FitSugar

Are You at Risk For Meniere's Disease?

FitSugar — Tue, 02 Dec 2008 11:00:00 -0800

If you've ever had a little too much to drink, you probably experienced that dizzy sensation where you feel like the room is spinning, know as vertigo in medical-ese. Unfortunately, people diagnosed with Meniere's disease don't have to drink in order to experience such debilitating dizzy spells. Vertigo episodes occur out of the blue, with no apparent cause, in some cases lasting up to eight hours. Aside from dizziness, this disease may also cause ringing in the ear (tinnitus), hearing loss, sweating, uncontrollable eye movements, and vomiting.

Sounds unbearable. To find out if you're at risk for Meniere's disease read more.

Meniere's is a disorder of the inner ear that usually occurs in men and women in their 30s. Scientists aren't sure what causes this disease, but it may be related to any of these reasons: middle ear or respiratory infections, stress, fatigue, syphilis, Lyme disease, a history of allergies, smoking, alcohol use, or head injury. Although Meniere's is not contagious, it may be genetic.

Unfortunately, there's no known cure for Meniere's disease, but a person can help prevent dizzy episodes by lowering the endolymphatic pressure in her inner ear. To do this, medication may help, as well as stress reduction and a low-sodium, no caffeine, no alcohol diet. If symptoms become severe and the person can't work or drive, surgery may be necessary. If these symptoms sound familiar, it's best to get tested by your doctor.

Source

Meniere’s disease

admin — Wed, 03 Sep 2008 17:51:28 -0700

Illustrations

Ear anatomy

Tympanic membrane

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

Meniere's disease is a disorder of the inner ear affecting balance and hearing, characterized by abnormal sensation of movement (vertigo), dizziness, loss of hearing in one or both ears, and noises or ringing in the ear (tinnitus).

Alternative Names

Hydrops; Endolymphatic hydrops

Causes, incidence, and risk factors

The fluid-filled semicircular canals (labyrinths) of the inner ear, in conjunction with the cranial nerve VIII, control balance and sense of body position. Meniere's disease involves a swelling of part of the canal (endolymphatic sac). The endolymphic sac controls the filtration and excretion of the fluid in the semicircular canals.

The exact cause of Meniere's disease is unknown. In some cases, it may be related to middle ear infection (otitis media), syphilis, or head injury. Other risk factors include recent viral illness, respiratory infection, stress, fatigue, use of prescription or nonprescription drugs including aspirin, and a history of allergies, smoking, and alcohol use. There may be genetic risk factors as well.

About 100,000 people per year develop Meniere's disease.

Symptoms

Abnormal sensation of movement of self or the environment (vertigo)
- May be episodic
- Lasts from minutes to more than 8 hours
- Worse with sudden movement
Dizziness
Hearing loss in one ear
- Low frequency noises lost first
- Extent of hearing loss may change
Noises or ringing in one ear (tinnitus)
Nausea, vomiting
Sweating (may be profuse)
Uncontrollable eye movements

Signs and tests

A neurologic examination may show an abnormality of cranial nerve VIII that may include abnormalities of hearing, balance, or eye movement.

Tests to distinguish Meniere's disease from other causes of vertigo may include:

Head CT scan or head MRI scan
Caloric stimulation (tests reflexes of the eyes) -- abnormal results indicate Meniere's disease
Evoked potential studies (BAER)
Electronystagmography
Audiology/audiometry

Treatment

There is no known cure for Meniere's disease. Treatment is focused on lowering the pressure within the endolymphatic sac and on treating symptoms, which tend to occur in discrete "attacks."

Medications such as antihistamines, anticholinergics, and diuretics may lower endolymphatic pressure by reducing the amount of endolymphatic fluid. A low-salt diet to reduce fluid retention may also help (see sodium in diet).

Symptoms such as dizziness, vertigo, and associated nausea and vomiting may respond to sedative/hypnotics, benzodiazepines like diazepam, and anti-emetics.

Surgery on the labyrinth, endolymphatic sac, or the vestibular nerve may be required if symptoms are severe and do not respond to other treatment.

Hearing aids may be needed for severe hearing loss.

Avoid sudden movements that may aggravate symptoms. Help may be needed with walking due to loss of balance during attacks. Rest during severe episodes, and gradually increase activity. During episodes, avoid bright lights, TV, and reading, which may make symptoms worse.

Avoid hazardous activities such as driving, operating heavy machinery, climbing, and similar activities until one week after symptoms disappear.

Physical therapy aimed at acclimation to various positions may be useful.

Expectations (prognosis)

The outcome varies. Meniere's disease can often be controlled with treatment. Recovery may occur spontaneously. However, the disorder may be chronic or disabling.

Complications

Inability to walk or function due to uncontrollable vertigo
Hearing loss on the affected side

Calling your health care provider

Call for an appointment with your health care provider if symptoms of Meniere's disease, such as hearing loss, ringing in the ears, or dizziness, occur or worsen.

Prevention

There is no known prevention for Meniere's disease, but prompt treatment of ear infection and other related disorders may be helpful.

Review Date: 8/7/2006

Reviewed By: Daniel Kantor, M.D., Director of the Comprehensive MS Center, Neuroscience Institute, University of Florida Health Science Center, Jacksonville, FL. Review provided by VeriMed Healthcare Network.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

A.D.A.M. Copyright

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-2009 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

adam.com

Source Doc: 1_000702

Dizziness

admin — Thu, 04 Sep 2008 19:05:12 -0700

Overview

Definition
Alternative Names
Common Causes
Home Care
Call your health care provider if
What to expect at your health care provider's office
Prevention
References

Illustrations

Carotid stenosis, X-ray of the left artery

Carotid stenosis, X-ray of the right artery

Vertigo

Balance receptors

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

Dizziness is lightheadedness, feeling like you might faint, being unsteady, loss of balance, or vertigo (a feeling that you or the room is spinning or moving).

Most causes of dizziness are not serious and either quickly resolve on their own or are easily treated.

Alternative Names

Lightheadedness - dizzy; Loss of balance; Vertigo

Common Causes

Lightheadedness happens when there is not enough blood getting to the brain. This can happen if there is a sudden drop in your blood pressure or you are dehydrated from vomiting, diarrhea, fever, or other causes. Many people, especially as they get older, experience lightheadedness if they get up too quickly from a lying or seated position. Lightheadedness often accompanies the flu, hypoglycemia, common cold, or allergies.

More serious conditions that can lead to lightheadedness include heart problems (such as abnormal heart rhythm or heart attack), stroke, and severe drop in blood pressure (shock). If any of these serious disorders is present, you will usually have additional symptoms like chest pain, a feeling of a racing heart, loss of speech, change in vision, or other symptoms.

The most common causes of vertigo are benign positional vertigo and labyrinthitis. Benign positional vertigo is vertigo that happens when you change the position of your head. Labyrinthitis usually follows a cold or flu and is caused by a viral infection of the inner ear. Meniere's disease is another common inner ear problem. It causes vertigo, loss of balance, and ringing in the ears.

Much less commonly, vertigo or feeling unsteady is a sign of stroke, multiple sclerosis, seizures, a brain tumor, or a bleed in your brain. In such conditions, other symptoms usually accompany the vertigo or imbalance.

Home Care

If you tend to get lightheaded when you stand up, avoid sudden changes in posture.

If you are thirsty or lightheaded, drink fluids. If you are unable to keep fluids down from nausea or vomiting, you may need intravenous fluids. These are delivered to you at the hospital.

Most times, benign positional vertigo and labyrinthitis go away on their own within a few weeks. During attacks of vertigo from any cause, try to rest and lie still. Avoid sudden changes in your position as well as bright lights. Be cautious about driving or using machinery.

Some vertigo can be reduced by working with a physical therapist. Medications from your doctor may help you feel better.

Such medications include antihistamines, sedatives, or pills for nausea. For Meniere's disease, surgery may be necessary.

Call your health care provider if

Call 911 or go to an emergency room if someone with dizziness also has:

A head injury
Fever over 101°F, headache, or very stiff neck
Convulsions or ongoing vomiting
Chest pain, heart palpitations, shortness of breath, weakness, inability to move an arm or leg, or change in vision or speech
Fainting and losing consciousness for more than a few minutes

Call your doctor if:

You have never had dizziness before.
Symptoms you have had in the past are different (for example, last longer than usual, are worse than before, or are interfering with your daily activities).
Medication is the suspected cause. Talk to your health care provider before making any changes to your medication.
You have any hearing loss.

What to expect at your health care provider's office

Your doctor will perform a physical exam, focusing on your heart, head, ears, and nervous system, and ask question such as:

Does your dizziness feel like lightheadedness, vertigo, or imbalance?
Does your dizziness occur with a change in body position?
What other symptoms occur when you feel dizzy?
When did your dizziness begin?
Are you always dizzy or does the dizziness come and go?
How long does the dizziness last (minutes, hours)?
Did another illness develop before or after the dizziness began? How much later?
Have you had any nausea and vomiting?
Do you have a significant amount of stress or anxiety?

Diagnostic tests that may be performed include:

Blood pressure measurements and tests
ECG
Hearing tests
Neurological tests
Balance testing (ENG) may be required.
MRI

Prevention

Promptly treat ear infections, colds, flus, sinus congestion, and other respiratory infections. This may help prevent labyrinthitis and Meniere's disease.

If you have a cold, the flu, or other viral illness, drink plenty of fluids to prevent getting dehydrated.

References

da Costa SS. Meniere's disease: overview, epidemiology, and natural history. Otolaryngol Clin North Am. 2002; 35(3): 455-495.

Tusa RJ. Dizziness. Med Clin North Am. 2003; 87(3): 609-641, vii.

Swartz R. Treatment of vertigo. Am Fam Physician. 2005; 71(6): 1115-1122.

Review Date: 4/3/2007

Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Daniel Kantor, M.D., Director of the Comprehensive MS Center, Neuroscience Institute, University of Florida Health Science Center, Jacksonville, FL. Review provided by VeriMed Healthcare Network (5/16/2006).

A.D.A.M. Copyright

adam.com

Source Doc: 1_003093

MRI of the head

admin — Thu, 04 Sep 2008 19:15:48 -0700

Overview

Definition
Alternative Names
How the test is performed
How to prepare for the test
How the test will feel
Why the test is performed
What abnormal results mean
What the risks are
Special considerations

Illustrations

Brain

MRI scans

Lobes of the brain

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

An MRI of the head is a noninvasive procedure that uses powerful magnets and radio waves to construct clear, detailed pictures of brain tissues.

Conventional radiography and computed tomographic (CT) imaging use potentially harmful radiation (x-rays) that passes through a patient to generate images. Magnetic resonance imaging (MRI) is based on the magnetic properties of atoms, and there is no exposure to the same type of radiation used in x-rays and CT scans.

A powerful magnet generates a magnetic field roughly 10,000 times stronger than the Earth's. A very small percentage of hydrogen atoms within the body will align with this field. Radio wave pulses are broadcast towards the aligned hydrogen atoms in tissues of interest, returning a signal of their own. The slight differences of those signals from different tissues enables MRI to tell the difference between various organs, and potentially, provide contrast between benign and malignant tissue.

Any imaging angle, or "slice", can be projected, and then stored in a computer or printed on film. MRI can easily be performed through clothing and bones. However, certain types of metal in or around the area of interest can cause significant errors in the reconstructed images. These errors are called artifacts.

Alternative Names

Nuclear magnetic resonance - cranial; Magnetic resonance imaging - cranial; Head MRI scan; MRI - cranial; NMR - cranial; Cranial MRI

How the test is performed

Since MRI makes use of radio waves very close in frequency to those of ordinary FM radio stations, the scanner must be located within a specially shielded room to avoid outside interference.

You will lie on a narrow table which slides into a large tunnel-like tube within the scanner. In addition, a small device may be placed around the head. This is a special body coil which sends and receives the radio wave pulses. It is designed to improve the quality of the images.

If contrast dye is used, it will be injected into a small vein of the hand or forearm. A technologist will operate the machine and observe you during the entire study from an adjacent room.

Several sets of images are usually required, each taking from 2 to 15 minutes. Depending on the sequences performed and the possibility of the need for a contrast dye, a complete scan may take up to a hour or more. Newer scanners with more powerful magnets, updated software, and advanced sequences may complete the process in less time.

How to prepare for the test

No special tests, diets, or medications are usually needed. An MRI may be performed immediately after other imaging studies.

Because of the strong magnets, certain metallic objects are not allowed into the room. Items such as jewelry, watches, credit cards, and hearing aids can be damaged. Pins, hairpins, metal zippers, and similar metallic items can distort the images. Removable dental work should be taken out just prior to the scan. Pens, pocketknives, and eyeglasses can become dangerous projectiles when magnet is activated and should not accompany the patient into the scanner area.

Because the strong magnetic fields can displace or disrupt the action of implanted metallic objects, people with cardiac pacemakers cannot be scanned and should not enter the MRI area. MRI also should not be used for people with metallic objects in their bodies such as inner ear (cochlear) implants, brain aneurysm clips, some artificial heart valves, older vascular stents, and recently placed artificial joints. The technologist will usually provide you with a questionnaire which lists the potentially dangerous items.

Sheet metal workers, or persons with similar potential exposure to small metal fragments, will first be screened for metal shards within the eyes with x-rays of the skull. The patient will be asked to sign a consent form confirming that none of the above issues apply before the study will be performed.

A hospital gown may be recommended, or the patient may be allowed to wear a sweat suit or similar clothing without metal fasteners.

How the test will feel

There is no pain. The magnetic field and radio waves are not felt. Some people experience a claustrophobic feeling from being inside the scanner. The table may be hard or cold, but you can request a blanket or pillow.

The machine produces loud thumping and humming noises during normal operation. Ear plugs are usually given to the patient to reduce the noise. A technologist observes the patient during the entire procedure and may be spoken to through an intercom in the scanner. Some MRI scanners are equipped with televisions and special headphones to help the examination time pass.

Excessive movement can blur MRI images and cause errors in the image. If the patient has difficulty lying still or is very anxious, they may be given medicine to relax them (a sedative), by mouth or through a vein. There is no recovery, unless sedation was necessary. After an MRI scan, you can resume normal diet, activity, and medications.

Why the test is performed

MRI provides detailed pictures of the brain and nerve tissues from multiple angles without obstruction by overlying bone. In fact, about 90% of all MRI scans are for brain or spine disorders.

MRI is the procedure of choice for most brain disorders. MRI is particularly useful in brain and neurological disorders, because it can clearly show different types of nerve tissue. It provides clear pictures of the brainstem and posterior brain, which are difficult to view on CT scan. It is also useful for the diagnosis of demyelinating disorders. These are disorders such as multiple sclerosis, which cause destruction of the myelin covering of the nerve.

MRI is a noninvasive procedure that can evaluate blood flow and the flow of cerebrospinal fluid (CSF). MRI can distinguish tumors or other lesions from normal tissues. MRI is sometimes used to avoid the dangers of angiography or of repeated exposure to radiation.

What abnormal results mean

The sensitivity of an MRI depends, in part, on the experience of the radiologist.

An MRI of the head may reveal disorders including:

Primary brain tumors
Metastatic brain tumors
Structural abnormalities of the brain, brain ventricles, and pituitary gland
Pituitary masses
Lesions or masses (any location)
Acoustic neuroma
Optic glioma
Arteriovenous malformations of the head
Brain aneurysms
Damage to basal ganglia (an area of the brain that regulates movement)
Subdural hematoma, blood clots
Intracranial hemorrhage (more than 48 hours old)
Radiation damage to the brain
Brain swelling
Demyelinating diseases
Tissue destruction in the brain
Brain abscess
Abnormalities of blood flow (such as carotid artery stenosis)

Additional conditions under which the test may be performed:

Acromegaly
Amyotrophic lateral sclerosis
Throat cancer
Chronic subdural hematoma
Cushing's syndrome
Deep intracerebral hemorrhage
Delirium
Dementia
Dementia due to metabolic causes
Diabetes insipidus; central
Hemorrhagic (bleeding) stroke
Huntington's disease
Hypertensive intracerebral hemorrhage
Hypopituitarism
Intracerebral hemorrhage
Lobar intracerebral hemorrhage
Melanoma of the eye
Meniere's disease
Multi-infarct dementia
Multiple endocrine neoplasia (MEN) I
Multiple sclerosis
Normal pressure hydrocephalus (NPH)
Partial (focal) seizure
Partial complex seizure
Petit mal seizure
Pituitary Cushing's (Cushing's disease)
Prolactinoma
Reye's syndrome
Senile cerebral amyloid angiopathy
Senile dementia/Alzheimer's type
Acute sinusitis
Chronic sinusitis
Stroke
Stroke secondary to atherosclerosis
Stroke secondary to cardiogenic embolism
Stroke secondary to FMD
Stroke secondary to syphilis
Temporomandibular joint (TMJ) syndrome
Toxoplasmosis
Transient ischemic attack (TIA)
Wernicke-Korsakoff syndrome
Wilson's disease

What the risks are

There is no ionizing radiation involved in MRI. To date, there have been no documented significant side effects of the magnetic fields and radio waves used on the human body during an MRI scan.

The most common MR intravenous contrast agent, gadolinium, is very safe, and although there have been documented allergic reactions to it, it is an extremely rare occurrence. However, gadolinium should not be given if you are pregnant because of potential harm to the fetus.

If sedation is used, there are associated risks of over-sedation. The technologist monitors the patient's vital signs, including heart rate and breathing as needed.

People have been harmed in MRI machines when they did not remove metal objects from their clothes or when metal objects were left in the room by others.

Special considerations

MRI is superior to computed tomography (CT) in most cases where differentiation of soft tissues is necessary. It can view organs without obstruction by bone and foreign bodies. It is capable of showing the tissues from multiple viewpoints and is a noninvasive way to evaluate blood flow.

A CT scan may be preferred for:

Acute trauma of the head and face
Acute (less than 72 hours) neurological dysfunction
Early symptoms of stroke
Subarachnoid or intracranial hemorrhage (within the first 24 - 48 hours)
Skull bone disorders, disorders involving the bones of the ear

Review Date: 10/25/2006

Reviewed By: Stuart Bentley-Hibbert, M.D., Ph.D., Department of Radiology, Weill Cornell Medical Center, New York, NY. Review provided by VeriMed Healthcare Network.

A.D.A.M. Copyright

adam.com

Source Doc: 1_003791

Eye movements - uncontrollable

admin — Thu, 04 Sep 2008 19:04:10 -0700

Overview

Definition
Alternative Names
Considerations
Common Causes
Home Care
Call your health care provider if

Illustrations

External and internal eye anatomy

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

Uncontrollable eye movements are involuntary, rapid, and repetitive movement of the eyes.

Alternative Names

Back and forth eye movements; Involuntary eye movements; Nystagmus; Rapid eye movements from side to side; Uncontrolled eye movements

Considerations

Nystagmus refers to rapid involuntary movements of the eyes that may be from side to side (horizontal nystagmus), up and down (vertical nystagmus) or rotary. Depending on the cause, these movements may be in both eyes or in just one eye. The term "dancing eyes" has been used in regional dialect to describe nystagmus.

The involuntary eye movements of nystagmus are caused by abnormal function in the areas of the brain that control eye movements. The exact nature of these disorders is poorly understood. Nystagmus may be either congenital (present at birth) or may be acquired (caused by disease or injury later in life).

CONGENITAL NYSTAGMUS

Congenital nystagmus is more common than acquired nystagmus. It is usually mild, does not change in severity, and is not associated with any other disorder.

Affected people are not aware of the eye movements, although they may be noticed by a careful observer. If the movements are of large magnitude, visual acuity (sharpness of vision) may be less than 20/20. Surgery may improve visual acuity.

Rarely, nystagmus occurs as a result of congenital diseases of the eye that cause poor vision. Although this is rare, an ophthalmologist should evaluate any child with nystagmus to check for this.

ACQUIRED NYSTAGMUS

A less-common cause of nystagmus is disease or injury of the central nervous system.

In young people the most common cause of acquired nystagmus is head injury from motor vehicle accidents. In older people the most common cause is stroke (blood vessel blockage in the brain). Any disease of the brain (such as multiple sclerosis or brain tumors) can cause nystagmus if the areas controlling eye movements are damaged.

Because control of eye movements is affected by input from the labyrinth (the part of the inner ear that senses movement and position), inner ear disorders such as Meniere's disease can also lead to acquired nystagmus. Other causes may include Dilantin (an antiseizure medication) or alcohol intoxication.

Nystagmus may be observed through the following procedure: If the affected person spins around for about 30 seconds, stops, and tries to stare at an object, the eyes will first move slowly in one direction, then move rapidly in the opposite direction. The orientation of these alternating movements (side-to-side, up-and-down, or in a circular pattern) depends on the type of nystagmus.

Common Causes

Nystagmus is a symptom of many different disorders. Your health care provider will take a careful history and perform a thorough physical examination, which will emphasize the nervous system and inner ear.

Questions asked in a medical history may cover the following areas:

When was it first noticed?
How often does it occur?
Has it ever happened before?
Is it getting better, worse, or staying the same?
Are there side-to-side eye movements?
Are there up-and-down eye movements?
What medications are being taken?
What other symptoms are present?

Diagnostic tests that may be performed include:

CT scan of the head or MRI of the head
Electro-oculography: An electrical method of measuring eye movements using tiny electrodes.

Home Care

There is no therapy for most cases of congenital nystagmus. Availability of treatment for acquired nystagmus will vary with the cause. In most cases, except for those caused by Dilantin or alcohol intoxication, nystagmus is irreversible.

Call your health care provider if

Nystagmus is detected or suspected.

Review Date: 3/5/2007

Reviewed By: Daniel Kantor, M.D., Director of the Comprehensive MS Center, Neuroscience Institute, University of Florida Health Science Center, Jacksonville, FL. Review provided by VeriMed Healthcare Network.

A.D.A.M. Copyright

adam.com

Source Doc: 1_003037

EEG

admin — Thu, 04 Sep 2008 19:17:56 -0700

Overview

Definition
Alternative Names
How the test is performed
How to prepare for the test
How the test will feel
Why the test is performed
Normal Values
What abnormal results mean
What the risks are

Illustrations

Brain

Brain wave monitor

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

An electroencephalogram (EEG) is a test to detect problems in the electrical activity of the brain.

Alternative Names

Electroencephalogram; Brain wave test

How the test is performed

Brain cells communicate by producing tiny electrical impulses. In an EEG, electrodes are placed on the scalp over multiple areas of the brain to detect and record patterns of electrical activity and check for abnormalities.

The test is performed by an EEG technician in a specially designed room that may be in your health care provider's office or at a hospital. You will be asked to lie on your back on a table or in a reclining chair.

The technician will apply between 16 and 25 flat metal discs (electrodes) in different positions on your scalp. The discs are held in place with a sticky paste. The electrodes are connected by wires to an amplifier and a recording machine.

The recording machine converts the electrical signals into a series of wavy lines that are drawn onto a moving piece of graph paper. You will need to lie still with your eyes closed because any movement can alter the results.

You may be asked to do certain things during the recording, such as breathe deeply and rapidly for several minutes or look at a bright flickering light.

How to prepare for the test

You will need to wash your hair the night before the test. Do not use any oils, sprays, or conditioner on your hair before this test.

Your health care provider may want you to stop taking certain medications before the test. Do not change or stop medications without first talking to your health care provider.

You should avoid all foods containing caffeine for 8 hours before the test.

Sometimes it is necessary to sleep during the test, so you may be asked to reduce your sleep time the night before.

How the test will feel

This test causes no discomfort. Although having electrodes pasted onto your skin may feel strange, they only record activity and do not produce any sensation.

Why the test is performed

EEG is used to help diagnose the presence and type of seizure disorders, to look for causes of confusion, and to evaluate head injuries, tumors, infections, degenerative diseases, and metabolic disturbances that affect the brain.

It is also used to evaluate sleep disorders and to investigate periods of unconsciousness. The EEG may be done to confirm brain death in a comatose patient.

EEG cannot be used to measure intelligence or diagnose mental illness.

Normal Values

Brain waves have normal frequency and amplitude, and other characteristics are typical.

What abnormal results mean

Abnormal findings may suggest the following:

Seizure disorders (such as epilepsy or convulsions)
Structural brain abnormality (such as a brain tumor or brain abscess)
Head injury
Attention deficit problems
Encephalitis (inflammation of the brain)
Hemorrhage (abnormal bleeding caused by a ruptured blood vessel)
Cerebral infarct (tissue that is dead because of a blockage of the blood supply)
Sleep disorders (such as narcolepsy)
Drug or alcohol abuse
Migraines (in some cases)
Hallucinations
Syncope
Vertigo

EEG may confirm brain death in someone who is in a coma. Note: a normal EEG does not mean that a seizure did not occur.

Additional conditions under which the test may be performed:

Arteriovenous malformation (cerebral)
Benign positional vertigo
Cerebral aneurysm
Complicated alcohol abstinence (delirium tremens)
Creutzfeldt-Jacob disease
Delirium
Dementia
Dementia due to metabolic causes
Febrile seizure (children)
Generalized tonic-clonic seizure
Hepatic encephalopathy
Hepatorenal syndrome
Insomnia
Labyrinthitis
Meniere's disease
Metastatic brain tumor
Multiple sclerosis
Optic glioma
Partial (focal) seizure
Partial complex seizure
Petit mal seizure
Pick's disease
Senile dementia (Alzheimer's type)
Shy-Drager syndrome
Syphilitic aseptic meningitis
Temporal lobe seizure

What the risks are

The procedure is very safe. If you have a seizure disorder, a seizure may be triggered by flashing lights or by hyperventilation. The health care provider performing the EEG is trained to take care of you if this happens.

Review Date: 9/25/2006

Reviewed By: Kenneth Gross, M.D., Neurology, North Miami, FL. Review provided by VeriMed Healthcare Network.

A.D.A.M. Copyright

adam.com

Source Doc: 1_003931

Cranial CT scan

admin — Thu, 04 Sep 2008 19:15:42 -0700

Overview

Definition
Alternative Names
How the test is performed
How to prepare for the test
How the test will feel
Why the test is performed
What abnormal results mean
What the risks are
Special considerations

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

A cranial CT scan is computed tomography of the head, including the skull, brain, orbits (eye sockets), and sinuses.

Alternative Names

Head CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses

How the test is performed

A head CT will produce an image from the upper neck to the top of the head. It is important that once your head is in place, you do not move it during the test; if you are unable to keep your head still, immobilization may be needed. All jewelry, glasses, dentures, and other metal should be removed from the head and neck to prevent obstruction of the images.

A contrast dye may be injected into a vein to further check a mass. The mass becomes brighter with contrast dye if it has a lot of blood vessels. Contrast dye is also used to produce an image of the blood vessels of the head and brain.

The total amount of time in the CT scanner is usually a few minutes.

How to prepare for the test

Generally, there is no preparation necessary.

How the test will feel

The contrast dye injection may cause a slight temporary burning sensation in the arm, metallic taste in the mouth, or whole body warmth. This is a normal occurrence and will disappear in a few seconds.

Otherwise, the CT scan is painless.

Why the test is performed

A CT scan is recommended to help:

Evaluate acute cranial-facial trauma
Diagnose an acute stroke
Check for suspected subarachnoid or intracranial hemorrhage
Check for causes of headaches
Check for causes of loss of sensory or motor function
Determine if there is an abnormal development of the head and neck

CT scans are also used to view the facial bones, jaw, and sinus cavities.

What abnormal results mean

There may be signs of:

Trauma
Bleeding (for example, chronic subdural hematoma or intracranial hemorrhage)
Stroke
Masses or tumors
Abnormal sinus drainage
Sensorineural hearing loss
Malformed bone or other tissues
Brain abscess
Cerebral atrophy (loss of brain tissue)
Brain tissue swelling
Hydrocephalus (fluid collecting in the skull)

Additional conditions under which the test may be performed:

Acoustic neuroma
Acoustic trauma
Acromegaly
Acute (subacute) subdural hematoma
Amyotrophic lateral sclerosis
Arteriovenous malformation (cerebral)
Benign positional vertigo
Throat cancer
Central pontine myelinolysis
Cerebral aneurysm
Cushing's syndrome
Deep intracerebral hemorrhage
Delirium
Dementia
Dementia due to metabolic causes
Drug-induced tremor
Encephalitis
Epilepsy
Essential tremor
Extradural hemorrhage
Familial tremor
General paresis
Generalized tonic-clonic seizure
Hemorrhagic stroke
Hepatic encephalopathy
Huntington's disease
Hypertensive intracerebral hemorrhage
Hypopituitarism
Intracerebral hemorrhage
Juvenile angiofibroma
Labyrinthitis
Lobar intracerebral hemorrhage
Ludwig's angina
Mastoiditis
Melanoma of the eye
Meniere's disease
Meningitis
Metastatic brain tumor
Multi-infarct dementia
Multiple endocrine neoplasia (MEN) I
Neurosyphilis
Normal pressure hydrocephalus (NPH)
Occupational hearing loss
Optic glioma
Orbital cellulitis
Otitis media; chronic
Otosclerosis
Partial (focal) seizure
Partial complex seizure
Petit mal seizure
Pituitary tumor
Primary brain tumor
Primary lymphoma of the brain
Prolactinoma
Retinoblastoma
Reye's syndrome
Schizophrenia
Senile dementia/Alzheimer's type
Acute sinusitis
Stroke secondary to atherosclerosis
Stroke secondary to cardiogenic embolism
Stroke secondary to FMD
Stroke secondary to syphilis
Subarachnoid hemorrhage
Syphilitic aseptic meningitis
Temporal lobe seizure
Toxoplasmosis
Transient ischemic attack (TIA)
Wilson's disease

What the risks are

Iodine is the usual contrast dye. Some patients are allergic to iodine and may experience a reaction that may include hives, itching, nausea, breathing difficulty, or other symptoms.

As with any x-ray examination, radiation is potentially harmful. Consult your health care provider about the risks if multiple CT scans are needed over a period of time.

Special considerations

A CT scan can decrease or eliminate the need for invasive procedures to diagnose problems in the skull. This is one of the safest means of studying the head and neck.

Review Date: 10/25/2006

Reviewed By: Stuart Bentley-Hibbert, M.D., Ph.D., Department of Radiology, Weill Cornell Medical Center, New York, NY. Review provided by VeriMed Healthcare Network.

A.D.A.M. Copyright

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Source Doc: 1_003786

Electronystagmography

admin — Thu, 04 Sep 2008 19:10:26 -0700

Overview

Definition
Alternative Names
How the test is performed
How to prepare for the test
How the test will feel
Why the test is performed
Normal Values
What abnormal results mean
What the risks are

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

Electronystagmography is a test to look at voluntary and involuntary eye movements. It evaluates the acoustic nerve, which aids with hearing and balance.

Alternative Names

ENG

How the test is performed

Patches called electrodes (similar to those used with ECG, but smaller) are placed to above, below, and to the side of each eye. They may be attached by adhesive or by a band around the head. Another electrode is attached to the forehead.

The electrodes record eye movements when a standard caloric stimulation test is done. This test stimulates the inner ear and nearby nerves by delivering cold and warm water to the ear canal at different times. Sometimes, the test is done using air instead of water. Each ear is tested separately.

When cold water enters the ear, it should cause rapid, side-to-side eye movements. The eyes should move away from the cold water and slowly back. Next, warm water is placed into the ear. The eyes should now move towards the warm water then slowly away.

Patients may also be asked to use their eyes to track objects, such as flashing lights.

The electrodes detect the length and speed of eye movements, and a computer records the results.

The test takes about 90 minutes.

Electronystagmography provides exact measurements of eye movements rather than the objective observation of standard caloric stimulation. It can record behind closed eyelids or with the head in a variety of positions.

How to prepare for the test

No preparation is necessary. Check with your health care provider if you are taking any medications.

How the test will feel

There is minimal discomfort. You may find cold water in the ear uncomfortable. Brief vertigo may occur during the test.

Why the test is performed

The test is used to determine whether a balance or nerve disorder is the cause of dizziness or vertigo.

Your doctor may order this test if you have dizziness or vertigo, impaired hearing, or suspected toxicity from certain antibiotics.

Normal Values

Distinct involuntary eye movements should occur after instillation of cold or hot water into the ear canal.

What abnormal results mean

Abnormal results may be a sign of damage to the nerve of the inner ear or other parts of the brain that control eye movements.

Any disease or injury that damages the acoustic nerve can cause vertigo. This may include:

Congenital disorders
Injury
Rubella
Blood vessel disorders with hemorrhage (bleeding), clots, or atherosclerosis of the blood supply of the ear
Cholesteatoma and other ear tumors
Some poisons
Medications that are toxic to the ear nerves, including aminoglycoside antibiotics, some antimalarial drugs, loop diuretics, and salicylates
Multiple sclerosis
Movement disorders such as progressive supranuclear palsy

Additional conditions under which the test may be performed:

What the risks are

A risk is associated with the caloric stimulation part of the test. Excessive water pressure can injure a previously damaged eardrum, but this rarely occurs. Caloric stimulation should not be performed if your eardrum has been perforated because of the risk of causing ear infection.

Review Date: 4/30/2007

Reviewed By: Joseph V. Campellone, M.D., Division of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network.

A.D.A.M. Copyright

adam.com

Source Doc: 1_003448

Audiology

admin — Thu, 04 Sep 2008 19:09:03 -0700

Overview

Definition
Alternative Names
How the test is performed
How to prepare for the test
How the test will feel
Why the test is performed
Normal Values
What abnormal results mean
What the risks are
Special considerations
References

Illustrations

Ear anatomy

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

An audiology exam tests your ability to hear sounds. Sounds vary according to the intensity (volume or loudness) and the tone (the speed of sound wave vibrations).

Hearing occurs when sound waves move to the nerves of the inner ear and then the brain. Sound waves can travel to the inner ear by air conduction (through the ear canal, eardrum, and bones of the middle ear) or bone conduction (through the bones around and behind the ear).

INTENSITY of sound is measured in decibels (dB):

A whisper is about 20 dB
Loud music (some concerts) is around 80 to 120 dB
A jet engine is about 140 to 180 dB

Usually, sounds greater than 85 dB can cause hearing loss in a few hours. Louder sounds can cause immediate pain, and hearing loss can develop in a very short time.

TONE of sound is measured in cycles per second (cps) or Hertz:

Low bass tones range around 50 to 60 Hz
Shrill, high-pitched tones range around 10,000 Hz or higher

The normal range of human hearing is about 20 Hz to 20,000 Hz, and some animals can hear up to about 50,000 Hz.

Alternative Names

Audiometry; Hearing test; Audiography (audiogram)

How the test is performed

The first steps are used to estimate the need for an audiogram. The specific procedures may vary, but they generally involve blocking one ear at a time and checking for the ability to hear whispers, then spoken words or the sound of a ticking watch.

A tuning fork may be used. The tuning fork is tapped and held in the air on each side of the head to test the ability to hear by air conduction. It is tapped and placed against the mastoid bone behind each ear to test bone conduction.

Audiometry provides a more precise measurement of hearing. Air conduction is tested by having you wear earphones attached to the audiometer. Pure tones of controlled intensity are delivered, to one ear at a time. You are asked to raise a hand, press a button, or otherwise indicate when you hear a sound. The minimum intensity (volume) required to hear each tone is graphed. An attachment called a bone oscillator is placed against the bone behind each ear (mastoid bone) to test bone conduction.

How to prepare for the test

No special preparation is needed.

How the test will feel

There is no discomfort. The length of time varies. An initial screening may take about 5 to 10 minutes. Detailed audiometry may take about 1 hour.

Why the test is performed

This may be a screening test to detect a hearing loss at an early stage. It may also be used when there is difficulty in hearing from any cause.

Common causes of hearing loss include:

Chronic ear infections
Ruptured eardrum
Acoustic trauma
Occupational hearing loss
Head injury
Inherited conditions
Diseases of the inner ear
Medications that can be toxic to the nerve of the inner ear, including certain antibiotics (such as neomycin), diuretics, and large doses of salicylates (such as aspirin)

Normal Values

The ability to hear a whisper, normal speech, and a ticking watch is normal.
The ability to hear a tuning fork through air and bone is normal.
In detailed audiometry, hearing is normal if tones from 250 Hz through 8000 Hz can be heard at 25 dB or lower.

What abnormal results mean

There are many different kinds and degrees of hearing loss. Some include only the loss of the ability to hear high or low tones, or the loss of only air or bone conduction. The inability to hear pure tones below 25 dB indicates some extent of hearing loss.

The extent and kind of hearing loss may give clues to the cause and the prognosis (probable outcome).

The following conditions may affect test results:

Acoustic neuroma
Acoustic trauma
Age-related hearing loss
Alport syndrome
Labyrinthitis
Meniere's disease
Occupational hearing loss
Otosclerosis
Ruptured or perforated eardrum

What the risks are

There is no risk.

Special considerations

There are many different hearing function tests. Simple screenings involve making a loud noise and watching to see if it startles the patient. Detailed screenings include brainstem auditory evoked response testing (BAER). This test uses electroencephalogram to detect brain wave activity when sounds are made.

A newer hearing test called otoacoustic emission testing (OAE) can be used in the very young (such as newborns) or when standard tests do not produce reliable results.

References

Cummings CW, Flint PW, Haughey BH, et al. Otolaryngology: Head & Neck Surgery. 4th ed. St Louis, Mo; Mosby; 2005:3466-3479.

Kerschner JE. Neonatal hearing screening: To do or not to do. Pediatr Clin North Am. June 2004; 51(3): 725-36, x.

Review Date: 2/19/2007

Reviewed By: Alden J. Pearl, M.D., Clinical Assistant Professor, Department of Otolaryngology, State University of New York Health Science Center at Brooklyn, Brooklyn, NY. Review provided by VeriMed Healthcare Network.

A.D.A.M. Copyright

adam.com

Source Doc: 1_003341

Caloric stimulation

admin — Thu, 04 Sep 2008 19:10:12 -0700

Overview

Definition
Alternative Names
How the test is performed
How to prepare for the test
How the test will feel
Why the test is performed
Normal Values
What abnormal results mean
What the risks are
Special considerations
References

HEALTH GUIDE REFERENCE FROM A.D.A.M

Definition

Caloric stimulation is a test which uses differences in temperature to diagnose ear nerve damage.

Alternative Names

Caloric test

How the test is performed

This test stimulates the inner ear and nearby nerves by delivering cold and warm water to the ear canal at different times. Sometimes, the test is done using air instead of water.

One ear is tested at a time.

When cold water enters the ear, it should cause rapid, side-to-side eye movements called nystagmus. The eyes should move away from the cold water and slowly back.

Next, warm water is placed into the ear. The eyes should now move towards the warm water then slowly away.

Patches called electrodes, placed around the eyes, detect the movements. A computer records all the results.

Ice cold water may be used if there are no responses.

How to prepare for the test

Do not eat a heavy meal before the test. Avoid caffeine, alcohol, allergy medications, and sedatives at least 24 hours prior to the test, as these can affect the results. (However, do not stop taking medicines without first talking to your doctor.)

How the test will feel

Some people find cold water in the ear uncomfortable. Brief, but severe vertigo may occur during the test.

Why the test is performed

Caloric stimulation is done to check the acoustic nerve, which provides hearing and helps with balance.

This test may be recommended if you have:

Dizziness or vertigo
Hearing loss that may be due to certain antibiotics
Certain types of anemia
Possible psychological causes of vertigo

It may also be done to look for brain damage in persons in a coma.

Normal Values

Rapid, side-to-side eye movements should occur when cold or warm water is placed into the ear. The eye movements should be similar on both sides.

What abnormal results mean

Abnormal results mean there may be damage to the nerve of the inner ear, which controls balance. If the rapid, side-to-side eye movements do not occur even after ice cold water is given, permanent damage to the nerve has probably occurred.

Abnormal results may suggest:

Congenital disorders (present at birth)
Trauma
Rubella
Blood vessel disorders with hemorrhage (bleeding)
Blood clots
Atherosclerosis of the blood supply of the ear
Cholesteatoma and other ear tumors
Certain types of poisonings
Damage to the ear nerves due to ceratin antibiotics, antimalarial drugs, diuretics, and salicylates

The test may also be done to diagnose or rule out:

What the risks are

Excessive water pressure can injure a previously damaged eardrum, but this rarely occurs since the amount of water to be used is measured in advance. Caloric stimulation should not be performed if the eardrum is perforated because of the risk of causing ear infection. Caloric testing should not be performed during an acute vertigo episode as it can make symptoms worse.

Special considerations

Caloric stimulation is approximately 80% accurate in differentiating nerve damage as a cause of vertigo. Other tests may be required to confirm the diagnosis.

References

Cummings CW, Flint PW, Haughey BH, et al. Otolaryngology: Head & Neck Surgery. 4th ed. St Louis, Mo; Mosby; 2005:3179-3189.

Casselbrant ML. Balance disorders in children. Neurol Clin. Aug 2005; 23(3): 807-29, vii.

Review Date: 2/12/2007

Reviewed By: Alden J. Pearl, M.D., Clinical Assistant Professor, Department of Otolaryngology, State University of New York Health Science Center at Brooklyn, Brooklyn, NY. Review provided by VeriMed Healthcare Network.

A.D.A.M. Copyright

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Source Doc: 1_003429