatient clinic. Twenty-eight of 437 patients were excluded because of symptomatic or unclassifiable headache. Of 409 patients with idiopathic headache, 70.4% had definite migraine or tension-type headache (IHS 1.1, 1.2, 2.1, 2.2), 20.5% had a migrainous disorder (IHS 1.7) and 9.1% had headache of the tension-type not fulfilling the criteria (IHS 2.3). In the differential diagnosis of migraine and tension-type headache the intensity of pain, aggravation of headache by physical activity, nausea and vomiting were the most important features. The quality of pain, photo- and phonophobia were less helpful and location least important. The duration of migraine attacks was less than 2 h in 19.0% of the migraine patients. In general, the diagnostic criteria of migraine were highly specific but less sensitive, and those of tension-type headache highly sensitive but less specific. The agreement between IHS criteria and those of Vahlquist was marked (kappa = 0.57). We conclude that the IHS criteria are useful for classifying headache in children and adolescents referred to a headache outpatient clinic. A forthcoming modification of the IHS criteria should consider a reduction of the minimum duration of migraine attacks from 2 h to I h and should try to increase the sensitivity of the criteria for migraine and the specificity of the criteria for tension-type headache.     

Headache prevalence among adolescents--the German DMKG headache study

This population-based cross-sectional study examined the 3-month prevalence of headache, migraine and tension-type headache (TTH) among adolescents aged 12-15 years in Germany. Students (n = 3324) from 20 schools completed a questionnaire on general and headache-specific pain which included a sociodemographic module. The headache-specific questionnaire complied with the respective revised criteria of the International Headache Society (IHS). 'Modified criteria' changed the item 'duration' in migraine (>30 min instead of > 4 h). The overall 3-month prevalence of headache was 69.4% (boys 59.5%, girls 78.9%), with 4.4% of the adolescents suffering from frequent (>or=14 days/3 months) and severe (grade 8-10 on a 10-point visual analogue scale) headache and 1.4% (boys 0.9%, girls 1.9%) from headache >or= 15 days/month. The 3-month prevalence of migraine was 2.6% (boys 1.6%, girls 3.5%) applying strict IHS criteria and 6.9% (boys 4.4%, girls 9.3%) with modified criteria; 12.6% (boys 8.3%, girls 16.7%) suffered from probable migraine, 0.07% fulfilled the criteria for chronic migraine, 4.5% (boys 4.6%, girls 4.3%) suffered from TTH, 0.2% from chronic TTH and 15.7% (boys 14.5%, girls 16.9%) from probable TTH. Headache and migraine were more common in girls than in boys and in teenagers, especially in girls, aiming at higher education. Recurrent headache and primary headache disorders are common complaints among German adolescents, especially among girls.     

American Headache Society members' assessment of headache diagnostic criteria

OBJECTIVE: We assessed the views of physicians interested in headache as to the diagnosis of the most commonly occurring and currently controversial headaches. BACKGROUND: The International Headache Society (IHS) classification system has received wide professional endorsement and considerable empirical support, but in the United States, their adoption by clinicians may be proceeding more slowly. Questions remain, including what diagnostic criteria for migraine and tension-type headache clinicians may continue to favor over those outlined by the IHS, to what extent is the "transformed migraine" diagnosis used in clinical practice, and how is analgesic rebound headache diagnosed with regard to the various quantitative measures of analgesic use. METHODS: Members of the American Headache Society rated the importance of IHS and non-IHS diagnostic criteria for migraine and tension-type headache and for analgesic rebound headache. Respondents also described their use of the proposed transformed migraine diagnosis. RESULTS: Two-thirds (67.3%) of the respondents reported use of the IHS criteria or the IHS criteria in conjunction with clinical judgment. For migraine and tension-type headache, IHS criteria were rated with high importance, but some respondents reported using additional non-IHS diagnostic criteria and de-emphasizing certain IHS criteria. For chronic headache, almost two-thirds (63%) of respondents reported using the transformed migraine diagnosis. For analgesic rebound headache, respondents preferred to make the diagnosis based on medication consumption that is lower than amounts stipulated in the IHS classification system. CONCLUSIONS: There remains a number of physicians interested in headache who do not use the IHS classification system, who modify the IHS criteria in practice, and who use the "transformed migraine" diagnosis for patients with chronic daily headache.     

The International Headache Society (IHS) Headache Classification as applied to a headache clinic population

Four hundred patients attending a headache clinic were classified using the IHS criteria. The majority required more than two, often three or four, diagnoses. Even though migraine was the most common diagnosis, only 1/4 of those with a migraine diagnosis had it as the only diagnosis. Seventy-five percent of migraine patients had coexistent chronic tension-type headache (CTTH), drug-induced headache or both. Ninety-six percent of patients diagnosed as having migraine with aura also suffered from migraine without aura. More than 1/3 of patients (37.7%) attending the clinic suffered from chronic daily headache (CDH) (chronic cluster headache excluded), which is not included as a separate entity in the IHS classification. Pure CTTH formed only a small minority of CDH, whereas 86.6% of CDH had migraine as one of the diagnoses. Drug-induced headache was a prominent second or third diagnosis. The advantages and disadvantages of multiple verses single diagnosis in CDH and the need to recognize the natural history of headache disorders in the classification are discussed.     

Prevalence and clinical characteristics of an experimental model of 'ice-cream headache' in migraine and episodic tension-type headache patients

This study was designed to compare the prevalence and clinical characteristics of 'cold-induced headache' between migraine and episodic tension-type headache patients. Seventy-six migraine and 38 episodic tension-type headache patients were included in the study. An experimental model of an 'ice-cream headache' was developed for the study. The pain occurrence period, its location and quality were recorded for each patient who felt pain in their head during the test procedure. Pain in the head occurred in 74% of migraine and 32% of 'tension-type headache' patients. Although the most frequent pain location was the temple in both groups of patients, this rate was greater than twofold in migraine patients when compared with episodic tension-type headache patients. While headache quality was throbbing in 71% of migraine patients, it was so in only 8% of the episodic tension-type headache patients. Considering all the results, it seems that 'cold-stimulus headache' is not only more frequent in migraine patients, but also its location and quality differ from 'tension-type headache'.     

Chronic daily headache in children and adolescents presenting to tertiary headache clinics

BACKGROUND: Adults with chronic daily headache often describe a transformation from episodic migraine and partial retention of migrainous features. Although chronic daily headache has not been investigated as carefully in the pediatric population, one study showed a predominance of coexisting daily headache and episodic migraine, without a clear history of transformation. OBJECTIVE: To identify the clinical features of chronic daily headache in children and adolescents, to evaluate the efficacy of current headache classification criteria, and to compare the features of coexistent daily and episodic headaches so as to determine whether they represent separate syndromes or different stages in the "transformation" process. DESIGN: We surveyed 189 consecutive patients, 18 years of age or younger, who presented for initial evaluation of daily or near daily headache at one of 9 tertiary headache clinics. Data were collected in semistructured interviews employing a standard questionnaire and analyzed using Statistical Analysis Systems and Stata statistical software computer programs. RESULTS: Of the patients enrolled, 70% were female and 87% were white. Mean age was 13.0 +/- 3.1 years. Male gender was associated with a higher degree of reported disability. A family history of headache (typically migraine) was described in 79%. Use of nonsteroidal anti-inflammatory drugs 5 days per week or more was reported by 44% of patients. The International Headache Society (IHS) criteria failed to classify 64% of patients and criteria proposed by Silberstein et al failed to classify 31% of patients. Participating physicians misclassified patients according to criteria of the IHS and Silberstein et al in one third of cases. Nearly one quarter of patients reported two separate headache types with distinguishing characteristics. "Baseline" headache was present 27.3 +/- 4.1 days per month with a mean pain intensity of 5.9 +/- 2.1 on a 10-point scale. Superimposed episodic headache occurred 4.7 +/- 3.8 days per month with a mean pain intensity of 8.4 +/- 1.4, and was more often accompanied by other migrainous symptoms. After logistic regression to control for pain intensity, the only statistically significant difference between the two headache types was a lower prevalence of tension-type head pain with the superimposed headache. CONCLUSIONS: Our data suggest that rather than having two coexistent headache types, children and adolescents with chronic daily headache have a single syndrome that, in many cases, will paroxysmally worsen and gather migrainous features.     

Are infrequent episodic,frequent episodic and chronic tension-type headache inherited? A population-based study of 11 199 twin pairs

The objective was to investigate the importance of genetic and environmental factors for infrequent episodic, frequent episodic and chronic tension-type headache. Twin pairs recruited from the population-based Danish Twin Registry received a posted questionnaire. Only twin pairs where both twins replied were included. A total of 3523 monozygotic (MZ), 4150 dizygotic (DZ) same-gender and 3526 DZ opposite-gender twin pairs were included. The prevalence of frequent episodic and chronic tension-type headache was significantly more frequent in women than men, and significantly higher in those with co-occurrence of migraine. The concordance rates were significantly higher in MZ than same-gender DZ twin pairs with no or frequent episodic tension-type headache, while the difference was not significant in chronic tension-type headache. The concordance rates of infrequent episodic tension-type headache in MZ and same-gender DZ twin pairs was significantly different in women but not in men, although the difference was small in both genders. We conclude that genetic factors play a role in no and frequent episodic tension-type headache, while infrequent episodic tension-type headache is caused primarily by environmental factors. The data regarding chronic tensiontype headache were limited, so no firm conclusion could be drawn. Greppi-Sicuteri Commitee: Giorgio Zanchin, Miguel J.A. Lainez, Marcello Fanciullacci, Paolo Martelletti, Arne May, Lorenzo Pinessi     

Genetics of tension-type headache

Abstract The objective of this study was to investigate the importance of genetics in tension-type headache. A MEDLINE search from 1966 to December 2006 was performed for “tension-type headache and prevalence” and “tension-type headache and genetics”. The prevalence of tensiontype headache varies from 11 to 93%, with a slight female preponderance. Co-occurrence of migraine increases the frequency of tension-type headache. A family study of chronic tension-type headache suggests that genetic factors are important. A twin study analysing tension-type headache in migraineurs found that genetic factors play a minor role in episodic tension-type headache. Another twin study analysing twin pairs without co-occurrence of migraine showed a significantly higher concordance rate among monozygotic than same-gender dizygotic twin pairs with no or frequent episodic tension-type headache, while the difference was minor in twin pairs with infrequent episodic tensiontype headache. Frequent episodic and chronic tension-type headache is caused by a combination of genetic and environmental factors, while infrequent episodic tensiontype headache is caused primarily by environmental factors. 1 This is a “Springer Open Choice” article. Unrestricted non-commercial use, distribution, and reproduction in any medium is permitted, provided the original author and source are credited.     

Specificity and Sensitivity of Temporalis ES2 Measurements in the Diagnosis of Chronic Primary Headaches

We have evaluated the specificity and sensitivity of temporalis ES2 measurements for the diagnosis of primary headaches. Ninety-four outpatients diagnosed according to IHS criteria were prospectively included: 25 had chronic tension-type headache (code 2.2.), 15 episodic tension-type headache (code 2.1.), 20 migraine without aura (code 1.1.) and 34 chronic daily headaches with daily analgesics/ergotamine abuse (code 8.2.). In chronic tension-type, the sensitivity of the ES2 test was 84% at the 0.1 and the 0.5 Hz, but only 56% at the 2Hz stimulation rates. Its specificity was 100% at 0.1Hz, 90% at 0.5Hz and 95% at 2Hz compared to migraine; positive predictive values were at similar levels. Sensitivity of ES2 at 0.1 Hz was 67% in episodic tension-type headache, but its positive predictive value versus migraine was excellent. Comparing chronic tension-type headache and analgesic abusers, the specificity and positive predictive value of the ES2 test for diagnosing chronic tension-type headache were less satisfactory (60%) while the negative predictive values, however, remained good (83% at 0.1Hz).
The results confirm that the temporalis ES2 test has a higher diagnostic sensitivity in chronic and episodic tension-type headache, but that it has a high negative predictive value for both types of tension-type headache compared to other primary headaches. For diagnostic purposes, the 0.1Hz stimulation rate seems optimal. The 2Hz stimulation rate is the least sensitive, although it may induce total disappearance of ES2 in up to 40% of patients. ES2 is of limited usefulness for separating chronic tension-type headache and chronic drug-abuse headache, possibly because the latter group comprises both tension-type headache and migraine patients.     

Responsiveness of non-IHS migraine and tension-type headache to sumatriptan

In a long-term efficacy and satiety study, 424 patients were treated with sumatriptan (6 mg sc) for 1,904 migraine attacks. The patients were diagnosed with migraine based on IHS criteria but individual migraine attacks treated in the study were physician diagnosed; not necessarily required to meet IHS criteria. A re-analysis of the treatment response to open label sumatriptan (6 mg sc) indicated that 43 patients had treated at least one migraine that fulfilled IHS criteria for tension-type headache. Analysis of this population revealed they treated 232 headaches. Of these headaches, 114 were classified per IHS criteria as migraine; 76 as tension-type; and 42 as. non-IHS migraine (not classifiable as IHS migraine or IHS tension-type headache). Of the 114 migraines a positive response to sumatriptan occurred in 109 (96%) cases; of the 76 tension-types, 73 responded to sumatriptan (97%); of the 42 non-IHS migraine, 40 (95%) responded to sumatriptan. An equivalent response to sumatriptan among three diagnostic groups of headache supports the concept of a common biologic mechanism involving 5HT₁ receptors that spans a range of clinical presentations.     

Evaluation of chronic daily headache—comparison to criteria for chronic tension-type headache

The purpose of this study was to evaluate the adequacy of the International Headache Society (IHS) criteria for chronic tension-type headache and, if appropriate, suggest modifications of the IHS classification. We evaluated 100 consecutive patients with chronic daily headache. Approximately two-thirds of our patients fulfilled the criteria for chronic tension-type headache. Most of the patients who failed to meet the criteria did so because they had more than one migrainous feature. Approximately 50% of patients took excessive amounts of analgesic medication. We conclude that the IHS criteria should be modified to include chronic daily headache evolving from migraine; subtypes with and without medication overuse should be distinguished.