Eighteenth-century specimen of 25 year-old man suffering from hydrocephalus from the Hunterian Museum of the Royal College of Surgeons, London.

DEFINITION: Hydrocephalus, (pronounced /ˌhaɪdrɵˈsɛfələs/), also known as ‘water on the brain’, is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid (CSF) in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head, convulsion, and mental disability. Hydrocephalus can also cause death. The name derives from the Greek words ὑδρο- (hudro-) “water”, and κέφαλος (kephalos) ‘head’. [Wikipedia]

DESCRIPTION: ‘I was fetched to a little infant not ten days old that was born with two of the above-mentioned Tumours. They were of the shape of cupping glasses of the middle size…I felt the Holes they thrust out at; each Hole was round, I suppose of the compass of an Half-crown, and, as I afterwards found, had their Cystis from the Dura Matter. The infant seemed to be dying when I came; it died that night. The next day I opened it, and found it was as I have said. There was also great quantity of Water floating within the Meninges, and in the Ventricles of the Brain, and a gelatinous substance all about the Vessels on the upper part’. [Richard Wiseman, Eight Chirurgicall Treatises (1676) p. 134].