“Privileged & Confidentialâ€‌ - Brad .“Privileged & Confidential ... •Ommaya reservoir: Generally

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  • Medical Video Review

    Shunt Malfunctions Brad Sobolewski, MD

    February 28, 2012

  • Privileged & Confidential

    This document is covered under the attorney-client privilege. This document is also part of the quality assessment and peer review activities of CCHMC and, as such, is a confidential document not subject to discovery pursuant to Ohio Revised Code (ORC) Sections 2305.24, 2305.25, and 2305.252. All committees involved in the review of this document, as well as those individuals preparing and submitting information to such committees, claim all privileges and protection afforded by ORC Sections 2305.24, 2305.25, 2305.251, and 2305.252 and any subsequent legislation. The information contained is solely for the use of the individual or entity intended. If you are not the intended recipient, be aware that any disclosure, copying, distribution, or use of the contents of this document is prohibited.

  • Background information

    School aged M w/ MRCP spastic quadriplegia d/t grade III IVH as neonate

    VP shunt shortly after birth

    Epilepsy: no seizures in 3 years, on Trileptal

    On Baclofen for spasticity

    Uses wheelchair, stands with support

    Picture board to communicate

  • 20 minute seizure last night, first in 3 years

    Diastat x2 at home

    No fevers or recent infectious Sx

    No changes to meds or missed doses

    Uncertain of whether or not he was still seizing

    Got Ativan IV x1 then fosphenytoin

    20ml/kg NS bolus

    Head CT

    This isnt normal for him -The Dad

  • The head CT

    Then Now

  • We need to get him intubated -The Neurosurgeon

    Neurosurgery eval at bedside

    Elected to intubate

    Lido, etomidate and sux

    Bedside shunt tap

    Diagnosis:

    Shunt malfunction

  • Ventricular system

    4th

    CISTERNS Subarachnoid space

    3rd

    LATERAL LATERAL

    STATS Total volume 50ml Production 20ml/hr Turnover 3-4x/day

  • Hydrocephalus

    Imbalance of absorption and production of CSF

    Estimated incidence of 1/500-1000 children

    125,000+ shunts

    OBSTRUCTIVE: Ventricular system is blocked

    Not possible to have complete obstruction

    COMMUNICATING: Subarachnoid system blocked

  • Etiology

    Congenital

    infection: Rubella, CMV, Toxo, Syphilis

    Acquired: Infection, trauma, tumors, head bleeds

    Neural tube defects: associated with Chiari or aqueductal stenosis. Linked to teratogens and deficiency of folate.

    Isolated: aqueductal stenosis (inflammation d/t intrauterine infection)

    X-Linked hydrocephalus: stenosis of aqueduct of Sylvius

  • Etiology CNS malformations

    Often accompanies NTD Brainstem and Cerebellum are displaced caudally

    Chiari II

  • Large posterior fossa cyst continuous with 4th ventricle Abnormal cerebellar development Hydrocephalus in 70-90%

    Dandy-Walker

    Etiology CNS malformations

  • Obstructive Hydrocephalus

    Ventricular system is blocked

    CSF accumulates proximally

    4th

    CISTERNS Subarachnoid space

    3rd

    LATERAL LATERAL

  • Communicating Hydrocephalus

    Subarachnoid system blocked

    Results in impaired absorption

    Entire system is dilated

    Causes

    IVH/SAH

    Meningitis

    Scarring after inflammatory process

  • Pseudotumor cerebri

    Isnt it due to overproduction of CSF?

    Pathogenesis unknown

    Cerebral venous outflow abnormalities

    Increased CSF outflow resistance at arachnoid or lymphatic level

    Obesity related changes to intracranial venous pressure

    Altered Na and H2O retention mechanisms

    Abnormal Vitamin A metabolism

  • Excessive CSF Production

    Rare

    Only really happens in cases of a functional choroid plexus papilloma

  • Symptoms of hydrocephalus

    Headache

    Vomiting: increased ICP in the posterior fossa

    Behavioral changes

    Drowsiness: midbrain/brainstem dysfunction

    Visual changes: Optic Nerve compression

    Incoordination

    Loss of developmental milestones

    Head circumference increases rapidly

    Sunsetting eyes: fixed downward gaze

    Pro-Tip: These symptoms obviously vary based on the age of the patient

  • Shunt Devices

    Proximal portion is placed in a ventricle (usually R)

    Could also be in an intracranial cyst or lumbar subarachnoid space

    Distal portion

    Internalized: peritoneum, pleura, atrium

    Externalized EVD: Acute hydrocephalus for pressure monitoring, infected shunt

    Ommaya reservoir: Generally for administration of drugs (antibiotics or chemo)

  • Shunt Complications

    Mechanical Obstruction (Malfunction/Failure) proximal tip is obstructed with cells, choroid plexus, or debris

    Kinking of the tubing

    Migration of the distal end

    Infection

    Acquired Chiari I due to over draining

    Slit ventricle syndrome

    Intraventricular hemorrhage (subdural)

  • Shunt infections

    Risk of 5-15% overall

    Sx are generally few, fever is variable

    Paucity of meningeal Sx as there is no communication between shunt and meninges

    VP shunt infections can manifest as peritonitis

    VA shunt infections as bacteremia/endocarditis

  • Shunt infections

    Increased risk

    Highest in initial month after placement

    Risk extends up to 6 months post op

    Patients requiring serial revisions

    Intracranial hemorrhage

    Cranial fracture with CSF leak

    Craniotomy

  • Shunt infections

    What are the most common infectious agents

    Proximal end: skin flora

    50% coag negative staph, 33% S. aureus

    Distal end: peritonitis/intestinal perforation or hematogenous seeding

    Streptococci, gram negative (P. aeruginosa), anaerobes, mycobacteria, fungi

  • Shunt infections

    Treatment

    No RCTs or prospective data

    Remove the device + IV antibiotics (vanc + gram negative)

    Decreasing risk

    Periop Vanc

    Antibiotic impregnated catheters

  • Shunt malfunctions

    Mechanical failure

    Majority of 1st failures due to obstruction

    Shunt over drains

    Ventricles shrink

    Tip gets clogged against choroid plexus

    15% due to fractured tubing

  • Shunt malfunctions

    Median survival of a shunt (before need for revision)

    child under 2 years of age is 2 years

    over two years of age is 8 - 10 years

    Also associated with decreased survival

    Shunts inserted prior to first birthday

    Inserted when pt. weighed

  • Symptoms associated with shunt malfunctions

    PEC, 2008

    647 visits to the ED

    78% younger than age 1 at time of insertion of shunt

    38% failure rate at 3 years, 8.5% by infection

    Built a decision tree model

    Sign/Symptom +LR -LR

    Bulging fontanel 44.6 1.84

    Irritability 13.7 1.75

    Nausea/Vomiting 11.1 1.58

    Accelerated head growth 6.02 1.86

    Headache 4.28 1.22

  • Shunt series

    Radiographs of the skull, neck, chest, and abdomen

    Look for mechanical breaks, kinks, and disconnections in the shunt

    Utility

    Pitetti, PEC, 2007 Retro review of 291 kids (461 ED visits)

    78% had a shunt series

    15% (71/291) Dx with malfunction

    22 of these 71 had a normal head CT

    6 of these 22 had an abnormal shunt series

  • Neuroimaging

    Head CT

    Not always diagnostic, even if ventricles are bigger

    Cumulative radiation is a concern

    Iskandar Pediatrics, 1998 1/3 of patients Dx with shunt malfunction were not supported by CT findings

    Rapid sequence MRI is now being explored

  • Imaging test characteristics

    Zorc, PEC, 2002

    60/233 reviewed retrospectively had a shunt malfunction

  • Management of shunt malfunctions

    Replacement or externalization If infected the EVD is preferred Otherwise it is up to the surgeon No comparison studies in kids

    Bedside EVD Kakarla Neurosurg, 2008 retro review of 346 adults that had

    bedside EVD Analyzed success of placement, ideal ipsilateral frontal horn or

    3rd ventricle Highest success in cases of IVH and trauma Midline shift decr success Caveat: Not studied in shunted patients

  • Shunt tap

    Indications Diagnostic

    Suspected shunt blockage, infection or meningitis

    Therapeutic Severely raised ICP in the presence of a VP shunt

    Contraindications Skin infection over shunt site

    Coagulopathy

    Lack of shunt imaging/info

  • Shunt tap

    Procedure

    23 or 25G butterfly needle

    Aspiration can suck choroid plexus into the tube = bad

    Utility

    Opening pressure >25cm H2O associated with distal obstruction in 90%

    Poor flow associated with proximal shunt in >90%

  • Shunt tap

    When should a shunt tap be performed?

    Miller J. Neurosurg Peds, 2008

    Retro review of 155 patients

    Low utility overall, doesnt often contribute to Dx

    Risks

    Infection

    Changes in flow dynamics post shunt tap can cause a partially working shunt to malfunction

  • Man

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    Miller, J. Neu