Pediatric Neurosurgery : Hydrocephalus Flashcards
Which one of the following statements LEAST accurately describes CSF production?
a. Neonates produceCSF at a rate of 25 ml/day
b. Infants have a total CSF volume of 25 ml
c. Adults produce CSF at a rate of approximately 0.5 ml/min
d. Ventricles contain 25 ml of CSF
e. Raised intracranial pressure does not affect formation of CSF at the choroid plexus
b. Infants have a total CSF volume of 25 ml
Infants have a total CSF volume of 50 ml (150 ml in
adults), and in both infants and adults there is 25 ml
of CSF in the ventricles.Neonates produce CSF at a
rate of 25 ml/day, which increases to two thirds of
the adult capacity as an infant. Adults produce
CSF at a rate of 0.35 ml/min¼20 ml/h (approximately 500 ml/day).
The estimated frequency of hydrocephalus in children is which one of the following?
a. 1 in 100
b. 1 in 250
c. 1 in 500
d. 1 in 1500
e. 1 in 5000
c. 1 in 500
It is estimated that hydrocephalus may occur with
the frequency of 1 in every 500 children. Causes
include genetic (e.g. X-linked aqueduct stenosis),
other congenital causes (e.g. myelomeningocele
and Chiari malformation) and more common
acquired causes such as intraventricular
hemorrhage, trauma, tumors, and infection.
An infant has a head CT performed because of alarge head and failure to thrive. The diagnosis of hydrocephalus is made. Congenital hydrocephalus is most commonly caused by which one of the following maternal infections?
a. Toxoplasmosis
b. Rubella
c. Influenza
d. HIV
e. Group B Streptococci
a. Toxoplasmosis
Congenitally acquired TORCHES infections
(Toxoplasma, Other, Rubella, CMV, HErpes,
Syphilis) are known to cause intrauterine growth
restriction, microcephaly, intracranial calcifications,
conjunctivitis, hearing loss, rash, hepatosplenomegaly and thrombocytopenia. Post-infectiouscauses
of intrauterine and neonatal hydrocephalus due to aqueduct stenosis are also in this group, with Toxoplasma being the most frequent intrauterine infection associated with it, and viral causes including
mumps and CMV
A 9-year-old child with VP shunt comes with headache and lethargy. CT head, blood, unchanged and shunt series are normal. Risk of CSF infection secondary to percutaneous shunt tap is which one of the following?
a. 0.0002%
b. 0.002%
c. 0.02%
d. 0.2%
e. 2%
d. 0.2%
In a recent study, of 542 shunt taps performed in
266 children using a standard protocol (by neurosurgical department personnel only), there were 14 infected shunts but only one child (with redness over shunt track) whose first CSF tap was
negative but then returned 11 days later with
fever and irritability and whose repeat CSF tap grew Staphylococcus aureus. They state: “Assuming
that this patient’s shunt infection was secondary
to the shunt tap, the infection rate would be 1
(0.18%) in 542. If one removes the 14 infected
shunts, because theoretically a shunt tap leading
to another infection might be masked by the antibiotics used to treat the first diagnosed infection, the rate would be 1 (0.19%) in 528. Because there were often multiple taps in the same patient, the incorporation of a time separation between the first and second tap can be used to ensure that the second tap was indeed negative. If one assumes a reasonable time interval to be 3 months, that would eliminate 162 taps, changing the incidence to 1 (0.27%) in 366.”
Which one of the following statements regarding the management of pediatric hydrocephalus is LEAST accurate?
a. Preoperative antibiotics reduces the risk of subsequent shunt infection in patients with hydrocephalus
b. There is insufficient evidence to recommend the routine use of endoscopic guidance in ventricular shunt placement
c. There is insufficient evidence to recommend occipital over frontal point of entry for ventricular catheters
d. There is no clear advantage for one shunt valve type over another
e. Antibiotic-impregnated shunt tubing may be associated with a lower risk of shunt infection compared to conventional silver-impregnated hardware
e. Antibiotic-impregnated shunt tubing may be associated with a lower risk of shunt infection compared to conventional silver-impregnated hardware
Which one of the following statements regarding the choice of endoscopic third ventriculostomy or ventriculoperitoneal shunt CSF diversion in children is LEAST accurate?
a. ETV is the standard of care for posthemorrhagic hydrocephalus in infants (<24 months old)
b. VP shunt is usually most appropriate for communicating hydrocephalus
c. ETV should be considered first for hydrocephalus due to congenital aqueduct stenosis
d. Late ETV failure (2 years) is less common than late VP shunt failure
e. Majority of ETV failure occurs in the first
3 months
a. ETV is the standard of care for posthemorrhagic hydrocephalus in infants (<24 months old)
The optimum treatment for hydrocephalus is controversial. Aside from obstructive hydrocephalus
in children older than 2 years and adults, in whom
ETV is often used, VPS placement remains the
standard of care. But the indications for performing ETV have recently broadened to communicating types of hydrocephalus and the success of
ETV in young infants for all causes of hydrocephalus has been increased by the addition of choroid
plexus cauterization. No completed randomized
trials have compared endoscopic and shunt treatment for pediatric hydrocephalus, and the International Infant Hydrocephalus Study is ongoing
(direct comparisons of VPS versus ETV for
infants [24 months of age] with aqueduct stenosis). Another randomized prospective trial is currently underway at CURE Children’s Hospital
of Uganda to compare ETV plus CPC versus
VPS alone in infants younger than 6 months of
age with post-infectious hydrocephalus. The best
criteria to determine optimum hydrocephalus
treatment are not known, since while acute symptoms may be alleviated ventriculomegaly may not completely resolve and continue to cause subtle
white matter injury or impair cognitive outcome,
hence brain volume may correlate better with cognitive outcome better than CSF volume.
An 8-month-old previously healthy child presents with acrocephaly and delayed milestones. MRI is shown below. Which one of the following is his most likely ETV success score?
a. 40
b. 50
c. 60
d. 70
e. 80
d. 70
Most ETV failures occur within the first 6 months
of surgery. ETV success score is a simple means
to predict 6-month success rate of ETV, with
scores ranging from 0 (meaning virtually no
chance of ETV success) to 90 (meaning a roughly
90% chance of ETV success). ETVSS is calculated as Age Score +Etiology Score +Previous
Shunt Score from the table above, and has
demonstrated internal and external validity.
A preterm neonate is born at 28 weeks gestation with a birth weight of 1000 g. Cranial US performed in the first 24 h of birth due to a bulging fontanelle and episodes of apnoea revealed Papile grade III germinal matrix hemorrhage with hydrocephalus. Which one of the following statements is most accurate?
a. The majority of intraventricular hemorrhage in low birthweight preterm infants is Grade III and IV
b. The proportion of infants with posthemorrhagic hydrocephalus who require permanent shunt placement is lower in preterm than term births
c. Sunset phenomenon consists of impaired downgaze
d. Term infants usually present with spontaneous apnea or bradycardia in the first 24 h after IVH
e. The rate of intraventricular hemorrhage
in both term and preterm babies is 30%,
but the mean Papile grade is higher in
preterms
b. The proportion of infants with posthemorrhagic hydrocephalus who require permanent shunt placement is lower in preterm than term births
The incidence of IVH increases inversely with
decreasing birthweight or EGA. In extremely
low birthweight preterm infants who survived
and could be followed up, 33% had a history of
intraventricular hemorrhage (IVH) of which
40% was Grade III or IV but eventually only 3%
required VP shunt placement for posthemorrhagic hydrocephalus (PHH). In term
babies, 15% had peri/intraventricular hemorrhage
and nearly all have grade I/II IVH. In preterm
babies, most IVH occurs within the first 72 h of
life and is diagnosed by bedside cranial US due
to deterioration over several days. Infants with
IVH should be observed closely with daily measurement of the occipitofrontal circumference
(OFC): increase in growth rate from 0.5 to 1 cm/
day for 2-3 consecutive days often suggests symptomatic hydrocephalus. Other features include
bulging fontanelle and splayed sutures, episodes
of spontaneous apnea or bradycardia, refractory
seizures, lethargy, and impaired upward gaze
(“sunset” phenomenon). Term infants with IVH
typically present with lethargy or seizures, but a
subset of infants presents with distress at birth,
and the remainder often present within the first
week. In contrast to ELBW preterm infants, many term infants have no or transient ventricular dilation in the period immediately after IVH but
significant proportion may eventually require a
shunt, usually during the first year of life.
Which one of the following statements regarding the treatment of CSF shunt infection is most accurate?
a. Evidence recommends shunt externalization over complete shunt removal as the preferred surgical strategy in management of CSF shunt infection
b. Evidence recommends the combination of intrathecal and systemic antibiotics for patients with CSF shunt infection when the infected shunt hardware cannot be fully removed
c. Evidence recommends the combination
of intrathecal and systemic antibiotics
for patients with CSF shunt infection
when caused by gram-negative organisms
d. Evidence recommends supplementation of antibiotic treatment with partial (externalization) or with complete shunt hardware removal
e. Evidence recommends the combination
of intrathecal and systemic antibiotics
for patients with CSF shunt infection
when the shunt must be removed and
immediately replaced
d. Evidence recommends supplementation of antibiotic treatment with partial (externalization) or with complete shunt hardware removal
Current management of CSF shunt infection is
dictated not by evidence, but rather by physician
preference and other possibly relevant patientlevel factors (for example, patient surgical risk,
ventricle size, and complexity of the shunt system). It is not surprising that there is significant
variation in CSF shunt infection treatment protocols between centers. An infected ventricular
shunt, as an infected foreign body, is difficult if
not impossible to sterilize using antibiotics
alone. We therefore accept not only that shunt
removal (and eventual replacement once CSF
sterility is achieved) requires multiple surgeries,
but also the risk of introducing secondary infection during a variable period of external drainage. Variations in whether the infected shunt
was externalized or completely removed, and
whether supplemental intrathecal antibiotics
were administered contribute to significant
between-study heterogeneity. Shunt infection
should be ideally managed with antibiotics, complete shunt removal, and placement of a temporary external ventricular drain, followed by reimplantation after CSF sterilization (48 h after last negative CSF). Although intrathecal administration of antibiotics appears to make theoretical sense because of enhanced CSF antibiotic concentrations, its practical application is controversial, owing in
large part to the potential adverse effects of intrathecal therapy, including neurotoxicity. The indications for intrathecal therapy are not well
established and presently range from use in any
shunt infection, use in only those infections in
which the CSF cannot be sterilized by systemic
antibiotics alone (for example, persistent positive
cultures), or use in those ventricular shunt infections caused by specific organisms (for example, gram-negative infections).
A 4-month-old child with a history of Escherichia coli neonatal meningitis returns with poor feeding and a bulging fontanelle. CT head is done which shows hydrocephalus and MRI is done for surgical planning. Which one of the following is likely to be the surgical goal in this patient?
a. Complex VP shunt with at least two proximal catheters
b. Single VP shunt following endoscopic fenestration of loculations
c. ETV and endoscopic fenestration of loculations
d. Endoscopic aqueductoplasty
e. Ventriculocisternal shunt
b. Single VP shunt following endoscopic fenestration of loculations
Given the high risk of failure of an ETV due to
age and post-infectious etiology (ETVSS¼10),
a VP shunt is more acceptable in this case but
endoscopic fenestration could reduce the number
of proximal catheters required for adequate
drainage of CSF to one (as well as reducing the
odds of shunt failure as there are less catheters/
connection points). Patients with both multiloculated and uniloculated hydrocephalus, isolated lateral and fourth ventricles, arachnoid cysts, and slit ventricle syndrome have not always
responded to simple shunting systems. The ventricular system may become trabeculated and
encysted following bacterial meningitis or germinal matrix hemorrhage. Hydrocephalus arising
from intraventricular septations is known as complex or loculated. The lateral ventricle may
become trapped due to obstruction of the Monro
foramina by noncolloid neuroepithelial cysts
(ependymal, choroid plexus, or arachnoid),
termed unilocular hydrocephalus, and in other
cases there may be multiple encysted compartments (multilocular). Traditional treatment is by placement of multiple shunts or multiperforated catheters which were multiple shunt revisions and high morbidity and mortality rates.
Multiple shunts have increased the risks of infection and mechanical obstruction, and their
removal has been problematic, with its associated
risk of intraventricular hemorrhage. Transcallosal fenestration via craniotomy may reduce shunt
revision rates or achieve shunt independence in
both multiloculated hydrocephalus and uniloculated hydrocephalus, but craniotomy itself carries concomitant risks. The specific risks associated with the transcallosal approach include venous infarction from sacrificed bridging veins, damage to the pericallosal arteries, disconnection syndromes after splitting the corpus callosum, and
damage to the fornices and subcortical nuclei.
Authors of many reports stress the operative simplicity of the stereotactic procedure in uniloculated hydrocephalus; however, it was associated with a high recurrence rate (up to 80%) because the cyst wall could not be widely fenestrated, making it unsuitable in cases of multiloculated hydrocephalus. In the present day where endoscopic fenestration (of loculations, cyst walls, septum pellucidum, etc.) is available, the aim of surgery is to control hydrocephalus, simplifycomplex shunts, reduce the shunt revision rate, avoid implanting a shunt if possible, and decrease operative morbidity. Fenestration of the septum pellucidum is indicated when there is an obstruction of one foramen of Monro causing the ipsilateral ventricle to dilate from trapped CSF.
Membranous/parenchymal obstructions of the
foramen of Monro causing unilateral hydrocephalus have been reported and endoscopic
foraminoplasty ¼/- stent can be considered.
Which one of the following statements regarding Lundberg waves seen during ICP monitoring is most accurate?
a. They represent aortic valve closure seen in normal patients
b. They are dicrotic representing arterial
pulsation seen in normal patients
c. B wave is mean ICP with pressure 20-50 mmHg lasting 30 s to a few minutes during sleep
d. A waves represent the cyclic variation in
systolic pressure due to oscillations in
autoregulation
e. C waves suggest ICP exceeding limits of
cerebral compliance
c. B wave is mean ICP with pressure 20-50 mmHg lasting 30 s to a few minutes during sleep
Each individual ICP waveform has three peaks:
percussion wave (P1) representing arterial pulsation, tidal wave (P2) representing intracranial
compliance and dicrotic wave (P3) representing
aortic valve closure. Lundberg waves describe
patterns of mean ICP in patients.
A 16-year-old child presents with cough related headache and sensory changes in her hands. Neurological examination is otherwise normal and there is no papilledema. MRI head and spine show a Chiari I malformation with 8 mm tonsillar decent and a small cervical syrinx at C3//4. Which one of the following statements regarding surgical management is most accurate?
a. Durotomy and tonsillectomy would be
mandatory in this case
b. C1-C3 laminectomy should also be performed in this case to treat the syrinx
adequately
c. Due to minimal tonsillar descent, primary treatment should be directed towards the syrinx (e.g. syringostomy) if her symptoms progress
d. Lumbar puncture should be performed
to exclude neurological cause of her
symptoms
e. Intraoperature ultrasound is less accurate at predicting those who do not need durotomy in the presence of tonsillar descent below C1 lamina
e. Intraoperature ultrasound is less accurate at predicting those who do not need durotomy in the presence of tonsillar descent below C1 lamina
Chiari malformation Type I (CM-I) is a craniocervical junction disorder that is associated with
deformity and elongation of the cerebellar tonsils
and is specifically characterized by tonsils’ descent
of more than 5 mm below the foramen magnum
into the spinal canal—a change in the flow of
CSF at the level of the foramen magnum is frequently associated with development of syringomyelia. Patients with Chiari I malformation
commonly undergo foramen magnum/suboccipital decompression (FMD) in order to restore free
flow of CSF across the craniocervical junction,
treating symptoms either related to raised ICP,
brainstem compression or syringomyelia. There
is no consensus on surgical indication, but a lower
threshold may be expected in symptomatic hindbrain herniation with syringomyelia compared
to asymptomatic hindbrain hernia with syrinx or
symptomatic hindbrain herniation without syrinx.
Variation in FMD technique is also possible at
multiple stages: extent of bony decompression,
indication for opening the dura and arachnoid,
need for tonsils coagulation and dural closure. A
recent review of all published studies of surgical
treatment of Chiari I showed that there was slight
variation in pediatric (97% FMD, 81% dural
opening, 47% arachnoid opening/dissection and
21% tonsillar resection) versus adult (100%
FMD, 97% dural opening, 70% arachnoid opening/dissection and 16% tonsillar resection) practice. In series reporting on syrinx association, the incidence was 69% in adult series, 40% in pediatric series, and 78% in mixed series. The traditional operation for CM-1 is FMD with bony decompression and dural opening with or without duraplasty. Some have contended that not all patients with CM-1 need durotomy, with bony decompression alone having been demonstrated as adequate/efficacious in a proportion of patients with CM-1, possibly as the dura of children may still
have some elasticity and expand following bony
decompression, leading to better CSF dynamics
at the craniocervical junction. The main advantage
of not needing to open the dura is that complications such as pseudomeningocoele, CSF leak, meningitis and hydrocephalus are reduced.
An 18-month old is treated for meningitis. After initially improvement, becomes less responsive on day 10 and imaging is performed. Which one of the following is LEAST appropriate?
a. Subduroperitoneal shunt
b. Percutaneous needle drainage
c. Transventricular tap
d. External subdural drain
e. Burr hole drainage
c. Transventricular tap
Subdural effusion occurs in 40-60% of infants
and young children with proven meningitis.
Small collections generally subside with observation alone and surgical drainage is only required
when if symptomatic or causing mass effect.
Options include serial percutaneous needle
drainage, burr hole drainage, external subdural
drain and subduroperitoneal shunt (SDP). External drains were placed whenever the fluid was
purulent, when the collection was estimated to
be too large to be cured with SDP alone, or when
raised ICP recurred after SDP, and be kept in
place for 1-2 weeks until fluid becomes clearer.
At the end of that period, whenever the patient
was dependent on the external drain, a subduroperitoneal drain was inserted. Removal of internal
subdural shunts should ideally be after a few
months. In rare cases of obstruction of the drainage associated with thick subdural membranes
exerting a mass effect on the brain, craniotomy
with membrane resection can be performed.
