Chronic migraine classification: current knowledge and future perspectives

In the field of so-called chronic daily headache, it is not easy for migraine that worsens progressively until it becomes daily or almost daily to find a precise and universally recognized place within the current international headache classification systems. In line with the 2006 revision of the second edition of the International Classification of Headache Disorders (ICHD-2R), the current prevailing opinion is that this headache type should be named chronic migraine (CM) and be characterized by the presence of at least 15 days of headache per month for at least 3 consecutive months, with headache having the same clinical features of migraine without aura for at least 8 of those 15 days. Based on much evidence, though, a CM with the above characteristics appears to be a heterogeneous entity and the obvious risk is that its definition may be extended to include a variety of different clinical entities. A proposal is advanced to consider CM a subtype of migraine without aura that is characterized by a high frequency of attacks (10-20 days of headache per month for at least 3 months) and is distinct from transformed migraine (TM), which in turn should be included in the classification as a complication of migraine. Therefore, CM should be removed from its current coding position in the ICHD-2 and be replaced by TM, which has more restrictive diagnostic criteria (at least 20 days of headache per month for at least 1 year, with no more than 5 consecutive days free of symptoms; same clinical features of migraine without aura for at least 10 of those 20 days).

Diagnostic issues in tension-type headache

The diagnosis of tension-type headache (TTH) is divided into two categories: episodic TTH and chronic TTH. It is important to differentiate TTH from other headaches, including primary and secondary headaches. Significant overlap in the diagnostic criteria makes it difficult to differentiate TTH from other headache disorders and, in particular, migraine. A controversy exists about whether TTH and migraine represent a continuum of the same pathophysiological process.

Depression and migraine

The objective of this study was to evaluate both the presence and intensity of depressive symptoms in patients with episodic migraine (EM) and transformed migraine (TM) or chronic migraine, comparing them with a control group. Beck Depression Inventory (BDI) was used for this purpose. The median of BDI score of the control group was significantly lower than the EM and TM groups (p<0.0005). Either the EM or the TM did not show any significant difference in relation to the median of BDI scores (p=0.12). The TM group showed a higher frequency of severe depression when analyzed qualitatively by dependence analysis. Symptoms of severe depression by means of qualitative analysis may strengthen a co-morbidity between depression and transformed migraine. This association might be considered rather a factor of TM perpetuation than a risk factor for the transformation of EM into TM.

Challenging or difficult headache patients

This article addresses interesting and enigmatic presentations of headache from a diagnostic and treatment perspective. The emphasis is on migraineurs and other headache patients who represent a significant burden for the primary care provider. In particular, the author focuses on undiagnosed migraine, menstrual migraine, migraine in pregnancy, intractable migraine and status migrainosus,transformed migraine, hemiplegic migraine, basilar migraine, "triptan syndrome," sudden onset of severe headache, post-traumatic headache, and headache in elderly patients.

Primary headache diagnosis among chronic daily headache patients

Chronic daily headache (CDH) refers to a group of non-paroxysmal daily or near-daily headaches with peculiar characteristics that are highly prevalent in populations of neurological clinics and not uncommon among non-patient populations. Most of the patients with CDH had, as primary diagnosis, episodic migraine, which, with the time, presented a progressive frequency, pattern modification and loss of specific migraine characteristics. Other CDH patients had chronic tension-type headache, new daily persistent headache and hemicrania continua, which evolved thru the time to the daily or near-daily presentation. The objective of this study was to determine the primary headache diagnosis among a population of chronic daily headache patients attending a tertiary center for headache treatment. During a 5-year period 651 consecutive chronic daily headache patients attending a private subspecialty center were studied prospectively. The criteria adopted were those proposed by Silberstein et al (1994, revised 1996). Five hundred seventy four patients (88.1%) had episodic migraine as primary headache before turning into daily presentation, 52 (8%) had chronic tension-type headache, 14 (2.2%) had hemicrania continua and 11 patients (1.7%) had new daily persistent headache. CDH is quite frequent in patients from clinic-based studies suggesting a high degree of disability. Emphasis on education of patients suffering from frequent primary headaches with regard to measures that are able to decrease suffering and disability as well as better medical education directed to more efficient ways to handle these patients are necessary to improve outcome of such a prevalent condition.

Clinical features of episodic migraine and transformed migraine: a comparative study

Transformed migraine (TM) is one of the most frequent types of chronic daily headache. Eighty patients: 40 with episodic migraine (EM) and 40 with TM with ages ranging from 18 to 60 years old were studied. Females were the majority. At first examination, the mean age was similar in both groups. The initial age of migraine attacks was significantly smaller in the TM group. Time history of episodic attacks was similar in both groups. In the EM group, the headache was predominantly located on only one side of the head; whereas in the TM group, on more than one side. There was variation in the character of pain and intensity in the TM group. Nocturnal awakening with headache, aura and family history did not show significant association with EM or TM. The TM was distinguished from the EM in relation to the frequency, location and pain intensity of the headache. Patients with early migraine headache onset may exhibit a further risk of developing TM.

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.

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

In a long-term efficacy and safety 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.

Transformed migraine, analgesic rebound, and other chronic daily headaches

Although the International Headache Society's classification of headache has greatly enhanced the diagnosis of migraine and cluster headache, its application in chronic headache has been less than satisfactory. Based on a review of the literature and the author's experience, this article demonstrates the need for an expanded and modified classification and broader understanding of chronic headaches. The author proposes new categories, including transformed migraine. Analgesic rebound is described as a major cause of chronic headaches. The comorbidity of chronic headache disorders is also discussed. The article concludes with a suggestion for management of chronic headaches.

Classification of chronic daily headache by International Headache Society criteria: limits and new proposals

We conducted a retrospective study of 150 patients with chronic daily headache (CDH) to determine how to categorize their headache according to the classification of the International Headache Society (IHS). All patients were first evaluated at Parma and Pavia Headache Centres (from January 1992 to March 1993) and had had headache for at least 15 days a month during the previous 6 months. Four patients were thereafter excluded due to poor reliability. The 146 patients who met our CDH criteria (92 with and 54 without clear-cut migraine attacks) could be classified into four groups: (i) chronic tension-type headache (CTTH)--27 patients; (ii) coexisting migraine plus CTTH--65 patients; (iii) unclassifiable daily headache--27 patients; and (iv) migraine and an unclassifiable interval headache--27 patients. Seventy-two percent of patients with CDH had migraine as the initial form of their headache. We therefore propose to revise the IHS classification for migraine, taking into account its evolution, and add two subcategories, migraine with interparoxysmal headache and chronic migraine.

A headache clinic-based approach to field trials of the International Headache Society criteria

Criteria for the diagnosis of headache disorders have recently been developed but require empirical validation. We present an approach to the evaluation of headache criteria in a headache clinic: define the group of headache sufferers to be studied, obtain data used in establishing the diagnosis, apply the diagnostic criteria and assess their usefulness. In applying this method to a group of patients with chronic daily headache, we found that approximately one-third would not fit the current criteria for chronic tension-type headache. We conclude that empiric validation of headache criteria based on subjective data is a complex and iterative process. Operational criteria for headache diagnosis to be used by primary care physicians should be validated in that setting and ideally should be relatively simple.

Transformed migraine

Chronic tension-type headache, which is included in the International Headache Classification, is present in only a minority of patients who present with chronic daily headache. The majority have what is termed transformed migraine, with a history of distinct episodes of migraine in the initial years which progresses into chronic daily headache. These patients with transformed migraine exhibit mixed features of migraine and chronic tension-type headache. Two distinct types of transformed migraine are identifiable, namely those related to excessive intake of medications (drug-induced transformed migraine) and those unrelated to excessive use of medications. The clinical features of transformed migraine and the drug-induced variety are described. The need for revision of the International Classification to include chronic daily headache and the subtypes of transformed migraine is pointed out.