This email may contain confidential or privileged material ...
“Privileged & Confidential” - Brad Sobolewski · “Privileged & Confidential ... •Ommaya...
Transcript of “Privileged & Confidential” - Brad Sobolewski · “Privileged & Confidential ... •Ommaya...
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 isn’t 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
• Isn’t 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 <3,000g
Pro-Tip: Children with NTD have longer shunt survival than children with hydrocephalus from other etiologies
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, doesn’t often contribute to Dx
– Risks
• Infection
• Changes in flow dynamics post shunt tap can cause a partially working shunt to malfunction
Man
agem
ent
of
a su
spec
ted
sh
un
t m
alfu
nct
ion
Miller, J. Neurosurg Pediatrics 2008
Treatments for elevated ICP in shunt malfunctions
• Do they work?
– Answer: Probably
– No literature on hypertonic/osmotic therapies
– General pearls are still useful prior to definitive management
ICP Management In shunt malfunctions NONE of these are as important as a trip to the OR
• Positioning
– Head midline, elevated 30o
• Maintain homeostasis
– Treat hypoxia (sats >95%), hypercarbia , hypotension, and hypoglycemia
– Temperature control
• Therapeutic cooling (fever incr metabolism and CBF)
– Mild sedation (don’t cause hypotension)
– Control severe shivering w/ paralytics
• Prophylactic fosphenytoin to patients at risk for seizures
– Parenchymal abnormalities, depressed skull fractures, and TBI
– No definitive evidence in children
ICP Management In shunt malfunctions NONE of these are as important as a trip to the OR
• Intubate if:
– Respiratory failure
– Loss of airway protective reflexes
– Refractory hypoxia
– GCS <8
– Acute herniation needing hyperventilation
ICP Management In shunt malfunctions NONE of these are as important as a trip to the OR
• In the intubated patient
– Avoid high pressures (decr venous return by incr intrathoracic pressure)
– Hyperventilation: though it can lower ICP (if you get ETCO2 25-30), aggressive hyperventilation leads to cerebral vasoconstriction and decr CBF
• Reserved for patients herniating or at imminent risk
ICP Management In shunt malfunctions NONE of these are as important as a trip to the OR
• Experimental therapies
– Hypothermia
– Indomethacin
• Stuff that doesn’t help
– Steroids (unless swelling from a tumor or abscess)
ICP Management In shunt malfunctions NONE of these are as important as a trip to the OR
• Hypertonic 3% saline – 6-10ml/kg over 5-10 min
– Generates an osmotic gradient between the intravascular space and cerebral tissue
– Effective plasma volume expander in multiple trauma patients
– May have beneficial effects on cerebrovascular regulation
– Effective to a serum osmo of 360
ICP Management In shunt malfunctions NONE of these are as important as a trip to the OR
• Mannitol 20% solution – 0.25-1g/kg over 10-20 min
– An osmotic diuretic
– Effective mainly around the lesion, where blood brain barrier integrity is impaired
– It may also reduce CSF production
– Hypovolemia is a real concern & pts will start diuresing in 20-30 minutes (in the scanner)
– Not effective above a serum osmo of 320
Patient follow-up
• Proximal catheter malfunction noted in OR
• Extubated POD #1
• Had some desats on floor – not related to seizures
• Follow up with Neurosurgery and Rehab
• Stable ventricles in September on CT
• No loss of milestones or cognitive decline