That Makes My Head Hurt

Migraines and seizures both involve abnormal electrical activity in the brain. There are two or three anti-epileptic drugs (AED’s) that are effective in the treatment of migraines. One, Topiramate, is used more widely for migraines even though it was originally developed for epilepsy. Not every AED is useful in treating migraines. There is clearly a big difference between the two conditions, but there are also some remarkable similarities….sadly. The fundamentals in an epileptic seizure is an abnormal discharge of neurons that can be seen by attaching electrodes to a patient’s  scalp for an EEG (electroencephalography). That is not the case for migraines. EEG’s do not register migraines. If you’ve ever experienced a migraine with an aura — those shimmering lights, zig-zag lines, or patches of lost vision — you’ve witnessed your brain doing something extraordinary. And science has a compelling explanation for what’s happening behind the scene. A wave of electrical disruption called cortical spreading depression. To understand it, you need to understand how neurons normally behave. Brain cells typically sit in a hyperpolarized  state, meaning the inside of the cell is more negatively charged than the outside. When a neuron receives an excitatory signal , the  balance shifts; a process called depolarization. Cortical spreading depression flips this script in a dramatic way. Instead of a controlled, localized depolarization, a massive wave sweeps across the cortex. Neurons in its path become so intensely depolarized that they essentially shut down  for a short period. They can’t fire. They can’t signal. They’re temporarily offline. The wave eventually passes, and the neurons recover. BUT the aftermath is where migraines begin. This electrical storm triggers the release of chemicals that activate pain-sensing nerves in the protective layers surrounding the brain. Once those pain pathways light up, the familiar migraine headache takes hold — sometimes lingering for hours, sometimes stretching into days. This hyperexcitability resembles what occurs in an epileptic seizure. The biggest difference is that, with a seizure, the brain gets lots of synchronized firing, but with migraines that pathway leads to cortical depression . Why some situations end in a migraine and others in a seizure are still being studied.