Migraine and epilepsy are both common neurological disorders with migraine affecting 12% of the population and epilepsy, 0.5 to 1%. But among migraineurs, 5.9% develop migraine after an incident of epilepsy. Both are considered to run in families and hence likely have a significant genetic component. Most migraineurs do not have epilepsy.
Underlying both conditions is a state of brain hyperexcitability, which can be attributed to genetic factors or an environmental event such as a head injury. Both are episodic disorders with symptoms occurring sporadically; during the time between attacks, individuals are symptom free.
Research suggests that the underlying pathophysiology of both relates to alteration in ion channels or ion transporters. Attacks for both disorders begin with neuronal firing in the brain. In migraine, this activity is described a cortical spreading depression (CSD) which is a relatively organized pattern of electrical disruption whereas in epilepsy the electrical disruption is much more chaotic.
Other similarities between migraine and epilepsy include:
- Triggers or risk factors produce an attack by reducing the excitability threshold. Common triggers are stress or let-down stress, sleep disturbance, hormonal changes, alcohol intake, and certain foods
- 5 phases are ascribed to the progress of the attacks associated with the disorders
- Prodromal symptoms
- Seizure or headache
- Antiepileptic drugs (AEDs) are used to prevent both disorders and believed to be effective by reducing neuronal hyperexcitability. Used as a preventive medication for frequent attacks of migraine, the prescribed dose of AEDs is usually much lower than for someone with epilepsy (for example, valproate and topiramate)
Recently, researchers studied 501 families that included 2 or more individuals with epilepsy. There were 730 epilepsy patients in the study. The results indicated that those who had close relatives with seizures also had the highest risk for attacks of migraine. The conclusion was that the link between epilepsy and migraine was due to shared biology.
I also found a great infographic about seizures, it is listing the most important and most interesting numbers regarding seizures:
Infographic via Mnepilepsy.org