A 60-year-old father-of-two has lived his entire life 'with only half a brain', doctors claim.
The Russian pensioner had no idea that there was a 'black hole' inside his skull where the left hemisphere of his brain should be.
The retired engineer has served in the Red Army, holds a university degree, and has raised a family without any health issues.
Medics in Moscow made the shocking discovery while running a CT scan when the man was admitted to hospital after a 'mini stroke'.
There are some extremely rare conditions in which missing parts of the brain cause severe disability and death at an early age – but this man's symptom-less case is 'very unique', doctors said.
The defect is like to have developed when the man was only an embryo, they said, and if technology had been able to detect it during pregnancy in the 1950s, it's likely his mother would have been told to terminate.
A 60 year old retired engineer has lived all his entire life 'with only half a brain', doctors in Russia claim. Pictured, a CT scan of the anonymous man's brain showing the missing left side
Medics in Moscow made the shocking discovery when the man was admitted to hospital after a 'mini stroke'. A doctor at Burnasyan Federal Medical Biophysical Centre explained that radiologists were puzzled when they found there was a 'hole' in the brain images
Neurologist Dr Marina Anikina, who has investigated the case, said: 'The man was admitted to a district clinic in the south of Moscow region due to an ischemic attack.
'This is a blood circulation failure in the brain. It is different from a stroke when part of the brain is irreversibly damaged.
'This patient had problems moving one arm and one leg.
'Radiologists performed a computer tomography of his head and were puzzled for some time – the part of the brain of the retired man where the ischemia attack was supposed to have happened was not there at all.
Normally a person has parts of their brain missing due to disease or injury.
It may be surgically removed or disconnected to treat seizure-causing disorders, but is only a last option in a very small number of patients - normally children.
The success rate for treating the seizures is extremely high and most children have excellent long-term results following without unexpected adverse outcomes.
Cephalic disorders are stem from damage to, or abnormal development of, the budding nervous system, including the brain, which are caused by a disturbance that occurs in the womb.
Holoprosencephaly is when the brain's right and left side do not divide, hydranencephaly is when the cerebral hemispheres are absent and replaced by fluid-filled sacs, and porencephaly, which is extremely rare, involves a cyst or cavity in a the hemispheres.
Damage to the developing nervous system during fetal development is a major cause of chronic, disabling disorders and sometimes death.
The degree to which damage to the developing nervous system harms the mind and body varies enormously.
Many disabilities are mild enough that the person is able to function independently through life.
Others are not - a large population is partially