| Restorative Neurosurgery | Trigeminal
Neuralgia | Normal Pressure Hydrocephalus
Normal Pressure Hydrocephalus
Symptoms of NPH
Characterized by three primary symptoms, NPH patients usually
exhibit:
Gait disturbance (difficulty walking)
Dementia or forgetfulness
Urinary incontinence (bladder control)
Otherwise known as the "three Ws:"
Weird,
Wet and Wobbly
However, not all symptoms are always apparent or present at
the same time.
It's not just "old age"
Because these three symptoms are often associated
with the aging process in general, and a majority of the NPH
population is older than 60 years, people often assume that they
must live with the problems or adapt to the changes occurring
within their bodies. Symptoms can be present for months or
even years before a person sees a physician. The symptoms
of NPH seem to progress with time. The rate of progress is
variable, and it is often a critical loss of function, or
disability, that brings patients to their doctors. It seems
that the longer the symptoms have been present, the less
likely it is that treatment will be successful. As a general
rule, the earlier the diagnosis, the better the chance for
successful treatment, but some people experiencing symptoms
for years can improve with treatment.
Gait Disturbances
Gait disturbances range in severity, from mild imbalance to
the inability to stand or walk at all. For many patients, the
gait is wide-based, short, slow and shuffling. People may have
trouble picking up their feet, making stairs and curbs difficult
and frequently resulting in falls. Gait disturbance is often
the most pronounced symptom and the first to become apparent.
Forgetfulness or Mild Dementia
Mild dementia can be described as a loss of
interest in daily activities, forgetfulness, difficulty dealing
with routine tasks and short-term memory loss. People do not
usually lose language skills, but they may deny that there are
any problems. Not everyone will have an obvious mental impairment.
Urinary Incontinence
Impairment in bladder control is usually characterized by urinary
frequency and urgency in mild cases, whereas a complete loss
of bladder control (urinary incontinence) can occur in more severe
cases. Urinary frequency is the need to urinate more often than
usual, sometimes as often as every one to two hours. Urinary
urgency is a strong, immediate sensation of the need to urinate.
This urge is sometimes so strong that it cannot be held back,
resulting in incontinence. In very rare cases, fecal incontinence
may occur. Some patients never display signs of bladder problems.
Diagnosis of NPH
Diagnosis of NPH is often difficult due to the symptoms being
similar to other disorders. In many cases the NPH is thought
to be mild dementia, Alzheimer's, Parkinson's or simply old age
factors. Many cases go completely unrecognized and are never
treated.
Usually, NPH causes the ventricles to enlarge
due to increased CSF within the skull. If a person exhibits symptoms
of hydrocephalus a physician may perform several tests to determine
if shunting is an option. The most common diagnostic tools are
neuro-imaging devices such as CT or MRI and a careful clinical
assessment. Once the diagnosis of NPH is suspected there is no
single perfect test to determine if a patient will respond to
the shunt.
Diagnostic Procedures
Diagnostic procedures for normal pressure hydrocephalus may
include one or more of these tests: ultrasound, computerized
tomography (CT), magnetic resonance imaging (MRI), lumbar puncture
or tap, continuous lumbar CSF drainage, intracranial pressure
(ICP) monitoring, measurement of cerebrospinal fluid outflow
resistance or isotopic cisternography, and neuropsychological
testing.
Ultrasound: a device that uses sound to outline the structures
within the skull.
CT Scan (Computerized
Tomography): creates a picture of the
brain by using x-rays and a special scanner. It is safe, reliable,
painless, and relatively quick (about 15 minutes). An x-ray beam
passes through the head, allowing a computer to make a picture
of the brain. A CT will show if the ventricles are enlarged or
if there is obvious blockage.
MRI: is safe and painless, and will take approximately 30 minutes
or longer. MRI uses radio signals and a very powerful magnet
to create a picture of the brain. It will be possible to detect
if the ventricles are enlarged as well as evaluate the CSF flow
and provide information about the surrounding brain tissues.
The MRI provides more information than the CT, and is therefore
the test of choice in most cases. MRI scans can also assess how
fast CSF moves through a particular part of the brain called
the cerebral aqueduct. Patients with cardiac pacemakers or certain
other metallic implants cannot have MRI scans because of potential
interference with the pacemaker.
Lumbar Puncture or spinal
tap: This allows an estimation of
CSF pressure and analysis of the fluid. Under local anesthetic,
a thin needle is passed into the spinal fluid space of the low
back. Removal of up to 50 cc of CSF is done to see if symptoms
are temporarily relieved.
If removal of some CSF dramatically improves symptoms, even temporarily,
then surgical treatment may be successful. All physicians do
not advocate the use of a lumbar puncture as a screening test
for NPH since many people who experience little or no improvement
after the test may still improve with a shunt.
Lumbar catheter insertion: This is a variation of the lumbar
puncture. A spinal needle is inserted in the spinal fluid space
of the low back, then a thin, flexible tube (catheter) is passed
into the spinal fluid and the needle is removed. The lumbar catheter
allows for continuous and more accurate recording of spinal fluid
pressure, or for more continuous removal of spinal fluid over
several days to imitate the effect that a shunt would have. Patients
who respond dramatically to such spinal fluid drainage are likely
to respond to shunt surgery.
Intracranial pressure monitoring: ICP monitoring requires admission
to the hospital. A small pressure monitor is inserted through
the skull into the brain or ventricles to measure the ICP.
The pressure is not always high, and pressure monitoring (either
by lumbar catheter or the intracranial method) can detect an
abnormal pattern of pressure waves.
Measuring CSF outflow
resistance: This is a more involved test
that requires a specialized hospital setting. In essence, this
test assesses the degree of blockage to CSF absorption back into
the bloodstream. It requires the simultaneous infusion of artificial
spinal fluid and measurement of CSF pressure. If the calculated
resistance value is abnormally high, then there is a very good
chance that the patient will improve with shunt surgery.
Isotopic cisternography: This procedure involves
having a radioactive isotope injected into the lumbar subarachnoid
space (lower back) through a spinal tap. This allows the absorption
of CSF to be evaluated over a period of time (up to 96 hours)
by periodic scanning. This will determine whether the isotope
is being absorbed over the surface of the brain or remains
trapped inside the ventricles. Isotopic cisternography involves
spinal puncture and is considerably more involved than either
the CT or MRI. This test has become less popular because
a "positive" cisternogram result
does not reliably predict whether a patient will respond to
shunt surgery.
Neuropsychological Test: This testing involves asking a series
of questions used to determine if there is a loss of brain function
due to hydrocephalus.
Treatment of NPH
The treatment of choice for NPH patients who show a positive
response to diagnostic testing is the placement of a CSF shunt.
A shunt is an implantable device designed to drain CSF fluid
away from the brain thereby allowing the enlarged ventricles
to return to a normal state. As CSF fluid builds and the pressure
in the ventricle increases, a one-way shunt in the shunt opens,
and the excess CSF fluid drains into the abdomen where it is
easily absorbed. This technique is very effective in improving
the troubling symptoms of NPH.
With a traditional fixed pressure shunt, choice
of the correct pressure setting is very important as under-drainage
will not improve symptoms, whereas over-drainage can cause symptoms
in itself, or predispose to problems such as subdural hematoma.
Incorrect choice of a fixed pressure shunt requires removal
of the original shunt, and repositioning of a different one.
Surgical revisions such as this can be avoided if your neurosurgeon
is certified in the use of programmable shunt technology. With
a programmable shunt, the pressure setting can be adjusted
with a special magnetic programmer in your doctor's office,
eliminating the need for additional surgery if the initial
setting proves not to help.
CSF Shunts (VP Shunts)
Shunt systems come in a variety of models but always have two
similar components: a catheter, the tubing that transports and
diverts the CSF from the ventricles to either the abdominal cavity
or right atrium, and a shunt that regulates the pressure or flow
of CSF from the ventricles. Valves are manufactured to operate
at a specific pressure range. A surgeon chooses a pressure range
for the shunt based on experience and the needs of the patient.
Many shunt systems also have a flexible flushing chamber called
a reservoir. The reservoir may be housed within the shunt system
or added as a component along with the shunt system. The reservoir
serves several important functions. It permits the doctor to
remove samples of CSF for testing, using a needle and syringe.
The doctor also may inject fluid into the shunt system to test
for flow; to be sure the system is functioning.
The parts of a shunt system are named according to where they
are implanted (placed) in the body. The portion of the tube which
is inserted into the ventricles is called the ventricular catheter.
The peritoneal catheter is the portion of the tube that drains
CSF into the abdominal or peritoneal cavity.
If a drainage tube is placed into the right atrium of the heart
it is called the atrial catheter. To get a better understanding
of what a shunt system looks like, ask your doctor or nurse
to show you samples of the shunts they use. All of the components
of a shunt system are made from materials which are well known
to be tolerated by the body. For this reason, the entire shunt
system is implanted under the skin. There are no external parts.
Programmable Shunts
Use of a programmable shunt can significantly
increase the probability of shunt implantation being a one-time
procedure. If the pressure setting of a fixed pressure shunt
proves to be a mismatch after surgery, causing underdrainage
or overdrainage complications, the patient must undergo a complete
or partial shunt revision, sometimes more than once. This is
a limitation of all fixed pressure shunts.
The CODMAN(r) Programmable Shunt gives your doctor a choice
of 18 different programmable pressure settings. It is the same
size as traditional fixed pressure shunts and is implanted in
exactly the same way. Using an exclusive external programming
device, the surgeon selects the initial pressure setting prior
to the procedure, and can then easily adjust the setting at any
time and as many times as necessary without further surgery.
The large range of pressure settings allows the surgeon to make
very fine adjustments in the pressure in order to get the best
resolution of symptoms after the shunt is implanted. The totally
non-invasive adjustments take only seconds and can be done right
in the office with little or no patient discomfort.
Restorative Neurosurgery | Trigeminal
Neuralgia | Normal Pressure
Hydrocephalus
For consultation appointments with Dr. Duma
or for more information regarding his brain tumor, GammaKnife
radiosurgery, and Parkinson's Disease programs at Hoag Memorial
Presbyterian Hospital in Newport Beach, California (Orange County),
please contact:
949-642-6787
Or E-mail Dr. Duma directly: drduma@cduma.com
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