Electromyography (EMG) is an electrical test of the nerves and muscles. Neurologists use this test to aide in the diagnosis of a variety of disorders including neuropathy, radiculopathy, pinched nerves, spinal stenosis, carpal tunnel syndrome, myopathy, myostis, myasthenia gravis, and ALS.
The test includes two parts. The first involves stimulation of various nerves with a small electrical impulse. The nerve impulse is measured in several ways including the size of the response and how fast the nerve is conducting the impulse. This portion of the study is often referred to as nerve conduction velocities, or “NCVs” – a common misnomer. Much more than velocity is measured. Only a trained neurologist should administer this test if optimal results are desired.
The second portion of the test involves the use of a small needle to “listen” to the electrical activity of the muscles. This portion of the test is performed in two ways. The first is when the muscle is completely at rest. The second way is when the muscle is being “activated.” Accordingly, at times during the test, the examiner may ask the patient to “relax” or to contract a certain muscle, e.g. “curl your toes down” or “bend your arm toward your chest.”
Since the testing involves some small pins and some small electrical impulses, the procedure can be uncomfortable at times. However, the discomfort is very transient, does not require any sedation or anesthesia, and is tolerated by essentially everyone without significant difficulty or pain. This essential portion of the test is only minimally invasive but should NEVER be performed by a technician – only a trained neurologist should perform this portion of your procedure. Patients should arrive with clean, dry limbs and should avoid the use of creams, lotions, and moisturizers prior to the test. Patients are kindly requested to notify the physician of any bleeding disorders, liver disorders, or the use of blood thinners such as Coumadin (warfarin).
Botox (botulinum toxin injections) is a biological medication that is injected into overactive muscles to weaken the muscle. Botox is an FDA-approved treatment in the management of cervical dystonia (spasmodic torticollis), hemifacial spasm (uncontrollable clenching of one side of the face), blepharospasm (uncontrollable eye blinking), spasticity from stroke, and hyperhidrosis (excessive sweating). While not FDA approved for certain other conditions, Botox has been demonstrated to be effective in the treatment of MS, CP, and spinal cord injury. It has also been found effective in other forms of dystonia (including that associated with Parkinson Disease), muscle spasms, headache, migraine, and siallorhea (excessive drooling).
Botox is injected into specific muscles which are overactive, as determined by both the patient and the neurologist. Two or three days later, the muscles weaken slightly, thus facilitating the dexterity of a hand, improving walking, or decreasing pain, whichever the specific case may be.
Botox is administered through a “standard size” needle for limb muscle injections. In the facial muscles and around the eyes, a very small needle is used. Occasionally, the neurologist may use an EMG machine to help target the injections into the most ideal portion of the muscle.
Major side effects are very rare but could include swallowing difficulty, dry eyes, dry mouth, allergic reaction, and local pain - all of which are dependent on the site of location and the dose administered. Your neurologist will discuss these issues with you further and will take steps to avoid such reactions, including the use of small doses during the initiation of treatment.
Electroencephalography (EEG) is an electrical test of “brain waves” employed by neurologists in the diagnosis of seizures, epilepsy, dementia, and various states of confusion. The test involves the placement of an array of small, metal discs (electrodes) on the scalp surface. With the help of a computer, these electrodes then measure the electrical activity of the brain’s surface – a brain structure known as the cortex. Just as an EKG measures heart activity, EEG records brain activity as lines on paper or on a computer screen. The contour, shape, and frequency of these lines help the neurologist to interpret the recordings and their application to each individual patient.
EEG is a non-invasive test during which there is essentially no risk. Patient’s should arrive with clean, dry hair and should avoid the use of significant hair products (gels, sprays, etc) prior to the study. Occasionally, the test results may be augmented by having the patient be “sleep-deprived.” When requested, a patient will be asked to obtain half of their usual amount of sleep on the night preceding the testing. Medications should be continued unchanged prior to the test unless specifically instructed otherwise. To prepare for the test, please avoid any hair pieces, hair spray or gel products, just clean dry hair. Also, avoid caffeinated products the day the test.
Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily aligns all the water molecules in your body. Radio waves cause these aligned particles to produce very faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread. The MRI machine can combine these slices to produce 3-D images that may be viewed from many different angles.
MRI is a noninvasive way for your doctor to examine your organs, tissues and skeletal system. It produces high-resolution images that help diagnose a variety of problems. MRI is the most sensitive imaging test of the brain and spinal cord.
A Visual Evoked Potential test is done by showing the patient a visual stimulus, such as an alternating checkerboard pattern on a computer screen. Responses are recorded from electrodes that are placed on the back of your head and are observed as a reading on an electronencephalogram (EEG). These responses usually originate from the occipital cortex, the area of the brain involved in receiving and interpreting visual signals.
The VEP measures the time that it takes for a visual stimulus to travel from the eye to the occipital cortex. It can give the doctor an idea of whether the nerve pathways are abnormal in any way. For example, in multiple sclerosis, the insulating layer around nerve cells in the brain and spinal cord (known as the myelin sheath) can be affected. This means that it takes a longer time for electrical signals to be conducted to the eyes, resulting in an abnormal VEP. A normal VEP is sensitive in excluding a lesion of the optic nerve, along it's pathways in the anterior part of the brain.
An AEP test is the recording of very small electrical signals from areas of your brain in response to sounds that are not easily seen in a regular EEG. These parts of the brain are called the “brainstem” and “cortex”. The signals are so small that a computer must be used to pick out these special signals for the doctor to see. A series of clicks are delivered through an earphone to your ear. As the clicks travel from your ear through the various pathways in your brain, they produce electrical signals. These signals are added up by the computer to create the waveforms of your test.
AEP’s check the health of specific pathways in the brain. Some common reasons why patients come for this test are: weakness, nausea, vomiting, unusual ringing of ears, dizziness, hearing loss, vision problems, headaches, numbness, etc. It also is used to search for very subtle tumors affecting the hearing apparatus. It can also be used to help diagnose multiple sclerosis and other neurological diseases. By looking at the shapes and heights of the waves, when they occur, and how many there are, the doctor can tell whether or not there may be any problem in various regions of your brain devoted to hearing.