Important Considerations:

Shunts and Hydrocephalus

A shunt may become necessary for your child if there is a blockage or disruption of the cerebrospinal fluid pathways (hydrocephalus).

In children, brain tumors most commonly occur in the back of the brain (posterior fossa). As a tumor grows it may fill or compress the fourth ventricle, blocking the flow of cerebrospinal fluid. In other areas of the brain a tumor may similarly block or compress the ventricular system, causing hydrocephalus.

Treatment

The treatment for hydrocephalus may be to surgically implant a shunt system into the ventricular system. These shunts are usually placed in the lateral ventricle (right) but at times, depending on the location of the tumor, other ventricles may need to be shunted. The shunt will remove excess cerebrospinal fluid (CSF) and drain (shunt) it to another area of the body.

A shunt is a narrow, soft and pliable piece of tubing (approximately 0.25 cm. in diameter) which is surgically implanted into the ventricle through a small hole made in the skull.

All shunts have a valve system which regulates the pressure of the cerebrospinal fluid and prevents backward flow of fluid into the ventricles. Many shunts have reservoirs which can be used for removing CSF or administering drug therapy. A shunt may be pumped but this should only be done on a physician's order.

There are different types of shunts and placement procedures. To get a better idea of what a shunt looks like, ask to see one. Be sure to write down the name and type of the shunt your child has. This could be important information if your child runs into difficulty away from your medical centre.

Ventriculo-Peritoneal Shunt (VP Shunt)

The tubing that is connected to the valve is threaded underneath the scalp and down the neck. The shunt may be placed behind the ear or behind the hair line in the front part of the skull. A small incision may be made in the neck, along the pathway, in order for the surgeon to pass the shunt beneath the skin. The shunt is in the fatty tissue which lies just below the skin. A further incision is made in the abdomen and the end of the shunt is directed here. The cerebrospinal fluid can now drain into the abdominal cavity (not the stomach) where it can be absorbed. Different companies make different shunts, but the same principles apply to all. A common example is shown:

V-P Shunt Ventricles of the Brain

Ventriculo-Atrial Shunt (VA Shunt)

In this system, the shunt tubing is passed from the valve to the neck where it is inserted into a vein. It is then passed through the vein until the tip of the catheter (shunt) is in the atrium (a chamber) of the heart. In the heart, the CSF passes into the blood stream and is filtered along with other body fluids.

A Ventriculo-Peritoneal (VP) shunt is usually tried initially. Occasionally the abdomen cannot absorb fluid, and in these cases a Ventriculo-Atrial (VA) shunt system is used.

It may be useful for you to ask your neurosurgeon to show you an actual shunt. Be sure you know the name of your child's shunt.

Shunt Care

Occasionally, a shunt system will become blocked or infected. Shunt malfunction means that the shunt is not able to divert enough CSF away from the ventricles of the brain.

Obstruction

When a shunt malfunction occurs, it is a problem with a partial or complete blockage of the shunt. It can occur in any component of the shunt from the tip in the ventricle to the valve (upper end), or to the catheter in the abdomen (lower end). Only the blocked part is fixed and this involves an operation to do so.

Infections

Shunt infection is usually caused by a child's own bacterial organisms, and is not acquired from exposure to other children or adults who are ill.

Infants                 |      Toddlers          | Children and Adults
________________________|________________________|___________________________
Enlargement of the      | Head enlargement       | Vomiting
baby's head             |                        |
                        |                        |
Fontanelle is full and  | Vomiting               | Headache
tense when the infant   |                        |
is upright and quiet    |                        |
                        |                        |
Prominent scalp veins   | Headache               | Vision problems
                        |                        |
Swelling along the shunt| Irritability and/or    | Irritability and/or 
tract                   | sleepiness             | tiredness
                        |                        |
Vomiting                | A loss of previous     | Personality change
                        | abilities (sensory or  |
                        | motor function)        |
                        |                        |
Irritability            | Seizures               | Seizures
                        |                        |
Sleepiness              |                        | Difficulty in waking
                        |                        | up or staying awake
                        |                        |
Downward deviation of   |                        | Loss of coordination
the eyes                |                        | or balance
                        |                        |
Seizures                |                        | Decline in academic
                        |                        | performance
                        |                        |
- - - Fever and redness along the shunt tract (with infection only) - - -
This list of symptoms is for your reference only, and is not a diagnostic aid. If you are in doubt about your child's medical condition, consult your physician immediately.

This section on shunts was adapted in part from "About Hydrocephalus... A Book for Parents", a booklet produced by:

Hydrocephalus Association,
2040 Polk St. #342,
San Francisco, California
94109
(415)-776-4713

Blood and Blood Products

Blood transfusion is the introduction of whole blood or blood products directly into the blood stream.

A unit or bag of blood drawn from a donor consists of almost 2 cups of whole blood and some anticoagulant and preservative. This blood can be given as it is, or it can be split into its component parts:

There are also some derivatives of plasma, such as:

Before receiving any blood transfusions, a blood test will be drawn to determine your child's blood group (such as A,B,AB or O) and Rh factor (positive or negative). Your child's and the donor's blood are also matched to see if either have any antibodies to the other. This is to make sure that blood given to your child is compatible with his/her own blood. In an extreme emergency, blood type O, known as the universal donor, will be given as a lifesaving measure. In addition to testing of the patient's blood, ALL donated blood is screened for the AIDS virus, the hepatitis B virus, as well as other infecting agents.

During surgery for brain tumors, some people require a blood transfusion. Transfusions may also be required if radiation or chemotherapy reduces the bone marrow's production of new blood.

Red cells carry oxygen from the lungs to the rest of the body, so they are very important. Lack of red blood cells causes anaemia. Your child may feel tired, fatigued or weak. These cells may need to be replaced with a packed red blood cell transfusion.

White blood cells are the major response by the immune system to infection. We are constantly exposed to bacteria or viruses which could make us quite ill but our immune system fights them off. If your child's white blood cell count is low, you may be asked to take special precautions to avoid infections such as avoiding other people with colds or infections, avoiding crowds (school, church, malls, movie theatres, etc.), and extra hand washing. At this time it is not possible to transfuse white blood cells. New drugs are being developed that can stimulate the body to make white blood cells. These growth factors (such as Neupogen [G-CSF, granulocyte colony stimulating factor]) must be given by injection and are usually only used if the white blood count is dangerously low after chemotherapy.

Likewise, blood platelets play an important part in protecting us. When we cut ourselves or bump a part of our body, the platelets collect at the site to help stop the bleeding. If their numbers are low, bleeding may occur which cannot be readily controlled. A blood transfusion may be necessary.

All transfusions of blood or blood products are given through an intravenous line (I.V or Port-a-Cath). During the transfusion, your child's pulse, blood pressure and temperature will be monitored closely to watch for any side effects to the blood being received. If a reaction does occur, he/she will be given a drug such as Tylenol or Benadryl (used with some allergic reactions) and the transfusion will be stopped. Fortunately, these reactions do not occur often.

Chemotherapy, often used for the treatment of brain tumors, may interfere with bone marrow function.

Once the treatment for the brain tumor has ended, the bone marrow's functional abilities gradually return to normal. During this time however, if your child is noted to be particularly pale, has less energy than is expected, bruises easily or experiences infection, you must promptly contact your oncologist. Blood or its by-products may yet be needed during this time as your child's bone marrow may not be able to produce enough on its own.

Across the country there are varying policies regarding the donation of blood for a family member. Should you have questions regarding policy and procedures, ask your physician and he/she will direct you to the appropriate source.

Eye Signs and Symptoms in Brain Tumors

Introduction

If your child experienced visual changes as symptoms or a result of treatment, the following section will help you understand the visual system and conditions that may result.

Being aware and sensitive to your child's visual abilities and/or restrictions will help you to determine if any change has occurred. Contact your doctor if you feel your child's vision has changed.

A change in vision is frequently a symptom that causes a person to seek medical help.

A person's visual system includes not only the eye itself but also the visual pathways that travel from the back of the eye (retina) all the way through to the back of the brain to the occipital lobes. Doctors who specialize in the eye and visual system are called Neuroopthalmologists.

The visual system is important in helping to make the initial diagnosis of a brain tumor and in continuing the management of the patient once the tumor has been treated.

Visual messages travel from the back of the eye along the two optic nerves and meet near the area of the pituitary gland called the optic chiasm. Here, the two nerves fuse together. Half of the pathways cross and the nerves travel back through the brain, through the temporal and parietal lobes, before arriving at the back of the brain (occipital lobes).

Visual fields are what the person can see in all directions with both eyes open and looking straight ahead. Each eye has a right and left visual field. These overlap the fields of the opposite eye.

Visual Fields

Papilledema

By looking in the eye, the physician may see swelling of the optic nerves. This may be an indication of increased intracranial pressure, caused by the growing tumor or obstruction of cerebral spinal fluid. This may cause slow and progressive visual loss involving both eyes. Many children complain of blurred vision before the diagnosis of a brain tumor is made.

Vision Loss to One Eye

If a tumor is causing pressure to one optic nerve before it arrives at the optic chiasm, there may be some loss of vision in one eye (Visual Fields, box A). Patients may notice that there is a "hole" in their vision or they may find that their vision is getting more and more blurred. These changes cannot be corrected with glasses. One eye only is affected.

Vision Loss to Both Eyes

When patients have problems with their visual pathways at the optic chiasm, both eyes will be involved (Visual Fields, box B). This is because the pathways from each eye become crossed at this point. Patients with these problems usually find that half of their vision is missing to one side. If the problem occurs right at the chiasm area (e.g. a pituitary tumor) the common visual problem would be a loss of vision on both outsides, so that looking straight ahead there is a loss of vision originating with the right eye on the right side, and with the left eye on the left side.

When patients have difficulty behind the optic chiasm, the visual loss, because of the arrangement of the visual fibres, would be half or part of the vision on the one side so that the patient would have either the right side of the right eye vision lost and the right side of the left eye vision lost, or the reverse. See (Visual Fields, boxes C and D).

Tumors in the brain affecting the vision pathways behind the optic chiasm cause loss of the visual field on the opposite side in both eyes. For example, a tumor in the right side of the brain may cause loss of the left visual field in both eyes.

Double Vision (Diplopia)

We see clearly because our eyes always move together. There are many muscles which allow this to occur. The eye muscles receive a signal for movement from nerves which travel from the brain stem through the brain to the eye muscles.

A tumor itself, or the pressure it causes, might hinder the nerve's ability to work, resulting in an imbalance in the action of the eye muscles. When this happens, one or both eyes may fall out of alignment with each other. Double vision may be the result.

The nerves involved are the third, fourth and sixth cranial nerves. If the third cranial nerve is involved, the eye may move outward and the eyelid may droop. The pupil of the eye may be large and not react well to light. If the fourth nerve is involved, the affected eye will move outward and up. They may not be able to look up. If the sixth nerve is involved, the eye will move inward toward the bridge of the nose.

Nystagmus

Sometimes the eyes move in a continuous beating or jerking motion over which the patient no longer has any control. This is called nystagmus, and although it does not cause any visual symptoms, it may be useful in working out which part of the brain is involved. Nystagmus may signify problems in the area of the brain stem or cerebellum.

Summary

The examination of the eyes, which involves looking in the eyes, assessing their movement and field of vision, is important in the first assessment and continued follow-up of patients with brain tumors. Any change in vision should always be reported to your physician.

CT and MRI Preparation

During the course of your child's treatment protocol, it will be necessary for him/her to have CT (Computerized Tomography) or MRI (Magnetic Resonance Imaging) scans done. These special pictures, taken at regular intervals, will help to monitor the effectiveness of the treatment and detect any recurrence early.

Often, an intravenous contrast agent ("dye") must be injected in order to see the tumor more clearly as part of a CT or MRI scan.

It is very important that all patients lie absolutely still for these procedures. This can be difficult for the child under 5 years of age; thus, a mild sedative may be given to allow the child to sleep. The sedation used may be given by mouth (orally), injected into a muscle (intramuscularly) or injected into a vein (intravenously).

Some facilities have programs to prepare children to undergo these tests without sedation. Play therapy may be used. Please inquire at your hospital.