In twentieth-century Montreal, epilepsy surgery became closely linked with the emerging science of mapping human brain function. Wilder Penfield and colleagues at the Montreal Neurological Institute developed an approach that became known as the Montreal procedure.
A surgical problem became a mapping problem
For focal epilepsy, surgeons needed to remove tissue involved in seizures while preserving language, movement and other essential functions. Penfield combined careful surgery with direct electrical stimulation of the exposed cortex and, later, electrocorticography.
Why patients were sometimes awake
During selected operations, cortical stimulation allowed the surgical team to identify areas involved in speech, movement and sensation while the patient responded. The purpose was functional preservation, not spectacle: mapping helped define what could and could not be safely removed.
EEG changed the operation
By the late 1930s, the Montreal team was already experimenting with invasive EEG recordings to help localise seizure-related activity. Later developments in imaging and intracranial recording refined presurgical evaluation further.
A worldwide legacy
The Montreal programme influenced epilepsy surgery internationally. Its central principle — combine seizure semiology, electrophysiology, anatomy and functional mapping rather than relying on one test — remains recognisable in modern presurgical assessment.
Sources
The Montreal procedure: the legacy of Wilder Penfield
Development of surgical therapy of epilepsy at the Montreal Neurological Institute
First invasive EEG monitoring for epilepsy surgery