Surgery

Ventriculoperitoneal Shunt

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Ventriculoperitoneal Shunt, Ventriculo-Peritoneal Shunt, VP Shunt, Ventriculoperitoneal Shunt Malfunction, CSF Shunt

  • See Also
  1. Hydrocephalus
  2. Myelomeningocele
  3. Spina bifida
  4. Cerebrospinal Fluid
  1. Intraventricular Hemorrhage of prematurity
  2. Spina bifida
  3. Lisencephaly
  4. Holoprosencephaly
  5. Meningitis complication
  • Technique
  • Shunt position
  1. VP Shunt proximal catheter tip
    1. Ventricles
  2. Reservoir and One-Way Valve
    1. Located at edge of skull
    2. Distal tube and proximal tube connect to the one-way valve (which does not allow back flow into brain)
    3. One way valve should be compressible (unless obstructed)
  3. VP Shunt course
    1. Subcutaneously via the right parietal scalp and down neck
  4. VP Shunt distal tip
    1. Peritoneum (most common)
    2. Alternative sites (if limited by prior peritonitis history)
      1. Pleural space
      2. Right atrium
      3. Lumbar region
  • Complications
  • Shunt
  1. Mechanical shunt malfunction (presumed cause until proven otherwise)
    1. Shunt obstruction (see management below)
    2. Detached shunt tubing or otherwise broken shunt
    3. Shunts Fracture most commonly in the distal tubing (esp. near clavicle or lower ribs)
    4. Cannula dislodged with inadequate drainage
    5. Shunt failure occurs in 40% within 1 year and in 50% by 2 years after implantation
  2. Infection
    1. Complicates 3-10% of shunt procedures
      1. Accounts for up to 60% of shunt-related mortality
      2. Very old and very young are at highest infection risk
    2. Causes
      1. Typically within 8 weeks of shunt placement, manipulation or revision (accounts for 70% of shunt infections)
      2. Ascending infection may occur (e.g. peritonitis from Appendicitis)
    3. Findings of suspected shunt infection
      1. Meningismus
      2. Fever without a source
      3. Persistent Abdominal Pain
    4. Consult with neurosurgery
      1. Neurosurgery typically performs shunt tap as described below
      2. In some cases, neurosurgery will remove the shunt and temporize with external ventricular drain
    5. Start Antibiotics as soon as shunt tap completed
      1. In some cases they will recommend starting Antibiotics prior to shunt tap
      2. Vancomycin is typically used
      3. Staphylococcus epidermidis (or other skin flora) causes 75% of shunt infections
        1. Also cover for abdominal flora (due to distal tubing in Abdomen)
  3. Intraabdominal complications (especially if distal tip migration)
    1. Ascites
    2. Peritonitis
    3. Ruptured Viscus
  4. Excessive removal of fluid (less common now with programmable shunts)
    1. Postural Headache
    2. Subdural Hematoma (result from tearing of bridging veins)
  • Complications
  • Shunt obstruction
  1. Initial symptoms
    1. Headache
    2. Lethargy or Somnolence
    3. Vomiting
    4. Children with subacute presentation may have behavioral changes, feeding problems, irritability, Headaches
  2. Later symptoms suggestive of imminent Herniation
    1. Cranial Nerve palsy
    2. Unilateral pupilary dilation (Blown Pupil)
    3. Upward Gaze Paralysis (eye sunsetting)
    4. Cushing's Triad (Hypertension, Bradycardia, Irregular breathing)
    5. Altered Mental Status
    6. Bulging Fontanelle or Bradycardia (infants)
  3. Findings
    1. Shunt one-way valve (at lateral skull) is not compressible
  4. Unrelated findings
    1. Seizure Disorders are common among children with Hydrocephalus
      1. Shunt obstruction presents with Seizures uncommonly (<3% of cases)
      2. Isolated Seizure without other findings does not require additional evaluation
    2. Head Trauma
      1. VP Shunts do not appear to significantly increase complications from minor Head Trauma
  • Imaging (and other diagnostics)
  1. CT Head (or MRI Brain)
    1. Normal CT Head with unchanged ventricles in 11% of shunt obstruction cases
    2. Abnormal CT with enlarged ventricles indicates neurosurgical revision of shunt
    3. Shunt malfunction suspected despite negative Head CT
      1. Consult with neurosurgery
      2. Consider shunt tap
  2. Head Ultrasound
    1. Consider in infants with open Fontanelles
  3. Shunt Series XRays
    1. Views include anterior skull, lateral skull, Chest XRay, KUB Xray
    2. Consider if Trauma to tubing or suspected kinking or tube disruption (e.g. subcutaneous fluid collection)
    3. Shunts Fracture most commonly in the distal tubing (esp. near clavicle or lower ribs)
    4. VP Shunt series, however, adds little if CT Head is without acute changes
      1. Docter (2019) J Emerg Med PMID: 31806435 [PubMed]
  4. Head Circumference
    1. Compare measurement to prior Head Circumference measurements (significant increase ay suggest obstruction)
  • Management
  • Shunt Malfunction with signs Herniation
  1. Emergency - involve neurosurgery immediately!
  2. Mortality shunt obstruction: 1-2%
  3. Evaluate for symptoms of obstruction (see symptoms above)
  4. Evaluate for findings of imminent Herniation (see symptoms above)
  5. Obstruction is proximal in 80% of cases (proximal tip lodges)
  6. Distal obstructions may also occur in the peritoneum
  7. Reduce Intracranial Pressure
    1. See Increased Intracranial Pressure
    2. Emergent neurosurgery Consultation
    3. Consider shunt tap if neurosurgery not available (see below)
    4. Raise head of bed
    5. Mannitol
      1. Hypertonic Saline does not appear to be an effective alternative
  • Procedure
  • Shunt Tap
  1. Indications (only in cases where neurosurgery is not available in an adequate time frame)
    1. Suspected shunt malfunction with ill appearing patient
    2. Signs of shunt obstruction with Herniation
  2. Preparation
    1. Patient lies supine
  3. Identify shunt reservoir
    1. Shunt reservoir sits a few centimeters inferior to entry point in skull
    2. Palpable firm hub or tube swelling along the shunt course
      1. Second hub may be palpable in some patients
      2. Either hub may be accessed
    3. Mark hub site
  4. Technique
    1. Use sterile technique
      1. Apply antiseptic solution (Betadine or Chlorhexidine) to skin overlying hub
      2. Drape the skin and wear sterile gloves
    2. Insert 25 gauge butterfly needle into hub, perpendicular to scalp
      1. Attach 3-way stopcock and 5 cc syringe
    3. Allow CSF to freely flow
      1. Attach manometer (from Lumbar Puncture kit)
        1. Distal obstruction if CSF flows and opening pressure >15-20 cm H2O
        2. Proximal obstruction if no CSF flow (not correctable in emergency department)
        3. Only drain enough fluid until opening pressure <20 cm H2O
      2. Do not apply back pressure with the syringe (risk of Subdural Hematoma)
      3. CSF under pressure of obstruction should fill the syringe with force
    4. Post-procedure
      1. Send CSF for Gram Stain and culture
      2. Anticipate marked clinical improvement after shunt tap
  • References
  1. Jhun and Roepke in Herbert (2016) EM:Rap 16(3): 17-8
  2. Majoewsky (2012) EM:Rap 12(9): 4
  3. Behar and Claudius in Majoewsky (2013) EM:Rap 13(9): 9