The Wade-Dahl-Till (WDT) valve is a

cerebral shunt A cerebral shunt is a device permanently implanted inside the head and body to drain excess fluid away from the brain. They are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid (CSF). If ...

developed in 1962 by hydraulic engineer Stanley Wade, author

Roald Dahl Roald Dahl (13 September 1916 – 23 November 1990) was a British novelist, short-story writer, poet, screenwriter, and wartime fighter ace of Norwegian descent. His books have sold more than 250 million copies worldwide. Dahl has be ...

, and neurosurgeon Kenneth Till. In 1960, Dahl's son Theo developed

hydrocephalus Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased intracranial pressure, pressure inside the skull. Older people may have headaches, double vision, poor ...

after being struck by a taxicab. A standard Holter shunt was installed to drain excess fluid from his brain. However, the shunt jammed too often, causing pain and blindness, risking brain damage and requiring emergency surgery. Till, a neurosurgeon at London's

Great Ormond Street Hospital Great Ormond Street Hospital (informally GOSH or Great Ormond Street, formerly the Hospital for Sick Children) is a children's hospital located in the Bloomsbury area of the London Borough of Camden, and a part of Great Ormond Street Hospit ...

for children, determined that debris accumulated in the hydrocephalic ventricles could clog the slits in the Holter valves, especially with patients such as Theo who had bad bleeding in the brain and brain damage. Dahl knew Wade to be an expert in precision hydraulic engineering, from their shared hobby of flying

model aircraft A model aircraft is a small unmanned aircraft. Many are replicas of real aircraft. Model aircraft are divided into two basic groups: flying and non-flying. Non-flying models are also termed static, display, or shelf models. Aircraft manufactur ...

. (In addition to building his own model aircraft engines, Wade ran a factory at

High Wycombe High Wycombe, often referred to as Wycombe ( ), is a market town in Buckinghamshire, England. Lying in the valley of the River Wye surrounded by the Chiltern Hills, it is west-northwest of Charing Cross in London, south-southeast of Ayl ...

for producing precision hydraulic pumps.) With Dahl coordinating the efforts of the neurosurgeon and the hydraulic engineer, the team developed a new mechanism using two metal discs, each in a restrictive housing at the end of a short silicone rubber tube. Fluid moving under pressure from below pushed the discs against the tube to prevent retrograde flow; pressure from above moved each disc to the "open" position. As Till reported in ''

The Lancet ''The Lancet'' is a weekly peer-reviewed general medical journal and one of the oldest of its kind. It is also the world's highest-impact academic journal. It was founded in England in 1823. The journal publishes original research articles, ...

'', the invention was characterized by “low resistance, ease of sterilisation, no reflux, robust construction, and negligible risk of blockage”. By the time the device was perfected, Theo had healed to the point at which it was no longer necessary to implant the shunt in his skull. However, several thousand other children around the world benefited from the WDT valve before medicine technology progressed beyond it. The co-inventors agreed never to accept any profit from the invention.

References

External links

* {{cite patent , country = US , number = 3233610 , status = patent , title = Hydrocephalus shunt pump , gdate = 1966-02-08 , fdate = 1963-05-24 Implants (medicine) Roald Dahl 1962 in technology