General Neurosurgery and CSF Disorders Flashcards
Which one of the following statements regarding intracerebral hemorrhage is LEAST accurate?
a. Rate of spontaneous intracerebral hemorrhage in a 70-year-old is approximately 0.15% per year
b. Rate of intratumoral hemorrhage in glioma is 2-4%
c. Enoxaparin increases the risk of hemorrhage in melanoma and renal cell carcinoma brain metastasis
d. Risk of recurrent intracerebral hemorrhage after an initial bleed is 3-5% per year
e. Long-term aspirin therapy reduced the
risk of ICH in patients with unruptured
intracranial aneurysms
c. Enoxaparin increases the risk of hemorrhage in melanoma and renal cell carcinoma brain metastasis
Which one of the following statements
regarding balancing the risk of thromboembolism with risk of intracranial bleeding is most accurate?
a. In patient with metallic mitral valve replacement risk of thrombosis off anticoagulation is 8% per year
b. In a patient with brain metastasis from
nonsmall cell lung cancer risk of ICH
on LMWH is 35%
c. In a patient with glioma risk of ICH on
warfarin is threefold higher
d. In a patient with acute ICH and a proximal DVT, the risk of fatal PE off anticoagulation is lower than the risk of recurrent
ICH on anticoagulation
a. In patient with metallic mitral valve replacement risk of thrombosis off anticoagulation is 8% per year
The use of IVC filters in patients with brain
tumors has been associated with substantial
complication rates (over 50% experience
recurrent VTE, IVC or filter thrombosis, or
post-thrombotic syndrome), and the risk of
hemorrhage secondary to anticoagulation is
Risk of ICH with and without Antithrombotic Drugs
Risk of ICH Risk of ICH with Anticoagulation Risk of ICH Antiplatelet
General
population
0.016-0.033 per year
(0.15% per year in
70-year-olds)
0.3-1% per year (INR 2-3) Excess risk of 0.2-1.2
per 1000-patient-years
with aspirin
Unruptured
intracranial
aneurysm
<7 mm anterior
circulation: 0.1% per year
7-12 mm anterior circn:
2.5% per year
>13 mm or posterior
circulation: 3-20% per
year
Paucity of data. Worse outcome of
aneurysmal SAH if on warfarin. IV
thrombolysis appears safe in acute stroke
patients with unruptured intracranial
aneurysm
Lower risk of aneurysm
rupture in cohort of
ISUIA on aspirin
Glioma 2-4% 2-4% (INR well controlled)
Brain
metastasis
15% (NSCLC) to 35%
(melanoma/RCC)
No change from baseline (enoxaparin or
well controlled warfarin)
Acute ICH ICH expansion in first
24 h: 15-38% of patients
ICH expansion
24 h-2 weeks: 1-2%
3-5% After 24 h Unclear
Prior ICH 2-3% per year 3-5% per year Possibly with lobar ICH
Acute
infarction
Unclear 0.9% (warfarin) 0.2% (aspirin)
1% (clopidogrel or
dual)
260 PART III CRANIAL NEUROSURGERY
not as high as originally feared. The relatively
low incidence of intratumoral hemorrhage is a
particularly important issue for patients who
need anticoagulation for reasons other than
VTE (e.g. atrial fibrillation) in whom IVC filter
is not appropriate. Although randomized
comparisons are not available in brain tumor
patients, indirect comparisons from case series
suggest that carefully controlled oral anticoagulation with warfarin is reasonably safe and associated with fewer serious complications than
routine use of IVC filters.
Which one of the following statements
regarding hydrocephalus is most accurate?
a. Communicating hydrocephalus is usually
caused by the presence of intracranial mass
lesions
b. Noncommunicating hydrocephalus is
usually treated with spinal CSF diversion
c. Excess CSF production is likely to produce a communicating, nonobstructive hydrocephalus
d. Endoscopic third ventriculostomy is
appropriate in cases of foramen of Monro
obstruction
e. Ventriculoperitoneal shunts are contraindicated where there is obstruction of
CSF entering the cortical subarachnoid
space
c. Excess CSF production is likely to produce a communicating, nonobstructive hydrocephalus
A 75-year-old male having problems with his
gait urinary incontinence for the past
6 months, and recently, his short-term
memory. When he started to walk he had a
“magnetic” gait but normal armswing.
Mini-mental state examination was 27/30.
His CT head is shown below. Which one
of the following is the next appropriate step
in management?
a. Reassure that this is part of normal aging
and discharge
b. Amantadine trial
c. ICP monitoring
d. Lumbar puncture tap test
e. Ventriculoperitoneal shunt
d. Lumbar puncture tap test
Normal pressure hydrocephalus is a clinical syndrome characterized by gait apraxia (90% of
patients), dementia, and incontinence with ventriculomegaly and normal CSF pressure on lumbar
puncture. If the gait improves after a single
large-volume lumbar puncture (30-50 mL), serial
large-volume lumbar punctures can be performed
daily for 3 days the diagnosis is probable, and,
more importantly, the patient will likely respond
to treatment by shunting. In those where lumbar
puncture fails or is contraindicated, a ventricular
reservoir can be inserted and testing undertaken
a few months later. Gait in patients with NPH
is described as being “magnetic” in nature,
characterized by a broad base and slow, small steps
with reduced height clearance as though the feet
are “stuck to the floor” but also include unsteadiness, recurrent falls, shuffling, and reduced walking speed (confused with parkinsonism). Urinary
incontinence maybe neurological or a consequence of gait disturbance or the cognitive impairment. NPH is estimated to account for less than
5% of all cases of dementia hence commoner
causes such as Alzheimer’s must be excluded, as
well as mimics such as Binswanger’s disease (also
produces a frontal dysexecutive syndrome). Imaging should show ventricular enlargement not
entirely attributable to cerebral atrophy or congenital enlargement (Evans’ index >0.3 or comparable measure), bicaudate ratio >0.25, and another
supportive feature: enlargement of the temporal
horns of the lateral ventricles not entirely attributable to hippocampal atrophy; callosal angle of 40
degrees or greater; evidence of altered brain water
content, including periventricular signal changes
not attributable to microvascular ischemic changes
Hydrocephalus Classification Study Group: Point of Obstruction Model
Point of Obstruction Differential Treatments
Foramen of Monro Tumor, congenital absence,
ventriculitis, functional
Shunt (unilateral or bilateral)
Endoscopic septostomy
Aqueduct of Sylvius Tumor, congenital stenosis, secondary Shunt
Endoscopic third
ventriculostomy
4th ventricle foramina Infection, tumor, severe Chiari Shunt
Endoscopic third
ventriculostomy
Surgical opening
Between spinal and cortical
subarachnoid space
Subarachnoid hemorrhage
Infection
Shunt
Endoscopic third
ventriculostomy
LP shunt
Arachnoid villi Subarachnoid hemorrhage
Infection
VP or LP shunt
Venous hypertension Pseudotumor cerebri (PTC)
Congenital hydrocephalus
Sinus thrombosis
Bariatric surgery for obesityrelated PTC
VP or LP shunt
Anticoagulation
Venous sinus stent (debated)
262 PART III CRANIAL NEUROSURGERY
or demyelination; presence of aqueductal or fourth
ventricular flow void on MRI. Current guidelines
deal primarily with idiopathic as opposed to secondary NPH, which can occur years after trauma,
subarachnoid hemorrhage, intracranial surgery, or
meningitis. Continuous ICP monitoring has demonstrated the presence of waves of increased ICP,
particularly during rapid eye movement (REM)
sleep. It has been suggested that these abnormal
CSF pressure spikes, called B waves, slowly
increase ventricular size by exerting intermittent
high pressure on the brain parenchyma that results
in ischemic damage. Abnormalities of the aging
brain parenchyma may make it more susceptible
to these forces. Despite the uncertainty regarding
its evolution, NPH is a syndrome that is treatable
by CSF diversion (i.e. shunt insertion).
Which one of the following statements
regarding management of idiopathic normal
pressure hydrocephalus is most accurate?
a. CSF outflow resistance is normally higher
than 13 mmHg/mL/min
b. CSF outflow resistance greater than 18 mmHg/mL/min correlated with shunt responsiveness in NPH
c. Lundberg A waves usually visible during
sleep in NPH patients
d. Presence of Lundberg B waves for greater
than 80% of ICP monitoring suggests
poor outcome with VP shunt
e. External lumbar drainage of CSF carries a
lower risk of meningitis compared to lumbar infusion study
b. CSF outflow resistance greater than 18 mmHg/mL/min correlated with shunt responsiveness in NPH
There is no single test for idiopathic NPH, but
supplementary tests can increase the prognostic
accuracy to greater than 90%. A lumbar puncture
“tap test” has been shown to produce a specificity
of 100% with a sensitivity of 26%, provided that it
is performed at a high volume (i.e. withdrawal of
40-50 mL of CSF). Symptomatic improvement
after removal of CSF has a high positive predictive
value (73-100%) of a probably favorable outcome
with shunt placement. It has to be remembered
that improvement after a shunt is often delayed
in many patients, so a simple tap test would not
be expected to reveal all patients who might benefit
from a shunt. However, the low sensitivity of the
“tap test” precludes using this method as a diagnostic tool for exclusion. Prolonged external lumbar drainage in excess of 300 mL is associated with
high sensitivity (50-80%), specificity (80%), and
positive predictive value (80-100%), but requires
inpatient stay and carries a risk for the complications of nerve root irritation, hemorrhage, and
CSF infection. Measurement of CSF outflow
resistance (reflecting the capacity of CSF absorption pathways) via a daycase lumbar infusion or
ventricular reservoir infusion test with a
pressure-volume study is also established. In the
Dutch NPH study, outflow resistance greater than
18 mmHg/mL/min had a specificity of 87% and a
sensitivity of 46%. Although isolated measurements of CSF pressure in patients with communicating hydrocephalus and NPH may be in the
normal range, overnight ICP monitoring may
reveal dynamic phenomena such as increased
Lundberg “B waves.” B waves are slow waves of
ICP lasting 20 s to 2 min. The presence of B waves
for more than 80% of the period of ICP monitoring is thought to indicate that it is much more
likely than not that shunting would be helpful.
A 75-year-old man diagnosed with normal
pressure hydrocephalus underwent VP shunt insertion 3 months ago. A Codman Hakim Progammable valve was set to 160 mmHg on discharge. CT head today shows no significant change in ventricular size (persistent ventriculomegaly). He reports no significant improvement in his symptoms. You undertake a shunt reservoir tap which records a pressure of 5 cm H2O in the supine and 10 cm H2O in the sitting position. Which one of the following statements is the most
accurate conclusion?
a. There is evidence of shunt obstruction
b. There is evidence of shunt overdrainage
c. He is likely a shunt nonresponsive NPH
patient
d. ICP monitoring as an inpatient is
appropriate
e. Adjusting the shunt setting down further
should be tried
e. Adjusting the shunt setting down further should be tried
It is the patient in whom the association between
clinical findings and ventriculomegaly is uncertain (e.g. NPH) and fails to improve after shunt
surgery (or only minimally improves) who represents a clinical challenge. As a result, the failure to
improve might be attributed to an incorrect diagnosis, or a shunt nonresponder (e.g. if valve at
lowest setting and shunt patency confirmed). If
imaging reveals a reduction in ventricular size, a
patient should be considered a nonresponder if
no clinical improvement occurred. For patients
in this scenario who remain with significant ventriculomegaly, strategies for improving drainage
should be considered (e.g. removal of antisiphon
device, or a programmable valve with a lower
pressure limit) as they may have a low-pressure
hydrocephalus state. Downward adjustments in
valve opening pressure are unlikely to benefit
the patient and instead increase the risk of subdural hematoma. Even if shunt flow is documented, one should pursue other interventions as one
cannot exclude functional underdrainage. For
example, if there is an ASD, remove it. If the
patient has a fixed-pressure valve or a flowrestricting valve, change it to an adjustable
differential pressure valve (no ASD). It is our
observation that ventriculoatrial shunts provide
more drainage than ventriculoperitoneal shunts
do, and therefore we offer a shunt revision to a
ventriculoatrial shunt as well. It is only the case
in which the patient has a ventriculoatrial shunt
with a differential pressure valve set to 30 mm
H2O or less that an operative intervention is
not recommended.
Which one of the following approaches is
LEAST likely to be appropriate for management of entrapped 4th ventricle?
a. 4th ventricular-peritoneal shunt
b. Endoscopic Aqueductal stent and lateral
ventriculoperitoneal shunt
c. Endoscopic third ventriculostomy and
aqueductoplasty
d. Foramen magnum decompression with
expansion duraplasty
e. 4th ventricular-cisternal shunt
d. Foramen magnum decompression with expansion duraplasty
Entrapped fourth ventricle has been used to
describe the situation in which the fourth ventricle no longer communicates with either the third
ventricle and/or the basal cisterns. It is thought
that secondary aqueduct stenosis from adhesions,
obstruction of the foramina of Luschka or
Magendie, or infective debris pooling in the basal
cisterns may be responsible for this condition.
Patients may have the typical symptoms and signs
of hydrocephalus or more atypical symptoms
such as lower cranial nerve dysfunction. Patients
with prolonged infection or multiple shunt
operations are particularly at risk for this syndrome. In cases of hydrocephalus caused by
membranous occlusion or short segment stenosis
of the aqueduct of Sylvius, endoscopic aqueductoplasty (EA) with and without stenting has been
reported. The burr hole for EA is placed more
anteriorly than the one for standard ETV. Stenting of the aqueduct may be performed for
patients at high risk for aqueductal restenosis or
patients with a trapped fourth ventricle. The stent
is usually a ventricular catheter with additional
holes. Shunted patients with a trapped fourth
ventricle often have slit-like lateral ventricles,
making them poor candidates for the standard
EA so a suboccipital approach for retrograde
aqueductoplasty and stenting can be performed.
EA restores the physiologic CSF pathways and
eliminates the risk for basilar artery injury. There
are no arachnoidal adhesions around the aqueduct to interfere with CSF flow. The risk for
injuring the hypothalamus is avoided, especially
during cases when the floor of the third ventricle
is thickened and a considerable amount of force is
required to perforate the floor. Strictures at the
aqueduct are usually not as tough to penetrate;
thus, less force is required for fenestration. A
major risk of EA is injuring the periaqueductal
gray matter and the floor of the fourth ventricle.
Other complications reported, especially in long
stenoses, include midbrain injury causing transient or permanent dysconjugate eye movements,
Parinaud-syndrome, and cranial nerve palsies. In
cases with long stenoses, ETV may be a more
appropriate procedure.
A 3-year-old female presents with headache
and transient obscurations of her vision.
Which one of the following would you start
her on?
a. Acetazolamide
b. Bromocriptine
c. Corticosteroids
d. Furosemide
e. Topiramate
a. Acetazolamide
The pseudotumor cerebri syndrome (PTCS) is
a perplexing syndrome of increased intracranial
pressure without a space-occupying lesion.
annual incidence of pseudotumor cerebri syndrome (PTCS) as 0.9/100,000 in the general
population, rising to 3.5/100,000 in women aged
15-44 years and 19.3/100,000 in women aged
20-44 years who weigh 20% or more than their
ideal body weight. When no secondary cause is
identified (e.g. venous obstruction, endocrine
disorders, medications), the syndrome is primary
and termed Idiopathic Intracranial Hypertension
(IIH). Symptoms include headache, transient
visual obscurations, pulsatile tinnitus, visual loss,
diplopia. Signs include 6th nerve palsy and papilledema. In addition, for the diagnosis to be made
brain imaging must show no structural causes of
raised ICP, and lumbar puncture CSF opening
pressure >25 cm H2O in relaxed adults and
>28 cm H2O in a (sedated) child with normal
CSF analysis. In the absence of papilledema or
6th nerve palsy, possible diagnosis of PTCS is
suggested by MRI showing at least three of:
empty sella, flattening of the posterior aspect of
the globe, distension of perioptic subarachnoid
space (¼/- tortuous optic nerve), transverse
venous sinus stenosis. The main goal of treatment is preservation of vision. As such, patients
presenting with deteriorating vision require
more aggressive initial management. General
management strategied include weight loss
(including bariatric surgery in some cases), salt
restriction, acetazolamide, topiramate (headache
and causes weight loss), ventriculoperitoneal or
lumboperitoneal CSF shunting, optic nerve
sheath fenestration and in some cases venous
sinus stenting.
Which one of the following statements
regarding surgical management of pseudotumor cerebri is most accurate?
a. Optic nerve sheath fenestration provides better visual outcomes than VP shunt in IIH
b. Choroid plexotomy is routinely used in IIH in patients with recurrent shunt blockage
c. Venous sinus stenting is first line treatment in IIH patients with MRI proven venous sinus stenosis
d. Endoscopic third ventriculostomy is
appropriate substitute when optic nerve
sheath fenestration is not possible
e. Lumboperitoneal shunt rate failure in IIH is 10%
a. Optic nerve sheath fenestration provides better visual outcomes than VP shunt in IIH
Surgery is usually indicated for visual loss or
worsening of vision that is attributable to papilledema, rather than chronic headache. The two
surgical treatments are optic nerve sheath fenestration (ONSF) and shunting. There have been
no prospective, randomized trials of surgical
treatments. ONSF as the preferred treatment of
visual loss from IIH, perhaps because visual outcomes were better documented with this procedure. ONSF tends to be more effective in acute
papilledema than chronic papilledema and is
not indicated once the papilledema has resolved.
Studies show that bilateral improvement in vision
often occurs after a unilateral procedure. The
complications of ONSF include failure, ischemic
264 PART III CRANIAL NEUROSURGERY
optic neuropathy, transient diplopia, and transient blindness. Because the ventricles are not
enlarged in PTCS, lumboperitoneal shunting
was previously preferred over ventriculoperitoneal (VP) shunting but usually require multiple
revision and failure rate is approximately 50%
in PTCS. The most common reasons for revision
are shunt obstruction, intracranial hypotension/
subdurals, and lumbar radiculopathy. Visual deterioration may be the only sign of shunt failure and
may occur even if the shunt is functioning. Other
complications include infection, abdominal pain,
CSF leak, hindbrain herniation, and migration of
the peritoneal catheter. Cisterna magna shunting
has been described, but image-guided placement
of VP shunts is now favored. Bariatric surgery
may be an option for the long-term management
of IIH in morbidly obese patients but is not helpful for acute management. Transverse sinus stenosis in association with IIH prompted
endovascular stenting as a treatment for the disorder, though there is debate as to whether it is
cause or a sign of raised ICP. Despite some positive results, the need for long term anticoagulation has resulted in subdural/epidural hematoma
(and also complicates other surgical interventions
which may need performing), anaphylaxis, and
hearing loss.
Which one of the following statements regarding hydrocephalus is LEAST accurate?
a. Negative pressure hydrocephalus may be
associated with a CSF leak
b. Low pressure hydrocephalus may be due
to alteration in transmantle pressure
c. Benign external hydrocephalus usually
resolves by 2-years of age
d. Subdural hygromas are difficult to distinguish from chronic subdural hematomas
radiologically
e. Normal pressure hydrocephalus is diagnosed using ICP monitoring
e. Normal pressure hydrocephalus is diagnosed using ICP monitoring
