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Neurodiagnostics & Neuroradiology at The Queen’s Medical Center

» Conditions & Treatments » Neuroscience » Neurodiagnostic Testing


Neurodiagnostic studies assist with evaluation of the electrical activity in the brain and nervous system. Tests are performed by Queen’s Neuroscience Institute technologists. The results are then interpreted by a specially-trained physician.

Electroencephalogram (EEG)

An electroencephalogram, or EEG, records the electrical activity of the brain through highly sensitive electrodes placed at measured intervals on a patient’s scalp. An EEG may be appropriate to evaluate a variety of neurological symptoms including:

What to Expect with EEG Testing

The EEG test usually takes about 90 minutes and is not painful. The principal role of the patient is simply to remain still, relaxed and comfortable.

The head is measured and electrodes are placed on the scalp with a paste-like substance. During the test, the patient may be asked to take repeated deep breaths and will be shown a strobe light that flashes at different speeds. Both activities can help reveal brain patterns that are useful for diagnosis.

At times, physicians may order a sleep EEG to observe brain patterns that occur during sleep. For this test, the patient may be asked to stay awake most of the night before the EEG appointment.

24-Hour EEG Monitoring with Video

24-Hour Video EEG Monitoring is a simultaneous recording of an EEG and video-recorded behavior over extended periods. It is useful in diagnosing patients with intermittent or infrequent disturbances of electrical activity of the brain. This test may be done in an outpatient setting (Ambulatory EEG) or may be done in the hospital due to the long duration and complexity of the recording.

Evoked Potential (EP)

An Evoked Potential, or EP, is a recording of electrical activity from the brain, spinal nerves or sensory receptors to specific external stimulation.

EPs are helpful in evaluating a wide range of neurological problems, including:

What to Expect with Evoked Potential

Electrodes are applied to the scalp and other areas of the body, commonly the legs and arms. A series of stimuli is introduced, and a computer records the neurological responses. Hundreds of responses are received, amplified and averaged by a computer. The final response is plotted and graphed by computer and interpreted by physicians who analyze the waveforms and their speed of transmission.

There are different types of EP which evaluate different parts of the brain or spinal cord. Common examples include brainstem auditory evoked potential (BAER), visual evoked potential (VEP) and somatosensory evoked potential (SSEP).

  • Auditory: The BAER helps in evaluating the auditory nerve pathways from the ears through the lower portion of the brain. Electrodes are attached to the scalp and earlobes, and earphones are placed over the ears. The earphones deliver a series of clicks or tones to each ear separately.
  • Visual: VEPs evaluate the visual pathways of the nervous system from the eyes to the occipital (visual) cortex of the brain. Electrodes are applied to the scalp, and the patient is asked to focus on a pattern on a video screen while remaining fully alert. Each eye is tested separately.
  • Somatosensory: SSEPs assess pathways from nerves in the arms or legs, through the spinal cord, to the brainstem or cerebral cortex. Electrodes are placed on the scalp, along the spinal cord and along the arms or legs. A small electrical current is then applied to the skin overlying nerves on the arms or legs. The current creates a tingling sensation but is usually not painful. Each arm or leg is tested separately.

Transcranial Doppler (TCD) Ultrasound

Transcranial Doppler ultrasound assesses the blood flow velocity, or the speed at which blood flows, in the major arteries of the brain. The assessment of blood flow velocity helps to decide whether there is a narrowing or blockage in some of the arteries in the brain.

TCD technology is an important noninvasive diagnostic tool used in the Neuroscience Intensive Care Unit for the evaluation of subarachnoid hemorrhage-induced cerebral vasospasm.

What to Expect with Transcranial Doppler Ultrasound

The TCD ultrasound is a painless, noninvasive procedure and takes approximately one hour to complete.

The test is done by using a small probe over the temples. The skull is thin in this area and provides a “window” for the ultrasound beam. The probe is also placed over the eyelids, at the back of the neck and the sides of the neck.

For More Information About Neurodiagnostic Testing

To learn more about Neurodiagnostic Testing or to schedule an appointment, please call Queen’s Neuroscience Institute Outpatient Center at 808-691-8866.


Being able to look at the brain and spinal cord are essential parts of diagnosing and treating neurological illnesses. We offer advanced imaging technologies at The Queen’s Medical Center, the only hospital in Hawai‘i that provides 24/7 emergency services for CT, MRI, and biplanar angiography. A CT/PET scanner is also available to detect small cancer cells not visible by other technologies.

A list of commonly performed neuroimaging and neuroradiology is below.

Biplanar Angiogram

The biplanar angiogram is an advanced machine that allows our neurological specialists to see a brain’s blood vessels in 3 dimensions(3-D). It assists our team in providing the safest care in removing blood clots from blood vessels, stopping bleeding and treating brain aneurysms. This advanced technology is a vital part of the Queen’s Comprehensive Stroke Center.

CT Scan (Computerized Tomography Scan) and Portable CT Scan

A Computerized Tomography Scan, or CT Scan, allows our physicians to look for the development of new bleeding or swelling in the brain if a patient comes in with stroke or other types of brain injuries.

When the patient is too sick to be taken to the radiology department, we use a Portable CT Scan. The machine can be taken to any part of the hospital, including the operating room or ICU, and ensures that all of our patients are able to have the procedure done regardless of their location or severity of their condition.

Magnetic Resonance Imaging (MRI)

Queen’s utilizes Magnet Resonance Imaging, more commonly known as MRI, to view the anatomy of the brain with high accuracy and precision. With three MRI scanners readily accessible around the clock, and another available for advanced research, our team of physicians is able to quickly make important medical decisions using the information obtained from the MRI.

Medical conditions that benefit from the information received from an MRI include:

Positron Emission Tomography (PET) Scan

To detect small cancer cells that may not be visible by the MRI or CT, we utilize a Positron Emission Tomography scan, or PET scan. This type of nuclear imaging study allows our team to ensure that there are no undetected cancer cells after a diagnostic workup and treatment.