Neurology

EEG is the name commonly used for electroencephalography. An EEG is an important test for diagnosing epilepsy because it records the electrical activity of the brain.

• It is safe and painless.
• Electrodes (small, metal, cup-shaped disks) are attached to your scalp and connected by wires to an electrical box. (The wires can only record electrical activity; they do not deliver any electrical current to your scalp.) The box in turn is connected to an EEG machine.
• The EEG machine records your brain's electrical activity as a series of squiggles called traces. Each trace corresponds to a different region of the brain.

Sometimes neurological conditions are caused by changes in the structure of the brain. Tests and procedures which take pictures of the brain, called "neuroimaging," can tell doctors whether you have one of these conditions. The most common neuroimaging tests are computed tomography (CT scan) and Magnetic Resonance Imaging (MRI scan). Both produce a picture of how the brain looks. Your child may need a general anaesthetic for their imaging study.

NCS are tests of the speed of conduction of impulses through a nerve. A doctor performs the tests with a technician.

The nerve is stimulated, usually with patch-like electrodes placed on the skin. One electrode stimulates the nerve with a very mild electrical impulse and the other electrodes record the resulting electrical activity.

The impulse will feel like a small electric shock. Depending on how strong the stimulus is you will feel it to varying degrees and it may be uncomfortable for you. You should feel no pain once the test is finished.

This test is used to diagnose nerve damage or destruction. Information from the test can tell the doctor what part of the nerve is damaged and give an idea as to the disease causing the damage. There are no risks from this test.

The test will need to be interpreted afterwards so the results will not be available at the time of the test but will be sent to the referring doctor.

EMG is a test that assesses disorders of muscles and the nerves controlling them. A doctor performs this test.

For an EMG, a needle electrode is inserted through the skin into the muscle. The electrical activity detected by this electrode is displayed on a monitor. This is usually performed with a nerve conduction study.

You may be asked to contract the muscle (for example, by bending your arm) which will give the doctor information about how muscles respond to messages from nerves.

There may be some discomfort with the insertion of the electrodes (similar to an injection into a muscle). Afterwards, the muscle may feel tender or bruised for a few days.

There is a very low risk of bleeding or infection at the site of the needle but this is minimal.

EMG is most often used when people have symptoms of weakness and examination shows impaired muscle strength. It can help to tell the difference between problems with a muscle versus problems with the nerves supplying the muscle.

Cerebral Spinal Fluid (CSF) is the fluid that surrounds the brain and spinal cord. It is often helpful when diagnosing certain conditions to examine this fluid for cells and chemicals/proteins. A lumbar puncture also allows the doctor to examine the pressure of this fluid.

A doctor performs the test in the following manner:

• The patient lies on his or her side, with the knees pulled up toward the chest. Sometimes the test is done with the person sitting up, but bent over.
• After the back is cleaned, the doctor injects a local anaesthetic which makes the skin and surrounding area numb.
• A spinal needle (which is long but smaller in diameter to that used to take a blood test) is inserted between two of the lumbar vertebrae (bones at the base of the spine).
• Once the needle is properly positioned, spinal fluid pressure is measured, and fluid is collected.
• The needle is removed, the area is cleaned, and a bandage is placed over the needle site. You will need to lie flat for 20 minutes to one hour after the test.

Risks of major complications with a lumbar puncture are low but will be discussed with you before the procedure.

Epilepsy is a condition where people have seizures or ‘fits’. Seizures may present in many forms but are due to bursts of electrical activity within the brain. The problem can be with the electricity of the brain on its own or due to some underlying structural lesion of the brain.

Anyone can have a seizure if the stimulus is great enough to exceed a threshold in the brain. Factors such as fever, changes in blood chemistry, anxiety, sleep deprivation or alcohol may influence the onset of a seizure. Although some disorders and traumas play a role in developing epilepsy most people who have epilepsy have no known reason.

A seizure may present as a convulsion, unusual body movement, a change in awareness or simply a blank stare. The person may be unconscious or completely unaware of what is happening. What type of symptoms people have depends on what part of the brain is involved.

The diagnosis of epilepsy is made on the basis of the history so it is useful when you come to clinic if someone who has witnessed an event can come with you. Depending on your symptoms and examination findings you may undergo an EEG test and/or an MRI of your brain to aid in the diagnosis and planning of treatment. Not everyone needs these tests and the doctor will talk with you about what is needed.

Epilepsy is usually treated with medication to prevent seizures. There will also be implications for driving if you are diagnosed with this condition, as it needs to be well controlled before you can drive. Your doctor will discuss this with you.

For more information visit www.epilepsy.org.nz

Most headaches are not due to significant underlying problems but you may be referred if your GP is worried about the nature of your headaches or you are having difficulty controlling them with standard treatment.

Migraine headaches are repeated or recurrent headaches, often accompanied by other symptoms. They can be triggered by certain factors/events/foods. In some people, a visual disturbance called an aura happens before the headache starts.

Other symptoms that may precede or accompany the headache include loss of appetite, nausea, vomiting, increased sweating, irritability, fatigue and intolerance of light or noise. The headache may last several hours to days.

There is no cure for migraine headaches but treatment is aimed at: preventing migraines from occurring, stopping the migraine once early symptoms develop, and treating the symptoms of migraine (e.g. pain, nausea).

For more information about migraines and headache visit https://migrainefoundation.org.nz/about-migraine/

There are a number of different conditions that affect the nerves and muscles beyond the central nervous system (brain and spinal cord). Myopathy refers to disease affecting the muscles. Neuropathy refers to disease affecting the nerves.  There are also diseases that affect the junction between the nerves and muscles.

For more information visit https://www.mda.org.nz/