Chronic daily headache: correlation between the 2004 and the 1988 International Headache Society diagnostic criteria

BACKGROUND: In a previous study, we compared the 1988 International Headache Society (IHS) criteria and the Silberstein-Lipton criteria (S-L) in a subspeciality clinic sample of 638 patients with chronic daily headache (CDH) assessed both clinically and with headache diaries. Both systems allowed for the classification of most patients with CDH. The 1988 IHS classification required multiple diagnoses and was more complex to apply. OBJECTIVES: The aim of this study was to revisit the same database, now comparing the prior classification systems with the new 2004 IHS classification. In contrast with the 1st edition, the 2nd edition includes criteria for chronic migraine (CM), new daily persistent headache (NDPH), and hemicrania continua (HC). METHODS: We reviewed the clinical records and the headache diaries of 638 patients seen between 1980 and 2001 at a headache center. All patients had primary CDH according to the S-L criteria. RESULTS: Using the S-L criteria as a reference, of the 158 patients with transformed migraine (TM) without medication overuse, just 9 (5.6%) met 2004 IHS criteria for CM. Most of the subjects were classified using combinations of migraine and CTTH diagnoses, much like the 1988 IHS classification. Similarly, using the new IHS system, just 41/399 (10.2%) subjects with TM with medication overuse were classified as probable CM with probable medication overuse. Most patients with NDPH without overuse were easily classified using the 2004 criteria (95.8%). Regarding NDPH with medication overuse, the diagnostic groups were much like results for the 1st edition. All patients with chronic tension-type headache (CTTH) and hemicrania continua (HC) according to the S-L system were easily classified using the 2004 IHS criteria. CONCLUSIONS: We conclude that the 2004 IHS criteria facilitate the classification of NDPH without medication overuse and HC. For subjects with TM according to the S-L system, the new IHS criteria are complex to use and require multiple diagnoses. Very few patients with TM in the S-L system could be classified with a single diagnosis in the 2004 IHS classification. In fact, CM was so rare that it would be virtually impossible to conduct clinical trials of this entity using the 2004 IHS criteria. Clinical trials of this entity should therefore be conducted using the S-L criteria. Finally, we propose that in the 3rd edition of the IHS classification, the diagnosis of NDPH be revised so as not to exclude migraine features.     

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.     

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.     

The classification of chronic daily headache in adolescents--a comparison between the second edition of the international classification of headache disorders and alternative diagnostic criteria

OBJECTIVES: To compare the second edition of the International Classification of Headache Disorders (ICHD-2) and the Silberstein-Lipton (S-L) criteria in the classification of adolescents with chronic daily headache (CDH). METHODS: We reviewed the clinical records and the headache diaries of 170 adolescents (13 to 17 years) seen between 1998 and 2003 at a headache center. Relevant information was transferred to a standardized form that included operational criteria for the ICHD-2. CDH subtypes were classified according the criteria proposed by S-L into transformed migraine (TM) with (TM+) and without medication overuse (TM-), chronic tension-type headache (CTTH), new daily persistent headache (NDPH), and hemicrania continua (HC). RESULTS: From the 69 patients with TM- according the S-L criteria, most (71%) could be classified as chronic migraine (CM), while a minority of patients required a combination of diagnosis, mainly migraine and CTTH (14.4%). Of the patients with TM+, just 39.6% met the criteria for probable CM (PCM) with probable medication overuse (PMO). If instead of 15 migraine days per month, we considered 15 or more days of migraine or probable migraine, 84% of the subjects with TM- and 68.7% of those with TM+ could be classified. Of the 27 subjects classified as NDPH without medication overuse according to the S-L system, the majority (51.2%) were also classified as NDPH according the ICHD-2. Interestingly, three (11.1% of the subjects with NDPH without medication overuse) were classified as CM in the ICHD-2 because these patients had an abrupt onset of 15 or more days of migraine per month. All patients with NDPH with medication overuse according to the S-L criteria required a combination of diagnoses in the ICHD-2. All subjects with CTTH received a single diagnosis in both classification systems. CONCLUSIONS: (i) Among adolescents with TM, the majority (58.1%) could be classified as CM, according to the ICHD-2. These results were driven by TM without medication overuse. (ii) If the ICHD-2 criteria for CM are revised to require 15 days of migraine or probable migraine, the proportion of patients with TM- who meet the criteria for CM increases from 71% to 84%; for TM+, the proportion with probable chronic migraine and PMO increases from 30% to 68%. (iii) About half of the patients with NDPH according to the S-L criteria have too many migraine features to meet ICHD-2 criteria for NDPH.     

Epidemiology of chronic daily headache

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.     

Quality of life differs among headache diagnoses: analysis of SF-36 survey in 901 headache patients

This paper presents the results of health-related quality of life (HRQoL) in 901 patients consecutively visiting a headache clinic of a national medical center in Taipei, Taiwan. HRQoL was evaluated with the Medical Outcome Study-Short Form (SF-36) and the Hospital Anxiety and Depression Scale (HADS). According to the classification criteria for chronic daily headache (CDH) proposed by Silberstein et al. (Neurology 47 (1996) 871) five hundred and ninety-three (66%) patients had CDH, of whom transformed migraine (TM) was diagnosed in 310, and chronic tension-type headache (CTTH) in 231. One hundred and ninety-three patients had episodic migraine. All SF-36 scale scores significantly correlated with the HADS scores and the intensity and frequency of pain. Compared with the normative data, a pervasive multi-dimensional decline of the SF-36 scores was noted among the headache patients except for the physical functioning scale. The decline was most remarkable in the role limitations of physical and emotional dimensions and in the bodily pain. An increasing impairment of the SF-36 scores was noted from migraine to CTTH to TM. After controlling for the HADS, age, gender, education, and chronic illness by multiple linear regression analyses, the patients with TM had the worst SF-36 profile; whereas, the patients with CTTH and migraine had compatible results. This study is the first to demonstrate that the SF-36 scores differ among headache diagnoses. Psychological distress, as well as the percentages of the types of patients, greatly influenced the SF-36 scores in hospital-based headache samples. Our findings also suggest that improvement in the pain profile as well as psychological well-being can predict a generalized improvement in the SF-36 scales in headache patients.     

Diagnostic issues in chronic daily headache

A number of patients attending specialty headache centers complain of very frequent, almost continuous headaches, which are usually grouped together under the term chronic daily headache (CDH), a category which does not appear in the International Headache Society (IHS) classification published in 1988. More than 10 years later, this issue is still debated, also in light of the foreseen revised classification. Several terms have been used to define the clinical picture of CDH, and different criteria have been proposed for the diagnosis of these forms. In most cases, CDH appears to evolve from an episodic migraine, but the temporal limits between an episodic and a no-longer episodic form of migraine are questionable. Although some theoretic problems remain unresolved, it seems that the next revision of the IHS classification can no longer ignore the existence of CDH.     

Chronic daily headache and the revised international headache society classification

Chronic daily headache (CDH) is surprisingly common. It is best defined as a primary headache disorder with head pain on most days. There are a number of possible secondary causes of persistent headache, including traumatic, vascular, neoplastic, and infectious processes, all of which must be ruled out when the patient with frequent headache is evaluated. However, most patients with CDH seem to have a primary neurophysiologic disorder. This category of primary CDH does not seem to be a homogeneous disorder, but rather one with important subtypes. Several authors have proposed subdivisions of primary CDH such as chronic migraine, evolved migraine, transformed migraine, chronic tension-type headache, new daily persistent headache, and hemicrania continua. The International Headache Society (IHS) Classification published in 1988 did not address CDH other than to define a category “chronic tension-type headache.rd The revised IHS Classification (ICHD II) attempts to characterize CDH more thoroughly with the addition of chronic migraine and new daily persistent headache diagnoses, but this complex issue continues to defy easy categorization. This article provides a review of thinking about the nature of primary CDH and how ICHD II attempts to organize this category for much needed research purposes.     

Classification of Daily and Near-Daily Headaches: Proposed Revisions to the IHS Criteria

SYNOPSIS
The International Headache Society (IHS) headache classification, while a major advance, does not adequately classify the daily and near-daily headache disorders known as chronic daily headache (CDH). We believe that chronic daily headache is a group of disorders which includes chronic tension-type headache (CTTH), transformed migraine (TM), new daily persistent headache (NDPH), and hemicrania continua (HC). We propose specific criteria for transformed migraine, new daily persistent headache, and hemicrania continua, and have modified the criteria for chronic tension-type headache.     

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.     

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.     

Chronic daily headache in children and adolescents: a clinic based study from India

Chronic Daily Headache (CDH) is uncommon in Indian children compared to their adult counterpart. This is a retrospective study looking at the headache phenomenology of CDH in Indian children and adolescents. The validity of the case definitions of subtypes of chronic primary headaches mentioned in the IHS 2004 classification have been evaluated. 22 children (age range 8-15 years; M : F-16 : 6) diagnosed as having primary CDH using a modified definition seen between 2002 and 2003 have been studied. CDH has been defined as daily or near daily headaches > 15d/month for > 6 weeks. The rationale for this modified definition has been discussed. Majority of children (15/22) had a more or loss specified time of onset of regular headache spells resembling New Daily Persistent Headache (NDPH) but did not fulfil totally the diagnostic criteria of NDPH as laid down by IHS 2004. In all cases headache phenomenology included a significant vascular component. Headache phenomenology closely resembled Chronic Tension Type Headache (CTTH) in 4 patients and Chronic Migraine in 3 patients. However, in no patient in these groups, a history of evolution from the episodic forms of the diseases could be elicited. Heightened level of anxiety mostly related to academic stress and achievement was noted in the majority (19/22). Only a minority of patients (3/22) had anxiety and depression related to interpersonal relationships in the family. Medication overuse was not implicated in any patient. CDH in children in India is very much different from CDH in adults with the vast majority of patients exhibiting overlapping features of migraine and tension-type headache. There is need for a modified diagnostic criteria and terminology for chronic primary headaches in children.     

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.     

Chronic tension-type headache in children and adolescents

In this study, the causes, predisposing factors and clinical features of chronic daily headache in children and adolescents were studied within the population of patients attending a specialist headache. The International Headache Society's (IHS) criteria for the diagnosis of chronic tension type headache (CTTH) were assessed for their applicability in the paediatric age group. Over a period of three years, demographic and clinical data were collected prospectively on all children who attended the clinic and suffered from daily attacks of headache. One hundred and fifteen children and adolescents (32% of all clinic population) had chronic daily headache, of whom 93 patients (81%) fulfilled the IHS criteria for the diagnosis of CTTH. They were between 3-15 years of age (mean: 11.1, SD: 2.3) and their female to male ratio was 1.2 : 1. Around one third of the patients also suffered from migraine (mainly migraine without aura). The headache was described as mild in 60.9%, moderate 36.5% and severe 2.6%. Headache was located at the forehead in 53% or over the whole of the head in 29.6%. Pain was described as 'just sore' or dull by 73.9%. During attacks of headache, at least half the patients reported light intolerance, noise intolerance, anorexia or nausea. Thirty-two percent of patients had at least one underlying chronic disease that may have contributed to the pathogenesis of the CTTH. Eleven percent had serious stressful events related to family illnesses and in four patients headaches were triggered by family bereavement. Fourteen percent were investigated with neuroimaging and 22% were referred for clinical psychology assessment and management. In conclusion, CTTH is a common cause of headache in children attending a specialist headache clinic. The clinical features closely match those of adult population and the IHS criteria for the diagnosis of CTTH can be adapted for use in children. Predisposing stressful risk factors, physical or emotional, are present in a large proportion.     

Clinical and descriptive analysis of chronic daily headaches

With an ad hoc, previously validated clinical record, we analysed the headache characteristics in 245 patients (F, 78.4%, M, 21,6%; mean age, 43.1±12.9 years) affected by chronic daily headache (CDH) attending 9 Italian headache centers. Migraine without aura was the episodic headache preceding CDH in 72.3% of the cases. We divided CDH into 3 categories: chronic tension-type headache (CTTH), chronic coexisting migraine and tension-type headache (CCMTTH), and chronic migraine (CM). CCMTTH accounted for 46.5% of the cases, followed by CM (30.2%) and CTTH (23.3%). Female prevalence was more marked in CCMTTH and CM groups, in which episodic headache started earlier. Migraine without aura was the episodic headache preceding CDH not only in most cases of CCMTTH (83.0%) and CM (91.9%), but also in 25% of CTTH patients.Analgesics misuse (abuse of weak analgesics and/or combination drugs in almost all the cases) prevailed among CCMTTH (61%) and CM (89%) patients with respect to CTTH patients (37%).     

Chronic daily headache: old problems,new vistas

In 1988 the problems concerning chronic daily headache (CDH) were neglected by the classification of the International Headache Society (IHS). More than ten years later, this issue is still debated, also in light of the foreseen revised classification. Several terms have been used to define the clinical picture of CDH, and different criteria have been proposed for the diagnosis of these forms. In most cases, CDH appears to evolve from an episodic migraine, but the temporal limits between an episodic and a no-longer episodic form of migraine are questionable. A decreased threshold for headache recurrence in CDH is currently hypothesized, and it may be due to either an impaired control system or a sensitization of the trigeminal neurons, occurring regardless of the original nature of headache. The identification of genetic alterations and neurobiological changes underlying the different forms of CDH may greatly facilitate any nosographic and therapeutical approach to this broad spectrum of disorders.     

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.     

Chronic daily headache in a paediatric headache centre

The prevalence and the clinical features of chronic daily headache (CDH) were studied in 968 children and adolescents observed during a period of one year in the Headache Centre of the Anna Meyer Paediatric Hospital of Florence. Nine hundred and fortyfour patients (97.52%) had primary headache according to ICHD-II, 24 subjects had secondary headache and 56 patients had CDH (5.93% of primary headaches). The mean age of subjects with CDH was higher than general (13.5 vs. 11.5 years), with a female preponderance (69.6% vs. 30.4%). According to the ICHD-II, headaches were classified as chronic migraine in 10 patients (1.5.2 ICHD-II), chronic tension-type headache in 36 (2.3 ICHD-II), new daily persistent headache in 8 (4.8 ICHD-II) and 2 patients reported mixed pattern (chronic migraine+chronic tension type headache). Medication overuse was not implicated in our patients.     

Primary chronic daily headache: clinical and pharmacological aspects. A clinic-based study in Oman

This study on primary chronic daily headache was based on the 1996 proposed revision of the diagnostic criteria of the International Headache Society (IHS). To investigate the relative frequency, clinical characteristics, and associated features of primary chronic daily headache in Omani patients, 171 patients visiting the Neurology Clinic at Sultan Qaboos University Hospital were evaluated. Forty-five percent was diagnosed as suffering from primary chronic daily headache (female to male ratio, 1.7:1). Sixty-two percent suffered from transformed migraine and 34% from chronic tension-type headache. The average age across sexes was 32.3 +/- 12.3 years. A dull heavy feeling in the head was reported by 58% of patients and was associated in less than one third with associated features characteristic of migraine. All headache types shared the same trigger factors. All patients were taking medication, predominantly analgesics, at the time of their first visit. We concluded that primary chronic daily headache is very common with the relative frequency of transformed migraine being similar to that found in Mediterranean studies. Also in Oman, chronic use/overuse of analgesics and nonsteroidal anti-inflammatory drugs is a problem that coexists with primary chronic daily headache. Finally, the proposed revised IHS criteria are highly recommended as a standard classification system for this type of headache.     

Predictors of response to botulinum toxin type A (BoNTA) in chronic daily headache

OBJECTIVE: To evaluate predictors of response to botulinum toxin type A (BoNTA; BOTOX, Allergan Inc., Irvine, CA, USA) in patients with chronic daily headache (CDH). BACKGROUND: Chronic migraine (CM) and chronic tension-type headache (CTTH) form the majority of CDH disorders. Controlled trials indicate that BoNTAis effective in reducing the frequency of headache and number of headache days in patients with CDH disorders. A recent migraine study found that patients with imploding or ocular types of headaches were responders to BoNTA, whereas those with exploding headaches were not. To date, there are no data on factors that might predict response to BoNTA in patients with CDH. METHODS: A total of 71 patients with CM and 11 patients with CTTH were treated with 100 units BoNTA. Every patient received at least 2 sets of injections at intervals of 12-15 weeks; fixed sites, fixed dose, and "follow-the-pain" approaches were used for the injections. A detailed medical history was taken for each patient in addition to recording Migraine Disability Assessment Scale (MIDAS) scores at baseline and every 3 months after each set of injections. Headache frequency was assessed throughout the study from baseline to weeks 24-27. Patients recorded the frequency, severity, and duration of headaches in Headache Diaries. Patients were divided into responders (> or = 50% reduction in both headache frequency and MIDAS scores compared with baseline) and nonresponders (< 50% reduction in either of the above variables). Variables analyzed for predictors of response include headache that is predominantly unilateral or bilateral in location, presence of cutaneous allodynia (scalp allodynia), and presence of pericranial muscle tenderness (also referred to as muscle allodynia). Chi-square analysis was used for parallel-group comparisons (proportion of CM responders vs proportion of CM nonresponders and proportion of CTTH responders vs proportion of CTTH nonresponders). RESULTS: In the CM group, 76.1% (54 /71) of patients were responders to BoNTA, of which 68.5% (37/54) had headache that was predominantly unilateral in location and the remaining 31.5% (17/54) had headache that was predominantly bilateral in location (both P < .01 vs CM nonresponders). Of the 23.9% (17/71) CM nonresponders, 76.5% (13/17) reported predominantly bilateral headache and in the remaining 23.5% (4/17) the headache was unilateral. In the CM responders group, 81.5% (44/54) had clinically detectable scalp allodynia, while pericranial muscle tenderness was present in 61.1% (33/54) (both P < .01 vs CM nonresponders). The presence of scalp allodynia and pericranial muscle tenderness in the CM nonresponders was 11.8% (2/17) and 17.6% (3/17), respectively. In the CTTH group where all patients (100%, 11/11) had bilateral headache, 36.4% (4/11) of patients were responders to BoNTA. All of those CTTH responders (100%, 4/4) had pericranial muscle tenderness (P < .05 vs CTTH nonresponders). None of the CTTH nonresponders had pericranial muscle tenderness. No clinically significant serious adverse events (AEs) were reported. Mild AEs, eg, injection-site pain that persisted for 1-9 days, were reported in 11 patients. One patient had transient brow ptosis. CONCLUSIONS: A greater percentage of patients with CM responded to BoNTA than patients with CTTH. Headaches that were predominantly unilateral in location, presence of scalp allodynia, and pericranial muscle tenderness appear to be predictors of response to BoNTA in CM, whereas in CTTH, pericranial muscle tenderness may be a predictor of response.