Diagnostic Tests

Computed tomography scan (also called a CT or CAT scan)
A diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat and organs. CT scans are more detailed than general x-rays.

Brainstem Auditory Evoked Response (BAER)
The brainstem auditory evoked response (BAER) test measures responses in brain waves that are stimulated by a clicking sound to check the central auditory (hearing) pathways of the brainstem. The child will be asked to lie on a reclining chair or bed and remain still. Electrodes are placed on the scalp and on each earlobe. Clicking noises or tone bursts will be heard through earphones, and the electrodes pick up the brain's response and record it on a graph.

Magnetic resonance imaging (MRI)
A magnetic resonance imaging scan is usually called an MRI. It may also be called a nuclear magnetic resonance (NMR) or a magnetic field scan. It is a medical test that takes pictures of the inside of the body. Each picture or “slice” shows only a few layers of body tissue at a time. The MRI machine uses a large magnet and a computer to make pictures of your body. Pictures taken this way may help caregivers find and see problems in the body more easily. This test usually takes between 15 and 90 minutes.

Myelogram
An injection of x-ray contrast fluid in order to highlight spinal nerves and the spinal canal. It is a commonly used test for determining causes of back or leg pain or weakness (lumbar myleogram) or neck and arm pain or weakness (cervical myleogram).

Ultrasound (also called sonography)
A diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.

Electroencephalography (EEG)
A non-invasive test that graphically records the electrical impulses of the brain cells.

Electromyography (EMG)
A recording of electrical activity in the muscles.

Visual evoked potential (VEP)
A test which checks the pathway from the eyes to the brain. This test may help uncover the cause of visual disturbances and other conditions.

Electronystagmography (ENG) Test
This is the most commonly used test to evaluate the vestibular system (balance portions of the inner ear, nerve and brain). When the head is in motion, the inner-ear balance organs send signals to the eye muscles to keep vision in focus. Therefore, eye movements can be used to evaluate the balance system. Electrodes are taped near to the eyes, and a computer records results as patients follow a moving light with their eyes and as they sit and lie in different positions. Each ear canal also is irrigated with small amounts of warm and cool water (caloric test) as the patient lies on an examination table. The water causes a temperature change that creates eye movements (nystagmus) that can be measured and compared for each ear. The patient’s physician uses the information obtained from the ENG, along with information from other clinical tests, to make a diagnosis and recommendations for treatment. This type of ENG cannot be used with infants, very small children, or if there is a perforation (hole) in the eardrum. In these cases, rotary chair is the most appropriate test.

Rotary chair testing
This test provides another means of assessing inner ear function and is often better tolerated than the ENG. Rotary chair testing can be sued to test patients of all ages, including infants. The patient sits in a chair in a small, dark booth. Small children and infants sit on a parent’s lap for this procedure. Electrodes are attached near the eyes and the computer-driven chair rotates gently back and forth at several acceleration rates. This motion stimulates the inner balance system and causes eye movements (nystagmus) that are recorded by a computer and monitored with an infrared camera. Unlike the ENG, rotary chair testing cannot provide specific diagnostic information about each ear individually. The rotary chair test is particularly useful when confirming a suspected loss of inner ear balance function in both ears and determining the extent of residual function. It is also a reliable method of monitoring the effects of ototoxic medications on the inner balance system over time.


Posturography
Moving platform posturography (MVP), or posturography for short, is a method of quantifying balance (although the definition of balance can be tricky). It is most applicable in situations where balance needs to be followed quantitatively, to determine whether a disorder is getting better or worse, or the response to treatment.

Brain SPECT
A SPECT scan integrates two technologies to view your body: computed tomography (CT) and a radioactive material (tracer). The tracer is what allows doctors to see how blood flows to tissues and organs. The computer collects the information emitted by the gamma rays and translates them into two-dimensional cross-sections. These cross-sections can be added back together to form a 3D image of your brain.

Echo planar imaging
MR systems equipped with Echo Planar Imaging (EPI) packages can use special emergency or fast protocols to do a basic head study in as little as five to twenty seconds.

Transcranial Doppler
Doppler ultrasound scanning measures blood flowing through the carotid arteries or the arteries at the bases of the brain. This test assesses the risk of stroke.

Video EEG
The Video EEG Monitoring Test is a more specialized form of an EEG test in which the patient is constantly monitored over a video screen. This allows doctors to observe brainwave activity during the time a seizure or spell is occurring.

24-Hour ambulatory EEG
This test is used to distinguish non-epileptic from epileptic turns in situations where the child cannot be confined to a bed for inpatient or outpatient video EEG monitoring. It may be used to capture events that are situational.

Automated perimetry
This is an important tool to detect and monitor blind spots caused by glaucoma.

Stereotactic surgery
Stereotactic surgery is brain surgery guided by CT scanning. The surgeon, viewing three-dimensional images, is able to deliver a single, high dose of radiation to the exact diseased location in the brain or spinal cord. This precise dose does not injure the areas of the brain closest to the tumor.

Stereotactic radiosurgery
Stereotactic radiosurgery uses sophisticated 3-D computerized imaging to precisely target a narrow x-ray beam and deliver a high concentrated dose of radiation to the affected area. Stereotactic radiosurgery is not surgery in the conventional sense because there is no incision involved and general anesthesia is not required for adults.

Polysomnogram
A polysomnograph is a test of sleep cycles and stages through the use of continuous recordings of brain waves (EEG), electrical activity of muscles, eye movement (electrooculogram), breathing rate, blood pressure, blood oxygen saturation, and heart rhythm and direct observation of the person during sleep.

Pneumocardiogram with PH probe
This “sleep test” uses six channels to monitor an infant’s sleep pattern to check for reflux, periodic breathing, apnea, and heart rate abnormalities. The six channels include: ECG to monitor heart rate, a thermistor in the nose and above the lip to observe airflow from the nose and mouth, and actimeter in the hand to check for activity of the infant, pH probe inserted into the esophagus to measure the acidity of gastric contents which may indicate reflux, and an oxygen saturation monitor to watch for desaturation during sleep.