Transcript Hydrocephalus

Review
Normal Pressure Hydrocephalus
Supattra Tribuddharat
13/10/48
Ventricular system
CSF production 0.2-0.35 ml/min; total volume 120 ml
lateral ventricle  foramen of Monro third ventricle, cerebral aqueduct
fourth ventricle foramina of Luschka and Magendie subarachnoid space 
arachnoid granulations dural sinus  venous drainage.
Hydrocephalus
 A disturbance of formation, flow, or absorption of
CSF  an increase in volume in CNS
 Communicating / non Communicating
(full communication between ventricles and
subarachnoid space)
 Cerebral atrophy and focal destructive lesions
vacant space filled with CSF
(hydrocephalus ex vacuo)
Normal pressure hydrocephalus (NPH)
 First described in 1965 by Hakim and Adams
 Clinical triad of symtoms :
- gait disturbance
- dementia
- incontinence
 Image: communicating hydrocephalus
 Potenially reversible by shunting: symptoms <2y
Etiology of NPH
• Idiopathic : ~50%,elderly > 60 y, worse response
to shunting (30–50%)
• Secondary : ~50%, younger age, better response
to shunting (50–70%)
- head injury
- subarachnoid haemorrhage
- meningitis
- neurosurgery
Etiology of idiopathic NPH
Combination of mechanisms > a single cause
• Decreased CSF resorption at arachnoidal villi or
granulations  increases transmantle pressure (CSF
pressure within ventricles > in subarachnoid space)
 ventricular enlargement
• Short-lasting CSF pulsations (B waves) periodically
apply pressure to the ventricular walls and have a
water-hammer effect that enlarges the ventricles
Anatomy
• Enlarged third ventricle
• Dilation of the occipital, frontal, and
temporal horns of the lateral ventricles.
• Presumably, the periventricular white
matter is stretched and dysfunctional as a
result of inadequate perfusion, without
actually being infarcted
Clinical features
 Considerable variation in nature, severity, and
course of progression
 Gradually progressive disorder
 Gait disturbance : the most readily recognized
feature
 Cognitive disturbances : not occur in all patients
 Signs and symptoms of INPH are typically
bilateral
Gait disorder
• An initial manifestation of NPH
• Mechanisms: enlargement of the ventricles
1. compression motor neuron fibers passing
through corona radiata (an early hypothesis;
pyramidal tract: not supported by recent study)
2. a disorder of subcortical motor control
• with progression of extensive subcortical white
matter changes, pyramidal tract involvement may
become more likely
 described as “apractic,” “bradykinetic,”
“glue-footed,” “magnetic,” “parkinsonian,”
“short-stepped,” and “shuffling.”
 Bradykinetic, broad-based, and shuffling
 Mimics PD: start hesitation, difficulty
turning, freezing
 Increased tone and with brisk tendon
reflexes in the lower limb
 Plantar responses may be flexor or extensor,
unilaterally or bilateral
Differentiate NPH from PD:
• May occur but less commonly : rigidity,
tremor, and slowing of rapid, alternating
movements
• Does not respond significantly to
carbidopa/levodopa
• No true ataxia or weakness, described as
gait apraxia.
Parkinsonian symptoms in INPH : abnormal
pulsatile CSF flow affecting the substantia
substantia nigra and/or striatum,
Dementia
• Mental deterioration is frequently mild and
subcortical
• Memory problems, poor attention,
bradyphreni and slowing of information
processing
• It progresses less rapidly than the dementia
of Alzheimer disease
Incontinence
• Usually urinary but may be fecal.
• Increased frequency and urgency may be seen in
early stages ; progression to frank urinary
incontinence with disease progression.
• Results from disruption of periventricular pathways
to the sacral bladder center  decreased inhibition of
bladder contractions and  instability of bladder
detrusors
• more advanced stages : indifference to the episodes
of incontinence, is associated with frontal executive
dysfunction.
Unexpected manifestration
• Papilledema
• Seizure
• headache
Brain Imaging
• MRI or CT must be performed to assess
ventricular size and to rule out ventricular
obstruction.
• Either CT or MRI can document
noncommunicating ventriculomegaly
sufficient to satisfy the brain imaging
requirements for routine diagnosis of INPH.
• CT scan or MRI
- Ventricular enlargement out of proportion to
sulcal atrophy
- Prominent periventricular hyperintensity
(transependymal flow of CSF)
- Prominent flow void in the aqueduct and third
ventricle, the so-called “jet sign,” (presents as a dark
aqueduct and third ventricle on a T2-weighted image
where remainder of CSF is bright)
– Thinning and elevation of corpus callosum on
sagittal images
– Rounding of frontal horns
• May have hyponatremia (SIADH)
a rounded frontal horn
The arrow points to transependymal flow.
T2-weighted MRI showing dilatation of ventricles out of proportion to
sulcal atrophy
Measurement of CSF-OP
• Normal CSF-OP averages 122 ±34mmH2O
• INPH, CSF-OP averages 150 ±45 mmH2O
•
(60-240 mm H2O)
• Transient high pressures (“B waves”) are detectable
during prolonged intraventricular monitoring in adults
with symptomatic INPH
• OP is elevated > 18 mm Hg indicate secondary or
noncommunicating hydrocephalus than INPH
DIAGNOSING IDIOPATHIC NPH
 Require clinical history, physical examination, and
brain imaging
 Diagnosis of INPH is complicated
 Resemble, or occur in combination with, various
disorders that are prevalent in the elderly, such as
CVD, neurodegenerative disorders (e.g., AD, PD,
LBD), primary urological disorders, spinal
stenosis, and other conditions.
 May be useful to classify INPH into “probable,”
“possible,” and “unlikely” categories,
PROGNOSTIC TESTS FOR
PREOPERATIVE ASSESSMENT OF INPH
1. CSF Removal via High-volume “Tap Test”
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Remove large volumes of CSF (40–50 ml)
An objective improvement in gait
Complications : ± headaches
62% sensitivity , 33% specificity
Good PPV for shunt response INPH
Specificity is low, many patients who might benefit
from shunting will be missed
• Therefore, INPH candidates not be excluded on
the basis of a negative tap test.
2. CSF Ro (outflow resistance)
• A pump introduces CSF or saline 4ml at a rate
1ml/sec through a needle placed in the lumbar
subarachnoid space
• Complications: headaches and meningismus
• Sensitivity 46%, specificity87%
• CSF Ro may be helpful in increasing prognostic
accuracy for identifying SRINPH when tap test
results are negative
3. ELD Test (external lumbar drainage)
• Draining 10 ml CSF/ hour for 72 hrs (total, 720 ml)
• Complications: bacterial meningitis and root irrigation
• more patients who do not improve with CSF tap test
will show improvement with prolonged drainage and
benefit from shunting
• The PPV is high, 80 to 100%,
• However, hospital admission is required.
• Reported complication rates with ELD are generally
low but may be significant in terms of added
Treatment
• Medication
: No definitive evidence exists that medication can
successfully treat NPH.
• Surgical Care:
:Surgical CSF shunting remains the main
treatment modality.
• No randomized prospective clinical trials were
conducted comparing different measures or
protocols of shunt outcome assessment.
• no validated, universally accepted scale for
assessment of treated or untreated INPH outcome.
• Shunt outcome can be based on the documentation
of either the clinical impairment, improvement
after treatment, or both. Grading of either the
functional status or the clinical criteria of gait,
incontinence, and dementia
Patients with a good response to the above procedure
are candidates for ventriculoperitoneal or
ventriculoatrial shunting.
– Best results :- patients who have no adverse risk
factors;
-responded favorably to a
large-volume LP;
-definite
evidence of dementia and ataxia,
- CT
scan or MRI evidence of chronic hydrocephalus,
- a normal CSF at lumbar puncture.
– Some evidence indicates that patients with gait
disturbance, mild or no incontinence, and mild
dementia fare best among shunt surgery patients.
Thank you
– a baseline neuropsychological evaluation and a timed walking
test.
– undergo a lumbar puncture with removal of approximately 50 cc
of CSF. The above evaluations are repeated 3 hours later.
– A clear-cut improvement in mental status and/or gait predicts a
favorable response to shunt surgery.
– Improvement in gait may be seen in the form of reduced time to
walk a fixed distance, reduced gait apraxia, or reduced freezing
of gait.
– Reduction in bladder hyperactivity also may be a sign of good
outcome from shunting. Occasionally, improvement may be
delayed and appear 1-2 days after the large-volume lumbar
punctures.
– When clinical suspicion is high and the patient is a good
candidate for surgery, repeated lumbar punctures are indicated
over the next 1-2 days.
– Some clinicians use an indwelling CSF catheter in lieu of
repeated lumbar punctures. This method carries a higher risk of
meningeal infection but may allow for a more accurate