ECG (Electrocardiogram)
Definition
An electrocardiogram (ECG) is a test that records the electrical activity of the heart.
ECG is used to measure the rate and regularity of heartbeats as well as the size and position of the chambers, the presence of any damage to the heart, and the effects of drugs or devices used to regulate the heart (such as a pacemaker). See also stress test and Holter monitor (24h).
CT SCAN
| CT scanning has revolutionized the field of
radiology. It has made high quality cross sectional
images of body parts possible. Introduced roughly 25
years ago, the technology which had been progressively
improving, has now been revolutionized by Spiral CT
technology. The CT scanner at DCHRC is a fourth
generation whole body multi-slice spiral CT scanner.
Spiral CT scanning has significant advantages for the
cancer patients. |
| The entire region of interest can be scanned
very fast, usually in a single breath hold.
The scan can therefore be completed during
peak enhancement of the tissues by the
injected contrast material. This makes
abnormalities more obvious, delineates them
better and also improves their pick up rate. |
| Short scanning time (less than
30 seconds) avoids inconvenience to very sick
and restless patients. |
| Very high quality re-constructions including
3 D images can be made including Bronco
Endoscopies. |
| High quality angiogram can be produced by
the computer from the data obtained without
any need of invasive procedure. |
|
EEG (Electroencephalography)
Definition
EEG is an essential component in the evaluation of epilepsy. The EEG provides important information about background EEG and epileptiform discharges and is required for the diagnosis of specific electroclinical syndromes. Such a diagnosis carries important prognostic information, guides selection of antiepileptic medication, and suggests when to discontinue medication.
Following a seizure (ie, during the postictal period) the EEG background may be slow. However, interictal background EEG frequencies that are slower than normal for age usually suggest a symptomatic epilepsy (ie, epilepsy secondary to brain insult). Normal background suggests primary epilepsy (ie, idiopathic or possibly genetic epilepsy). Thus EEG background offers important prognostic and classification information.
ENG
(Electronystagmography)
The purpose of the ENG is to determine whether or not dizziness may be due to inner ear disease. There are four main parts to the ENG. The calibration test evaluates rapid eye movements. The tracking test evaluates movement of the eyes as they follow a visual target. The positional test measures dizziness associated with positions of the head. The caloric test measures responses to warm and cold water circulated through a small, soft tube in the ear canal.
The ENG test is the gold-standard for diagnosis of ear disorders affecting one ear at a time. For example, the ENG is excellent for diagnosis of vestibular neuritis. The ENG is also useful in diagnosis of BPPV and bilateral vestibular loss, although the rotatory chair test is better at the diagnosis of bilateral vestibular disorders than is the ENG. The calibration and tracking tests are intended to diagnose central nervous system disorders, such as cerebellar degenerations. These tests are generally insensitive compared to an examination by a neurologist or an MRI scan. ENG, however, is much less expensive than an MRI in most institutions.
BERA (Brainstem Auditory Evoked Response)
Alternative names
Evoked auditory potentials; BAEP - brainstem auditory evoked potentials; Evoked response audiometry
Definition
The brainstem auditory evoked response (BAER) test measures responses in brain waves that are stimulated by a clicking sound to evaluate the central auditory pathways of the brainstem.
How the test is performed
You are positioned on a reclining chair or bed and are asked to relax and remain still. Electrodes are placed on your scalp and on each earlobe. You hear clicking noises or tone bursts through earphones, and the electrodes pick up the brain's response and record it on a graph.
How to prepare for the test
You may be asked to wash your hair the night before the test.
VER (Visual Evoked Response)
A VEP test evaluates the visual pathways in your brain.
During the test, you watch a video monitor with a moving
pattern. Watching the moving pattern produces electrical
activity in your brain that is measured by several
electrodes attached to your head.
What is it?
- The test evaluates the visual pathways in your brain.
- It checks on the health of the "internal"
parts of your visual system.
Why is a VEP performed?
- It is used if you are experiencing double vision,
blurred vision, loss of part or all of your vision, eye
injuries, head injuries, or weakness of eyes, arms, or
legs.
Does it hurt?
- No, you will experience no pain or discomfort.
- The VEP is not a vision test such as is done for
glasses, nor is it a treatment of any kind.
What should you do to prepare for the test?
- Wash your hair before coming to the test. Do NOT use
sprays, oils, or dressings of any kind.
- Eat normal meals.
- Continue taking prescribed medications unless given
other instructions by your doctor.
- Bring glasses or contact lenses with you if you wear
them.
- Come well rested so you can be alert during the test.
How is the VEP performed?
- After your head is measured, electrodes are glued on
specific locations on your scalp.
- Nothing goes into or under your skin.
- Each electrode is checked with a meter to ensure
proper functioning.
- A patch will be placed over one of your eyes.
- You will recline in a special chair and be asked to
stare at a little red dot on a video monitor.
- Each eye will be tested separately.
Audiometry
Synonyms and related keywords: tympanometry, acoustic
reflex testing, eustachian tube function testing, acoustic
immittance tests, perilymphatic fistula test, acoustic
reflex threshold, acoustic reflex decay, middle ear
effusion, perforation of the tympanic membrane, patency of
pressure equalization tubes, tympanosclerosis, hypermobility
of the tympanic membrane, eustachian tube dysfunction, glue
ear, otosclerosis, ossicular discontinuity, acoustic neuroma,
CN VIII disorder, CN VII disorder, hearing loss, brainstem
disorder
The primary purpose of impedance audiometry is to
determine the status of the tympanic membrane and middle ear
via tympanometry. The secondary purpose of this test is to
evaluate acoustic reflex pathways, which include cranial
nerves (CN) VII and VIII and the auditory brainstem. This
test cannot be used to directly assess auditory sensitivity,
although results are interpreted in conjunction with other
threshold measures.
Acoustic immittance is a measurement of energy or air
pressure flow, which involves the ear canal, eardrum,
ossicular chain, tensor tympani, stapedius muscle, cochlea,
CNs VII and VIII, and the brainstem. Mass, mobility, and
resistance of the outer and middle ear systems affect this
test. The reciprocal of acoustic immittance is acoustic
impedance. Particularly in earlier years, these measurements
were performed in impedance rather than immittance measures;
thus, the term impedance audiometry sometimes is used.
For excellent patient education resources, visit
eMedicine's Ear, Nose, and Throat Center. Also, see
eMedicine's patient education article Perforated Eardrum.
Acoustic immittance tests
The following tests are included in the category acoustic
immittance tests:
- Tympanometry
- Eustachian tube function
- Perilymphatic fistula test (efficacy questionable)
- Acoustic reflex thresholds
- Acoustic reflex decay
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