VP Shunts

Division of Child NeurologyDepartment of Pediatrics

Goryeb Children’s Hospital Atlantic Health System

Cerebral Shunts To treat hydrocephalus / reduce ICP

Proximal end inserted into a CSF source (usually blocked) Ventricle Lumbar cistern of the spinal cord

Distal end inserted near absorptive epithelial surface or directly into the blood stream: Peritoneal cavity of the abdomen (most common)

VP shunt = ventriculo-peritoneal shunt LP shunt = lumbar-peritoneal shunt

Right Atrium of the heart (VA shunt) Pleural cavity of the lung (VPL shunt)

VP SHUNT VA SHUNT

LP SHUNT

Cerebral Shunts

May also insert distal end into: gallbladder (mixes with bile) ureter (mixes with urine)

Variety of forms: made of different materials (silicone) different types of pumps and uni-directional

valves +/- programmable

Shunt Complications

More common in childhood May require immediate shunt revision or shunt

re-programming Shunt complications often mimic the symptoms that

prompted initial shunting headache double vision nausea / vomiting altered mentation (lethargy / irritability) bulging fontanelle

Shunt failure rate 2 years after insertion - up to 50%

“Sunsetting Eyes”: clinical sign of increased intracranial pressure

Infection Incidence 1-20 %, average 10 % Usually intra-operative contamination of surgical wound by

skin flora Common microbial agents

Staph epi (coagulase negative staph) > 50% Staph aureus 20 % Gram negative bacilli 15 % Candida

Symptoms – ICP, fever, WBC No correlation with shunt type Risk factors for shunt infection

age < 6 months

4 Distinct Clinical Syndromes of Shunt Infection

1. Colonization of the shunt - most common

2. Wound infection

3. Peritonitis / distal infection

4. Meningitis

1. Colonization of the Shunt

MOST COMMON Symptoms of shunt malfunction > infection Lethargy, headache, vomiting, full fontanelle Low grade fever Within months of shunt insertion CSF from ventricle or lumbar puncture STERILE

Unusual to see signs of meningitis / ventriculitis CSF minimally abnormal

Infecting organism in SHUNT RESERVOIR Blood cultures negative unless VA Shunt colonization

If VA shunt, more severe systemic symptoms Septic pulmonary emboli Pulmonary hypertension Infective endocarditis

For more chronic VA shunt colonization hypo-complementemic glomerulonephritis =

Ag-Ab complex deposition in glomeruli “Shunt Nephritis” hypertension, microscopic hematuria, elevated BUN and

creatinine, anemia

2. Wound Infection

Obvious infection or dehiscence along the shunt tract

Within days-to-weeks of shunt procedure Staph aureus - most common isolate Fever common Symptoms of shunt malfunction follow

3. Distal Infection / Peritonitis

Abdominal symptoms without signs of shunt malfunction common

Pathogenesis: perforation of bowel at time of insertion translocation of bacteria across the bowel wall

Gram negative isolates, mixed flora cultured from distal portion of shunt catheter

4. Meningitis

Pathogens: Strep pneumo N. meningitidis Hib

Presentation typical of acute bacterial meningitis

Treatment of Shunt Infection

1. IV anti-staph PCN (if resistant, IV vancomycin)

2. intra-shunt vancomycin (monitoring CSF levels to avoid toxicity) due to poor penetration of most abx into CSF across inflamed

meninges

3. externalize the distal shunt

For gram negative infections : 3rd generation IV cephalosporin Intra-shunt aminoglycoside

Treatment of Shunt Infection

Often need to remove shunt colonization, wound infection, distal peritonitis for meningitis, IV abx without shunt removal

After reservoir CSF sterile x 48 hour, can insert new shunt on other side

High rate of infection relapse due to: Abx therapy alone (no shunt externalization or removal) Abx therapy + partial shunt revision

Prevention of Shunt Infection

Meticulous cutaneous preparation and surgical technique

?? perioperative IV abx, intra-ventricular abx, abx impregnated shunt tubing, soaking the shunt in abx

Other Shunt Complications Obstruction

Proximal – build-up of excess protein in CSF, slowly clogs the valve

Distal – build-up of excess peritoneal protein blocks distal tip Over-drainage (see below) Slit Ventricle Syndrome (see below)

Over-drainage Intraventricular CSF drains too rapidly brain collapses on

itself extra-axial fluid (CSF or blood) collects to fill the spatial void external compression of brain brain damage, stretching of bridging veins subdural hemorrhage

Over-drainage

Other Shunt Complications Slit Ventricle Syndrome

CSF slowly over-drains over several years after shunt procedure

uncommon, but results in need for many shunt revisions symptoms similar to typical shunt malfunction BUT

cyclical (appear, subside, appear, subside…, over years) symptoms alleviated by lying prone due to:

overdrainage simultaneous with brain growth (brain growth fills the intraventricular space, leaving the ventricles collapsed)

compliance of brain decreases, preventing ventricles from enlarging collapsed ventricles can also block shunt valve (a form of

obstruction)

Slit Ventricle Syndrome

Other Shunt Complications Intra-ventricular hemorrhage

occurs at any time during or after a shunt insertion or revision

can occur in nearly 31% of shunt revisions

A large dural hole around the ventricular catheter may predispose to CSF flow through the dural opening leading to the formation of subcutaneous tract

Distal VP shunt catheter protruding from anus

Conditions requiring shunting

Obstructive / Non-communicating Hydrocephalus due to Aqueductal Stenosis

CT of the brain:

- large frontal and temporal horns of lateral ventricles - large third ventricle

- 4th ventricle small

4th

3rd

Obstructive / Non-communicating Hydrocephalus due to Chiari Malformation

low lying tonsils alone (Chiari I) – usually asymptomatic low lying tonsils + hydrocephalus (Chiari II) – diffuse headache

Chiari II (+ lumbosacral myelomeningocele)Chiari I

Non-Obstructive / Communicating Hydrocephalus as a complication of prior Meningitis

CT of the brainreveals enlarged frontal and temporal horns of the lateral ventricles andenlarged 3rd and 4th ventricles.

4th

3rd

Dandy-Walker Malformation: aplasia / hypoplasia of cerebellar vermis (midline cerebellum missing or underdeveloped)

Hydrocephalus due toChoroid Plexus Papilloma(CSF secreting intraventricular tumorwhich obstructs ventricular system)

Conditions with enlarged CSF spaces that usually do NOT

require shunting

Benign External Hydrocephalus

Porencephaly

Holoprosencephaly

Lissencephaly “smooth brain”- achieve maximum 3-5 month dev milestones- may be caused by LIS-1 gene mutation (Miller-Diecker lissencephaly) - microcephaly, MR, seizures

Schizencephaly: “clefted brain”

Multifocal Cystic Encephalomalacia (hx of neonatal meningitis)