The unusual case of a man with a tiny brain caused by massive ventricular enlargement, who has led a normal life, is studied in a clinical picture in this week's edition of The Lancet.

The man was 44-years-old at the time, married with two children, and worked as a civil servant. He went to hospital after suffering mild left leg weakness. He was treated by Dr Lionel Feuillet and colleagues, Hôpital de la Timone and Faculté de Médecine, Université de la Méditerranée, Marseille, France, who authored the clinical picture.

Analysis of the man's medical history revealed at the age of six months, he had had a shunt inserted into his head to drain away hydrocephalus (water on the brain), of unknown cause. At the age of 14, he had complained of unsteadiness and left leg weakness, which cleared up after the shunt was revised. His neurological development and medical history were otherwise normal.

Neuropsychological testing revealed the man had an intelligence quotient (IQ) of 75, his verbal IQ was 84 and his performance IQ was 70. A CT scan (see attached pdf) showed severe dilation of the brain's lateral ventricles, while an MRI scan revealed massive enlargement of the lateral third and fourth venricles, a very thin cortical mantle and a posterior fossa cyst. The treatment team diagnosed a non-communicating hydrocephalus, with probable narrowing of Magendie's foramen, one of the channels through which water on the brain normally drains away.

The leg weakness improved shortly after neuroendoscopic verntriculocisternostomy - the opening up and draining of the ventricles. However the symptoms soon returned. After a new shunt was inserted into the brain, the symptoms were relieved. However, the findings after a second CT scan did not change.

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