EMG, EEG AND AEEG TESTING
This study is usually performed as a workup for pain, numbness or tingling in an arm or leg. It tests the condition of the nerves from the spine into the extremity to the foot or hand. There are two parts to the test, the nerve conduction study and the needle EMG Study.
During the nerve conduction portion of the study, mild electrical impulses are sent along the course of a nerve in the arm or the leg. You will feel a brief snapping sensation on the skin. The intensity of the impulse will be increased until the desired response is obtained. The electrical impulse will make the muscles in your arm and leg contract. The sensation you feel is much like that of a static electric shock.
The needle EMG portion of the study involves the insertion of very thin pin electrodes into the skin. The electrode is moved around slightly after insertion. Several muscles are tested in each extremity. You will feel a cramping sensation at the area of needle insertion. The electrodes that are used are disposable electrodes that are used only on you. They are designed for minimal pain and discomfort.
The EMG and nerve conduction study is a mildly uncomfortable test. Many patients come to the test anxious because they have heard how painful it is. Almost all leave feeling they worried for nothing. Every effort is made by our providers to make you feel as relaxed and comfortable as possible.
An electroencephalogram (EEG) evaluates electrical activity produced by the brain, which can signify or rule out certain conditions, most commonly seizure disorders. The test takes about an hour to complete, and the results are automatically sketched on paper, while a video monitor records the movement of the patient, which can disrupt the test.
It is easier to read an EEG of an adult than one of a child, since there is less variance in brain activity. There is often so much variance in brain activity that a reading taken on a child may be consistent with epilepsy where none exists. Generally, seizure disorder in children, without the presence of identifiable seizures, requires additional testing to have confirmed results.
As a test progresses, if it is used to examine seizure disorder, a person may be directed to look at flashing lights, which might trigger a seizure. The lights are stopped if the readings show that a person is in pre-seizure mode. This means that the person generally doesn’t have a seizure during the test, but that it shows electrical activity consistent with what would become a seizure.
An EEG may also be used to evaluate other conditions. For example, people who come to a hospital in an altered state of consciousness, perhaps after a head injury, would probably have this test performed. People with tumors or with brain abscesses may also show lack of electrical activity in some aspects of the test. An EEG can also measure a total lack of brain activity, confirming the death of a patient.
WHAT IS AN AEEG?
An ambulatory electroencephalogram (EEG) is a study of brain activity conducted by sending a patient home wearing electrodes on the skull and carrying a recording device. Patients experiencing epilepsy and other neurological problems often have intermittent symptoms, and doing an ambulatory EEG increases the chances of recording the brain when something is happening. It is much less expensive than a study where a patient reports to a clinic and stays overnight or for several days, and is also less intrusive for the patient, as people can engage in regular activities during the test and are in fact encouraged to do so.
When people complain of seizures or other neurological symptoms, an EEG study can be done in a hospital to see if there is anything abnormal happening in the patient’s brain, but the results of the study may be variable, as it only records for 20 to 40 minutes. For an ambulatory EEG, a technician glues electrodes to the head with collodion, a strong and durable glue, attaches leads, and clips the leads to a recorder to pick up data. People do not need to have their heads shaved for the test, and the skull is usually covered in a net cap for protection.
While undergoing an ambulatory EEG, patients should take medications normally and engage in all the activities they regularly do, including working, going to school, and so forth. Exercise is usually safe, unless it involves getting wet, as the recording device cannot be exposed to water. Patients can wipe down their bodies with a wet washcloth, but should avoid tubs, showers, and saunas during the ambulatory EEG to avoid damaging the machine.
Usually, people are asked to keep an activity diary. This can be matched up with the machine’s output later to see if seizures are associated with particular triggers like activities or foods. The device also usually has what is known as an “event button.” When a patient experiences a seizure or another neurological abnormality, the button can be pushed to flag it in the machine’s record, drawing the doctor’s attention to the patient’s brain activity at that point in time.
The ambulatory EEG can last between 24 and 72 hours, depending on the patient. At the end of the test, the patient goes back to the office so the electrodes can be removed and the data can be retrieved. A doctor will discuss the results with the patient after having time to review them.