Kemel Ahmed Ghotme Ghotme and James M. Drake
Hospital for Sick Children, University of Toronto
Hydrocephalus, CSF, shunts, ventriculoperitoneal shunt, ventriculopleural
shunt, ventriculoatrial shunt, lumboperitoneal shunt, shunt selection,
ventricular insertion, peritoneal insertion, complications, shunt infection,
shunt occlusion, disconnection and fracture, migration, misplacement,
kinking, subcutaneous effusion, overdrainage, slit ventricle syndrome,
subdural collection, loculated ventricles, alternatives to shunt,
craniosynostosis, postoperative care, follow-up.
Cerebrospinal fluid (CSF) shunts are the most common and worldwide available
treatment for hydrocephalus. Before they became available, almost 50 years
ago, hydrocephalus used to be a lethal or a severely disabling condition.
Currently, shunts are a very common neurosurgical procedure, especially in
pediatric centers, and have improved survival and quality of life for many
patients with hydrocephalus all around the world. Notwithstanding, shunts
frequently are related to a high rate of complications and need for
re-intervention. Shunt malfunction is a frequent cause of consultation in
emergency service. Opportune diagnosis and appropriate and timely treatment
are crucial to prevent permanent damage or mortality in patients with
2. Types of Shunts
2.1. Definitive CSF shunts
- Ventriculoperitoneal shunt (VP shunt)
- Ventriculopleural shunt (VPL shunt)
- Ventriculoatrial shunt (VA shunt)
- Lumboperitoneal shunt (LP shunt)
2.2. Temporary CSF shunts
- External ventricular drainage (EVD)
- Ventriculosubgaleal shunt
- Ventricular catheter to a subgaleal reservoir
2.3. Other CSF shunts (not commonly used)
- IV ventricular catheters (Lapras catheter)
- Ventricular-ureter shunts
3. Shunt Components
- Ventricular catheter
- Distal catheter
- Other devices: connectors, tapping reservoirs, antisiphoning
4. The Decision to Treat
- All attempts to avoid a shunt should be made.
- Take alternatives to shunt into consideration.
- Patients with obstructive hydrocephalus should be considered as
candidates for endoscopic treatment: e.g., third ventriculostomy, septum
pellucidum fenestration, cyst fenestration, etc.
- Correction of the etiologic factor might solve hydrocephalus (e.g.,
tumor resection, hematoma evacuation).
- In some conditions, alterations of hydrodynamics of CSF could be
transient (e.g., subarachnoid or intraventricular hemorrhage, meningitis,
rapidly responsive tumor i.e., germinoma) and might resolve after
treatment. Consider a temporary external ventricular drainage,
ventriculosubgaleal shunt, or an access port to CSF.
5. Planning the Procedure
- Careful planning is crucial to a successful outcome.
- Shunt surgery is technically demanding and should not be relegated to
the most junior trainees.
- Coordination of the OR team–anesthesia, nursing, surgeons, and
equipment is critical.
- Patient characteristics
- CSF–free of blood, infection
- Skin–healthy, free of infection
- Appropriate ventricular access–larger ventricle, shortest path,
catheter away from choroid plexus, guidance (ultrasound, image guidance
available if needed) see table.
- Abdominal cavity–pristine, entry site away from gastrostomy
tubes, empty bladder.
- Shunt passer trajectory straight or intervening incision, awareness of
skull defects (i.e., post fossa craniotomy), away from central lines,
- Attention to co-morbidities–prematurity, malnutrition,
coagulopathy, remote sepsis, etc.
- Good surgical technique is the best way to decrease shunt
6. Shunt Selection
At this time, there is no shunt system or device that has been scientifically
proven to be superior to any other (1). Careful assessment of
patient’s condition should be made to precisely determine the need of
a shunt insertion, since this is a procedure that might be permanent and is
not free of complications (See part 9). It is always important to take into
- For most patients, a fixed medium-pressure valve which drains CSF in a
range of 70 to 100 mm Hg, is a reasonable choice.
- Special patient’s characteristics may influence valve selection,
although data to support this is weak.
- Patients with very large ventricles and thin cortex have a higher risk
of subdural collections. A flow-control valve (e.g., Orbis-Sigma valve)
or a programmable valve may prevent subdural collections or allow
non-operative treatment. A high-pressure valve is another
- Orbis-Sigma valves are also useful in patients with a history or risk
of slit ventricle syndrome.
- In premature infants, low-pressure valves may promote ventricular
decompression. Small contour valves reduce stress on the very thin
7.1. Surgical preparation and sterile protocol
- Consent–clear discussion risks, benefits, complications,
- Chlorhexidine body wash and shampoo is an alternative on night before
and morning of surgery.
- Consider scheduling as first procedure of day.
- Minimize flow of people into and out of OR.
- Preoperative scrub of the abdomen and scalp with an alcohol based
chlorhexidine solution or slow-release iodine soap/solution. Skin prep
should be allowed to dry.
- Prophylactic antibiotics are administered intravenously prior to or
during induction of anesthesia so that adequate tissue levels are present
at first incision. Cefazolin, 50 mg/Kg IV. In patients with history of
allergy to cephalosporins, clindamycin or vancomycin is the alternative.
One or 2 postoperative doses allowable.
- Adhesive clear film minimizes direct contact between skin and surgical
instruments, surgical gloves, and shunt hardware.
- Shunt hardware opened at last minute, may be immersed in antibiotic
- Manometric testing of shunt equipment unnecessary.
- “No-touch” technique for shunt hardware ideal but
difficult in some circumstances.
7.2. Selection of a site for burr hole placement
Table I: Key points for burr hole placement
7.3. Ventricular catheter placement
- Skin incision
- Small, usually curved, no shunt hardware
running underneath incision - i.e., partial inverted
- Periosteum partially intact to secure shunt
- Premature infants require meticulous care,
avoid charring delicate skin edges, using toothed retractor, or suture to
retract small skin flap.
- Burr hole
- Well beneath skin incision using standard
drill or craniotome.
- Thin skull - detach the “drill”
portion of perforator and gently turn with the surgeon’s
- Small infants with an open fontanelle may
require no bone removal or small rongeured bone opening along periosteal
- Dural opening
- Just large enough to admit the catheter to
avoid CSF leak.
- Can be made with cautery
- At the edge of the burr hole if using
- Occipital entry - ECG lead on forehead at
hairline, in midline as easily palpable target from Dandy’s
- Frontal entry - perpendicular to the skull
from Kocher’s point.
- Open fontanelle - ultrasound guidance for
trajectory and depth. In older patients, ultrasound through an enlarged
burr hole is a feasible, safe, and effective technique for the placement
of ventricular catheters (2).
- Catheter will pop into the ventricle as the
ependyma is breached with clear flow of CSF.
- Advance the catheter at least 2 cm so that all
the perforations on the tip are within the ventricle, soft pass remainder
to predetermined depth.
- Avoid multiple passes.
- Sample CSF, secure and occlude catheter to
avoid dislodgement, excessive CSF egress.
7.4. Peritoneal entry
- Mini-laparotomy, abdominal trocar, or laparoscopy.
- Typically small transverse periumbilical incision.
- Confirm entry into free peritoneal cavity with blunt dissector.
- Seek the assistance of general surgeons for previous significant
7.5. Subcutaneous dissection and tunneling
- Before placing ventricular catheter
- From either end is acceptable
- Make gentle curve at the tip of tunneler to control path.
- Extreme care to avoid vital structures, ensuring that the device is
neither too deep nor superficial.
- If difficulties make intervening incision.
- Establish subcutaneous pocket for the shunt valve and test fit prior to
connecting ventricular catheter.
7.6. Connection of devices
- Secure non-absorbable ties must be used in all connecting points. Silk
ties are preferred, since polypropylene sutures can cut silicone
catheters or connecting devices.
- If possible, knots should lay in the internal surface of the catheter,
i.e., as far as possible from the skin, to avoid skin erosion especially
in younger patients.
- The valve/ventricular catheter junction should be sutured to underlying
periosteum, to prevent migration.
7.7. Confirmation of patency
- Distal flow of CSF must be confirmed before introduction in the distal
- If the ICP is low, the distal end of the catheter may be dropped below
the level of the head to promote drainage. A low capacity syringe i.e., 5
cc can also be used to apply gentle aspiration, in order to clear
airlocks or debris from the catheter (3).
- Perhaps the most important part of the operation, particularly in
- Scalp–gentle meticulous apposition of the skin in two layers.
Absorbable skin sutures usually provide secure skin closure and avoid the
emotional trauma of suture removal in younger children.
- For atrophic, radiated, or otherwise compromised skin, non-absorbable
sutures which can be left for weeks are an option.
- Abdomen–secure closure of anterior rectus sheath, peritoneum
does not require closure.
- Don’t forget to close intervening incision and inspect shunt
path for any inadvertent skin disruptions.
- Injection of local anesthetic into skin edges will assist with
8. Post-Operative Care
- Patients with large ventricles should probably be nursed relatively
flat in the first 24 hours to avoid subdural collections.
- Patient with thin skin i.e., premature and neonates should avoid lying
on the shunt valve to prevent skin erosion.
- Adequate analgesia, usually acetaminophen, supplemented with NSAIDS or
- Advancement of diet should be rapid.
- Early postoperative imaging - ultrasound or CT optional, particularly
if there are any concerns.
- Patients can be discharged usually within 48 hours.
- Families should be counseled about signs of infection, shunt
9. Complications: Diagnosis and Treatment
A probability of occurrence of shunt malfunction of 81% at 12 years of
follow-up has been reported in multicentric studies (4). Complications of
shunts may have clinical, psychological, and economical consequences.
- General shunt infection rate of less than 5% is reported by many
centers. The aim is to reach a shunt infection rate lower than 1%.
- Most shunt infections occur within 2 months of surgery, including
revisions, although delayed infections are possible.
- In most of the infections, the organism is spread from the surgical
wound either directly from the adjacent skin or by contamination of
gloves or instruments with the patient’s flora.
- Main bacteria infecting CSF shunts are staphylococci (40% S.
epidermidis and 20% S. aureus). The organisms responsible for the
remaining 40% include coryneforms (Propionibacterium), streptococci,
enterococci, aerobic Gram-negative rods, and yeasts.
- In late infections, a Gram-negative bacilli infection must be suspected
and a primary cause (i.e., abdominal) should always be ruled out and
- Risk factors for shunt infections include: young age (immaturity of
immune system, vulnerability of thin skin), poor condition of the skin
(malnourishment, dermatitis), intercurrent systemic infections, prior CNS
infections, repeated procedures (multiple revisions), and
surgeon’s experience, amongst others.
- Types of infection and diagnosis
- Wound infection: Incision or shunt track with
signs of inflammation, purulent discharge, with or without fever or
leukocytosis, and organisms seen on Gram stain or culture.
- Meningitis/ventriculitis: Fever, meningismus,
lethargy or decreased level of consciousness, CSF leukocytosis, and
organisms seen on Gram stain or culture.
- Peritonitis: Fever, abdominal tenderness, and
organisms seen on Gram stain or culture. Abdominal pseudocyst and
abdominal abscess may present with mass, with or without fever. Abdominal
ultrasound is useful for diagnosis.
- VA shunt infection: Fever, leukocytosis,
positive blood culture, with or without evidence of shunt nephritis or
- Infected shunt apparatus: Minimal signs of CSF
contamination with bacteria recovered from purulent exudate in or on
shunt material, Gram stain of CSF withdrawn from the shunt under sterile
- If infection is highly suspected or confirmed,
proper IV antibiotic regimen should be started. Consider ceftriaxone +
vancomycin as empiric treatment until cultures are obtained, then
reassess. Consider Infectious Diseases team consultation.
- Infected hardware must be removed and an
external drainage (EVD) should be placed until antibiotic treatment is
completed and sterility of CSF is confirmed with at least 3 negative CSF
cultures, taken every 3 days from EVD insertion.
- In patients with slit ventricles, insertion of
an EVD may be difficult. Consider externalization of peritoneal catheter
as an interim step.
- Consider intraventricular antibiotics in the
presence of Gram negative infections or to treat organisms sensitive to
antibiotics that have poor CSF penetration.
- Once infection is treated and CSF is sterile,
a new shunt can be placed in a different surgical site. All precautions
to avoid new infections should be taken.
- Antibiotics alone, without shunt apparatus
removal, can be considered in cases of infection by organisms that cause
meningitis in the general population and infect patients with shunts or
cause hydrocephalus and are discovered at time of shunt insertion (e.g.,
H. influenzae, meningococcal, and gonococcal meningitis). Failure to
clear CSF within 48 to 72 hours should prompt removal of the shunt
9.2 Mechanical complications
- Shunt occlusion represents about a half of
shunt complications in pediatric series.
- Occlusion can occur at three different levels:
proximal catheter, valve system, or distal catheter.
- The risk for occlusion is higher during the
immediate postoperative period (due to debris, clots or misplacement of
catheters) than during the next months and decreases progressively with
time, maintaining a steady rate of 0.5% per month (1). Choroid plexus
ingrowth, ependymal reaction, and immune reaction predominate as
causative agents in delayed occlusions.
- Clinical picture includes irritability,
lethargy, bulging fontanelle, sunset eyes, and increasing head
circumference in newborns and infants, whereas headaches, nausea and
vomiting, papilledema, increased frequency of seizures (if previously
present), or decreased level of consciousness are found in older children
with occluded shunts.
- Diagnosis is confirmed with increased
ventricular size in CT scan, compared with baseline. Shunt series can
confirm some causes of occlusion or make differential diagnosis with
disconnection/fracture, migration or misplacement of catheters.
- NB–patients can have a shunt
obstruction with normal sized ventricles, they may just be larger than
their usual slit ventricles, or they may not expand their ventricles with
shunt occlusion. Do not assume because the ventricles are small, that the
shunt could not be blocked.
- ICP monitoring can be helpful in cases where a
diagnosis of occlusion is not clear.
- Shunt revision is the treatment for shunt
occlusions. Unless there is preoperative evidence of distal obstruction,
the proximal end and valve should be revised first. Partial or total
replacement of the shunt is often required.
- Disconnection and fracture
- Shunt disconnection or fracture constitutes
the second most frequent cause of mechanical shunt malfunction.
- Disconnection is defined as a loss of
continuity of shunt at connecting points between catheters, valves,
and/or connectors, whereas fracture is an actual breakage of the catheter
with separation between the segments.
- Associate, but not necessarily causative
factors for broken shunts are: growth spurt, aging brittle partially
calcified shunt, multiple proximal revisions, local trauma over shunt,
sports activity without evident trauma, trunk elongation post scoliosis
correction, and shunt design (multiple-pieces shunts have more risk of
disconnection than one-piece shunts) (5).
- The most common place for breakage is the
neck, followed by the scalp either proximal or distal to valve or
- Patients with broken shunts may present with
headaches, irritability, nausea and vomiting, lethargy, papilledema,
oculoparesis, pain, or fluid collections along shunt tract and a palpable
gap. Asymptomatic patients are usually diagnosed during routine follow-up
imaging in outpatient clinic or as an incidental radiological finding.
- Diagnosis of disconnection or fracture is
confirmed on plain x-rays (shunt series). CT scan can show increase in
ventricular size, no change at all.
- Symptomatic patients require shunt revision as
soon as possible. Partial or total replacement is required, although
sometimes, reconnection is feasible.
- Asymptomatic patients may remain stable for
years, due to patent fibrous tracts (demonstrated by nuclear medicine
studies or contrast shuntogram) and develop symptoms on a delayed
fashion. If the patient is shunt dependant, revision should be performed
as soon as possible (5).
- If shunt independence is suspected, proper
investigations should be conduced to prove it, and then make a decision
to observe or treat. Some alternatives include nuclear medicine scans,
contrast shuntogram, ICP monitoring, and careful review of
patient’s history (etiology of hydrocephalus, previous revisions,
- To migrate, a shunt needs to be pulled and to
be able to move in the subcutaneous tissue. Loose or improper connection
will allow catheters to be released and migrate. Overdissection of the
subcutaneous tissue also predisposes to migration.
- Valves not fixed in the subcutaneous tissue
either by ligature or inherent valve shape, have a high risk to migrate
into the distal site or, in a retrograde fashion into the ventricles.
Cylindrical valves, unless properly secured, are very prone to migration.
- Migration may occur early after shunting or
with time and patients present a clinical picture very similar to
disconnection and fracture.
- Improper placement
- The shunt can be improperly placed at the
level of the ventricles or at the level of the drainage cavity.
- Signs and symptoms of improper placement are
similar to shunt occlusion and appear in the early postoperative period.
- Once suspected, shunt series and head CT scan
are used to confirm diagnosis. A lateral abdominal film may be necessary
to detect a pre-peritoneal distal catheter.
- Overdrainage is caused by an increase of the differential pressure
applied to the shunt system above the opening pressure of the valve plus
the pressure of the drainage cavity (1). This can happen normally with
postural changes, REM sleep, straining, etc.
- Overdrainage can cause symptomatic orthostatic hypotension, subdural
CSF collections, slit ventricle syndrome, craniosynostosis, and
loculation of the ventricles.
- The risk of overdrainage can be minimized by increasing the opening
pressure of the valve (programmable valves), adding a siphon-resistive
device to the system, or using a flow-regulating device (Orbis-Sigma
- Subdural collections
- The risk of subdural collection (hematoma,
hygroma), caused by disruption of the arachnoid or the stretched
subarachnoid vessels, is related to the drainage capacity of the shunt,
the size of the ventricles and the compliance of the brain.
- Prevention of subdural collections can be
achieved by avoiding a shunt in presence of a valid alternative (third
ventriculostomy) and the use of overdrainage-limiting devices).
- These collections can be asymptomatic but in
some patients can cause focal motor deficits, seizures, or deterioration
of level of consciousness.
- Diagnosis is made by head CT scan or, less
commonly, MRI of the brain.
- Not all subdural collections require
treatment, since some of them can resolve spontaneously. In other cases,
drainage limitation by upgrading the valve pressure or use of a
flow-rate-limiting system can be successful. In some instances a
subduro-peritoneal shunt (without a valve or with a lower pressure than
the ventricular one) is required to restore a pressure gradient between
the ventricles and the subarachnoid spaces.
- Slit ventricle syndrome
- Slit ventricle syndrome is defined as a
transient intracranial hypertension occurring in patients having a patent
shunt and slit ventricles.
- Headache is the most common symptom of this
condition. Some patients can present with nausea/vomiting, visual
alterations, or decreased level of consciousness.
- CT scan shows very small ventricles. ICP
monitoring can be necessary to confirm diagnosis and for the
- Overdrainage limitation and/or skull expansion
are strategies to solve this complex problem.
- Acquired post-shunt craniosynostosis is a
relatively common complication, but in most cases, is mild. Rarely, they
require reoperation of the shunt system or cranioplasty.
- Cases of true craniocephalic disproportion
require conventional cranioplasty interventions (strip craniectomy,
cranial vault reconstruction).
- Loculation of the ventricles
- Although most commonly seen in inflammatory or
infectious processes, overdrainage can cause loculated ventricles. This
is usually due to an obstruction of foramen of Monroe or aqueduct of
Sylvius secondary to asymmetric drainage of one ventricle.
- Loculated ventricles may require two or more
drainage systems connected to the same valve by means of a Y-connector or
a 2-way connector.
- When possible, the most satisfactory solution
is to reestablish communication between the ventricles by neuroendoscopic
- Orthostatic hypotension
- Clinical symptoms of orthostatic hypotension
(e.g., headaches, nausea or dizziness) are frequently observed in older
patients after shunt insertion.
- Usually these symptoms disappear after a short
period of time as the patient adapts to the new hydrodynamic
- In some cases, it is necessary to upgrade the
opening pressure of the valve, or to use a higher resistant shunt.
9.4 Complications related to specific types of shunts
- Ventriculopleural shunts
- Pleural effusions are the most common
complication of this type of shunt. They are usually minor and do not
require treatment. If restrictive pulmonary problems are diagnosed, a
thoracentesis can be considered. In some cases, a different drainage
cavity must be found.
- Pleural empyemas are uncommon. If present, the
shunt must be removed, external CSF drain placed, and proper antibiotic
and surgical drainage established.
- Ventriculoatrial shunts
- Improper placement is one of the most common
problems of VA shunt. Fluoroscopy is usually utilized to correctly
localize the tip of the catheter in the right atrium.
- Bacterial endocarditis is the most important
infectious complication of VA shunts. Echocardiogram is the indicated
diagnostic test and shunt removal associated to proper antibiotic regimen
is the treatment of election.
- Nephritis has also been reported as a
complication of VA shunts. Treatment often requires changing the shunt
- Lumboperitoneal shunts
- Acquired Chiari malformation with tonsillar
herniation has been described with lumboperitoneal shunts.
- Some other complications include scoliosis and
hyperlordosis, limited spinal flexion, transient back pain, sciatica,
transient neck pain, lower limb neurological changes, arachnoiditis, and
rarely, migration of the LP shunt.
- LP shunts should be restricted to cases of
pseudotumor cerebri or exceptional cases of communicating
9.5 Other complications
- Minor symptoms, such as subtle deterioration of intellectual function
or episodic headaches can lead to surgery, without a strict demonstration
of shunt malfunction.
- Instead of performing unnecessary surgery, extensive preoperative
investigation, including CSF flow measurement and ICP monitoring is
recommended in unclear cases (1).
- Typically patients are seen at 3 months, 1 year and annually, or
semiannually. An interim scan at 3 months and baseline scan at one year
when the ventricles are usually at their smallest.
- Annual scans and shunt series in asymptomatic patients are likely
unnecessary, but ideal frequency is undetermined.
- The family or patient should be advised to carry a disc with them at
all times (especially vacations) containing the most recent head CT
demonstrating the patient’s stable and baseline ventricular size.
This will be helpful to the neurosurgeon on call in the other state or
hospital to more effectively evaluate the patient if they arrive in their
- Drake JM, Saint-Rose C: The Shunt Book.
Blackwell Science, Cambridge, MA, 1995.
- Whitehead WE, Jea A, Vachhrajani S, Kulkarni A, Drake J: Accurate
placement of cerebrospinal fluid shunt ventricular catheters with
real-time ultrasound guidance in older children without patent
fontanelles. Technical note. J Neurosurg: Pediatr 107;406-410, 2007.
- Frim DM, Gupta N: Chapter 14. Pediatric Neurosurgery. Landes
Bioscience, Georgetown, TX, 2006.
- Saint-Rose C, Piatt JH, Renier D, Pierre-Kahn A, Hirsch JF, Hoffman HJ,
Humphreys RP, Hendrick EB: Mechanical complications in shunts. Pediatr
Neurosurg 17:2-9, 1991-1992.
- Ghotme K, Drake J, Lamberti-Pasculli M, Rutka J: Management of Shunt
Disconnections and Fractures in Children: Experience at the Hospital for
Sick Children. Unpublished data, presented at the 2007 AANS Pediatric
Section Meeting, South Beach, Fl.