The commonly spouted wisdom that people only use 10 percent of their brain power may have been dismissed as a myth, but one French man seems to be managing fine with just a small fraction of his actual brain.
In fact the man, who works as a civil servant in southern France, has succeeded in living an entirely normal life despite a huge fluid-filled cavity taking up most of the space where his brain should be.
Neurologists at the University of Marseille described the incredible case in the latest edition of the medical journal Lancet published Friday.
They describe how the 44-year-old man went to the hospital in 2003 because he felt a mild weakness in his left leg. When the doctors went to look at his brain to see if the problem lay there, they found, well, pretty much nothing but a great black hole.
The man told the hospital that as a child he had suffered from hydrocephalus (also known as "water on the brain"), a condition in which an abnormal ammount of cerebrospinal fluid accumulates in the brain cavities, causing pressure inside the skull. To treat the condition, a valve known as a "shunt" had been inserted in his head to drain away the fluid when he was a six-month old baby. It was removed when he was 14.
This information prompted the doctors to give him a computed tomography scan (CT) and a magnetic resonance imaging scan (MRI). They then saw that there was what they -- somewhat euphemistically -- called a "massive enlargement" of the lateral ventricles, chambers that hold the fluid which cushions and protects the brain and which are usually tiny.
Dr. Lionel Fuillet, who headed the team that treated the man, told the Agence France Presse agency that a huge cavity had built up filled with fluid, while a thin sheet of functioning brain tissue, the proverbial grey matter, "was completely pushed back to the inner walls of the cranium."
Tests showed that the man's IQ is 75 -- the average is 100 -- but he was not considered physically or mentally disabled. Fuillet said that his condition had not impared his development or his socialization. He is married with two children and works in the tax office -- which is perhaps not the most "taxing" of jobs.
"The case is extreme, but there are other cases of patients with incredibly little brain matter," Florian Heinen, a brain development expert at the Dr. von Hauner's Children's Hospital at Munich University, explained to the Süddeutsche Zeitung. "Obviously these few nerve cells can achieve just as much as the millions more cells that other people have."