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Hydrocephalus

Getting the Diagnosis, Part 1


The following excerpt is taken from Chapter Two of Hydrocephalus: A Guide for Patients, Families, and Friends by Chuck Toporek & Kellie Robinson, copyright 1999 by O'Reilly & Associates, Inc. For book orders/information, call 1-800-998-9938. Permission is granted to print and distribute this excerpt for noncommercial use as long as the above source is included. The information in this article is meant to educate and should not be used as an alternative for professional medical care.
By the time you receive the diagnosis for the condition of hydrocephalus, it is likely that you or your child have already been through a gamut of tests.

This first of a three-part series describes the process of being diagnosed with hydrocephalus. Articles include:

Symptoms

With newborns, hydrocephalus is detected almost immediately as the child's head may be larger than normal or misshapen. However, with older children or adults, hydrocephalus usually starts to reveal itself with a variety of signs and symptoms weeks or months before it is detected.

Common symptoms of an increase of intracranial CSF pressure include:

  • Abnormally large head or increased head growth in infants or children (macrocephaly).
  • Frequent headaches, particularly late at night or early in the morning.
  • Awkwardness or stumbling when walking (gait disturbance).
  • Vision problems, including double vision (diplopia).
  • Concentration or mental difficulties.
  • Nausea or vomiting.
  • Incontinence.
  • Lethargy.
  • Neck pain.

Persons with hydrocephalus might not have all of these symptoms. With infants and small children, the most visible symptom will be macrocephaly. In teenagers and adults, headaches, gait disturbance, and concentration and mental difficulties are likely to be more prominent.

In order to help your doctor or neurosurgeon diagnose the condition quickly, keep track of symptoms that you observe on a daily basis. Keep a notepad handy and write down the symptoms that occur, noting the date and time they happen. This information helps your doctor or neurosurgeon see if there is a pattern to when certain symptoms occur, and can prove to be quite valuable in evaluating the situation.

Abnormal head growth

With infants and small children, the primary indicator that hydrocephalus could be present is an abnormally large head (macrocephaly). Unlike adults, the sutures of a child's skull aren't fused together. It is important for your pediatrician to track the growth rate of your child's head to ensure that the slow progression of macrocephaly can be detected early. If left undetected and untreated, your child's skull could continue to expand because of abnormally large ventricles (also known as ventriculomegaly). Macrocephaly can cause the following signs and symptoms:

  • Irritability.
  • High-pitched crying or screaming.
  • Split sutures of the skull.
  • Distended veins in the scalp.
  • Bulging or widening of the fontanels that would cause the head to be misshapen.
  • Absence of upward gaze, which is known as sunsetting; most frequently present in the instance of acute non-communicating hydrocephalus.
  • Impaired lateral gaze (sunsetting of one or both eyes).
  • Loss of vision.
  • Weakness or spasticity of the limbs.

Head sizes for male and female infants grow at different rates. Your child's pediatrician should have current head growth charts for each sex, not one chart that offers a median value for both. With infants who were born prematurely, head size should be charted by age according to conception, not by birth age. Your child's pediatrician should continue to chart and monitor the growth of your child's head until he reaches six or seven years old.

My son was five months old when they started thinking it was time to shunt him; his head circumference had been borderline since birth but it was at that age it really took off in size.

If you notice the head of your child is abnormally large, it is advisable to seek medical attention as soon as possible. Keep in mind that head size is something that is attributable to many causes; if both parents have large heads, it could be possible that your child's head size is genetically determined and normal. When in doubt, check it out.

Since my daughter was two weeks old, I had been going to her pediatrician complaining that something was wrong with her. They told me it was colic. We lived with that explanation for some time, then they told me it was probably a reaction to her formula. Again, we bought that for a while. The only symptom our daughter had was piercing screams in the night and never sleeping ... and I mean never! The doctor said this was very common, so we tried to go on with our lives coping with a sleepless child.

When she was around six months of age I asked the pediatrician to check her head-it looked a little odd-but the doctor said nothing was wrong and that I was being over-protective and too critical of her.

At 13 months old, she was finally diagnosed with hydrocephalus and then needed three operations in 18 days.

Headaches

Headaches are a common symptom of the onset of hydrocephalus, particularly with adults. Headaches can be caused as a result of increased cranial pressure (ICP), either within the ventricles or on the surface of the brain. The actual headache occurs when pressure of surrounding fluid and brain matter place pressure on blood vessels and the meninges.

The severity of headaches can range from mild, dull headaches that come and go intermittently, to ones that are debilitating. It may be difficult to tell the difference between a regular headache and a headache caused by increased ICP.

Gait disturbance

Gait disturbance-a reduction or loss of walking motor skills-is usually the first symptom in adults. As intracranial pressure increases, nerve fibers (axons) of the brain become stretched as the ventricles enlarge. Axons take a long course around the ventricles to reach the motor cortex in the frontal lobe. Thus, when the ventricles expand, the axons are stretched, causing ataxia (a lack of control of voluntary muscles).

If hydrocephalus remains undetected and untreated, a person's gait will worsen. Gait disturbance can reveal itself as poor coordination, imbalance, stumbling, falling down for no apparent reason, and even loss of the ability to walk or stand.

My mom had shunt surgery in March. After about five months, she started to show NPH [normal pressure hydrocephalus] symptoms again. She cannot walk or eat, and is semi-conscious, exactly like before the first shunt surgery. The doctor said she will be fine again after she has her shunt revision tomorrow. I hope he is right.

Vision problems

Vision problems often occur in patients who have or are developing hydrocephalus. Increased intracranial pressure can cause the following vision-related symptoms:

  • Non- or slow-reacting pupils.
  • Sunsetting of the eyes (also known as Parinaud's syndrome).
  • Light sensitivity.
  • Impaired lateral gaze.
  • Rapid, involuntary eye movements (nystagmus).
  • Double vision.

Papilledema, swelling of the optic nerve, indicates ICP. If absent, it does not exclude elevated ICP, as it occurs in the minority of patients. Papilledema is diagnosed by looking in the eye with an ophthalmoscope. Symptoms for papilledema include decreased visual acuity, blurring vision, and light sensitivity. Decreased visual acuity first presents itself with intermittent light sensitivity that progresses. If hydrocephalus is not treated promptly, papilledema can lead to blindness.

Concentration or mental difficulties

Concentration and/or mental difficulties often develop in patients with hydrocephalus. Unfortunately, these effects can also last well after shunts have been placed.

Family members will need to help monitor symptoms. Look for any deviation from normal behavior, such as problems with visual and spatial relations, short-term memory loss, or difficulty with verbal and non-verbal problem-solving. Also be alert for signs of lethargy. For example, you might have a difficult time waking your child. Or you might notice a change in social activities; she might become withdrawn and easily lose interest in whatever she's doing.

How hydrocephalus is diagnosed

Initially, hydrocephalus is detected when one or more of the symptoms of the condition become evident. For example, in an infant, you might notice that your child's head is bulging or is larger than normal (macrocrania or macrocephaly). In a small child, you might notice that your child has painful headaches, gait disorder, or vision problems.

When hydrocephalus is first suspected, your primary care physician should then refer you to a neurosurgeon for further evaluation and testing. A neurosurgeon is a doctor trained to operate on the brain, spinal cord, and other nervous structures of the body. If other problems are present, such as seizures or vision problems, the physician should also refer you to a neurologist or a neuro-ophthalmologist.

Neurological examination

Before the neurosurgeon orders any tests, such as a CT or MRI scan, she will likely perform a neurological examination. This exam includes a history of neurological milestones, and a physical examination to check for possible neurological deficits. Below are some of the signs the neurosurgeon will look for as an indicator that hydrocephalus could be present.

Premature infants

Premature infants are more likely to develop hydrocephalus as a result of an intraventricular hemorrhage (IVH), which can cause post-hemorrhagic hydrocephalus. The neurosurgeon will feel the fontanel, or soft spot on the cranium where the sutures of the skull are still open, to see if it is fuller than normal. She will also check the infant's head circumference to see if it is within the normal range. Fullness of the fontanels and a large head are indicators that hydrocephalus is present.

Additionally, she will check to see if muscle tone is normal. If an IVH or hydrocephalus is suspected, the neurosurgeon may first order an ultrasound of your child's head rather than order a CT or MRI scan.

Full-term infants (from birth through 1 year old)

As with premature infants, your child's neurosurgeon will check the size of the cranium and the fontanel for fullness. Since your child is older and more developed, the neurosurgeon will also check his eyes and reflexes. One of the things the neurosurgeon will look for is whether or not your child has a startle response. If he lacks a startle response, it may could indicate loss of sensation to that part of the body.

As your child grows, some indicators of a possible neurological deficit are that he is not meeting some of his developmental goals. These include smiling, crawling, walking, and being able to roll over.

Children (ages 1 through 12)

After your child is one year old or older, the neurosurgeon will examine him to see if he is reaching mental and physical developmental milestones.

Mental milestones:

  • Is your child communicating verbally?
  • Is your child doing well in school? Has he fallen behind his peers in recent months?
  • Does your child have a hard time remembering things?
  • Has there been a noticeable change in your child's personality in the past few weeks or months?

Physical milestones:

  • Did your child begin to show signs of walking by the time he was one year old?
  • Is your child's gait steady or unbalanced? Does he tend to drift to one side when he walks? The neurosurgeon will be looking closely to see if your child moves symmetrically.
  • Can your child balance on one foot?
  • With his eyes closed, can your child place both feet together, side by side, and maintain his balance?

The neurosurgeon will check your child to see if his arms and legs are strong, or if there is a deficit in one side or the other. She will test tendon and muscle reflexes, and will also check for any loss of sensation in the extremities.

By looking into your child's eyes, she will be able to check for papilledema. The neurosurgeon will place an index finger in front of your child's face and ask him to follow its movement from side to side, and up and down. This is to check for possible paresis (paralysis) of the abducens (or sixth cranial) nerve. The sixth cranial nerve controls lateral (side to side) eye movements.

The neurosurgeon will also ask your child to walk heel-to-toe with head up and arms extended, forward and backward, to evaluate his gait and balance. If he has difficulty performing this test, it could be an indication that there is pressure on the cerebellum.

The neurosurgeon will check the plantar, or Babinski, reflex. This reflex test is done by drawing a blunt object, such as the handle of an instrument, along the outer edge of the foot from the heel to the little toe. The normal, or flexor, response is to have the toes bunch together and move in a downward motion. However, if the big toe moves upward, the result is an extensor response, or Babinski reflex. A Babinski reflex is a clear indication of some form of brain or spinal cord disease. It should be noted that infants will normally have a positive, or upward, Babinski reflex, whether hydrocephalus is present or not. As a result, the neurosurgeon will probably skip this test until your child has reached his first birthday.

The neurosurgeon will test finger-to-nose reaction by holding up an index finger and asking your child to touch his index finger to the doctor's finger and then his own nose, as quickly as possible. This test is primarily performed to see if there is any type of cerebellar impairment on either side of the brain. If he cannot perform this test, either by missing the doctor's finger or his own nose, it could indicate the presence of some form of visual impairment (e.g., papilledema).

The neurosurgeon will also test for pronator drift. In a standing position, the doctor will ask your child to close his eyes, then extend both arms in front, palms up. The neurosurgeon will be looking to see if one arm wavers or drifts down and to the side, which can be an indication of injury to the motor areas of the brain.

Adults

For teens and adults being tested for hydrocephalus, many of the same tests will be done as are done for older children.

Radioisotope cisternography

Radioisotope cisternography, or nuclear cisternogram, is a test often performed when normal pressure hydrocephalus (NPH) is suspected. Radioisotopes are used to help the radiologist and neurosurgeon monitor the flow of CSF within the subarachnoid spaces, ventricles and the basal cisterns.

In a cisternogram, the patient is injected with anywhere from 85 to 500 microliters (5c) of either radioiodine serum albumin (RISA) or indium diethlenetriamine pentacetic acid (DTPA) in the lumbar subarachnoid space following a lumbar puncture. A scintilliscope is used to scan for the isotopes at various timed intervals to track the flow of the radioisotope through the shunt system. In a person without NPH, the radioisotope can be detected flowing into the subarachnoid spaces and basal cisterns, with little accumulation in the ventricles. However, if the radioisotope primarily stays within the ventricles and little or no radioactivity is detected over the hemispheres of the brain, then NPH can be assumed.

You can expect a brief moment of discomfort during the initial lumbar puncture; however, the injection of the radioisotope does not hurt.

Ultrasonography (ultrasound)

Ultrasonography uses high-frequency sound waves to outline the structures within the body. The resulting ultrasound is caused by the reflection of the sound wave bouncing off the part of the body being studied.

Ultrasound is used to diagnose congenital hydrocephalus in utero (when the child is still within the mother's womb). Hydrocephalus can be detected in utero during normal prenatal screening in the 28th week of pregnancy and sometimes earlier. The obvious indication that hydrocephalus is present is that the fetus will have an abnormally large head.

When hydrocephalus is detected in utero, the parents will normally be referred to a pediatric neurosurgeon who will work with the obstetrician to provide proper care for the mother and unborn child.

Ultrasound is used most often on infants, as their cranial sutures have not yet joined together. Ultrasound cannot be used once the soft spot has filled with bone. The primary benefit of using ultrasonography on infants is that they can be imaged while awake from portable equipment that can be brought crib-side, unlike CT and MRI scans which may require infants to be sedated for testing. Although the ultrasound allows the ventricle size to be measured accurately, it cannot image the surface of the brain and some of the posterior fossa.

CT and MRI scans

Until the introduction of computed tomography, or CT, scanners in 1971, the only option for imaging the brain of a child or adult was with traditional X-rays. Diagnosis of hydrocephalus and other brain malformations was difficult because X-rays do not provide enough contrast to see the tissues of the brain.

Within a few short years of introduction, CT imagery became a household word as CT scanners became more common in university and medical research facilities. Since CT scans provided clearer pictures of the body's internal organs, tissues and bones, they quickly became a standard diagnostic tool for surgeons, significantly reducing the need for exploratory surgery.

Magnetic resonance imaging, or MRI, received FDA approval for clinical use in the United States in 1985. Instead of using X-rays, MRIs use radio waves in combination with a magnetic field to create pictures of the body's internal structures. These images provide a clearer view of gray and white matter of the brain, as well as the vascular system. Though expensive, MRIs are the primary diagnostic test used by most neurosurgeons today.

Preparing yourself or your child for CT or MRI scans

CT and MRI scans are relatively painless procedures, unless your neurosurgeon orders the imagery to be contrast-enhanced-then you'll receive an injection or temporary IV, which allows the contrasting agent to flow into the bloodstream.

On the day of the procedure, arrive at the imaging center 15 to 30 minutes prior to the time of the appointment. This will allow you time to complete the necessary paperwork and to meet with the technician to go over medical history. If the imaging series is to be contrast-enhanced, arriving early will give the technicians extra time to get an IV started.

If your child is being tested and has any apprehension about the procedure, ask the technician to explain the test to her. If asked, most technicians will give children a tour of the imaging console and of the equipment in the scanner room before the test to help allay any fears.

In order to perform the test, the patient will be asked to disrobe and change into a surgical gown, and to remove any type of metallic jewelry. Adults should refrain from wearing makeup or using hair spray, as these may interfere with the imaging device. Next, the patient will be asked to lie on the scanner table, which slides inside the circular drum that houses the imaging equipment, and asked to lie perfectly still while inside the CT or MRI machine so the images don't blur. Infants and small children may be given a mild sedative to help keep them still.

CT and MRI scans take pictures of the complete cranial and intracranial anatomy, including the subarachnoid spaces and the structures of the posterior fossa. These pictures, called slices, are taken in sections laterally (side-to-side) and sagittally (front-to-back) at different intervals.

How long does a CT or MRI scan take?

With modern scanners, a CT scan can be as quick as a simple two to five minute procedure, while an MRI series can take as long as an hour, depending on the type of scan and whether or not enhancement materials are used. To pass the time, some CT and MRI machines come equipped with headphones so patients can listen to favorite music while in the chamber. This can be especially comforting to young children who receive MRI scans, as the "clunking" noise from the magnets can be loud and scary.

Risks of CT and MRI scans

Two possible risks for patients who undergo CT scanning are exposure to radiation and a reaction to the use of iodinated contrast material.

CT scans use low doses of ionizing radiation to do the imaging. The average CT scan exposes the patient to radiation doses of five to ten rads (an absorbed dose of radiation) per slice. Although any damage is a rare occurrence, frequent head CT scans can place the patient at risk of radiation exposure which can damage the eyes and possibly cause cataracts. One way of reducing the risk of radiation exposure to the eyes is a method called angled gantry, in which the CT scanner is angled away from the eyes, reducing the dose of radiation the eyes receive.

The chance of radiation damage is minimal compared to the benefit of an accurate diagnosis.

After my daughter had undiagnosed symptoms for a year, I was at my breaking point and wanted action taken. I went in to see the doctor and told them to run some tests like a CT scan immediately. Their response was, "Why expose a child to radiation?"

Dumb question when you are talking about a life. The CT scan confirmed that she had hydrocephalus since birth. They shunted her immediately.

Another risk of CT scanning is the use of iodinated contrast material, which is administered intravenously. This type of imaging series is known as "contrast-enhanced." Although the amount of iodine used is relatively low, there is a 1 in 10,000 chance of a patient experiencing anaphylactic shock (an allergic reaction), and a 1 in 40,000 chance of death. Other possible reactions to contrast material include damage to the kidneys (nephrotoxity) and/or damage to nerve cells (neurotoxity).

Since MRIs use powerful magnets to help produce the images, MRIs should not be performed on patients who have pacemakers or metallic implants, such as aneurysm clips (more commonly known as brain clips). Patients with pacemakers should not be subjected to MRI scans as there is a possibility that the magnetic field of the machine could render the pacemaker inoperable.

Neurosurgeons sometimes use brain clips in operations on people with hydrocephalus or who have had tumors or cysts removed. Brain clips might be used to deal with an intracranial bleed, complication in surgery, stroke, or even sometimes to attach a ventricular catheter. However, most brain clips today are made of a non-magnetic material, so this shouldn't be an issue. If you know you have brain clips, but are unsure what type of material they are made of, ask your neurosurgeon.

CT versus MRI: advantages and disadvantages

CT scanning requires patients to remain motionless for the duration of the test, however the scan may only take two to five minutes. There is the small risk of exposure to radiation. MRI scans also require patients to stay motionless during the test, which can last anywhere from 30 to 60 minutes, depending on the type of contrast or imaging being done. Since an MRI can take so long to perform, infants and young children often require sedation so they won't move during the procedure.

A concern shared by many families and their doctors is the cost of a CT versus MRI scan. The average CT scan costs only $300 to $500 to perform, while an MRI could run as high as $2,000. If cost is a limiting factor for you, talk this over with your physician before he orders any diagnostic tests. Also, it is a good idea to check with your medical insurance provider to find out whether they will cover the cost of an MRI. Some insurance companies may only cover a portion of the cost, so it's important to find out what portion you will be required to pay, if any.

For routine, annual examinations, our insurance company will only cover 80 percent of the cost for an MRI. However, if the MRI is being done for an emergency-something they consider a legitimate reason-then they will cover it 100 percent.

Both CT and MRI have their advantages, but what it really boils down to is which image will give the neurosurgeon the best view of the problem he is trying to diagnose. Until there is an accepted and set standard for the treatment and monitoring of hydrocephalus, neurosurgeons will continue to differ on their choice of imaging device. Ask your doctor to explain his thinking on which test to order. If you have serious concerns, consider getting a second opinion before proceeding.

Possible misdiagnoses

Although rarely misdiagnosed with today's modern imaging techniques, the condition of hydrocephalus is occasionally mistaken for benign extra-axial fluid of infancy, and Alzheimer's disease in adults.

Benign extra-axial fluid of infancy

At birth and for the first few months, the child's head circumference will be normal, but will suddenly start to grow rapidly over a short period of time. Since abnormal head growth is an indicator that hydrocephalus may be present, the child should be referred to a pediatric neurosurgeon for further evaluation. A CT series of the head will be ordered to check the size of the ventricles and for the presence of cysts or tumors.

When CT images return, the neurosurgeon will see that the size of the ventricles are normal or slightly enlarged, and there is no indication of an intracranial mass. What they will notice, however, is an abnormal accumulation of cerebrospinal fluid in the subarachnoid space (the area between the skull and the hemispheres of the brain). This is known technically as benign extra-axial fluid of infancy, and can also be called a benign subdural hygroma, or external hydrocephalus.

In cases of benign extra-axial fluid of infancy, the subarachnoid accumulation is normally reabsorbed by the time the child reaches 18 to 24 months of age. Once the benign extra-axial fluid has been detected, your child's neurosurgeon will require follow-up scans to ensure the fluid accumulation is being reabsorbed by the brain.

Alzheimer's disease

Alzheimer's disease is commonly confused with normal pressure hydrocephalus (NPH), as some of the symptoms of both are the same. Indicators of NPH include urinary incontinence, gait disturbance, and dementia-one of the prime symptoms of Alzheimer's disease.

When NPH is suspected in an adult or elderly patient, it is recommended that a CT or MRI of the head be conducted to evaluate ventricular size. If scans of the head are inconclusive (i.e., ventricles seem to be of normal size), it is recommended that a lumbar puncture be performed to determine the CSF pressure within the subarachnoid space. Another test that can be performed to differentiate between the two is a radioisotope cisternogram to monitor the flow of CSF within the brain.

Asking for a second opinion

Once hydrocephalus is detected, and if shunting is recommended, it is important to act upon the neurosurgeon's recommendations as soon as possible. The longer the condition is left uncontrolled, the greater the risk of neurological damage.

It is your right to ask for a second opinion. Neurosurgery, whether performed on a child or an adult, has inherent risks and many possible complications. Ask your neurosurgeon if there is time for you to obtain a second opinion. If there is, your neurosurgeon should assist you in finding another neurosurgeon in your area. Your neurosurgeon should also assist you in arranging the appointment since the medical records and any CT or MRI films will need to be transferred. If the neurosurgeon indicates there is some urgency in performing the shunt placement or revision, ask him if it is possible to have another neurosurgeon meet with you as soon as possible.

It is in your best interest to make sure that the neurosurgeon explains hydrocephalus to you clearly, in terms you can understand.

I have gone for third, fourth, and fifth opinions until I found someone who I could connect with and believe that they were treating my son like they would treat their own. You have to follow your gut feelings when it comes to this stuff. We are just parents, many without fancy medical degrees, but we know our kids. We have that "parental radar" that goes off when we are concerned... follow that feeling.


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