Wade-Dahl-Till valve
Encyclopedia
The Wade-Dahl-Till valve is a cerebral shunt
developed in 1962 by hydraulic engineer Stanley Wade, author Roald Dahl
and neurosurgeon Kenneth Till.
In 1960, Dahl's son Theo developed hydrocephalus
after being struck by a car. 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 determined that debris accumulated in the hydrocephalic ventricles
could clog the slits in the Holter valves, especially with patients, such as Theo, who had had bleeding in the brain.
Dahl knew Wade to be an expert in precision hydraulic engineering, from their shared hobby of flying model aircraft
. (In addition to building his own model aircraft engines, Wade ran a factory at High Wycombe
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 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 not necessary for him; however several thousand other children benefited from the WDT valve before medicine technology progressed beyond it.
The co-inventors agreed never to accept any profit from the invention.
Cerebral shunt
Cerebral shunts are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid . If left unchecked, the cerebral spinal fluid can build up leading to an increase in intracranial pressure which can lead to intracranial hematoma, cerebral edema,...
developed in 1962 by hydraulic engineer Stanley Wade, author Roald Dahl
Roald Dahl
Roald Dahl was a British novelist, short story writer, fighter pilot and screenwriter.Born in Wales to Norwegian parents, he served in the Royal Air Force during the Second World War, in which he became a flying ace and intelligence agent, rising to the rank of Wing Commander...
and neurosurgeon Kenneth Till.
In 1960, Dahl's son Theo developed hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
after being struck by a car. 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 determined that debris accumulated in the hydrocephalic ventricles
Ventricular system
The ventricular system is a set of structures containing cerebrospinal fluid in the brain. It is continuous with the central canal of the spinal cord.-Components:The system comprises four ventricles:* right and left lateral ventricles* third ventricle...
could clog the slits in the Holter valves, especially with patients, such as Theo, who had had bleeding in the brain.
Dahl knew Wade to be an expert in precision hydraulic engineering, from their shared hobby of flying model aircraft
Model aircraft
Model aircraft are flying or non-flying models of existing or imaginary aircraft using a variety of materials including plastic, diecast metal, polystyrene, balsa wood, foam and fibreglass...
. (In addition to building his own model aircraft engines, Wade ran a factory at High Wycombe
High Wycombe
High Wycombe , commonly known as Wycombe and formally called Chepping Wycombe or Chipping Wycombe until 1946,is a large town in Buckinghamshire, England. It is west-north-west of Charing Cross in London; this figure is engraved on the Corn Market building in the centre of the town...
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
The Lancet is a weekly peer-reviewed general medical journal. It is one of the world's best known, oldest, and most respected general medical journals...
, 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 not necessary for him; however several thousand other children benefited from the WDT valve before medicine technology progressed beyond it.
The co-inventors agreed never to accept any profit from the invention.