11/14/24, 10\:38 AM Ventriculoperitoneal (VP) Shunts in Adults

Ventriculoperitoneal (VP) Shunts in Adults

Table of contents
Key points ⚡
Succinct notes to superpower your revision
VP shunt\: drains CSF from the brain's ventricles into the peritoneal cavity, used to manage raised intracranial pressure.
Hydrocephalus\: commonest indication; can be communicating (CSF absorption issues) or obstructive (blockage in
ventricles).
Communicating hydrocephalus\: caused by subarachnoid haemorrhage, meningitis, normal pressure hydrocephalus,
trauma; lumbar puncture (LP) safe in these cases.
Obstructive hydrocephalus\: caused by aqueductal stenosis, tumours, post-haemorrhagic clots; LP contraindicated due to
herniation risk.
VP shunt anatomy\: ventricular catheter inserted into lateral ventricles, drains into the peritoneal cavity via tubing under the
skin.
Shunt malfunction\: blockage, disconnection, or infection are common causes of acute presentations with symptoms of
hydrocephalus or meningism.
Investigations\: CT head, shunt series (X-rays of chest and abdomen), blood tests (in
lumbar puncture if no obstruction.
Complications\: infection, shunt blockage, disconnection, intracranial haemorrhage, abdominal complications.
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A comprehensive topic overview

Introduction

A ventriculoperitoneal (VP) shunt is a medical device that connects the ventricular system of the brain with the
peritoneal cavity. This allows cerebrospinal
While there are many indications for a VP shunt, the unifying physiological indication is intracranial pressure higher than
optimum for the individual.
The incidence of primary VP shunt insertion is highest in infants; over 40% of shunt operations in adults are revisional.
1
This article outlines the clinical knowledge relevant to assessing adults with a VP shunt.

Hydrocephalus and intracranial pressure

Hydrocephalus refers to the “ a c t i v e d i s t e n s i o n o f t h e v e n t r i c u l a r s y s t e m o f t h e b r a i n r e s u l t i n g f r o m t h e i n a d e q u a t e p a s s a ge
o f C S F f r o m i t s p o i n t o f p r o d u c t i o n w i t h i n t h e c e r e b r a l v e n t r i c l e s t o i t s p o i n t o f a b s o r p t i o n i n t o t h e s y s t e m i c c i r c u l a t i o n”
2
.
In most cases, the increase in CSF volume distends the ventricles, leading to ventriculomegaly on cranial imaging. While
high intracranial pressure (ICP) is commonly associated with hydrocephalus, it is not always the case.
Idiopathic normal pressure hydrocephalus is characterised by out-of-proportion dilatation of the ventricles, while the
intracranial pressure is within the normal range. On the other hand, idiopathic intracranial hypertension is characterised by
high ICP without ventricular distension.
People with non-compliant (sti
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The practical point is that people with a VP shunt had pathological CSF dynamics. Ventriculomegaly is not universal. As
hydrocephalus is the most common indication for VP shunt, the following sections discuss hydrocephalus.
Figure 1. Non-contrast computed
tomography of the head showing
hydrocephalus.

Types of hydrocephalus

There are various classi
(non-communicating) hydrocephalus is most helpful in this discussion.
Communicating hydrocephalus
Communicating hydrocephalus refers to ventricular distension in the presence of a patent ventricular system. Conditions
that cause this either reduce CSF absorption or increase CSF production.
Causes of communicating hydrocephalus include\:
Subarachnoid haemorrhage
Post-meningitis hydrocephalus
Normal pressure hydrocephalus
Leptomeningeal disease
Post-traumatic hydrocephalus
Post-operative hydrocephalus
While idiopathic intracranial hypertension does not have features of hydrocephalus, the ventricular system is patent in most
cases.
Obstructive hydrocephalus
In contrast to communicating hydrocephalus, obstructive hydrocephalus refers to ventricular distension with a blockage
within the cerebral ventricular system.
Causes of obstructive hydrocephalus include\:
Post-haemorrhagic hydrocephalus
Aqueductal stenosis
Lesion-related compression
Chiari I malformation
Ventricular adhesion
Communicating versus obstructive hydrocephalus
Dilumbar puncture can be
safely performed if the patient has communicating hydrocephalus.
In contrast, a lumbar puncture risks cerebral herniation if there is high intracranial pressure in a patient with
obstructive hydrocephalus.

Relevant anatomy

Cerebral ventricle

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The relevant ventricular anatomy for a VP shunt is the lateral ventricles. Each lateral ventricle consists of a body, a frontal
(anterior) horn, a temporal (inferior) horn, and an occipital (posterior) horn.
The trigone or atrium is where the temporal horn, the occipital horn and the body meet. The insertion site of the ventricular
catheter is either in the occipito-parietal region or frontal region. There are craniometric landmarks to aid catheter
insertion with their eponymous names such as Frazier’s, Keen’s, Dandy’s, and Kocher’s points.
Figure 2. Anatomy of the cerebral ventricular system

Abdomen

The anterior abdominal wall is the most important anatomy relating to VP shunt insertion.
Commonly, a neurosurgeon chooses a site superior and lateral to the umbilicus over the rectus abdominis muscle. The
layers into the peritoneal cavity are subcutaneous fat, anterior sheath of rectus abdominis muscle (anterior rectus sheath),
rectus abdominis muscle

Neck and thorax

The shunt tubing goes within the super
chest is not required for inserting a VP shunt. The carotid artery and internal jugular vein are close to the shunt tract; the
thoracic cavity is deep to the clavicle.

Insertion of a VP shunt

Shunt con

The simplest VP shunt con
proximal and distal catheters are impregnated with rifampicin and clindamycin.
3
The shunt valve serves to regulate CSF drainage depending on position and pressure. The technicality of valve selection
involves choosing valves with di
without an antisiphon or gravitational device.
In general, the most important aspects to consider are the di
programmable valve and its opening pressure.
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Figure 3. VP shunt apparatus.

The patient must be appropriately consented. For patients without the mental capacity to decide on surgery, discuss with
someone who has the lasting power of attorney for well-being or follow the appropriate legal framework.
The indication for inserting a VP shunt and, if present, any alternatives should be discussed.
Risks of VP shunt insertion include infection, bleeding, pain, malpositioning, shunt infection, shunt blockage, shunt
disconnection or fracture, re-operation, damage to the brain, seizure, injury to the neck blood vessels, injury to the lung,
injury to the abdominal organ(s), deep vein thrombosis, pulmonary embolism, stroke, heart attack, and risk to life.

Operative preparation

The shunt components should be selected before starting the operation. Minimal sta
gloves-changing before handling the shunt apparatus can reduce the risk of shunt infection. 4
Operative time should be
minimised.
The patient is positioned supine with the head turned to the left and a shoulder bolster to align the head to the abdomen. If
used, neuronavigation should be set up for the insertion of a ventricular catheter. Abdominal and cranial incisions are
planned, prepped, and draped.

Abdominal stage

A transverse incision is made over the rectus abdominis muscle. Dissection is performed down into the peritoneal cavity
through the layers outlined above. The peritoneal opening is typically small (\<1cm) with its edges held with artery forceps or
similar instruments.
The neurosurgeon con
instrument. The wound is then covered with aqueous povidone-iodine-soaked gauze.

Cranial stage

An inverse-J incision is made down to the skull in the occipito-parietal region behind the ear. A burr hole is placed using a
perforator drill. The dura is cauterised and opened to ~3mm in diameter.
A small corticotomy is made as the entry point for the ventricular catheter. Tunnelling is then performed, taking care to
follow the super

Shunt insertion and assembly

A ventricular catheter is inserted into the lateral ventricle using landmark trajectory or under neuronavigation. Once CSF is
obtained, the catheter is passed to the desired length. The distal part of the ventricular catheter is trimmed and connected
to the valve.
When there is CSF out
enters the tunneller to travel down to the abdominal site. The metal tunneller is then removed. The surgeon checks for CSF
out
secure the shunt apparatus.
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Closure

A suture is placed in the abdomen to tighten the peritoneum around the tubing. Subcutaneous and subcuticular sutures
are then used to close the abdominal wound.
Cranially, the surgeon closes the galeal layer with the subcutaneous tissue. Sutures or surgical clips are used for skin
closure.
Types of shunt
VP shunt is one type of CSF diversion. Other types include ventriculo-atrial shunt, ventriculo-pleural shunt, lumbo-
peritoneal shunt, and endoscopic third ventriculostomy.
There are also other circumstances where a shunt tubing may be inserted, for example, into a cyst.

Acute presentations with a VP shunt

Causes

The commonest causes of acute presentations associated with a VP shunt are shunt malfunction and infection.
Shunt malfunction may be blockage, disconnection, or fracture. Patients present with symptoms of hydrocephalus if the
shunt is not working.
Meningism with or without hydrocephalic symptoms raises the suspicion of central nervous system infection.

Investigations

The
A shunt series includes a chest X-ray and an anteroposterior and lateral abdominal X-ray. If a patient has a programmable
valve, a skull X-ray where the X-ray beam is perpendicular to the valve can demonstrate the valve setting.
In patients with a VP shunt for communicating hydrocephalus and with a patent ventricular system on the CT scan, a
lumbar puncture (LP) can obtain CSF for analysis. Blood biochemical tests, including in
important.
Investigations for shunt patients
It is essential to ascertain the indication for the VP shunt from the patient or their next of kin. Most patients have a
pocket card stating the shunt valve they have.
Key investigations to consider when assessing for shunt complications include\:
Non-contrast CT head
Shunt series (X-ray radiographs covering neck, chest, and abdomen)
Blood tests, including in
Consider lumbar puncture

References

Fernández-Méndez R, Richards HK, Seeley HM, Pickard JD, Joannides AJ. Current epidemiology of cerebrospinal
surgery in the UK and Ireland (2004–2013). J N e u r o l N e u r o s u r g P s y c h i a t r y 2019; 90\: 747–54.
Rekate HL. A Contemporary De
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Mallucci CL, Jenkinson MD, Conroy EJ, e t a l . Antibiotic or silver versus standard ventriculoperitoneal shunts (BASICS)\: a
multicentre, single-blinded, randomised trial and economic evaluation. T h e L a n c e t 2019; 394\: 1530–9.
Muram S, Isaacs AM, Sader N, e t a l . A standardized infection prevention bundle for reduction of CSF shunt infections in
adult ventriculoperitoneal shunt surgery performed without antibiotic-impregnated catheters. J o u r n a l o f N e u r o s u r g e r y
2023; 138\: 494–502.

Image references

Figure 1. Case courtesy of Dr Matt Skalski. C e r e b r a l v e n t r i c u l a r s y s t e m . Licence\: [CC BY-SA]
Figure 2. Lucien MonCC BY-SA]
Figure 3. Cancer Research UK. V e n t r i c u l o p e r i t o n e a l s h u n t . Licence\: [CC BY-SA]

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