Epilepsy is a neurological disorder where patients suffer recurrent seizures: periods of excessive, synchronised activity across large populations of neurons. Seizures can involve the whole brain or specific parts of the brain, and in both these cases can be extremely debilitating, leaving patients unable to drive, perhaps involving loss of consciousness or convulsions, with strong negative effects on employment and life quality. For some patients the condition progresses over time if untreated, to affect further brain regions and functions.
Epilepsy is common, affecting around 1% of any population. For one third of these patients, seizures cannot be successfully managed with anti-epileptic drugs. For those patients with focal onset seizures (those beginning in one location) that don’t respond to anti-epileptic drugs, the best current treatment is often epilepsy surgery, by either resection or laser ablation.
An earlier view of focal onset seizures was that they must be caused by a single bad region or ‘focus’, so that identifying and removing this focus should cure the epilepsy. But more recent clinical evidence suggests that network interactions between brain regions can be crucial to seizures, and in some cases seizures may emerge from a new location after the original presumed ‘focus’ is removed.
With current medical knowledge it is difficult to know in advance which patients can successfully be seizure-free with only low-risk localised surgery ablating a small region, and which patients require a wider resection of multiple parts of the seizure network, or full temporal lobectomy, to achieve a successful outcome.