A hemispherectomy removes or disconnects one entire half of the brain, and this episode traces how that radical idea became a standard treatment for children with severe drug-resistant epilepsy. Walter Dandy performed the first one in 1928 to remove a glioma, Kenneth McKenzie used it for intractable epilepsy in 1938, and in 1950 R.A. Krynauw in South Africa reported striking improvements in children with infantile hemiplegia. Then, in 1966, Oppenheimer and Griffith documented what the empty cavity did over the years: superficial hemosiderosis from repeated microscopic bleeding and dangerous obstructive hydrocephalus.

Theodore Rasmussen’s functional hemispherectomy left the tissue in place but cut its connections, and later hemidecortication and the hemispherotomy developed by Delalande and Villemure refined the approach further. The hosts walk through who qualifies, from hemimegalencephaly to Rasmussen’s encephalitis, how surgeons map the seizure source, what the operation costs the patient in vision and fine motor control, and how the remaining hemisphere rewires itself through neuroplasticity.

• Children who arrive with dozens or even hundreds of seizures a day that no medication can stop
• Why every technique, old and new, yields seizure freedom of roughly 70 to 75 percent, and why the ILAE prefers hemispherotomy
• Severing the corpus callosum and the permanent loss of half the visual field in both eyes
• Modern risks: hydrocephalus in 14 to 23 percent of cases, mortality under 1 to 2.2 percent, and reoperation around 4.5 percent
• Long-term outcomes, including walking, reading, the HOPS prediction scale and about one fifth of patients finding employment