Clinical neurophysiology of headache

Changes in face and face pareidolia processing in patients with migraine: an ERP study

Migraine is a multifactorial brain disorder characterized by recurrent disabling headache attacks. One of the possible mechanisms in the pathogenesis of migraine may be a decrease in inhibitory cortical stimuli in the primary visual cortex attributable to cortical hyperexcitability. The aim of this study was to investigate the neural correlates underlying face and face pareidolia processing in terms of the event-related potential (ERP) components, N170, vertex positive potential (VPP), and N250, in patients with migraine. In total, 40 patients with migraine without aura, 23 patients with migraine and aura, and 30 healthy controls were enrolled. We recorded ERPs during the presentation of face and face pareidolia images. N170, VPP, and N250 mean amplitudes and latencies were examined. N170 was significantly greater in patients with migraine with aura than in healthy controls. VPP amplitude was significantly greater in patients with migraine without aura than in healthy controls. The face stimuli evoked significantly earlier VPP responses to faces (168.7 ms, SE = 1.46) than pareidolias (173.4 ms, SE = 1.41) in patients with migraine with aura. We did not find a significant difference between N250 amplitude for face and face pareidolia processing. A significant difference was observed between the groups for pareidolia in terms of N170 [F(2,86) = 14,75, P < 0.001] and VPP [F(2,86) = 16.43, P < 0.001] amplitudes. Early ERPs are a valuable tool to study the neural processing of face processing in patients with migraine to demonstrate visual cortical hyperexcitability.NEW & NOTEWORTHY Event-related potentials (ERPs) are important for understanding face and face pareidolia processing in patients with migraine. N170, vertex positive potential (VPP), and N250 ERPs were investigated. N170 was revealed as a potential component of cortical excitability for face and face pareidolia processing in patients with migraine.

Exteroceptive Suppression of Masseter Muscle Activity in Juvenile Migraineurs

The second exteroceptive suppression period (ES2) of masseter or temporalis muscle activity may be reduced in adults with chronic tension-type headache. In adults with migraine, ES2 was found normal or tended to be protracted. To date, no studies on exteroceptive suppression in children and adolescents with headaches have been published. We investigated the exteroceptive suppression of masseter muscle activity in 14 migraineurs and 19 controls between 6 and 18 years of age. It was elicited by electrical stimulation at the labial commissure. No differences were found regarding the first suppression period, but ES2 was significantly longer in the migraine group than in controls. The results of the migraine group suggest overactivity of the interneurons of the reflex loop due to impaired inhibitory control from superior antinociceptive systems already at the beginning of this headache disorder.

The Comorbidity of Migraine and Epilepsy in Children and Adolescents

Migraine and epilepsy share a number of clinical attributes, including pathophysiology and clinical expression. Both are paroxysmal in nature and thus constitute episodic disorders, yet either may be chronic and/or recurrent. Epileptic seizures and migraine headaches may be mistaken one for the other and may even overlap. In particular, occipital lobe seizures may be misdiagnosed as migraine auras. In this article, we review the relationship between migraine and epilepsy, including the known genetic contributions to both conditions, prodromal, ictal, and postictal headache and shared pathophysiology and treatment options. We describe clinical conditions in which both migraine and epilepsy are prominent features. Lastly, we discuss electronecephaographic abnormalities that have been known to occur in individuals with migraine.

A chronic animal model of migraine, induced by repeated meningeal nociception, characterized by a behavioral and pharmacological approach

BACKGROUND

Migraine is a chronic neurovascular disease characterized by recurrent unilateral headache, which induces incapacity. Despite all the progress that migraine research has provided, the neural mechanisms underlying the onset and maintenance of migraine attacks are poorly understood. Due to the complex characteristics of the disorder, it is difficult to develop a proper animal model that mimics all the clinical manifestations in humans.

OBJECTIVE

Taking into account the principal characteristics of the disease, the aim of this study is to develop a chronic animal model of migraine in which we can reproduce behavioral and pharmacological phenomena similar to those displayed by migraineurs.

RESULTS

Our animal model displayed behavioral and pharmacological results similar to those experienced by migraineurs. Specifically, there was a decrease in routine physical activity and an increase in resting behavior. Also, the animals exhibited a novel behavior that we called ipsilateral facial grooming behavior provoked by the meningeal nociception. Moreover, one of the drugs used as treatment for migraine reduced the manifestations previously described. Our results determine that the model mimics many of the clinical features that patients exhibit during migraine attacks. This model can contribute to further understanding of the pathophysiology and the study of novel therapeutic approaches.

Beta-blocker migraine prophylaxis affects the excitability of the visual cortex as revealed by transcranial magnetic stimulation

The objective of this study is to assess effects of beta-blocker migraine prophylaxis on cortical excitability determined by transcranial magnetic stimulation (TMS). Phosphene and motor thresholds (PT, MT) were investigated in 29 patients with migraine, in 15 of them prior to and following preventive medication with metoprolol and in 14 patients without prophylaxis. Following prophylaxis headache frequency significantly decreased (p = 0.005) and mean PT were significantly increased (51.5 ± 7.5 vs. 63.6 ± 8.4%) compared to patients without preventive treatment (53.7 ± 5.3 vs. 52.3 ± 6.3%; p = 0.040). Mean MT did not significantly differ either between groups or due to treatment. In the group of all patients, a significant inverse correlation between headache frequency and the level of PT was found (R = -0.629; p < 0.01). There was, however, no significant correlation in the subgroups of patients. We conclude that (a) clinical efficacy of beta-blocker treatment in migraine could be (at least partly) linked to its ability to modulate the excitability of the visual cortex and (b) the PT determined by TMS appears suitable to assess the effects of prophylaxis on cortical excitability in the individual patient. This may be useful in clinical trials investigating migraine preventive drugs.

Automatic evaluation of the exteroceptive suppression of the temporalis muscle activity

AIM

To set up a reliable automated method of allowing to identify the ES1 and ES2 periods of exteroceptive suppression of the temporal muscle (EST), thereby reducing their intra- and inter-individual variability.

MATERIALS AND METHODS

Analyses were performed in 79 healthy subjects with strict inclusion and exclusion criteria. Each individual underwent two separate examinations 1 week apart. Activity of the left and right temporal muscles was recorded in response to unilateral stimulation of the left and right labial commissures. Wave forms were successively rectified, averaged, and filtered; the intersections of the resulting curve with values corresponding to 50%, 60%, 70%, 75%, and 80% of the control period (20 ms preanalysis time) were automatically determined.

RESULTS

All subjects reached a 80% level of attenuation for ES2. The values of ES2 durations were normally distributed. The mean ES1 and ES2 durations didn't vary between the two recording session, and there was a good individual reproducibility from one session to the other. Though relatively high, the inter-individual variability was slightly lower in the second than in the first session.

CONCLUSIONS

Computed analysis of EST may contribute to decrease inter- and intra-individual test variability. Letting patient habituate through a first recording session could increase test sensitivity, too. The obtained values for ES2 duration are normally distributed and well-reproducible at both the population and individual level. We suggest taking into account both ES2 duration and level of attenuation.

Evoked potentials and transcranial magnetic stimulation in migraine: published data and viewpoint on their pathophysiologic significance

Migraine is a disorder in which central nervous sytem dysfunction might play a pivotal role. Electroneurophysiology seems thus particularly suited to study its pathophysiology. We have extensively reviewed evoked potential and transcranial magnetic stimulation studies performed in migraineurs in order to identify their pathophysiologic significance. Publications available to us were completed by a Medline search. Retrieved and personal data were compared with respect to methodology and interpreted according to present knowledge on cortical information processing. Results are in part contradictory which appears to be method-, patient- and disease- related. Nonetheless, both evoked potential and transcranial magnetic stimulation studies demonstrate that the cerebral cortex, and possibly subcortical structures, are dysfunctioning interictally in both migraine with and without aura. These electrophysiologic abnormalities tend to normalise just before and during an attack and some of them seem to have a clear familial and predisposing character. Besides the studies of magnetophosphenes which have yielded contrasting results, chiefly because the method is not sufficiently reliable, most recent electrophysiologic investigations of cortical activities in migraine favour deficient habituation and decreased preactivation cortical excitability as the predominant interictal dysfunctions. We propose that the former is a consequence of the latter and that it could favour both interictal cognitive disturbances as well as a cerebral metabolic disequilibrium that may play a role in migraine pathogenesis. To summarize, electrophysiologic studies demonstrate in migraine between attacks a cortical, and possibly subcortical, dysfunction of which the hallmark is deficient habituation.

Exteroceptive suppression patterns of masseter and temporalis muscles in central and peripheral headache disorders

The objective of this study was to compare the exteroceptive suppression patterns of masseter and temporalis muscles in patients with primary and secondary headache disorders originating from peripheral joint dysfunction. We accomplished the temporalis and masseter exteroceptive suppression in 28 patients with migraine, 25 patients with chronic tension-type headache (CTH), 22 patients with temporomandibular joint (TMJ) dysfunction and 18 healthy controls. The onset latencies and duration of the first suppression period (S1) was not significantly different between the patients and controls. The duration of the second suppression period (S2) was shorter in patients with CTH, migraine (analysed during attack) and TMJ dysfunction than those obtained from controls. A distinctive finding was significantly prolonged onset latency in patients with TMJ over those obtained from patients with CTH and migraine. We concluded that the onset latency of the S2 period is a useful parameter in the differential diagnosis of primary and peripheral headache disorders.

Assessment and psychological management of recurrent headache disorders

This article updates earlier reviews of recurrent headache disorders published in 1982 and 1992, selectively reviewing research published since 1990. Current issues in assessment (headache diagnosis, psychophysiology, comorbid psychopathology, quality-of-life assessment, and new assessment technologies) and psychological treatment (efficacy, therapeutic mechanisms, treatment delivery, and integration with drug therapy) are addressed. The author emphasizes the need to adapt psychological treatments to the severity of the headache disorder and to developments in drug therapy. Opportunities for the integration of biological, medical, and psychological science are highlighted.

Electroencephalographic abnormalities in aseptic meningitis and noninfectious headache. A comparative study

BACKGROUND

The finding of abnormalities on electroencephalogram (EEG) during the course of aseptic meningitis is often considered to be indicative of parenchymal brain involvement, even in absence of clinical signs of encephalitis.

OBJECTIVE

To investigate if patients with aseptic nonherpetic meningitis who have abnormal EEG recordings during the acute stage of the disease differ in clinical characteristics or cerebrospinal fluid findings from patients with aseptic meningitis and normal EEG recordings.

METHODS

The EEG records of 82 patients with aseptic meningitis were reviewed. A comparative group consisted of 41 age-matched patients with severe headaches without evidence of meningeal inflammation.

RESULTS

Significantly more patients with aseptic meningitis (28%) demonstrated abnormalities on EEG than controls (12%) (P =.048). Patients with aseptic meningitis and abnormal EEG findings (n = 23) did not differ in age, duration of symptoms, clinical course, cerebrospinal fluid cell count, or protein level from those with normal EEG findings (n = 59). However, all patients with aseptic meningitis who were confused (n = 5) also revealed EEG abnormalities (P<.00012). Patients with headache with normal EEG recordings did not differ from those with abnormal EEGs in age, sex, or duration of symptoms. Nevertheless, patients with common migraine (n = 9) showed abnormalities on EEG (P =.06) more frequently.

CONCLUSIONS

The finding of an abnormal EEG in patients with aseptic meningitis, clear mental state and absence of focal neurological signs should not be used as proof of encephalitis. Because pathological examination is usually not performed, it remains unclear if EEG abnormalities in patients with aseptic meningitis indicate a silent parenchymal inflammation, or reflect an infectious encephalopathy.

The postconcussion syndrome after mild head trauma part II: is migraine underdiagnosed?

The evidence for post-traumatic migraine as the cause of the postconcussion syndrome in a proportion of patients is reviewed.

CONCLUSION

patients suffering recurrent post-traumatic headaches or other elements of the postconcussion syndrome should be treated for migraine.

Auditory evoked potentials in the assessment of central nervous system effects of antimigraine drugs

Because the "intensity dependence" of cortical auditory evoked potentials (IDAP) is under serotonergic control, it can be used to assess central antimigraine effects of 5HT1B/1D agonists. We measured IDAP before and 2 h after naratriptan (5 mg, n = 19) and zolmitriptan (5 mg, n = 19) in healthy volunteers. IDAP was expressed as the amplitude-stimulus intensity function ("ASF slope"). Naratriptan tended to increase ASF slope (mean difference 0.23 +/- 0.62 microV/10 dB, p = 0.06) while zolmitriptan (0.08 +/- 0.95 microV/10 dB, p = 0.35) did not. We assessed the suitability of IDAP for measuring central antimigraine drug effects using repeatability data (see companion paper). We calculated the trade-off between the size of the expected drug effects (ASF slope difference) and the necessary sample size. Because of poor repeatability 36 to 80 subjects are required to detect ASF slope changes in the 0.25-0.5 microV/10 dB range. These data can be used to design trials using IDAP.

Personality and response to repeated visual stimulation in migraine and tension-type headaches

Migraine sufferers potentiate their visual evoked potentials (VEPs) from a short period of 2 min to a longer period of 15 min. As a lack of habituation is linked to higher level arousal, we thus hypothesized that short-term VEP potentiation might be correlated with an arousal-related personality trait. We therefore carried out short-term VEPs, Plutchik-van Praag's Depression Inventory, Zuckerman's Sensation-Seeking Scales (Form V), and Zuckerman-Kuhlman's Personality Questionnaire in 26 healthy subjects, 22 patients suffering from migraine without aura between attacks, 13 episodic and 20 chronic tension-type headaches. The chronic tension-type headache sufferers showed increased depression compared with other groups, which might be a consequence of the headache itself. Migraines, however, showed steeper habituation slopes of N1-P1 and P1-N2, decreased thrill and adventure-seeking, and general sensation-seeking than healthy controls; in addition, the habituation slope of P1-N2 was positively correlated with experience-seeking in migraine. The short-term VEP potentiation and the decreased thrill and adventure-seeking and general sensation-seeking in migraine might be related to a high level of cortical arousal and a low 5HT neurotransmission. In compliance with the long-term VEP study, the positive correlation between the P1-N2 habituation slope and experience-seeking in migraine suggests a continuous metabolic overload for the brain interictally, which can trigger the activation of a migraine attack.