<strong>Scans reveal a fluid-filled cavity in the brain of a normal man. </strong>

<em><a href="http://www.nature.com/news/2007/070716/pf/070716-15_pf.html" target="_blank">Nature</a> 20 July 2007, by </em>Louis Buckley

Three years ago, a 44-year-old man was admitted to hospital in Marseille, France, complaining of weakness in his left leg. He had no idea what doctors would find to be the source of the problem: a huge pocket of fluid where most of his brain ought to be.

<span class="articletext">Normally, fluid continuously circulates throughout the brain and is drained away into the circulatory system. But in this case, the man's drainage tubes had narrowed, resulting in an accumulation of fluid in the ventricles and an enlargement of the skull due to the great volume of fluid pressing against it. This had squeezed his brain into a narrow layer around the outside of the fluid, doctors report in the <em>Lancet.</em></span>

Full story at <em><a href="http://www.nature.com/news/2007/070716/pf/070716-15_pf.html" target="_blank">Nature</a></em>

<!--more-->"We were very surprised when we looked for the first time the CT scan," says Lionel Feuillet, a neurologist at the Mediterranean University, Marseille. "The brain was very, very much smaller than normal." Nevertheless, subsequent tests showed the man to have an IQ of 75 — at the lower end of the 'normal range'.

<span class="articletext">The patient was a married father with two children and a job as a civil servant. His problems with his left leg were a neurological symptom of the condition, says Feuillet.</span>

<strong>Water on the brain</strong>

The general condition caused by a build-up of fluid in the brain's ventricles — called hydrocephalus or 'water on the brain' — is relatively common, affecting about one in 1,000 people. It is most common in children but can affect adults too.

<span class="articletext">To release the trapped fluid doctors insert a tube called a 'shunt', allowing it to drain into the bloodstream and central nervous system. With this treatment most patients lead a fairly normal life. But neurological problems and other complications, such as brain infection and problems related to the shunt, are not uncommon. Left untreated, the condition is often fatal.</span>

<span class="articletext">It's likely that the man in this case had hydrocephalus from birth, says Feuillet. His medical records show that he was treated with a shunt at the age of 6 months, and again at 14 years old. But without further neurological problems the extent of his condition went un-noticed for decades.</span>

<span class="articletext">The fact that his medical record shows normal neurological development is remarkable, says Feuillet. "This case is unique to our knowledge. We have never encountered such severe hydrocephalus before." </span>

<span class="articletext">Many other medical conditions lead to brain shrinkage, including brain atrophy from Alzheimer's disease, explains Feuillet. "But in these cases, mental abilities are usually affected." For example, people with microcephaly — a condition in which the size of the head and brain is reduced (but the structure of the brain is normal) — can suffer from cerebral palsy, epilepsy, impaired vision and hearing, and autism. </span>

<span class="articletext">Happily, this patient has made a complete recovery following his treatment, reports Feuillet, although a subsequent scan showed no change in his brain size. So the man with the tiny brain lives on.</span>