Links between headaches and epilepsy: current knowledge and terminology

Migraine - a borderland disease to epilepsy: near it but not of it

BACKGROUND

Migraine and epilepsy are two paroxysmal chronic neurological disorders affecting a high number of individuals and being responsible for a high individual and socioeconomic burden. The link between these disorders has been of interest for decades and innovations concerning diagnosing and treatment enable new insights into their relationship.

FINDINGS

Although appearing to be distinct at first glance, both diseases exhibit a noteworthy comorbidity, shared pathophysiological pathways, and significant overlaps in characteristics like clinical manifestation or prophylactic treatment. This review aims to explore the intricate relationship between these two conditions, shedding light on shared pathophysiological foundations, genetic interdependencies, common and distinct clinical features, clinically overlapping syndromes, and therapeutic similarities. There are several shared pathophysiological mechanisms, like CSD, the likely underlying cause of migraine aura, or neurotransmitters, mainly Glutamate and GABA, which represent important roles in triggering migraine attacks and seizures. The genetic interrelations between the two disorders can be observed by taking a closer look at the group of familial hemiplegic migraines, which are caused by mutations in genes like CACNA1A, ATP1A2, or SCN1A. The intricate relationship is further underlined by the high number of shared clinical features, which can be observed over the entire course of migraine attacks and epileptic seizures. While the variety of the clinical manifestation of an epileptic seizure is naturally higher than that of a migraine attack, a distinction can indeed be difficult in some cases, e.g. in occipital lobe epilepsy. Moreover, triggering factors like sleep deprivation or alcohol consumption play an important role in both diseases. In the period after the seizure or migraine attack, symptoms like speech difficulties, tiredness, and yawning occur. While the actual attack of the disease usually lasts for a limited time, research indicates that individuals suffering from migraine and/or epilepsy are highly affected in their daily life, especially regarding cognitive and social aspects, a burden that is even worsened using antiseizure medication. This medication allows us to reveal further connections, as certain antiepileptics are proven to have beneficial effects on the frequency and severity of migraine and have been used as a preventive drug for both diseases over many years.

CONCLUSION

Migraine and epilepsy show a high number of similarities in their mechanisms and clinical presentation. A deeper understanding of the intricate relationship will positively advance patient-oriented research and clinical work.

Migraine Comorbidities

Novel knowledge about the interrelationships and reciprocal effects of migraine and epilepsy, migraine and mood disorders, or migraine and irritable bowel syndrome has emerged in recent decades. Over time, comorbid pathologies associated with migraine that share common physiopathological mechanisms were studied. Among these studied pathologies is epilepsy, a disorder with common ion channel dysfunctions as well as dysfunctions in glutamatergic transmission. A high degree of neuronal excitement and ion channel abnormalities are associated with epilepsy and migraine and antiepileptic drugs are useful in treating both disorders. The coexistence of epilepsy and migraine may occur independently in the same individual or the two may be causally connected. The relationship between cortical spreading depression (CSD) and epileptic foci has been suggested by basic and clinical neuroscience research. The most relevant psychiatric comorbidities associated with migraine are anxiety and mood disorders, which influence its clinical course, treatment response, and clinical outcome. The association between migraine and major depressive disorder can be explained by a robust molecular genetic background. In addition to its role as a potent vasodilator, CGRP is also involved in the transmission of nociception, a phenomenon inevitably linked with the stress and anxiety caused by frequent migraine attacks. Another aspect is the role of gut microbiome in migraine's pathology and the gut-brain axis involvement. Irritable bowel syndrome patients are more likely to suffer migraines, according to other studies. There is no precise explanation for how the gut microbiota contributes to neurological disorders in general and migraines in particular. This study aims to show that migraines and comorbid conditions, such as epilepsy, microbiota, or mood disorders, can be connected from the bench to the bedside. It is likely that these comorbid migraine conditions with common pathophysiological mechanisms will have a significant impact on best treatment choices and may provide clues for future treatment options.

Primary headache disorders in epileptic adults

Background

Epilepsy and primary headache disorders are two relatively common neurological disorders and their relationship is still a matter of debate. We aimed to estimate the prevalence and clinical features of primary headache disorders in patients with epilepsy.

Methods

62 subjects aged ≥ 18 years were recruited from the hospital’s neurology outpatient clinic in the period from January to April 2018. The subjects were further divided into two equal groups, epileptics and non-epileptics. They underwent a semi-structured interview including the ILAE 2017 epilepsy classification and the ICHD III-beta criteria for headache. Patients' demographic data and clinical characteristics of epilepsy and headache and temporal relationships between them were assessed. Patients who experienced headaches were grouped based on the type of headaches and on whether their headaches occurred in the pre-ictal, post-ictal or inter-ictal period.

Results

Primary headache disorders were more common in epileptic group (61.3%) than the non-epileptic group (32.2%) (p = 0.021). The tension-type headache was the most common (45.2%) followed by migraine-type headache (12.9%) in the epileptic group. Post-ictal headache was the most common type (29%). Inter-ictal headaches were significantly related to "focal to bilateral tonic–clonic" seizures (p = 0.046). The prevalence of headache among patients on polytherapy (69.2%) was higher than that of patients on monotherapy (52.9%).

Conclusions

In this study, headache was more common in epileptic patients. TTH was the most represented type of headache in patients with epilepsy. Headache occurred in patients with epilepsy most frequently during the post-ictal period.

Headache in patients with mesial temporal lobe epilepsy with hippocampal sclerosis

OBJECTIVE

It is remarkable that epilepsy and migraine are similar diseases with many parallel clinical features, as well as sharing common pathophysiological mechanisms. However, the pathogenetic role of hippocampal sclerosis (HS) in epilepsy and headache coexistence has not been clarified. In this study, we aimed to investigate the frequency of headache/migraine and the relationship between headache and HS lateralizations in patients with mesial temporal lobe epilepsy (MTLE), accompanied by HS.

METHODS

Consecutive patients with mesial temporal lobe epilepsy with hippocampal sclerosis (HS-MTLE) followed up in epilepsy outpatient clinic were included in this study, with their demographic and clinical characteristics, HS lateralization, and side (unilateral-right-left, bilateral), which were recorded. Using the questionnaires, the type of headache [migraine, tension headache (TTH)] was determined. Patients in whom migraine and TTH could not be completely separated were recruited for the unclassified group. The temporal relationship of headache and seizures (peri-ictal and/or interictal), pain lateralization, and side (unilateral-right-left, bilateral, unilateral + bilateral) were likewise determined.

RESULTS

There were 56 patients (30 females, 26 males; mean age 36.9 ± 12.1 years; mean epilepsy duration 19.3 ± 12.5 years) included in the study. Thirty-one patients (55.4%) stated they had a headache: of these, eighteen (32.1%) had migraine and 9 (16.1%) had TTH. Migraine accounted for 58.1% of headaches and TTHs was 29%. Headache was unilateral in 15 patients, and bilateral or bilateral + unilateral in 16 patients. Of patients with migraine, pain was unilateral in 10, and bilateral or bilateral + unilateral in 8. HS was right-sided in 24 patients, left-sided in 30 patients, and bilateral in 2 patients. In patients with right-sided HS, it was an ipsilateral headache; bilateral headache was found to be more common in patients with left-sided HS (p = 0.029). No relationship was found between the lateralization of the headache and the side of HS in patients with migraine.

CONCLUSION

The results of our study showed that approximately half the patients with HS-MTLE did have a headache, with one third noting migraine type headache; this highlighted that HS may play a pathogenetic role in the development of headache, especially migraine, in patients with epilepsy. Further comprehensive studies will enable us to understand whether accompanying headache, especially migraine attacks in patients with epilepsy, can be determinant for HS-MTLE, as well as if it has a lateralizing value for HS.

Activation of Peripheral and Central Trigeminovascular Neurons by Seizure: Implications for Ictal and Postictal Headache

An epileptic seizure can trigger a headache during (ictal) or after (postictal) the termination of the event. Little is known about the pathophysiology of seizure-induced headaches. In the current study, we determined whether a seizure can activate nociceptive pathways that carry pain signals from the meninges to the spinal cord, and if so, to what extent and through which classes of peripheral and central neurons. To achieve these goals, we used single-unit recording techniques and an established animal model of seizure (picrotoxin) to determine the effects of epileptic seizure on the activity of trigeminovascular Aδ-, C-, wide-dynamic range, and high-threshold neurons in male and female rats. Occurrence of seizure activated 54%, 50%, 68%, and 39% of the Aδ-, C-, wide-dynamic range, and high-threshold neurons, respectively. Regardless of their class, activated neurons exhibited a twofold to fourfold increase in their firing, which started immediately (1 min) or up to 90 min after seizure initiation, and lasted as short as 10 min or as long as 120 min. Administration of lidocaine to the dura prevented activation of all neuronal classes but not the initiation or maintenance of the seizure. These findings suggest that all neuronal classes may be involved in the initiation and maintenance of seizure-induced headache, and that their activation patterns can provide a neural substrate for explaining the timing and duration of ictal and possibly postictal headaches. By using seizure, which is evident in humans, this study bypasses controversies associated with cortical spreading depression, which is less readily observed in humans.SIGNIFICANCE STATEMENT This preclinical study provides a neural substrate for ictal and postictal headache. By studying seizure effects on the activity of peripheral (C and Aδ) and central (wide dynamic range and high-threshold) trigeminovascular neurons in intact and anesthetized dura, the findings help resolve two outstanding questions about the pathophysiology of headaches of intracranial origin. The first is that abnormal brain activity (i.e., seizure) that is evident in human (unlike cortical spreading depression) gives rise to specific and selective activation of the different components of the trigeminovascular system, and the second is that the activation of all components of the trigeminovascular pathway (i.e., peripheral and central neurons) depends on activation of the meningeal nociceptors from their receptors in the dura.

Comorbidity of Migraine and Epilepsy in Pediatrics: A Review

Migraine and epilepsy are classified as chronic paroxysmal neurologic disorders sharing many clinical features, as well as possible treatment options. This review highlights the similarities between migraine and epilepsy in pediatrics, focusing on epidemiologic, pathophysiological, genetic, clinical, and pharmacologic aspects. Despite the fact that several syndromes share symptoms of both migraine and epilepsy, further research is needed to clarify the pathophysiological and genetic basis of their comorbidity. Drugs used for prophylactic therapy of migraine and epilepsy have similar pharmacologic properties. The role of epileptic pharmacotherapy in the prophylaxis of migraine is assessed, including the use of conventional antiepileptic drugs, calcium channel blockers, and nonpharmacologic methods such as dietary therapy, supplements, and vagal nerve stimulation. Further randomized, controlled clinical trials assessing pharmacologic and nonpharmacologic methods for the treatment of both disorders are essential, in order to initiate new therapeutic approaches.

Prevalence and clinical characteristics of headache in juvenile myoclonic epilepsy: experience from a tertiary epilepsy center

The comorbidity of headache and epilepsy is often seen in neurological practice. The objective of this study was to assess the prevalence, types of, and risk factors for headache in juvenile myoclonic epilepsy (JME). We assessed a total of 200 patients and 100 healthy controls in our study. Headache was classified in participants using a self-administered questionnaire. Demographical, clinical features and headache characteristics were recorded. Seizure and headache temporal profiles were noted. Headache was present in 111 (56%) patients and 50 (50%) healthy participants. From these patients, 47 (42.3%) JME patients had migraine [30 (27%) migraine without aura (MO), 17 (15.3%) migraine with aura (MA)], 52 (46.8%) had tension type headache (TTH), 4 (3.6%) had both migraine and TTH, and 8 (7.2%) had other non-primary headaches. In the healthy control group, migraine was detected in 16 (32%) subjects, TTH in 33 (66%), both migraine and TTH in 1 (2%) subject. A positive migraine family history and symptom relief with sleep were more frequent in JME patients (p = 0.01). Headache was classified as inter-ictal in 82 (79.6%) patients and peri-ictal in 21 (20.4%) patients. In conclusion, the present study revealed that headache frequency was not significantly different between JME patients and healthy controls (p > 0.05). However, migraine frequency was higher in JME patients than healthy controls. Some migraine and TTH characteristics were different in between groups. We suggest that our results support both genetic relationship and shared underlying hypothetical pathopysiological mechanisms between JME and headache, especially migraine.

Epilepsy and headaches: Further evidence of a link

OBJECTIVE

Epilepsy and primary headaches are two of the most common neurologic conditions that share some common clinical characteristics, and can affect individuals of all age groups around the world. In recent years, the underlying pathophysiologic mechanisms potentially common to both headaches and epileptic seizures have been the subject of scrutiny. The objective of this study was to determine the frequencies and types of headaches in patients with epilepsy, and evaluate any temporal relationship with epileptic seizures.

METHOD

Demographic data, epilepsy durations, seizure frequencies, seizure types and antiepileptic medications used were captured of 349 patients who were followed up at our epilepsy outpatient clinic. Patients who experienced headaches were grouped based on the type of headaches and on whether their headaches occurred in the preictal, postictal or interictal period.

RESULT

Three hundred forty-nine patients (190 females, 159 males) were enrolled in the study. The patients' average age was 30.9±13.1 years, and average epilepsy duration was 13.5±10.9 years. The types of epileptic seizures were partial in 19.8% of patients, generalized in 57.9%, and secondary generalized in 20.3% of patients. Some 43.6% of the patients did not experience headaches, and 26.9% had migraine and 17.2% tension-type headaches. Headaches could not be classified in 12.3% of patients. The headaches occurred preictally in 9.6%, postictally in 41.6% and interictally in 8.6% of patients. The ratio of headaches was lower in male patients compared with females, and females experienced migraine-type headaches more frequently compared with males (p=0.006). Migraine-type headaches were less frequent a mong patients who experienced less than one seizure per year, but more frequent (p=0.017) among those who experienced more than one seizure per month, but less than one seizure per week. Migraine-type headaches were significantly more frequent (p=0.015) among patients receiving polytherapy compared with patients receiving monotherapy.

CONCLUSION

The results of this study suggest that headaches, particularly migraine-type headaches, were frequently experienced by patients with epilepsy, postictal headaches were more common, and the frequency of migraine attacks could be linked with seizure frequency and the type of treatment.