What are Neurodiagnostics?

When it is suspected that a patient's illness may have a root cause within the central nervous system (i.e. brain and spinal cord), the doctor may order neurodiagnostic tests. These tests will provide critical information to the practitioner about the functioning of the nervous system so that a clear diagnosis can be made. There are two general types of neurodiagnostic tools used by practitioners: 1. Imaging or scans [including X-ray, Computerized Tomography (CT), Magnetic Resonance Imaging (MRI), Magnetic Resonance Spectroscopy (MRS), and Positron Emission Tomography (PET) scans], which show pictures of the anatomy and/or biochemistry of the body, and, 2. electrical impulse detection, which examines the electrical impulses of the body's nervous system to determine if the system is functioning correctly.

Diagnostic scans

X-rays, CT and MRI scans provide a picture of the anatomy of the brain and spine in great detail so that neurosurgeons and neurologists can clearly see if something is wrong. For example, the presence of a brain tumor or a spinal fracture would be detected by these scans. Other imaging techniques, including MRS and PET scanning, provide information regarding the characteristics of the tissue being examined. For example, MRS and PET can help the surgeon to assess if a brain tumor is growing at a fast rate and/or if it has the potential to spread to other parts of the body.

The WKNI is unique in its ability to offer both MRS and PET scanning to patients. No other facility in the Dayton area can provide these cutting edge technologies for the patient. These advancements are especially critical in cases in which the diagnosis is difficult to determine.

Electrical impulse detection

The Clinical Neurophysiology Department at the Wallace-Kettering Neuroscience Institute (WKNI) performs electroencephalograms, 24-hour ambulatory electroencephalograms, long-term monitoring for epilepsy, evoked potentials, electrocorticography, and intraoperative monitoring.

1. Electroencephalogram (EEG): Sometimes referred to as the "brain wave test", an EEG records the electrical activity of the brain. EEGs are performed on patients who have experienced seizures, epilepsy, passing out, headaches, or brain attacks (strokes). An EEG can also be performed to determine the level of consciousness of a patient, mental status changes, and for determination of brain death.
   
   To perform an EEG, small metal disks are attached with a conductive cream to the scalp of the patient. The patient is asked to lie quietly for 20-30 minutes while data are being recorded. During the recording, the technologist will ask the patient to open and close his/her eyes, perform hyperventilation (breathing faster and deeper than usual), look at a strobe light, and go to sleep. These procedures enable the technologist to obtain detailed information for interpretation by the physician. The entire procedure, including patient set-up, takes approximately two hours. An EEG is also the basis for long-term monitoring for epilepsy.
   
   
2. 24-hour Ambulatory EEG: This EEG is differs from a routine EEG (above) in that the patient wears electrodes home for a 24-hour period so that more information can be gathered. The electrodes feed data into a small recorder that gathers information over the 24-hour period. During an ambulatory EEG, the patient wears electrodes attached to the scalp, to monitor brain waves, and the chest, to record the heart rate. The patient comes back to the hospital the next day for removal of the electrodes. The data in the recorder is then scanned and interpreted by the physician. Set up time for an Ambulatory EEG takes approximately two hours and unhooking the equipment takes about 30 minutes.
   
   
3. Long-Term Monitoring for Epilepsy (LTME): Epilepsy patients are observed through the use of an EEG with simultaneous video monitoring. This is done to document seizure activity over an extended period of time. The EEG brain electrodes are worn while the patient remains in the Epilepsy Monitoring Unit (EMU) for 24 hours or longer, depending on how much information is collected.
   
   We are very proud of the Epilepsy Monitoring Unit, which opened in the fall of 1997. Under the direction of epileptologist Robert Simkins, D.O., it is the first adult unit of its kind in the Dayton area. Partnered with the Epilepsy Center at the WKNI, the EMU staff works closely with WKNI physicians to provide the best electroneurodiagnostic services available.(link to WKNI Epilepsy website).
   
   
4. Evoked Potentials (EP): The EP provides a measurement of how long it takes an impulse to travel from a point of stimulation through the spinal cord to the brain. There are three modalities, or types, of EPs: Brainstem Auditory Evoked Response (BAER), Visual Evoked Response (VER), and Somatosensory Evoked Response (SSER) of the arms or legs. Evoked potentials are performed to detect and determine the severity of Multiple Sclerosis, spinal cord injury or disease, and brainstem injury or disease. Evoked potentials may also be used to determine brain death. To perform an EP, small metal disks are attached to the scalp and to various places along the path of the nerve being tested. The time needed to perform an EP varies, depending on the modality being done. It can take approximately two hours, including patient set-up, to perform one type of evoked potential. When performing multiple modalities, 4-6 hours may be needed.
   
   
5. Electrocorticography (ECOG): An electrocorticography is performed to take recordings directly from the surface of the brain through special electrodes. This is done to localize the exact area of abnormal seizure activity arising from the brain. At times, special electrodes may be placed on the brain's surface and left in place for several days to allow recording of EEG activity.
   
   
6. Intraoperative Monitoring (IOM): Many times, the neurodiagnostician is asked to monitor the electrical activity of the central nervous system while the patient is undergoing surgery. The electrical activity from the brain, brainstem, spinal cord, and/or peripheral nerves will often be recorded, especially when there may be a risk to vital neurological structures (such as the brain or spinal cord) during surgery. Electroencephalograms, evoked potentials, electrocorticography and electromyograms (to detect muscle innervation) are commonly performed during surgical procedures.

The Clinical Neurophysiology Department at WKNI

The Clinical Neurophysiology Department at the WKNI is one of approximately 72 accredited EEG labs in the United States. The Department is made up of highly trained technologists who are experts in the field of Electroneurodiagnostics. All of the tests performed in the Department are overseen by neurologists who have received specific training and experience in the field of Neurodiagnostics. All of the testing performed is in accordance with ACNS Guidelines.

Neurodiagnostics Links

American Clinical Neurophysiology Society
American Academy of Neurology
American Epilepsy Society