Topographic EEG mapping methods

After almost 40 years of research on EEG computer analysis, present clinical applications of this method remain limited. At the present time, EEG mapping is suited primarily for research. Despite the pitfalls of an uncritical application of EEG mapping, progress in clinical research made possible by EEG mapping techniques has been considerable. Some problems of data acquisition, display and statistical analysis are discussed in this paper. For headache research examination of the activated EEG, especially with photic stimulation, has greater diagnostic importance than mapping under resting conditions.     

Computerized EEG topography in childhood migraine between and during attacks

Topographic EEG mapping was performed in 58 migrainous children (mean age: 12.9 years; 39 without, 19 with aura) between attacks. Ten children were also recorded during an attack with visual aura. Between attacks there were no significant differences between migraineurs and age-matched controls. During visual aura a decrease in occipital alpha power contralateral to the affected hemifield was found in all patients. This was followed by a bilateral frontal increase in delta power, and, during the headache, by an increased delta activity in posterior-temporal and occipital electrode sites. The possible brain mechanisms underlying these EEG changes are discussed.     

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.     

Contingent negative variation in childhood migraine

Adult migraineurs without aura have an increased amplitude of the Contingent Negative Variation (CNV) between attacks. Given the potential diagnostic importance of this finding and the difficulties associated with diagnosing migraine in childhood it seemed important to assess CNV in children suffering from this disorder. Ninety-seven children aged between 8 and 14 years were recruited. Forty-two suffered from migraine, 34 from tension-type headache. Twenty-one healthy controls were also studied. CNV was recorded from Fz, Cz and Pz referenced to linked earlobes during 20 trials consisting of two tones of moderate intensity with an interstimulus interval (ISI) of 4 sec and an intertrial interval (ITI) of 10 to 14 sec. The second tone of each trial required a button press. EOG was recorded from the left eye. The 10 CNV responses with the least EOG artefact were selected and averaged. Children with migraine had a highly significantly more negative mean CNV amplitude at all three electrode sites than children with tension-type headache and also a more pronounced Post-Imperative-Negative-Variation (PINV). Migrainous children differed from controls only at Cz (ISI). There was also a highly significant increase of mean CNV amplitude and PINV at all three electrode sites in the control group compared to the tension headache group.     

Primary headaches: a convergence hypothesis

After reviewing the historic differentiation between migraine and tension-type headache, the authors note that the similarities between these two types of primary headaches outweigh the differences, and so hypothesize that these headaches share a common pathophysiology. The convergence hypothesis for primary headaches links the clinical features of an evolving headache to current pathophysiological models. The authors suggest that successive symptoms experienced clinically reflect an escalating pathophysiological process, beginning with the premonitory period and progressing into tension-type headache and, if uninterrupted, finally into migraine. The clinical manifestations of other headache types, such as so-called sinus headache or temporomandibular headache, may also be explained by this model. A convergence hypothesis for primary headaches has important implications for earlier recognition, diagnosis, and treatment.     

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.     

Osmophobia in juvenile primary headaches

This study was planned to investigate the prevalence of osmophobia in juvenile headache sufferers and to analyse the diagnostic utility of osmophobia in order to distinguish migraine without aura from episodic tension-type headache. We examined 305 consecutive patients presenting at our Paediatric Headache Centre. A semistructured questionnaire was given to 275 selected patients affected by migraine or tension-type headache. The prevalence of osmophobia during attacks was 18.5%, mainly in migraine patients (25.1%) vs. those with tension-type headache (8.3%). Osmophobia showed more specificity than phonophobia or photophobia in the differential diagnosis between migraine and tension-type headache. In conclusion, this study demonstrates that osmophobia resulted in a symptom with poor sensitivity (27.1%) but high specificity (92%) that could become a supportive diagnostic criterion even in children for the differential diagnosis between migraine without aura and tension-type headache.     

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.     

Prevalence of migraine, tension-type headache, and other headaches in Hong Kong

OBJECTIVE: To assess the prevalence of migraine and other headaches in Hong Kong in 1998. BACKGROUND: A community-based prevalence survey of headache was carried out from July 1992 to March 1993, and the prevalence rates were 1% for migraine, 2% for tension-type headache, and 1% for other headaches. A similar survey was carried out in May and June 1998 to interview individuals aged 15 years or older. Recurrent headache was defined as having two or more headaches unrelated either to influenza or a common cold within the past 12 months. METHODS: Respondents with recurrent headache were offered a personal interview for clinical validation. Of 3156 randomly selected individuals, 1436 responded. RESULTS: Headache was due to influenza or a common cold in 270 (18.8%) respondents; recurrent headache affected 533 (37.1%) respondents. The overall prevalence rates were 4.7% for migraine, 26.9% for tension-type headache, and 5.5% for other headaches. Clinical validation was available for 72 respondents. After adjustment for possible misclassification, the estimated prevalence rates became 12.5% for migraine, 18.7% for tension-type headache, and 6.0% for other headaches. There was a female preponderance for all types of headache with a peak in the 25- to 34-year-age group for tension-type headache. CONCLUSIONS: All types of headache were more common in the 1998 study, and the prevalence rates were closer to those of Western communities.     

Genetics in primary headaches

This tutorial describes different methods and results of genetic studies of primary headaches. A positive family history is imprecise, because it does not specify the number of affected, family size or relation to the proband. Nor does it include an interview of the possibly affected family members. Calculation of the familial aggregation after confirmation of the diagnosis by a physician is more precise. Compared to the general population, first-degree relatives of probands with migraine without aura, migraine with aura, chronic tension-type headache and cluster headache has a significantly increased risk of the proband’s disorder. These data are confirmed in twin studies. The primary headaches are caused by a combination of genetic and environmental factors. A major breakthrough was identification of 3 different genes all causing the rare autosomal dominant inherited familial hemiplegic migraine. The genes encode ion channels. So far no genes have been identified to cause the more common types of primary headaches.     

Noise as a trigger for headaches: relationship between exposure and sensitivity

OBJECTIVE: This study investigated how triggers acquire the capacity to precipitate headaches. BACKGROUND: Traditional clinical advice is that the best way to prevent headache/migraine is to avoid the triggers. Avoidance of anxiety-eliciting stimuli, however, results in sensitization to the stimuli, so is there a danger that avoidance of migraine/headache triggers results in decreased tolerance for the triggers? DESIGN: One hundred and fifty subjects, 60 of whom suffered from regular headaches, were randomly assigned to 5 experimental conditions, defined by length of exposure to the headache trigger of noise. METHODS: Subjects attended a laboratory session divided into 3 phases: preintervention test, intervention (1 of 5 levels of exposure to the trigger), and postintervention test. Response to the intervention was measured in terms of noise tolerance, sensitivity to noise, and nociceptive response to noise. RESULTS: A curvilinear relationship was found between length of exposure to the trigger and pain response for individuals who do not suffer from regular headaches, that is, short exposure was associated with sensitization and prolonged exposure with desensitization. The relationship for headache patients was less clear. CONCLUSIONS: The findings are consistent with the proposition that 1 etiological pathway to suffering from frequent headaches is via trying to avoid, or escape from, potential trigger factors. These results suggest that the traditional clinical advice to headache patients, that the best way to prevent migraine/headache is to avoid the triggers, runs the risk of establishing an insidious sensitization process thereby increasing headache frequency.     

A 3-year follow-up of headache diagnoses and symptoms in Swedish schoolchildren

Information is sparse concerning the incidence and prognosis of headache in children from the general population, especially of tension-type headache. In this study, headache diagnoses and symptoms were reassessed in 122 out of 130 schoolchildren after 3 years. Nearly 80% of those with headache at first evaluation still reported headache at follow-up. Although the likelihood of experiencing the same headache diagnosis and symptoms was high, about one-fifth of children with tension-type headache developed migraine and vice versa. Female gender predicted migraine and frequent headache episodes predicted overall headache at follow-up. The estimated average annual incidence was 81 and 65 per 1000 children, for tension-type headache and migraine, respectively. We conclude that there is a considerable risk of developing and maintaining headache during childhood. Headache diagnoses should be reassessed regularly and treatment adjusted. Girls and children with frequent headache have a poorer prognosis and therefore intervention is particularly important in these groups.     

EEG and Topographic Frequency Analysis in Migraine Attack Before and After Sumatriptan Infusion

Electroencephalographic changes occurring in patients with migraine have received much attention. Although in migraineurs a number of studies have been done after nitroglycerin-induced attacks, there is no reported EEG study before and after nitroglycerin-induced sumatriptan-treated attacks. We, therefore, studied the EEG topographic frequency analysis in 19 symptom-free, otherwise healthy, unmedicated patients with common migraine and in 19 age and sex-matched controls before nitroglycerin, at the time of maximum pain, and 30 minutes after sumatriptan. During headache attacks, an increase of slow rhythmic activity of the theta and delta range and a decrease of activity in the alpha and beta range were observed. These abnormalities disappeared 30 minutes after a sumatriptan injection. This suggests that common migraine is associated with disturbances of cortical electrogenesis and may provide insight into the causes of migraine and aid in the development of effective therapies.     

Prevalence of headache in Swedish schoolchildren, with a focus on tension-type headache

To estimate the prevalence of tension-type headache, migraine and other headaches, 1850 schoolchildren, age 7-15 years, from the city of Uppsala, were invited to complete a questionnaire. The response rate was 74.1%. To validate the information from the questionnaires, 131 children and their parents were interviewed. Using the criteria of the International Headache Society, the 1-year prevalence of tension-type headache and migraine was 9.8 and 11.0%, respectively. However, these prevalence rates increased considerably, to 23.0 and 17.0%, respectively, when excluding the criteria defining the number of earlier episodes and duration of headache. The prevalence of headache increased with age, similarly in girls and boys up to 11 years, and thereafter only in girls. The preponderance in teenage girls was even more pronounced for tension-type headache than for migraine. Our results indicate an increase over time in headache prevalence when compared with findings in a study conducted in the same city in 1955.     

Disability is the major determinant of the severity of depressive symptoms in primary headaches but not in low back pain

Pain syndromes are often associated with depression. In a prospective study we analysed if determinants of depression differ among patients with different primary headaches and between headaches and non-headache pain. During a 2-year period between 1 February 2002 and 31 January 2004, 635 subjects (migraine n = 231; tension-type headache n = 176; cluster headache n = 11; patients with low back pain n = 103; and healthy subjects n = 114) seen by two neurologists filled in a questionnaire on pain characteristics, the MIDAS questionnaire and the Beck Depression Inventory. A multivariate general regression model was used to identify independent predictors of the severity of depressive symptoms. Pain was most frequent in chronic tension-type headache and most intense in the cluster subgroup (P < 0.001, Kruskal-Wallis ANOVA). In univariate tests gender, age, pain frequency, pain intensity and disability were all significantly associated with the severity of depressive symptoms. In the multivariate model disability was the most important independent determinant of the severity of depressive symptoms in the pooled headache group as well as in the migraine and tension-type headache subgroups. In contrast to patients with headache, pain frequency and pain intensity were the significant independent predictors of the severity of depressive symptoms in patients with low back pain. In a multivariate model, after controlling for other factors, determinants of the severity of depressive symptoms were different in headache and non-headache pain subjects, suggesting a different mechanism for developing depression in primary headaches and in other pain syndromes.     

Passive paradigm single-tone elicited ERPs in tension-type headaches and migraine

The active 'oddball' event-related potential (ERP) P3 is elongated or reduced in migraine and tension-type headaches, indicating a deficit of active attention in these primary headaches. It is then reasonable to study the passive attention function in these headaches through the technology of passive paradigm single-tone elicited ERPs. We invited 32 patients suffering from chronic tension-type headache (CTTH), 17 from frequent episodic tension-type headache (FETH) and 32 from interictal migraine without aura, as well as 28 healthy subjects to undergo passive paradigm single-tone ERPs. There were no statistically significant differences when the mean latencies and amplitudes of N1, P2, N2 or the mean latencies of P3 of the four groups were considered. In contrast, the P3 amplitudes were significantly reduced in the patient groups when compared with healthy controls. However, no further significant difference was found between patient groups when considering P3 amplitude. Our study demonstrated a deficit of passive attention in CTTH, FETH and migraine, but could not separate these headache types in this regard. The reduced P3 in patients might be due to the head pain experienced.     

Acupuncture for recurrent headaches: a systematic review of randomized controlled trials

Objective : To assess whether there is evidence that acupuncture is effective in the treatment of recurrent headaches. Design :Systematic review. Study selection :Randomized or quasi-randomized clinical trials comparing acupuncture with any type of control intervention for the treatment of recurrent headaches. Data sources : Electronic databases (Medline, Embase, Cochrane Field for Complementary Medicine, Cochrane Controlled Trials Register), personal communications and bibliographies. Data collection and analysis : Information on patients, interventions, methods, and results were extracted by at least two independent reviewers using a pretested form. A pooled estimate of the responder rate ratio (responder rate in treatment group/responder rate in control group) was calculated as a crude indicator of trial results as meta-analysis of more specific outcome data was impossible due to heterogeneity and insufficient reporting. Results :Twenty-two trials, including a total of 1042 patients (median 36, range 10–150), met the inclusion criteria. Fifteen trials were in migraine patients, six in tension-headache patients, and in one trial patients with various headaches were included. The majority of the 14 trials comparing true and sham acupuncture showed at least a trend in favor of true acupuncture. The pooled responder rate ratio was 1.53 (95% confidence interval 1.11 to 2.11). The eight trials comparing acupuncture and other treatment forms had contradictory results. Conclusions :Overall, the existing evidence suggests that acupuncture has a role in the treatment of recurrent headaches. However, the quality and amount of evidence is not fully convincing. There is urgent need for well-planned, large-scale studies to assess effectiveness and efficiency of acupuncture under real life conditions.     

Cerebral mapping in subjects suffering from migraine with aura

Cerebral mapping of the spontaneous electroencephalographic activity was performed in 31 subjects suffering from migraine with aura and the results were compared with those of a matched control group. All the patients were examined during the interictal period. While traditional visual interpretation of EEG records was negative in all but five cases (16.1%) spectral analysis showed an asymmetry in alpha total power over the posterior regions in 13 cases (41.9%) and an asymmetry in alpha band peak frequency in 17 (54.8%). By means of cerebral mapping and statistical significance probability mapping we were able to demonstrate a significant increase in alpha total power in 13 cases (41.9%) and a regional increase in delta and theta total power in 20 cases (64.5%). In comparison with the control group, the migraine patients showed a widespread increase in slow activity (theta and delta) mostly over the temporal regions.     

Prevalence of primary headaches and cranial neuralgias in men and women aged 55-94 years (Bruneck Study)

The aim of the current study was to estimate the prevalence of all primary headaches and cranial neuralgias in the general community. As part of the population-based Bruneck Study, 574 men and women aged 55–94 years underwent extensive neurological and laboratory examinations involving a standardized headache interview. In the Bruneck Study population the lifetime prevalence of all primary headaches combined and of cranial neuralgias was 51.7 and 1.6%, respectively. Tension-type headache (40.9%) and migraine (19.3%) emerged as the most common types of headache. In men and women aged 55–94 years the 1-year prevalence of primary headaches was high at 40.5%. In this age range headaches caused significant impairment of health-related quality of life. The Bruneck Study has confirmed the high lifetime prevalence of primary headaches and cranial neuralgias in the general population and provided first valid prevalence data for all primary headaches based on International Classification of Headache Disorders, 2nd edition criteria.