Ventriculoperitoneal shunt complications: Difference between revisions

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==Background==
==Background==
[[File:Diagram showing a brain shunt CRUK 052.svg.png|thumb]]
*Also called a cerebral sinus fluid (CSF), VP, or cerebral shunt
*Highest incidence of postoperative complications of any neurosurgical procedure
*Highest incidence of postoperative complications of any neurosurgical procedure
*May drain into peritoneal cavity or less commonly the R atrium, pleural cavity, ureter, GB
**Majority in the first 2 years (40% in the first year<ref>Drake JM, Kestle JRW, Tuli S. CSF shunts 50 years on past, present and future. Child’s Nerv Syst. 2000; 16:800–804. </ref>)
*May drain into peritoneal cavity or less commonly the right atrium, pleural cavity, ureter, gallbladder


==Malfunctions==
[[File:vpvalve.png|thumb]]
===Obstruction===
====Background====
*Most common type of shunt malfunction
**Usually occurs at proximal tubing, followed by distal tubing followed by valve chamber
*Proximal obstructions usually occurs within first years of insertion
*Distal obstruction usually occurs only with shunts in place for >2yr


====Causes====
==Clinical Features==
#Proximal obstruction
*Typically develop over several days
##Tissue debris
##Choroid plexus
##Clot
##Infection
##Catheter-tip migration
##Localized immune response to the tubing
#Distal obstruction
##Kinking or disconnection of the tube
##Pseudocyst formation
##Infection


===Mechanical Failure===
===Adults===
====Causes====
*[[headache|Cephalgia]], [[nausea and vomiting]], [[lethargy]], [[ataxia]], [[altered mental status]]
#Fracture of tubing
*Paralysis of upward gaze ("sunset eyes"), dilated pupils, [[cranial nerve palsies]]
##Occurs many years after shunt placement in distal tubing
##May present w/ mild symptoms of incr ICP and local symptoms of pain, erythema, edema
#Disconnection
##Occurs shortly after insertion
#Migration
#Misplacement
##Usually manifests postoperatively


===Overdrainage (Slit Ventricle Syndrome)===
===Infants===
====Background====
*[[nausea and vomiting (peds)|Vomiting]], irritability, [[bulging fontanelle]]
*Overdrainage -> tissue occluding the orifices of the proximal shunt apparatus
**Often '''very subtle''': a caregiver-reported change in behavior predicts malfunction
**As pressure increases the occluding tissue diesengages allowing drainage to resume
 
**Leads to cyclic incr ICP complaints that worsen when pt stands
===Physical Exam===
*Neither sensitive nor specific
*[[AMS|Decreased level of consciousness]], erythema along shunt tract, [[bulging fontanelle]], [[nausea/vomiting]], irritability should raise suspicion
*Valve chamber abnormality
**Gently compress chamber and observe for refill
**Difficulty compressing chamber indicates distal flow obstruction
**Slow refill (>3s) indicates proximal obstruction
 
==Differential Diagnosis==
{{VP shunt prob DDX}}


===Loculation of Ventricles===
===Loculation of Ventricles===
====Background====
*Separate, noncommunicating CSF accumulations may develop within a ventricle
*Separate, noncommunicating CSF accumulations may develop within a ventricle
**Shunt device unable to drain entire ventricular system -> incr ICP
**Shunt device unable to drain entire ventricular system leading to increased ICP


===Abdominal Complications===
===Abdominal Complications===
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**Can lead to occlusion and/or abdominal pain (depending on size)
**Can lead to occlusion and/or abdominal pain (depending on size)


===Clinical Features===
==Evaluation==
*Develop over several days
[[File:NormalVPshunt.jpg|thumb|Slit-like ventricles are expected to be seen on CT in a well-functioning shunt]]
*Adults
*CBC, Chem7, coags
**Cephalgia, N/V, lethargy, ataxia, altered mental status
*Blood cultures
**Paralysis of upward gaze, dilated pupilsCN palsies
*Shunt tap if concerned for infection (this is usually done by or in consultation with neurosurgery)
*Infants
**A normal lumbar puncture does not rule out ventriculitis (shunt infection)
**Vomiting, irritability, bulging fontanelle
*Imaging
 
**Shunt series
===Work-Up===
***AP and lateral skull, AP chest and abdomen
#Physical Exam
***Identifies kinking, migration, or disconnection
##Neither Sn nor Sp
**[[head CT|CT]]
##Locate valve chamber
***Needed to evaluate ventricular size (if larger, concerning for elevated ICP)
###Gently compress chamber and observe for refill
***Very helpful to compare to previous study (many patients with shunts have abnormal baseline)
###Difficulty compressing chamber indicates distal flow obstruction
***One-third of patients with shunt malfunction will have normal head CT{{Citation needed|reason=Reliable source needed|date=March 2016}}
###Slow refill (>3s) indicates proximal obstruction
**[[Ultrasound]]
#Imaging
***If the baby has an open fontanelle, you may use US
##Shunt series
***Some literature for [[ultrasound]] of optic nerve diameter (if normal (3.3cm), lower chance of elevated ICP){{Citation needed|reason=Reliable source needed|date=March 2016}}
###AP and lateral skull, AP chest and abdomen
###Identifies kinking, migration, or disconnection
##CT
###Needed to evaluate ventricular size
###Very helpful to compare to previous study (many pts w/ shunts have abnormal baseline)
 
===Management===
#Assume shunt malfunction in pts w/ suggestive features regardless of findings on imaging
#Shunt Tap
##Should only be performed by emergency physician in an emergency
##Alleviates incr ICP and helps make definitive diagnosis
##Procedure
###Prepare tap site in sterile manner
###23ga needle or butterfly attached to a manometer is inserted into the reservoir
####If no fluid returns or flow ceases, a proximal obstruction is likely
###Measure opening pressure (nl = 12 +/- 2)
####Measure while reservoir outflow is occluded
####Opening pressure >20 indicates distal obstruction; low pressure indicates proximal
###Fluid removal (for incr ICP)
####Remove slowly to avoid choroid plexus bleeding
####Remove until pressure is 10-20
 
===Infection===
====Background====
*Occurrence
**50% within first 2 weeks of placement
**70% within 2 months of placement
**80% within 6 months of placement
**10% present >1 year after surgery
 
====Types====
*External Infection
**Involve the subcutaneous tract around the shunt
*Internal Infection
**Involves the shunt and CSF contained within the shunt


====Bacteriology====
==Management==
*50% of cases caused by S. epidermidis
*Assume shunt malfunction in patients with suggestive features regardless of findings on imaging
*Also caused by S. aureus, Gram-negatives, anaerobes
*Revisions are extremely common, low threshold to contact Neurosurgery
*[[Ventriculoperitoneal shunt drainage]]


====Clinical Features====
==Disposition==
#Internal Infection
##Mental status changes, HA, N/V, irritability
##Neck stiffness (33% of pts)
##Fever is often absent
##Abdominal pain (VP shunt)
#External Infection
##Swelling, erythema, tenderness along site of shunt tubing


====Management====
==See Also==
#Emergent neurosurgical consultation and admission
*[[CSF Studies]]
#Shunt tap
##LP often misses CSF shunt infections and has no role when shunt infection is suspected
#Imaging
##Useful to exclude mechanical shunt malfunction (often coexists w/ infection)
#Abx
##CTX + vancomycin


==Source==
==References==
Tintinalli
<references/>


[[Category:Neuro]]
[[Category:Neurology]]

Latest revision as of 02:59, 8 August 2021

Background

Diagram showing a brain shunt CRUK 052.svg.png
  • Also called a cerebral sinus fluid (CSF), VP, or cerebral shunt
  • Highest incidence of postoperative complications of any neurosurgical procedure
    • Majority in the first 2 years (40% in the first year[1])
  • May drain into peritoneal cavity or less commonly the right atrium, pleural cavity, ureter, gallbladder
Vpvalve.png

Clinical Features

  • Typically develop over several days

Adults

Infants

Physical Exam

  • Neither sensitive nor specific
  • Decreased level of consciousness, erythema along shunt tract, bulging fontanelle, nausea/vomiting, irritability should raise suspicion
  • Valve chamber abnormality
    • Gently compress chamber and observe for refill
    • Difficulty compressing chamber indicates distal flow obstruction
    • Slow refill (>3s) indicates proximal obstruction

Differential Diagnosis

Ventriculoperitoneal shunt problems

Loculation of Ventricles

  • Separate, noncommunicating CSF accumulations may develop within a ventricle
    • Shunt device unable to drain entire ventricular system leading to increased ICP

Abdominal Complications

  • Pseudocyst may form around the peritoneal catheter
    • Can lead to occlusion and/or abdominal pain (depending on size)

Evaluation

Slit-like ventricles are expected to be seen on CT in a well-functioning shunt
  • CBC, Chem7, coags
  • Blood cultures
  • Shunt tap if concerned for infection (this is usually done by or in consultation with neurosurgery)
    • A normal lumbar puncture does not rule out ventriculitis (shunt infection)
  • Imaging
    • Shunt series
      • AP and lateral skull, AP chest and abdomen
      • Identifies kinking, migration, or disconnection
    • CT
      • Needed to evaluate ventricular size (if larger, concerning for elevated ICP)
      • Very helpful to compare to previous study (many patients with shunts have abnormal baseline)
      • One-third of patients with shunt malfunction will have normal head CT[citation needed]
    • Ultrasound
      • If the baby has an open fontanelle, you may use US
      • Some literature for ultrasound of optic nerve diameter (if normal (3.3cm), lower chance of elevated ICP)[citation needed]

Management

  • Assume shunt malfunction in patients with suggestive features regardless of findings on imaging
  • Revisions are extremely common, low threshold to contact Neurosurgery
  • Ventriculoperitoneal shunt drainage

Disposition

See Also

References

  1. ↑ Drake JM, Kestle JRW, Tuli S. CSF shunts 50 years on past, present and future. Child’s Nerv Syst. 2000; 16:800–804.
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