Chronic daily headaches in children and adolescents: a study of clinical characteristics

The clinical characteristics of chronic daily headache were studied in 40 children and adolescents, as well as the associated factors responsible for maintenance of the continuous headache pattern. The study of the clinical headache characteristics, showed a female preponderance (75%), mean age of 11 years old at the first consultation, and onset of headache symptomatology at a mean age of 8.5 years old. The average time interval for the evolution of sporadic headache into chronic daily headache was 1.4 years, and psychosocial stressors were present, acutely or chronically, during the period of headache-frequency increase in 47% of the children. Headaches were classified as transformed migraine (65%), mixed pattern (17.5%) and chronic tension-type headache (17.5%). Sixty per cent of patients had mothers with migraine. Data regarding common analgesic use showed an average intake of 11.2 days/month.     

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.     

Chronic headaches: from research to clinical practice

Chronic daily headache (CDH) is a heterogeneous group of headaches that includes primary and secondary varieties. Primary CDH is a frequent entity that probably affects 4–5% of the population. It can be subdivided into headaches of short duration (<4 h/attack) like chronic cluster headache, and disorders of long duration (>4 h/attack). Primary CDH of long duration includes transformed migraine, chronic tension–type headache, and new daily persistent headache and hemicrania continua. Analgesics, ergots and triptan overuse are frequent in all types of CDH. We revise recent insights into the epidemiology, pathophysiology, clinical characteristics and prognosis of CDH.     

Chronic daily headache in Taipei, Taiwan: prevalence, follow-up and outcome predictors

We conducted a two-stage population-based headache survey among subjects aged > or = 15 in Taipei, Taiwan. Subjects with chronic daily headache (CDH) in the past year were identified, interviewed and followed-up. CDH was defined as a headache frequency > 15 days/month, with a duration > 4 h/day. Of the 3377 participants, 108 (3.2%) fulfilled the criteria for CDH, with a higher prevalence in women (4.3%) than men (1.9%). TM was the most common subtype (55%), followed by CTTH (44%). Thirty-four per cent of the CDH subjects overused analgesics. At the 2-year follow-up, 35% of the CDH subjects still had CDH. The significant predictors for persistent CDH at follow-up included: older age ( > or = 40 years) (RR = 2.4), CDH onset after 32 years (RR = 1.8), CDH duration > or = 6 years (RR = 2.0), medication overuse (RR = 1.8), and "daily" headache (RR = 2.1). We found that CDH is not uncommon in the community and its prevalence is similar among different populations. Older subjects and those with medication overuse may have a more protracted course of illness.     

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.     

Primary headaches in HIV-infected patients

Headache in patients with human immunodeficiency virus (HIV) infection may indicate life-threatening illnesses such as opportunistic infections or neoplasms. Alternatively, such patients may develop benign self-limiting headaches. Hence, defining the various types of headache in these patients is essential for proper management. This study describes the clinical characteristics of primary headaches occurring in a group of HIV-infected patients. Of 115 patients seen from 1990 to 1996, 44 (38%) had headaches. Primary headaches were present in 29 (66%) patients and secondary causes were identified in 15 (34%). Among those with primary headaches, migraine occurred in 22 (76%), tension-type headache in 4 (14%), and cluster headache in 3 (10%) patients. Half of those with migraine (n=ll), 1 patient with tension-type headache, and 1 patient with cluster headache developed chronic daily headaches which were severe and refractory to conventional headache or antiretroviral therapy. We conclude that primary headaches in patients with HIV infection are: (1) the commonest type of headache; (2) may present for the first time in individuals with severe immunosuppression; (3) usually bear no relationship to antiretroviral drug therapy; (4) polypharmacy, depression, anxiety, and insomnia are commonly associated comorbidities; (5) frequently do not respond to conventional management and carry a poor prognosis; and (6) do not require neuroradiological and/or cerebrospinal fluid evaluations.     

Chronic daily headache: a time perspective

OBJECTIVE: To determine the development and outcome of chronic daily headache in 258 headache practice patients, consisting of 50 men and 208 women. Chronic daily headache was defined as headaches occurring on at least 5 days per week for at least 1 year. METHODS: Two hundred fifty-eight patients with headache were interviewed and evaluated. Ninety-one patients were contacted by telephone for follow-up. RESULTS: Twenty-two percent of the patients had daily headaches from the onset, and 78% initially experienced intermittent headaches. Of the patients with initially intermittent headaches, 19% experienced an abrupt transition into daily headaches and 81%, a gradual one. In the patients with gradual transition, the transition of the initial, intermittent headaches into daily headaches took an average of 10.7 years. The initial headaches were mild in 33% of the patients and severe in 67%. The severe headaches were associated with nausea and vomiting significantly more often than the mild ones. However, the daily headaches that these patients ultimately developed were the same, regardless of whether the initial headaches were mild or severe. The patients who gradually developed daily headaches from initially intermittent headaches were contacted to determine the outcome of their headaches. Of these patients, 33% continued to have daily headaches and 67% again experienced intermittent headaches. Of the latter group, 88% of the patients who now had migraine also had migraine initially.     

Repetitive intravenous prochlorperazine treatment of patients with refractory chronic daily headache

OBJECTIVES: To investigate the efficacy and long-term outcome of intravenous prochlorperazine for the treatment of refractory chronic daily headache. BACKGROUND: Unlike dihydroergotamine, the treatment results of intravenous neuroleptics as first-line agents for refractory chronic daily headache have rarely been reported. METHODS: We retrospectively analyzed the data of inpatients with refractory chronic daily headache who received intravenous repetitive prochlorperazine treatment from November 1996 to March 1999. A semistructured telephone follow-up interview was done in September 1999. RESULTS: A total of 135 patients (44 men, 91 women) were recruited, including 95 (70%) with analgesic overuse. After intravenous prochlorperazine treatment, 121 (90%) achieved a 50% or greater reduction of headache intensity, including 85 (63%) who became headache-free. The mean hospital stay was 6.2 +/- 2.7 days, and mean total prochlorperazine used was 98 +/- 48 mg. Acute extrapyramidal symptoms occurred in 21 patients (16%). One hundred twenty-four patients (92%) were successfully followed up, with a mean duration of 14.3 +/- 7.5 months. Compared with pretreatment status, 93 patients (75%) considered their headache intensity decreased, and 86 patients (69%) considered their headache frequency decreased, although 40 (32%) still had a daily headache. Of the 87 patients with analgesic overuse who could be followed, 61 (70%) no longer overused analgesics. Poor response to prochlorperazine treatment (relative risk, 1.8) and presence of major depression (relative risk, 1.8) were predictors of persistent chronic daily headache at follow-up. CONCLUSIONS: Prochlorperazine was effective and safe in the treatment of patients with refractory chronic daily headache with or without analgesic overuse. Compared with dihydroergotamine, prochlorperazine seemed less effective at achieving "freedom from headache" during hospitalization, but had a similar outcome at follow-up.     

Opiate use to control bowel motility may induce chronic daily headache in patients with migraine

OBJECTIVES: To investigate whether opiate overuse might cause chronic daily headache in those with migraine, we studied patients who were taking codeine (or other opiates) for control of bowel motility after colectomy for ulcerative colitis. BACKGROUND: Analgesic overuse is considered by many to be one factor which can result in the transformation of migraine into a chronic daily headache pattern. Most of the evidence for this comes from patients with migraine who are taking increasing amounts of analgesia for headache. Many of these patients revert to an intermittent migraine pattern once the analgesics are stopped. METHODS: Women who were 1 year postcolectomy for ulcerative colitis were identified in several colorectal surgery practices in Calgary. They were sent a questionnaire designed to determine if they had a history of migraine prior to surgery, if they currently had chronic daily headache, what medications they were taking to control bowel motility, and what medications they were taking for headache. RESULTS: Twenty-eight patients who met our inclusion criteria returned completed questionnaires. Eight of these exceeded the recommended limits for opiate use in patients with headache. Eight patients met diagnostic criteria for migraine. Two patients had chronic daily headache starting after surgery. Both used daily opiates beginning after their surgery, and both had a history of migraine. The other six patients who used opiates daily did not have a history of migraine and did not have chronic daily headache. All patients with migraine who used daily opiates to control bowel motility following surgery developed chronic daily headache after surgery. CONCLUSIONS: Patients with migraine who use daily opiates for any reason are at high risk of developing transformed migraine with chronic daily headache. This risk appears much lower in patients without a history of migraine who use opiates for nonpain indications.     

From migraine to chronic daily headache: the biological basis of headache transformation

Migraine headache carries the potential of transforming into chronic daily headache (CDH) over a period of time. Although several risk factors for migraine progression to CDH have been identified, the biological basis of this transformation is unknown. In this review, the consequences of stressful life events and medication overuse, 2 risk factors associated with the development of CDH, on brain processes involved in headache are examined. The extensive overlap in both neural circuitry and cellular events that occur with stress, medication overuse, and migraine provide insight into potential mechanisms that may lead to CDH. Particular attention is devoted to the effect of stress and medication overuse on peripheral and central neuroimmune interactions that can facilitate pain signaling. These interactions include the degranulation of mast cells in the dura, causing the sensitization of primary afferent neurons, as well as the activation of glial cells in the brain that can lead to central sensitization. It is hypothesized that the biological processes involved in migraine headache are directly impacted by stress, medication overuse, and other risk factors, resulting in a reduced threshold for induction of headache and transformation of episodic migraine to CDH.     

Chronic daily headache in a tertiary care population: correlation between the International Headache Society diagnostic criteria and proposed revisions of criteria for chronic daily headache

The International Headache Society (IHS) has been criticized for its approach to classification of chronic daily headache (CDH); Silberstein and Lipton criteria provide an alternative to this approach. The aim of this study is to apply the alternative diagnostic approaches to a sample of CDH patients consulting in specialty care. Our sample consisted of 638 patients with CDH. Patients were classified according to both classification systems. Patients were predominantly female (65.0%), with ages ranging from 11 to 88 years. According to the Silberstein and Lipton classification, we found eight different diagnoses. The most common diagnosis was chronic migraine (87.4%), followed by new daily persistent headache (10.8%). Just six patients had chronic tension-type headache (CTTH). Applying the IHS criteria we found 14 different diagnoses. Migraine was found in 576 (90.2%) patients. CTTH occurred in 621 (97.3%), with only 10 (1.57%) having this as the sole diagnosis. We conclude that both systems allow for the classification of most patients with CDH when daily headache diaries are available. The main difference is that the IHS classification is cumbersome and requires multiple diagnoses. The Silberstein and Lipton system is easier to apply, and more parsimonious. These findings support revision of the IHS classification system to include chronic migraine.     

Prophylactic pharmacological treatment of chronic daily headache

Objective.—To review all the prophylactic pharmacological treatments for chronic daily headache from the past decade.
Background.—Chronic daily headache is among the most common diagnoses seen in specialized headache centers. Prior to 1988, there were no criteria for the diagnosis of chronic tension-type headache and chronic daily headache. An expanded chronic daily headache classification has been proposed.
Methods.—A MEDLINE search was performed using the following key words: chronic daily headache, intractable headache, transformed migraine, chronic tension headache, and chronic tension-type headache. We limited our review to those studies published in English in the last decade, including published abstracts and letters to the editor. Double-blind studies carried out prior to 1988 were also included.
Results.—Pharmacological treatments for chronic daily headache include antidepressants (tricyclics, tetracyclics, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors), anticonvulsants, muscle relaxants, 5-HT₁ agonists, ergots, 5-HT₂ antagonists, antianxiety agents, and miscellaneous drugs. Many of these reports are anecdotal, and most are open rather than double-blind studies.
Conclusions.—There is a great variety of pharmacological treatments available for chronic daily headache. Only the antidepressants have been extensively studied. Other medications may be used if these fail. Recommendations based on our experience at the Headache Unit of the Montefiore Medical Center are outlined here.     

The differential diagnosis of chronic daily headaches: an algorithm-based approach

Chronic daily headaches (CDHs) refers to primary headaches that happen on at least 15 days per month, for 4 or more hours per day, for at least three consecutive months. The differential diagnosis of CDHs is challenging and should proceed in an orderly fashion. The approach begins with a search for "red flags" that suggest the possibility of a secondary headache. If secondary headaches that mimic CDHs are excluded, either on clinical grounds or through investigation, the next step is to classify the headaches based on the duration of attacks. If the attacks last less than 4 hours per day, a trigeminal autonomic cephalalgia (TAC) is likely. TACs include episodic and chronic cluster headache, episodic and chronic paroxysmal hemicrania, SUNCT, and hypnic headache. If the duration is > or =4 h, a CDH is likely and the differential diagnosis encompasses chronic migraine, chronic tension-type headache, new daily persistent headache and hemicrania continua. The clinical approach to diagnosing CDH is the scope of this review.     

Prevalence and associated factors for episodic and chronic daily headache in the Colombian population

There are multiple risk factors for chronic daily headache (CDH), but they are usually assessed in an isolated form without an adequate control for confounders. CDH is considered a variant of episodic headache, but studies have not gathered enough evidence to evaluate simultaneously CDH and episodic in the same population. We set out to establish simultaneously the factors associated with chronic daily or episodic headache in a population setting, using a cross-sectional survey in a random sample of 1505 adult urban inhabitants (Bucaramanga, Colombia). The survey asked questions about headache, family and personal history of disease, and consumption or abuse of caffeine, alcohol, hypnotics and analgesics. The association among independent variables and CDH or episodic headache was made with multinomial logistic regression. Female gender, arterial hypertension or cranial trauma history, and a high score in the depression scale are associated with episodic headache and CDH. Parents with CDH, the complaint of multiple arousals during sleep and use of hypnotics are associated with CDH, but not with episodic headache. Age <36 years, alcoholism and snoring are factors associated only with episodic headache. Chronic daily headache and episodic headache have several common risk factors, but there are other factors not shared by both conditions.     

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 prophylaxis with tizanidine: a double-blind,placebo-controlled,multicenter outcome study

OBJECTIVE: To assess the efficacy of tizanidine hydrochloride versus placebo as adjunctive prophylactic therapy for chronic daily headache (chronic migraine, migrainous headache, or tension-type headache). BACKGROUND: Tizanidine is an alpha2-adrenergic agonist that inhibits the release of norepinephrine at both the spinal cord and brain, with antinociceptive effects that are independent of the endogenous opioid system. Previous open-label studies have suggested the drug may be effective for treatment of chronic daily headache. METHODS: Two hundred patients completed a 4-week, single-blind, placebo baseline period, with 134 fulfilling selection criteria and then randomized to tizanidine or placebo. Ninety-two patients completed at least 8 weeks of treatment (tizanidine, n = 45; placebo, n = 47), and 85 patients completed 12 weeks of treatment (tizanidine, n = 44; placebo, n = 41). Most patients (77%) met the diagnostic criteria for migraine of the International Headache Society; 23% had either chronic migrainous headache or chronic tension-type headache. Tizanidine was slowly titrated over 4 weeks to 24 mg or the maximum dose tolerated (mean, 18 mg; SD, 6.4; median, 20.0; range, 2 to 24), divided equally over three dose intervals per day. Overall headache index ([headache days x average intensity x duration in hours]/28 days) was the primary end point. RESULTS: Tizanidine was shown to be superior to placebo in reducing the overall headache index (P =.0025), as well as mean headache days per week (P =.0193), severe headache days per week (P =.0211), average headache intensity (P =.0108), peak headache intensity (P =.0020), and mean headache duration (P =.0127). The mean percentage improvement during the last 4 weeks of treatment with tizanidine versus placebo was 54% versus 19% for the headache index (P =.0144), 55% versus 21% for severe headache days (P =.0331), 35% versus 19% for headache duration (P =.0142), 35% versus 20% for peak headache intensity (P =.0106), 33% versus 20% for average headache intensity (P =.0281), and 30% versus 22% for total headache days (P =.0593). Patients receiving tizanidine also scored higher ratings of overall headache improvement on a visual analog scale (P =.0069). There was no statistically significant difference in outcome for patients with chronic migraine versus those with only migrainous or tension-type headache. Adverse effects reported by more than 10% of the patients included somnolence (47%), dizziness (24%), dry mouth (23%), and asthenia (19%). Dropouts due to adverse events did not differ significantly between tizanidine and placebo. CONCLUSIONS: The results support tizanidine as an effective prophylactic adjunct for chronic daily headache, including migraine, migrainous headache, and tension-type headache. These results also suggest the possible importance of an alpha2-adrenergic mechanism underlying the pathophysiology of this spectrum of headache disorders.     

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.     

Refractory chronic migraine: long-term follow-up using a refractory rating scale

Refractory chronic migraine (RCM) is often associated with disability and a low quality of life (QOL). RCM ranges in severity from mild to severe. There would be a benefit both clinically and in research use in categorizing RCM patients according to severity. This study utilized a unique RCM severity rating scale, tracking the clinical course over 10 years. A total of 129 patients, ages 19–72, were assigned a severity rating of 2–10 (10 = worst). Pain level and QOL were assessed. Over the 10 years, 73% of all pts. had a 30% or more decline in pain. Pain levels improved 45% in mild pts., 42% in mod. pts., and 36% in severe pts. Pain was the same, or worse, in 4% of mild, 15% of mod., and 18% of severe pts. QOL in the mild group improved 35% over 10 years. In moderate pts., QOL improved 32%, while for the severe group QOL improved 33%. While pain and QOL improved across all three groups at the end of 10 years, the severe group remained with significantly more pain and decreased QOL than in the milder groups. The medications that helped significantly included: opioids (63% of pts. utilized opioids), frequent triptans (31%), butalbital (17%), onabotulinumtoxinA (16%), stimulants (12%), and other “various preventives” (9%). RCM pts. were rated using a refractory rating scale with the clinical course assessed over 10 years. Pain and QOL improved in all groups. In the severe group, pain and QOL improved, but still lagged behind the mild and moderate groups. Opioids and (frequent) triptans were the most commonly utilized meds.     

Chronic daily headache: a scientist's perspective

Certain features of chronic daily headache, namely, increased headache frequency, expansion of headache area, and cutaneous allodynia, may imply sensitization of central nociceptive neurons in the trigeminal pathway. Repetitive activation of the trigeminal nerve can lead to a biologic and functional change in trigeminal nucleus caudalis neurons, characterized by a decrease in nociceptive threshold and receptive field expansion. Suppression of the endogenous pain control system can facilitate the process of central sensitization. Evidence of such suppression in patients with chronic daily headache includes decreased platelet serotonin, up-regulation of 5-HT2A receptors, increased platelet nitric oxide production, and increased levels of substance P and nerve growth factor in the cerebrospinal fluid. Results from a number of animal experiments have indicated that chronic analgesic exposure leads to changes in serotonin content and density of 5-HT2A receptors in the central nervous system. This plasticity of the serotonin-dependent pain control system may accelerate the process of sensitization; a biologic outcome that is expressed clinically by the development of chronic daily headache associated with analgesic overuse.     

The clinical characteristics of new daily persistent headache

New daily persistent headache (NDPH) is a subtype of chronic daily headache. The literature on NDPH is scant and its true aetiology is unknown. A retrospective chart review was carried out from a computerized database at the Jefferson Headache Centre from August 1997 to May 2000 to identify patients with NDPH using the Silberstein et al. criteria. Forty women and 16 men were identified. Age of onset ranged from 12 to 78 years. The peak age of onset was the second and third decade in women and the fifth decade in men. Eighty-two per cent of patients were able to pinpoint the exact day their headache started. Onset occurred in relation to an infection or flu-like illness in 30%. A prior headache history was found in 38% of patients. A family history of headache was documented in 29%. The duration of daily headache ranged from 1.5 h to 24 h; 79% were continuous. Nausea occurred in 68% of patients, photophobia in 66%, phonophobia in 61%, and lightheadedness in 55%. Laboratory testing and neuroimaging in all patients was normal except for Epstein-Barr virus antibody titres, which were positive in 71% of seven patients tested, representing past infection. NDPH appears to be a female-predominant disorder, marked by a continuous daily headache with associated migrainous symptoms. Over 80% of patients could state the exact date their headache began. One-third of patients developed NDPH with a flu-like illness.