Improved prehospital triage for acute cardiac care: results from HART-c, a multicentre prospective study.

BACKGROUND: Cardiac symptoms are one of the most prevalent reasons for emergency department visits. However, over 80% of patients with such symptoms are sent home after acute cardiovascular disease has been ruled out. OBJECTIVE: The Hollands-Midden Acute Regional Triage-cardiology (HART-c) study aimed to investigate whether a novel prehospital triage method, combining prehospital and hospital data with expert consultation, could increase the number of patients who could safely stay at home after emergency medical service (EMS) consultation. METHODS: The triage method combined prehospital EMS data, such as electrocardiographic and vital parameters in real time, and data from regional hospitals (including previous medical records and admission capacity) with expert consultation. During the 6­month intervention and control periods 1536 and 1376 patients, respectively, were consulted by the EMS. The primary endpoint was the percentage change of patients who could stay at home after EMS consultation. RESULTS: The novel triage method led to a significant increase in patients who could safely stay at home, 11.8% in the intervention group versus 5.9% in the control group: odds ratio 2.31 (95% confidence interval (CI) 1.74-3.05). Of 181 patients staying at home, only 1 (< 1%) was later diagnosed with ACS; no patients died. Furthermore the number of interhospital transfers decreased: relative risk 0.81 (95% CI 0.67-0.97). CONCLUSION: The HART­c triage method led to a significant decrease in interhospital transfers and an increase in patients with cardiac symptoms who could safely stay at home. The presented method thereby reduced overcrowding and, if implemented throughout the country and for other medical specialties, could potentially reduce the number of cardiac and non-cardiac hospital visits even further.

Anodal transcranial direct current stimulation in chronic migraine and medication overuse headache: A pilot double-blind randomized sham-controlled trial.

OBJECTIVES: Little evidence is available on the role of transcranial direct current stimulation (tDCS) in patients affected by chronic migraine (CM) and medication overuse headache (MOH). We aim to investigate the effects of tDCS in patients with CM and MOH as well as its role on brain activity. METHODS: Twenty patients with CM and MOH were hospitalized for a 7-day detoxification treatment. Upon admission, patients were randomly assigned to anodal tDCS or sham stimulation delivered over the primary motor cortex contralateral to the prevalent migraine pain side every day for 5 days. Clinical data were recorded at baseline (T0), after 1 month (T2) and 6 months (T3). EEG recording was performed at T0, at the end of the tDCS/Sham treatment, and at T2. RESULTS: At T2 and T3, we found a significant reduction in monthly migraine days (p = 0.001), which were more pronounced in the tDCS group when compared to the sham group (p = 0.016). At T2, we found a significant increase of alpha rhythm in occipital leads, which was significantly higher in tDCS group when compared to sham group. CONCLUSIONS: tDCS showed adjuvant effects to detoxification in the management of patients with CM and MOH. The EEG recording showed a significant potentiation of alpha rhythm, which may represent a correlate of the underlying changes in cortico-thalamic connections. SIGNIFICANCE: This study suggests a possible role for tDCS in the treatment of CM and MOH. The observed clinical improvement is coupled with a potentiation of EEG alpha rhythm.

Psychopathological comorbidities in medication-overuse headache: a multicentre clinical study.

BACKGROUND AND PURPOSE: In medication-overuse headache (MOH) patients, the presence of psychopathological disturbances may be a predictor of relapse and poor response to treatment. This multicentre study aimed to assess the occurrence of psychopathological disorders in MOH patients by comparing the incidence of psychopathological disturbances with episodic migraine (EM) patients and healthy controls (HC). METHODS: The psychopathological assessment of patients and HC involved the administrations of the Beck Depression Inventory, the Beck Anxiety Inventory, the Modified Mini International Neuropsychiatric Interview (M-MINI), the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the Leeds Dependence Questionnaire. RESULTS: The MOH, EM and HC groups (88, 129 and 102 subjects, respectively) differed significantly from each other for the presence of moderate/severe anxiety, whereas mood disorder and depression were revealed in similar proportions for both MOH and EM patients. By stratifying the M-MINI questionnaire results according to the number of psychiatric disorders, it was found that MOH patients had a more complex profile of psychiatric comorbidity. Furthermore, clinically relevant obsessive-compulsive disturbances for abused drugs assessed by Y-BOCS appeared to be more represented in the MOH group, whilst the prevalence of this trait in the EM group was comparable to that of HC (12.5%, 0.8% and 0%, respectively). CONCLUSIONS: Our study indicates the multiple presence of psychopathological comorbidities in patients with MOH. In light of this, it is recommended that the assessment of the psychopathological profile be included in an evaluation of MOH patients, allowing the clinician to more rapidly start an appropriate behavioural treatment, which would greatly improve MOH management.

Variability of the characteristics of a migraine attack within patients.

BACKGROUND: Migraine attacks may present different features in different patients and also within the same patient. The percentage of patients reporting stereotyped attacks and those reporting attacks with different phenotypes has not been the object of specific investigations. OBJECTIVE: The objective of this article is to evaluate the percentage of migraine patients reporting the same characteristics, in terms of phenotype and response to symptomatic medications on three consecutive migraine attacks. METHODS: Thirty patients with migraine without aura prospectively recorded the features of three consecutive attacks in a headache diary. Characteristics recorded were: pain intensity, presence of nausea, vomiting, photophobia, phonophophia, osmophobia, allodynia, cranial autonomic symptoms (at least one), and premonitory symptoms. Patients were allowed to take frovatriptan as symptomatic medication, whose efficacy was evaluated as the two hours pain-free status. RESULTS: None of the patients presented identical characteristics on the three studied attacks. This was still the case if we reduced the number of variables evaluated from 11 to seven of the eight core features indicated by the ICHD. Considering just six variables: unilaterality and quality of pain, presence/absence of nausea, vomiting, photophobia and phonophobia, only two patients (6%) had identical features on three consecutive attacks.With respect to the response to frovatriptan, 39% of patients had the same response, either positive (i.e. pain free after two hours) or negative (i.e. not pain free after two hours) on three consecutive attacks. CONCLUSION: Migraine attacks show a high variability not just among patients, but also within the same patient. Our data indicate that stereotypy of attacks is uncommon, and reinforces the underlying logic of the current operational classification system.

Impact of headache disorders in Italy and the public-health and policy implications: a population-based study within the Eurolight Project.

BACKGROUND: Migraine, tension-type headache (TTH) and medication-overuse headache (MOH) are disabling lifelong illnesses. The Eurolight project, a partnership activity within the Global Campaign against Headache, assessed the impact of headache disorders in ten countries in Europe using a structured questionnaire coupled with various sampling methods. Here we present the findings from the Italian population. METHODS: Questionnaires were distributed to a stratified sample (N = 3500) of the adult (18-65 years) inhabitants of Pavia province (1.05 % of the general population), randomly selected in cooperation with the local health service. Questions included demographic and diagnostic enquries, and assessment of various aspects of impact and health-care utilisation. RESULTS: Altogether 500 questionnaires were returned of which 487 were adequately completed for analysis (58 % female, 42 % male). Among these, gender-adjusted lifetime prevalence of headache was 82.5 %, higher in females than in males (91.2 % vs 72.4 %; p < 0.0001). Gender-adjusted 1-year prevalence was 74.2 % (females 87.7 %, males 61.1 %; p < 0.0001). The most prevalent headache type was migraine (gender-adjusted 1-year prevalence 42.9 %; females 54.6 %, males 32.5 %; p < 0.0001), followed by TTH (28.6 %; no gender-related difference); all causes of headache on ≥15 days/month were reported by 7.0 % of participants (females 10.6 %, males 2.0 %; p = 0.0002), of whom 2.1 %,, all female (p = 0.0064) concomitantly overused acute medications (therefore probable MOH). Only 16.6 % of responders reporting headache had received a diagnosis from a doctor, and very few (2.4 %) were taking preventative medications. Headache had negative impacts on different aspects of life: education, career and earnings, family and social life. Each person with headache had lost, on average, 2.3 days from paid work and 2.4 days from household work, and missed social occasions on 1.2 days, in the preceding 3 months. An increasing gradient for impact was observed from episodic to chronic forms of headache. CONCLUSIONS: Our study reveals that in Italy, as in other countries, migraine, TTH and MOH are highly prevalent and are associated with significant personal impact. These findings have important implications for health policy in Italy.

Cost of Chronic and Episodic Migraine. A pilot study from a tertiary headache centre in northern Italy.

BACKGROUND: Chronic migraine (CM) has a high impact on functional performance and quality of life (QoL). CM also has a relevant burden on the National Health Service (NHS), however precise figures are lacking. In this pilot study we compared the impact in terms of costs of CM and episodic migraine (EM) on the individual and on the National Health System (NHS). Furthermore, we comparatively evaluated the impact of CM and EM on functional capability and on QoL of sufferers. METHODS: We enrolled 92 consecutive patients attending the Pavia headache centre: 51 subjects with CM and 41 with episodic migraine (EM). Patients were tested with disability scales (MIDAS, HIT-6, SF-36) and with an ad hoc semi-structured questionnaire. RESULTS: The direct mean annual cost (in euro) per patient suffering from CM was €2250.0 ± 1796.1, against €523.6 ± 825.8 per patient with EM. The cost loaded on NHS was €2110.4 ± 1756.9 for CM, €468.3 ± 801.8 for EM. The total economic load and the different sub-items were significantly different between groups (CM vs. EM p = 0.001 for each value). CM subjects had higher scores than EM for MIDAS (98.4 ± 72,3 vs 15.5 ± 17.7, p = 0.001) and for HIT-6 (66.1 ± 8.4 vs 58.7 ± 10.1, p = 0.001). The SF-36 score was 39.9 ± 14,74 for CM and 66.2 ± 18.2 for EM (p = 0.001). CONCLUSIONS: CM is a disabling condition with a huge impact on the QoL of sufferers and a significant economic impact on the NHS. The adequate management of CM, reverting it back to EM, will provide a dual benefit: on the individual and on the society.

Dimerization of nitrophorin 4 at low pH and comparison to the K1A mutant of nitrophorin 1.

Nitrophorin 4, one of the four NO-carrying heme proteins from the salivary glands of Rhodnius prolixus, forms a homodimer at pH 5.0 with a Kd of ∼8 µM. This dimer begins to dissociate at pH 5.5 and is completely dissociated to monomer at pH 7.3, even at 3.7 mM. The dimer is significantly stabilized by binding NO to the heme and at pH 7.3 would require dilution to well below 0.2 mM to completely dissociate the NP4-NO homodimer. The primary techniques used for investigating the homodimer and the monomer-dimer equilibrium were size-exclusion fast protein liquid chromatography at pH 5.0 and (1)H{(15)N} heteronuclear single-quantum coherence spectroscopy as a function of pH and concentration. Preparation of site-directed mutants of NP4 (A1K, D30A, D30N, V36A/D129A/L130A, K38A, R39A, K125A, K125E, D132A, L133V, and K38Q/R39Q/K125Q) showed that the N-terminus, D30, D129, D132, at least one heme propionate, and, by association, likely also E32 and D35 are involved in the dimerization. The "closed loop" form of the A-B and G-H flexible loops of monomeric NP4, which predominates in crystal structures of the monomeric protein reported at pH 5.6 but not at pH 7.5 and which involves all of the residues listed above except D132, is required for dimer formation. Wild-type NP1 does not form a homodimer, but NP1(K1A) and native N-terminal NP1 form dimers in the presence of NO. The homodimer of NP1, however, is considerably less stable than that of NP4 in the absence of NO. This suggests that additional aspartate or glutamate residues present in the C-terminal region of NP4, but not NP1, are also involved in stabilizing the dimer.

A consensus protocol for the management of medication-overuse headache: Evaluation in a multicentric, multinational study.

INTRODUCTION: The management of medication-overuse headache (MOH) is often difficult and no specific guidelines are available as regards the most practical and effective approaches. In this study we defined and tested a consensus protocol for the management of MOH on a large population of patients distributed in different countries. SUBJECTS AND METHODS: The protocol was based on evidence from the literature and on consolidated expertise of the members of the consensus group. The study was conducted according to a multicentric interventional design with the enrolment of 376 MOH subjects in four centres from Europe and two centres in Latin America. The majority of patients were treated according to an outpatient detoxification programme. The post-detoxification follow-up lasted six months. RESULTS: At the final evaluation, two-thirds of the subjects were no longer overusers and in 46.5% of subjects headache had reverted back to an episodic pattern of headache. When comparing the subjects who underwent out-patient detoxification vs those treated with in-patient detoxification, both regimens proved effective, although the drop-out rate was higher in the out-patient approach. CONCLUSIONS: The present findings support the effectiveness and usability of the proposed consensus protocol in different countries with different health care modalities.

NMR investigations of nitrophorin 2 belt side chain effects on heme orientation and seating of native N-terminus NP2 and NP2(D1A).

Nitrophorin 2 (NP2), one of the four NO-storing and NO-releasing proteins found in the saliva of the blood-sucking bug Rhodnius prolixus, has a more ruffled heme and a high preference for a particular heme orientation (B) compared with nitrophorin 1 and nitrophorin 4, which show not a preference (A to B ratio of approximately 1:1), suggesting that it fits more tightly in the ß-barrel protein. In this work we have prepared a series of "belt" mutants of NP2(D1A) and (ΔM0)NP2 aimed at reducing the size of aromatic or other residues that surround the heme, and investigated them as the high-spin aqua and low-spin N-methylimidazole complexes. The belt mutants included Y38A, Y38F, F42A, F66A, Y85A, Y85F, Y104A, I120T, and a triple mutant of NP2(D1A), the F42L, L106F, I120T mutant. Although I120 has been mainly considered to be a distal pocket residue, CδH3 of I120 lies directly above the heme 3-methyl, at 2.67 Å, of heme orientation B, or the 2-vinyl of A, and it thus plays a role as a belt mutant, a role that turns out to be extremely important in creating the strong favoring of the B heme orientation [A to B ratio of 1:14 for NP2(D1A) or 1:12 for (ΔM0)NP2]. The results show that the 1D (1)H NMR spectra of the high-spin forms are quite sensitive to changes in the shape of the heme binding cavity. The single mutation I120T eliminates the favorability of the B heme orientation by producing a heme A to B orientation ratio of 1:1, whereas the single mutation F42A reverses the heme orientation from an A to B ratio of 1:14 seen for NP2(D1A) to 10:1 for NP2(D1A,F42A). The most extreme ratio was found for the triple mutant of NP2(D1A), NP2(D1A,F42L,L105F,I120T), in which the A to B ratio is approximately 25:1, a ΔG change of about -3.5 kcal/mol or -14.1 kJ/mol with respect to NP2(D1A). The seating of the heme is modified as well in that mutant and in several others, by rotations of the heme by up to 4° from the seating observed in NP2(D1A), in order to relieve steric interactions between a vinyl ß-carbon and a protein side chain, or to fill a cavity created by replacing a large protein side chain by a much smaller one; the latter was observed for all tyrosine to alanine mutants. These relatively small changes in seating have a measurable effect on the NMR spectra of the mutants, but are indeed minor in terms of overall seating and reactivity of the NP2(D1A) protein. The (1)H NMR resonances of the hemin substituents of the low-spin N-methylimidazole complexes of NP2(D1A,F42L,L105F,I120T) as well as NP2(D1A,I120T), NP2(D1A,Y104A), and NP2(D1A,F42A) have been assigned using natural abundance (1)H{(13)C} heteronuclear multiple quantum correlation and (1)H-(1)H nuclear Overhauser effect spectroscopy spectra.

Association of haplotype combination of serotonin transporter gene polymorphisms with monthly headache days in MOH patients.

OBJECTIVES: To evaluate the role of 5-HTTLPR, STin2 VNTR, and rs1042173T>G polymorphisms of the serotonin transporter gene (SLC6A4) as susceptibility factors for medication overuse headache (MOH) and to assess their value as predictors of the number of headache days per month, a potential marker of disease severity. METHODS: Genotyping was performed by PCR and PCR-RFLP on genomic DNA extracted from peripheral blood of 227 MOH patients and 312 control subjects. Logistic regression analysis was used to evaluate the association between the SL6A4 gene polymorphisms and MOH risk. The association between polymorphic variants and monthly headache days was evaluated by linear regression analysis. RESULTS: Logistic regression analysis, adjusted for age and gender, revealed a nominal association between rs1042173T>G and MOH risk (TT vs. TG + GG, OR: 1.58 95% CI: 1.05-2.37, P = 0.028). In the linear regression analysis adjusted for age, gender, primary headache diagnosis, acute drug overused and monthly drug number, STin2 VNTR was found nominally associated with monthly headache days (12/12 vs. others, difference: 1.55 days, 95% CI: 0.01-3.08, P = 0.050). When STin2 VNTR and rs1042173T>G were analyzed in haplotypic combination, a global haplotype association emerged with monthly headache days which remained significant after Bonferroni correction for multiple comparisons (global haplotype association P = 0.0056). CONCLUSION: Although a minor contribution of SLC6A4 variants in the genetic liability of MOH cannot be excluded, haplotype-based analysis of STin2 VNTR and rs1042173T>G polymorphisms allowed to identify a subgroup of MOH patients with a higher number of monthly headache and, possibly, with a more severe disease.

A basic diagnostic headache diary (BDHD) is well accepted and useful in the diagnosis of headache. a multicentre European and Latin American study.

AIMS: We tested the usability and usefulness of the basic diagnostic headache diary (BDHD) for the diagnosis of migraine, tension-type headache and medication-overuse headache in European and Latin American countries. METHODS: Patients were subdivided into two groups according to a 1:1 randomization list. Those in group 1 were sent the BDHD before their first visit to the headache centre and asked to complete it for at least 1 month. Those in group 2 made their first visit to the headache centre without receiving the BDHD. RESULTS: A total of 626 patients from nine countries and 16 centres completed the study. The BDHD entries were complete in 97.5% of cases. BDHD information and clinical interview were, when taken together, considered complete for diagnosis in 97.7% of cases in group 1 whereas the information obtained by clinical interview alone in group 2 was considered complete in only 86.8% of cases (p < 0.001). The median number of diagnoses per patient in group 1 was significantly higher than in group 2 (p = 0.04). The BDHD was very well accepted by both patients and doctors. CONCLUSIONS: It is concluded that the BDHD is a useful tool in the diagnostic assessment of the most frequent and disabling forms of primary headache and in headache management.

What do the patients with medication overuse headache expect from treatment and what are the preferred sources of information?

Lack of knowledge on patients' expectations to treatment may lead to misunderstandings and prevent successful outcome. Presently, treatment of medication overuse headache (MOH) leads to improvement in up to 75% of patients, but the relapse rate may exceed 40%. This study aimed to evaluate the preferences on information and expectations to treatment in patients entering a treatment programme for MOH. A questionnaire on patients' needs and preferences on information and expectations was distributed to 65 MOH patients from specialized headache clinics in Italy, Germany and Denmark. A total of 75% selected personal verbal information as their primary need, significantly higher than the percentage of patients who selected leaflets and website information 35 and 35%, respectively (p < 0.001). Telephone and E-mail consultation was requested by 59 and 48%, respectively. The information source preferred was again personal verbal information (82%), significantly higher than all other information sources (p < 0.001). In decreasing order, patients preferred telephone consultation (48%), E-mail consultation (44%), website information (41%), and leaflets (33%). 51% expected their headache to be cured, 71 and 57% requested effective prevention and fast relief of the headache episodes. 80 and 75%, respectively expected reduction in frequency and intensity. A total of 64% expected information about self-management and 52% expected to receive education on their headaches. The study demonstrates that patients in specialized headache centres prefer personal information, that expectations are very high, and that education and information are important. Providing the right information and thus give patients realistic expectations might enhance compliance and improve outcome.

Periodic limb movements both in non-REM and REM sleep: relationships between cerebral and autonomic activities.

OBJECTIVE: To investigate the temporal relationship between cerebral and autonomic activities before and during periodic limb movements in NREM and REM sleep (PLMS). METHODS: Patterns of EEG, cardiac and muscle activities associated with PLMS were drawn from polysomnographic recordings of 14 outpatients selected for the presence of PLMS both in NREM and REM sleep. PLMS were scored during all sleep stages from tibial EMG. Data from a bipolar EEG channel were analyzed by wavelet transform. Heart rate (HR) was evaluated from the electrocardiogram. EEG, HR and EMG activations were detected as transient increase of signal parameters and examined by analysis of variance and correlation analysis independently in NREM and REM sleep. Homologous parameters in REM and NREM sleep were compared by paired t-test. RESULTS: The autonomic component, expressed by HR increase, took place before the motor phenomenon both in REM and NREM sleep, but it was significantly earlier during NREM. In NREM sleep, PLM onset was heralded by a significant activation of delta-EEG, followed by a progressive increase of all the other bands. No significant activations of delta EEG were found in REM sleep. HR and EEG activations positively correlated with high frequency EEG activations and negatively (in NREM) with slow frequency ones. CONCLUSIONS: Our findings suggested a heralding role for delta band only in NREM sleep and for HR during both NREM and REM sleep. Differences in EEG and HR activation between REM and NREM sleep and correlative data suggested a different modulation of the global arousal response. SIGNIFICANCE: In this study, time-frequency analysis and advanced statistical methods enabled an accurate comparison between brain and autonomic changes associated to PLM in NREM and REM sleep providing indications about interaction between autonomic and slow and fast EEG components of arousal response.

Abnormalities of the vestibulo-collic reflex are similar in migraineurs with and without vertigo.

The amplitude and habituation of the click-evoked vestibulo-collic reflex (VCR) was found reduced between attacks in migraineurs without complaints of ictal or interictal vertigo or dizziness, compared with healthy subjects. As a next step we recorded VCR in 17 migraine patients (eight with migraine without aura and nine with migraine with aura) who presented ictal migrainous vertigo according to the criteria defined by Neuhauser et al., using a method described previously. Migraineurs with migrainous vertigo have similar VCR abnormalities as patients without vertigo, i.e. a decreased global amplitude and absence of habituation. Potentiation seemed more pronounced in migraineurs with vertigo (7.46 +/- 18.6), but the difference was not significant.

The usefulness and applicability of a basic headache diary before first consultation: results of a pilot study conducted in two centres.

We tested the usefulness and applicability of a simplified headache diary in the diagnosis of migraine (M), tension-type headache (TTH) and medication overuse headache (MOH). The diary was given to headache patients before their first consultation at the headache centre. Seventy-six naive headache patients completed the study. Their understanding of the diary proved highly satisfactory. The patients' level of compliance was also good, with 71% returning the diary completely filled in. The data entered in the diary were deemed complete for the diagnostic purpose in 93% of cases. The level of agreement between headache information gathered through clinical interview and the headache diary was satisfactory. When comparing the diary with the clinical interview, sensitivity was 92% for M, 75% for TTH and MOH. Specificity was 58% for M and TTH, 87% for MOH. Combined use of a diagnostic diary and clinical interview is recommended from the first consultation for headache.

The vestibulo-collic reflex is abnormal in migraine.

Interictal evoked central nervous system responses are characterized in migraineurs by a deficit of habituation, at both cortical and subcortical levels. The click-evoked vestibulo-collic reflex (VCR) allows the assessment of otolith function and an oligosynaptic pathway linking receptors in the saccular macula to motoneurons of neck muscles. Three blocks of 75 averaged responses to monaural 95-dB normal hearing level 3-Hz clicks were recorded over the contracted ipsilateral sternocleidomastoid muscle in 25 migraineurs between attacks and 20 healthy subjects, without vestibular symptoms. Amplitudes, raw and corrected for baseline electromyography, were significantly smaller in migraine patients. Whereas in healthy volunteers the VCR habituated during stimulus repetition (-4.96% +/- 14.3), potentiation was found in migraineurs (4.34% +/- 15.3; P = 0.04). The combination with a reduced mean amplitude does not favour vestibular hyperexcitability as an explanation for the habituation deficit in migraine, but rather an abnormal processing of repeated stimuli in the reflex circuit.

Search for correlations between genotypes and electrophysiological patterns in migraine: the MTHFR C677T polymorphism and visual evoked potentials.

Interictally, migraineurs have on average a reduction in habituation of pattern-reversal visual evoked potentials (PR-VEP) and in mitochondrial energy reserve. 5,10-Methylenetetrahydrofolate reductase (MTHFR) is involved in folate metabolism and its C677T polymorphism may be more prevalent in migraine. The aim of this study was to search in migraineurs for a correlation between the MTHFR C677T polymorphism and the PR-VEP profile. PR-VEP were recorded in 52 genotyped migraine patients: 40 female, 24 without (MoA), 28 with aura (MA). Among them 21 had a normal genotype (CC), 18 were heterozygous (CT) and 13 homozygous (TT) for the MTHFR C677T polymorphism. Mean PR-VEP N1-P1 amplitude was significantly lower in CT compared with CC, and tended to be lower in TT with increasing age. The habituation deficit was significantly greater in CC compared with TT subjects. The correlation between the cortical preactivation level, as reflected by the VEP amplitude in the first block of averages, and habituation was stronger in CC than in CT or TT. The MTHFR C677T polymorphism could thus have an ambiguous role in migraine. On one hand, the better VEP habituation which is associated with its homozygosity, and possibly mediated by homocysteine derivatives increasing serotoninergic transmission, may protect the brain against overstimulation. On the other hand, MTHFR C677T homozygosity is linked to a reduction of grand average VEP amplitude with illness duration, which has been attributed to brain damage.