Shunt Valve Sizes for Paediatric Hydrocephalus: Matching the Patient

DESU offers shunt valves in several sizes so the surgeon can match the implant to the child. Defit comes in Ultra Small, Small and Regular (35, 40 and 45 mm overall length), Decurve in a 23 mm paediatric and a 28 mm adult size, and adjustable Depus valves in paediatric and adult sizes. Which size suits a given patient is the surgeon’s decision.

All of these sit within DESU’s shunt systems range. Families looking for background can start with our patient guide on hydrocephalus.

Why does valve size matter in children?

Hydrocephalus is a build-up of cerebrospinal fluid (CSF) in the ventricles of the brain, and a ventriculoperitoneal (VP) shunt diverts that fluid to the abdomen. In adults, valve size is rarely the first question. In infants and young children it often is, for three plain reasons:

• Head size: a small skull leaves less room for the valve and the catheter route.
• Soft-tissue cover: an infant’s scalp is thin, and pressure from implanted hardware on thin skin is a recognised concern in paediatric shunt surgery.
• Growth: the child will grow around the implant, so the surgeon thinks about the system over years, not just at the time of surgery.

A range of valve sizes lets the surgeon choose a profile and footprint that fit the patient, rather than fitting the patient to a single valve.

What sizes does the Defit valve come in?

Defit is a fixed-pressure, flat-bottom silicone valve that contains no metal. Each of its three sizes is offered with low, medium and high pressure options:

Defit sizes are defined by their dimensions, not by age group. The table gives the surgeon the dimensions to judge against the patient: the thickness describes how far the valve will stand above the skull, and the lengths describe how much space it needs along the shunt route.

What sizes does the Decurve valve come in?

Decurve is a fixed-pressure, round burr-hole valve with a reservoir, made of polypropylene and silicone elastomer, and it contains no metal. It is prepared in two sizes for paediatric and adult patients:

• Paediatric Decurve: 23 mm nominal diameter.
• Adult Decurve: 28 mm nominal diameter.

Both sizes come in low, medium and high fixed pressures, as standard, semi-antibiotic-impregnated, full-antibiotic-impregnated and antisiphon-device systems. Because a burr-hole valve sits at the catheter entry point, its diameter is the dimension to compare with the patient’s anatomy. Where the surgeon prefers the valve away from the burr hole, the flat-bottom Defit sizes are the alternative.

Is there an adjustable valve for children?

Yes. Depus valves, which have a polysulfone body with a ruby ball and titanium spring mechanism, are offered both in low, medium and high fixed pressures and as adjustable valves in paediatric and adult sizes. Adjustable systems come in 3 Pressure and 5 Pressure versions.

An adjustable valve is located, read and set non-invasively with the Depus Adjustment Kit: the locator identifies the valve and the target directions of the pressure levels, the magnet sets the target pressure and the compass checks it. For a paediatric unit, that means the kit version matching the implanted valves should be available wherever follow-up takes place.

How do the paediatric options compare?

How does size selection fit the patient?

Size is rarely chosen on its own. In practice it is one of several linked decisions, all of them the surgeon’s, made with the instructions for use:

• Valve position: on the skull away from the burr hole (Defit) or at the burr hole (Decurve).
• Patient anatomy: head size and scalp thickness, set against valve thickness, length or diameter.
• Pressure: one fixed category, or an adjustable Depus valve if the setting may need to change.
• Imaging: Defit and Decurve contain no metal and are suitable for MRI and CT, which matters for children likely to be imaged repeatedly.
• Siphoning: an optional antisiphon device, with kit codes ending in “-ASD”.
• Antibiotic configuration: antibiotic-impregnated components, where the antibiotic is impregnated into the material and released in a controlled manner over 28 days. Impregnated catheters are orange, standard ones white.

The VP kits use the same catheters whatever the valve size: a 23 cm ventricular catheter (1.3 mm inner, 2.5 mm outer diameter) and a 120 cm peritoneal catheter (1.1 mm inner, 2.5 mm outer diameter), with a stylet and a right-angled connector. How much catheter is implanted is the surgeon’s decision.

What should a paediatric unit keep on the shelf?

A paediatric neurosurgery service usually needs more size coverage than an adult service of the same volume, because the patients themselves vary more. A practical starting range covers the smaller Defit sizes and the paediatric Decurve across the pressure categories the surgeons use, with antisiphon and antibiotic-impregnated configurations where they are part of local practice. Units that use adjustable valves add paediatric Depus valves and the matching Depus Adjustment Kit. Many units also carry adult sizes for older children and adolescents. Our article on paediatric EVD questions covers the drainage side of the same service.

Talk to a DESU product specialist

Our product specialists can help a paediatric unit plan a valve size range that fits its case mix and surgeons’ preferences. Write to sales@desu.tr, use the contact page, or request a quote.