Yes, some people can live with only one functioning cerebral hemisphere—but “living with half a brain” is shorthand for several very different medical situations, and outcomes vary.
For a small number of people with severe, treatment-resistant epilepsy, doctors may remove or disconnect one damaged cerebral hemisphere. Children can sometimes adapt remarkably well because the developing brain can reorganize functions, but that does not mean every patient has the same result.
What the 2019 Six-Person Study Actually Found
A 2019 Cell Reports study from Caltech examined six adults who had undergone surgical removal of one hemisphere during childhood. Researchers found that the participants still had recognizable functional brain networks and, as a group, unusually strong connections between some of those networks.
That is fascinating. It is also a study of six carefully selected people, not proof that losing or disconnecting half of the brain is harmless or that everyone will “thrive” afterward.
Sources: CaltechAUTHORS: Kliemann et al. (2019) and Caltech’s study summary.
Hemispherectomy and Hemispherotomy Are Not the Same Surgery
The terms are easy to mix up. Stanford Medicine Children’s Health explains that an anatomic hemispherectomy removes damaged brain tissue from one side of the brain. A hemispherotomy instead disconnects the damaged side from the healthy side so seizures cannot spread across the brain.
These are major neurosurgical procedures reserved for severe cases of epilepsy, and they carry real risks. They are not interchangeable terms.
Source: Stanford Medicine Children’s Health: Hemispherotomy.
Ozzy’s Case: A Stroke Before Birth and Surgery Years Later
Stanford Medicine Children’s Health has documented the case of Ozzy, who experienced a large middle cerebral artery stroke likely during the final week of pregnancy. The stroke destroyed about 85% of his left cerebral hemisphere. He later developed severe epilepsy and ultimately underwent a hemispherotomy after medications failed to control his seizures.
Ozzy’s story is a striking example of childhood neuroplasticity, but it is one patient’s medical history—not a template for what every child or adult can expect. The earlier version of this article also included a parasite anecdote that is not part of Stanford’s documented account and has been removed.
Source: Stanford Medicine Children’s Health: Living a Whole Life With Half a Brain.
So, Can Someone Live With Half a Brain?
Yes, in some cases. People who undergo hemispherectomy or hemispherotomy can retain or recover many important functions, especially when surgery happens in childhood and the healthy hemisphere has had time to reorganize. But the reasons for surgery, the procedure performed, the person’s age, the location and extent of brain damage, rehabilitation and other medical factors all matter.
The remarkable part is not that “half a brain is enough.” It is how adaptable the human brain can sometimes be under extraordinary circumstances.