Acoustic: Having to do with sound or hearing. The acoustic nerve (the 8th cranial nerve) is concerned with hearing and the sense of balance and head position. An acoustic neuroma is a tumor on the acoustic nerve.
Acoustic neuroma: A benign tumor that may develop on the hearing and balance nerves near the inner ear. The tumor results from an overproduction of Schwann cells -- small sheet-like cells that normally wrap around nerve fibers like onion skin and help support the nerves. When growth is abnormally excessive, Schwann cells bunch together, pressing against the hearing and balance nerves, often causing gradual hearing loss, tinnitus (ringing in the ears), and dizziness. If the tumor becomes large, it can interfere with the facial nerve, causing partial paralysis, and eventually press against nearby brain structures, becoming life-threatening.
Acute: Of abrupt onset, in reference to a disease. Acute often also connotes an illness that is of short duration, rapidly progressive, and in need of urgent care.
See the entire definition of Acute
Acyclovir: (Brand name: Zovirax) One of a group of antiviral drugs that acts against the herpes viruses, including:
- Herpes simplex 1 which causes cold sores
- Herpes simplex 2 which causes genital herpes
- Varicella-zoster which causes both chickenpox and shingles
- Epstein-Barr virus which causes infectious mononucleosis
Acyclovir inhibits the replication of viral DNA needed to reproduce itself. Virally infected cells absorb more acyclovir than normal cells and convert more of it to an active form which prolongs its antiviral activity where it is most needed. Acyclovir may reduce the severity and duration of a shingles attack if given soon after the onset of symptoms.
Alcoholism: Physical dependence on alcohol to the extent that stopping alcohol use would bring on withdrawal symptoms. In popular and therapeutic parlance, the term may also be used to refer to ingrained drinking habits that cause health or social problems. Treatment requires first ending the physical dependence and then making lifestyle changes that help the individual avoid relapse. In some cases, medication and hospitalization are necessary. Alcohol dependence can have many serious effects on the brain, liver, and other organs of the body, some of which can lead to death.
Antiviral: An agent that kills a virus or that suppresses its ability to replicate and, hence, inhibits its capability to multiply and reproduce.
See the entire definition of Antiviral
Antiviral agent: A medication or another agent that kills viruses or inhibits their capability to reproduce.
Bell's palsy: Paralysis of the nerve that supplies the facial muscles on one side of the face (the seventh cranial nerve, or facial nerve). Bell's palsy often starts suddenly. The cause may be a viral infection. Treatment includes protecting the eye on the affected side from dryness during sleep. Massage of affected muscles can reduce soreness. Sometimes cortisone medication, such as prednisone, is given to reduce inflammation during the first weeks of illness. The outlook is generally good; the vast majority of patients recover within weeks or months.
Bilateral: Affecting both sides. For example, bilateral arthritis affects joints on both the left and right sides of the body.
Brain: The portion of the central nervous system that is located within the skull. It functions as a primary receiver, organizer, and distributor of information for the body. It has a right half and a left half, each of which is called a hemisphere.
Brain stem: The stem-like part of the base of the brain that is connected to the spinal cord. The brain stem controls the flow of messages between the brain and the rest of the body, and it also controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is awake or sleepy. The brain stem consists of the midbrain, pons, and medulla oblongata.
Cancer: An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some cases, to metastasize (spread).
Carbon monoxide poisoning: A potentially deadly condition caused by breathing carbon monoxide gas, which prevents oxygenation of the blood. Common causes of carbon monoxide poisoning include malfunctioning furnaces and the use of kerosene heaters or similar devices in unventilated indoor spaces. Carbon monoxide is also emitted by automobile and other engines, so these should not be run in unventilated spaces, such as closed garages. Inexpensive alarms are available that can detect dangerous buildups of carbon monoxide. The treatment for carbon monoxide poisoning is immediate reoxygenation of the blood in a hospital.
Cornea: The clear front window of the eye, which transmits and focuses light into the eye. The cornea is more than a protective film; it is a fairly complex structure that has five layers.
Cranial: 1. Pertaining to the cranium or skull. 2. Toward the head. As opposed to caudad. The eye is cranial to the jaw. For a more complete listing of terms used in medicine for spatial orientation, please see the entry to "Anatomic Orientation Terms".
Cranial nerves: The nerves of the brain, which emerge from or enter the skull (the cranium), as opposed to the spinal nerves, which emerge from the vertebral column. There are 12 cranial nerves, each of which is accorded a Roman numeral and a name:
- Cranial nerve I: the olfactory nerve
- Cranial nerve II: the optic nerve
- Cranial nerve III: the oculomotor nerve
- Cranial nerve IV: the trochlear nerve
- Cranial nerve V: the trigeminal nerve
- Cranial nerve VI: the abducent nerve
- Cranial nerve VII: the facial nerve
- Cranial nerve VIII: the vestibulocochlear nerve
- Cranial nerve IX: the glossopharyngeal nerve
- Cranial nerve X: the vagus nerve
- Cranial nerve XI: the accessory nerve
- Cranial nerve XII: the hypoglossal nerve
CT scan: Computerized tomography scan. Pictures of structures within the body created by a computer that takes the data from multiple X-ray images and turns them into pictures on a screen. CT stands for computerized tomography.
Decompression:
1. In general, the removal of pressure.
2. In surgery, a procedure to remove pressure on a structure, as in decompression of the spinal cord.
3. The lessening of atmospheric pressure on deep-sea divers returning to the surface, or on persons ascending to great heights.
Diabetes: Refers to diabetes mellitus or, less often, to diabetes insipidus. Diabetes mellitus and diabetes insipidus share the name "diabetes" because they are both conditions characterized by excessive urination (polyuria).
Diabetes mellitus: Better known just as "diabetes" -- a chronic disease associated with abnormally high levels of the sugar glucose in the blood. Diabetes is due to one of two mechanisms:
(1) Inadequate production of insulin (which is made by the pancreas and lowers blood glucose) or
(2) Inadequate sensitivity of cells to the action of insulin.
The two main types of diabetes correspond to these two mechanisms and are called insulin dependent (type 1) and non-insulin dependent (type 2) diabetes. In type 1 diabetes there is no insulin or not enough of it. In type 2 diabetes, there is generally enough insulin but the cells upon it should act are not normally sensitive to its action.
Diagnosis: 1 The nature of a disease; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies. 3 The identification of any problem. The diagnosis was a plugged IV.
See the entire definition of Diagnosis
Donor: The giver of a tissue or an organ, such as a blood donor or kidney donor.
Dysfunction: Difficult function or abnormal function.
Ear: The hearing organ. There are three sections of the ear, according to the anatomy textbooks. They are the outer ear (the part we see along the sides of our head behind the temples), the middle ear, and the inner ear. But in terms of function, the ear has four parts: those three and the brain. Hearing thus involves all parts of the ear as well as the auditory cortex of the brain. The external ear helps concentrate the vibrations of air on the ear drum and make it vibrate. These vibrations are transmitted by a chain of little bones in the middle ear to the inner ear. There they stimulate the fibers of the auditory nerve to transmit impulses to the brain.
See the entire definition of Ear
Eighth cranial nerve: The eighth cranial nerve is the vestibulocochlear nerve.
See the entire definition of Eighth cranial nerve
Eyelid: The lid or cover of the eye, a movable fold of skin and muscle that can be closed over the eyeball or opened at will. Each eye has an upper and a lower lid. Also known as a palpebra.
Facelift: A surgical procedure that is designed to make the face appear younger by pulling loose facial skin taut and tightening and repositioning the underlying facial musculature. Excessive skin and/or fat may be removed during the procedure. Supplemental procedures'including necklift, blepharoplasty (eyelid surgery), autologous fat injection, forehead lift, and browlift; chemical or laser peel; and malar (cheek), submalar, or chin implants'may be necessary to achieve the desired results. Although they are infrequent, risks and complications of facelift surgery include bleeding; hematoma; bruising; infection; neurological dysfunction (loss of muscle function or sensation), which is usually temporary; widened or thickened scars; loss of hair around the incision site; asymmetry (unevenness between two sides); and skin necrosis (loss of skin due to tissue death). Also known as rhytidectomy.
Facial muscle: One of the 43 muscles in the human face. The facial muscles convey basic human emotions such as anger, sadness, fear, surprise, disgust, contempt and happiness by very clear facial signals.
Facial nerve: The facial nerve is the seventh cranial nerve. It is a mixed nerve that has fibers both going out and coming in (both efferent and afferent fibers). It supplies the muscles of facial expression.
See the entire definition of Facial nerve
Facial nerve paralysis: Loss of voluntary movement of the muscles of one side of the face due to abnormal function of the facial nerve. Paralysis of the facial nerve causes a characteristic drooping of one side of the face, inability to wrinkle the forehead, inability to whistle, inability to close an eye, and deviation of the mouth toward the other side of the face. Numerous conditions can cause facial nerve paralysis including infections, inherited diseases, tumors, toxins, and trauma. Bell's palsy is the development of facial nerve paralysis without an identifiable cause. The disease causes paralysis of the muscles of the side of the face on which the facial nerve is affected. One goal of treatment is to protect the eye on the affected side from dryness. Sometimes corticosteroid medication is given to reduce inflammation during the first weeks of illness. Surgical decompression to reduce swelling and pressure on the affcted nerve may also be
performed.
Family history: The family structure and relationships within the family, including information about diseases in family members.
Foramen: A natural opening. Although a foramen is usually through bone, it can be an opening through other types of tissue, as with the foramen ovale in the heart. The plural of foramen is foramina.
Fracture: A break in bone or cartilage. Although usually a result of trauma, a fracture can be the result of an acquired disease of bone, such as osteoporosis, or of abnormal formation of bone in a congenital disease of bone, such as osteogenesis imperfecta ('brittle bone disease'). Fractures are classified according to their character and location (for example, greenstick fracture of the radius).
Ganglion: The celebrated 2nd century Greek physician Galen ((c. 130-201 A.D.) who lived and worked in Rome first used the word ganglion to denote a nerve complex. Ganglion still is used to refer to an aggregation of nerve cell bodies. Another use of the word ganglion is for a tendon cyst that most commonly pops up near the wrist.
Gland: A group of cells that secrete a substance for use in the body. For example, the thyroid gland.
Herpes: A family of viruses. Herpes also refers to infection with one of the human herpesviruses, especially herpes simplex types 1 and 2.
Herpes zoster: Also called shingles, zona, and zoster. The culprit is the varicella-zoster virus. Primary infection with this virus causes chickenpox (varicella). At this time the virus infects nerves (namely, the dorsal root ganglia) where it remains latent (lies low) for years. It can then be reactivated to cause shingles with blisters over the distribution of the affected nerve accompanied by often intense pain and itching.
Hypoglossal nerve: The twelfth cranial nerve, which supplies the muscles of the tongue.
Idiopathic: Of unknown cause. Any disease that is of uncertain or unknown origin may be termed idiopathic. For example, acute idiopathic polyneuritis, diffuse idiopathic skeletal hyperostosis, idiopathic pulmonary fibrosis, idiopathic scoliosis, etc.
Immune: Protected against infection, usually by the presence of antibodies.
Immune system: A complex system that is responsible for distinguishing a person from everything foreign to him or her and for protecting his or her body against infections and foreign substances.
Incidence: The frequency with which something, such as a disease or trait, appears in a particular population or area.
Infection: The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body. An infection may cause no symptoms and be subclinical, or it may cause symptoms and be clinically apparent. An infection may remain localized, or it may spread through the blood or lymphatic vessels to become systemic (bodywide). Microorganisms that live naturally in the body are not considered infections. For example, bacteria that normally live within the mouth and intestine are not infections.
Inflammation: A localized reaction that produces redness, warmth, swelling, and pain as a result of infection, irritation, or injury. Inflammation can be external or internal.
Injury: Harm or hurt. The term "injury" may be applied in medicine to damage inflicted upon oneself as in a hamstring injury or by an external agent on as in a cold injury. The injury may be accidental or deliberate, as with a needlestick injury. The term "injury" may be synonymous (depending on the context) with a wound or with trauma.
Leg: In popular usage, the part of the body from the top of the thigh down to the foot, and in medical terminology, the portion of the lower extremity that runs from the knee to the ankle. The leg (in the medical sense) has two bones'the tibia (shinbone) and t
Lesion: An area of abnormal tissue change. Lesions vary in severity from harmless to serious.
Masseter: The muscle that raises the lower jaw.
Microscopic: So small it cannot be seen without the aid of microscope. As opposed to macroscopic (large enough to be seen with naked eye). A tiny tumor is microscopic while a big tumor is macroscopic.
Middle ear: A part of the ear that consists of the eardrum (tympanic membrane) and, beyond it, a cavity (tympanum). This cavity is connected to the pharynx (nasopharynx) via a canal known as the Eustachian tube. The middle ear cavity also contains a chain of three little bones, the ossicles (the malleus, incus, and stapes), which connect the eardrum to the internal ear. The middle ear communicates with the pharynx, equilibrates with external pressure, and transmits the eardrum vibrations to the inner ear.
Milligram: A unit of measurement of mass in the metric system equal to a thousandth of a gram. A gram is equal to the mass of one milliliter, one thousandth of a liter, of water at 4 degrees C.
Motor: Something that produces or refers to motion. For example, a motor neuron is a nerve cell that conveys an impulse to a muscle for contraction, which then moves a joint.
Mouth: 1. The upper opening of the digestive tract, beginning with the lips and containing the teeth, gums, and tongue. Foodstuffs are broken down mechanically in the mouth by chewing and saliva is added as a lubricant. Saliva contains amylase, an enzyme that digests starch. 2. Any opening or aperture in the body. The mouth in both senses of the word is also called the os, the Latin word for an opening, or mouth. The o in os is pronounced as in hope. The genitive form of os is oris from which comes the word oral.
MRI: Magnetic resonance imaging.
Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."
Neck: The part of the body joining the head to the shoulders. Also, any narrow or constricted part of a bone or organ that joins its parts as, for example, the neck of the femur bone.
Nerve: A bundle of fibers that uses electrical and chemical signals to transmit sensory and motor information from one body part to another. The fibrous portions of a nerve are covered by a sheath called myelin and/or a membrane called neurilemma. (Note that entries for specific nerves can be found under the names of the particular nerves. For example, the optic nerve is not under 'nerve, optic' but rather under 'optic nerve.')
Neuroma: A benign tumor that arises from a nerve as, for example, an acoustic glioma or optic glioma.
Pain: An unpleasant sensation that can range from mild, localized discomfort to agony. Pain has both physical and emotional components. The physical part of pain results from nerve stimulation. Pain may be contained to a discrete area, as in an injury, or it can be more diffuse, as in disorders like fibromyalgia. Pain is mediated by specific nerve fibers that carry the pain impulses to the brain where their conscious appreciation may be modified by many factors.
See the entire definition of Pain
Palsy: Paralysis, generally partial, whereby a local body area is incapable of voluntary movement. For example, Bell's palsy is localized paralysis of the muscles on one side of the face.
Paralysis: Loss of voluntary movement (motor function). Paralysis that affects only one muscle or limb is partial paralysis, also known as palsy; paralysis of all muscles is total paralysis, as may occur in cases of botulism.
Parotid gland: The largest of the three major salivary glands, it is located in front and below the ear and behind the jaw bone. The other two glands are the submandibular (submaxillary) and sublingual.
Physical therapy: A branch of rehabilitative health that uses specially designed exercises and equipment to help patients regain or improve their physical abilities. Abbreviated PT. PT is appropriate for many types of patients, from infants born with musculoskeletal birth defects, to adults suffering from sciatica or the after effects of injury or surgery, to elderly poststroke patients.
Poisoning: Taking a substance that is injurious to health or can cause death. Poisoning is still a major hazard to children, despite child-resistant (and sometimes adult-resistant) packaging and dose-limits per container.
Pregnancy: The state of carrying a developing embryo or fetus within the female body. This condition can be indicated by positive results on an over-the-counter urine test, and confirmed through a blood test, ultrasound, detection of fetal heartbeat, or an X-ray. Pregnancy lasts for about nine months, measured from the date of the woman's last menstrual period (LMP). It is conventionally divided into three trimesters, each roughly three months long.
Prognosis: The forecast of the probable outcome or course of a disease; the patient's chance of 'recovery.
Ramsay Hunt syndrome: A herpes virus infection of the geniculate nerve ganglion that causes paralysis of the facial muscles on the same side of the face as the infection. The geniculate ganglion is a sensory ganglion associated with the VIIth cranial nerve.
See the entire definition of Ramsay Hunt syndrome
Reflex: An involuntary reaction. For example, the corneal reflex is the blink that occurs upon irritation of the eye.
Rehabilitation: The process of helping a person who has suffered an illness or injury restore lost skills and so regain maximum self-sufficiency. For example, rehabilitation work after a stroke may help the patient walk and speak clearly again.
Resection: Surgical removal of part of an organ.
Saliva: a watery secretion in the mouth produced by the salivary glands that aids in the digestion of food. Saliva also serves to moisten and cleanse the mouth, including the tongue and teeth, and contains substances that can play a role in the prevention of infection. Saliva aids digestion by moistening food and contains enzymes that begin the digestion process. Also known as spit.
Scan: As a noun, the data or image obtained from the examination of organs or regions of the body by gathering information with a sensing device.
Sensitivity: 1. In psychology, the quality of being sensitive. As, for example, sensitivity training, training in small groups to develop a sensitive awareness and understanding of oneself and of ones relationships with others. 2. In disease epidemiology, the ability of a system to detect epidemics and other changes in disease occurrence. 3. In screening for a disease, the proportion of persons with the disease who are correctly identified by a screening test. 4. In the definition of a disease, the proportion of persons with the disease who are correctly identified by defined criteria.
Skull: The skull is a collection of bones which encase the brain and give form to the head and face. The bones of the skull include the following: the frontal, parietal, occipital, temporal, sphenoid, ethmoid, zygomatic, maxilla, nasal, vomer, palatine, inferior concha, and mandible.
Steroid: One of a large group of chemical substances classified by a specific carbon structure. Steroids include drugs used to relieve swelling and inflammation, such as prednisone and cortisone; vitamin D; and some sex hormones, such as testosterone and estradiol.
Stroke: The sudden death of brain cells due to lack of oxygen, caused by blockage of blood flow or rupture of an artery to the brain. Sudden loss of speech, weakness, or paralysis of one side of the body can be symptoms. A suspected stroke can be confirmed by scanning the brain with special X-ray tests, such as CAT scans. The death rate and level of disability resulting from strokes can be dramatically reduced by immediate and appropriate medical care. Prevention involves minimizing risk factors, such as controlling high blood pressure and diabetes. Abbreviated CVA. Also known as cerebrovascular accident.
Surgery: The branch of medicine that employs operations in the treatment of disease or injury. Surgery can involve cutting, abrading, suturing, or otherwise physically changing body tissues and organs.
Syndrome: A combination of symptoms and signs that together represent a disease process.
Taste: A perception that results from stimulation of a gustatory nerve. Taste belongs to the chemical sensing system. Tasting begins when molecules stimulate special cells in the mouth or throat. These special cells transmit messages through nerves to the brain, where specific tastes are identified. Gustatory, or taste, cells react to food and beverages. The taste cells are clustered in the taste buds of the mouth and throat. Many of the small bumps that can be seen on the tongue contain taste buds. Smell contributes to the sense of taste, as does another chemosensory mechanism, called the common chemical sense. In this system, thousands of nerve endings'especially on the moist surfaces of the eyes, nose, mouth, and throat'give rise to sensations such as the sting of ammonia, the coolness of menthol, and the irritation of chili peppers. People can commonly identify four basic taste sensations: sweet, sour, bitter, and salty. In the mouth, these tastes, along with texture, temperature, and the sensations from the common chemical sense, combine with odors to produce the perception of flavor. Flavors are recognized mainly through the sense of smell. If a person holds his or her nose while eating chocolate, for example, the person will have trouble identifying the chocolate flavor'even though he or she can distinguish the food's sweetness or bitterness. That is because the familiar flavor of chocolate is sensed largely by odor.
Tear: A drop of the salty secretion of the lacrimal glands which serves to moisten the conjunctiva and cornea.
Therapy: The treatment of disease. Therapy is synonymous with treatment.
Tongue: A strong muscle that is anchored to the floor of the mouth. The tongue is covered by the lingual membrane, which has special areas to detect different types of tastes. The tongue muscles are attached to the lower jaw and to the hyoid bone, a small, U-shaped bone that lies deep in the muscles at the back of the tongue and above the larynx. On the top surface of the tongue are small nodules, called papillae, that give the tongue its rough texture. Between the papillae, at the sides and base of the tongue, are the taste buds, which are small bulb-like structures. The muscle fibers of the tongue are heavily supplied with nerves. Babies have more taste buds than adults, and they have them almost everywhere in the mouth, including the cheeks. The tongue aids in the formation of the sounds of speech and aids in swallowing.
Trauma: A physical or emotional injury.
Tumor: An abnormal mass of tissue. Tumors are a classic sign of inflammation, and can be benign or malignant (cancerous). There are dozens of different types of tumors. Their names usually reflect the kind of tissue they arise in, and may also tell you something about their shape or how they grow. For example, a medulloblastoma is a tumor that arises from embryonic cells (a blastoma) in the inner part of the brain (the medulla). Diagnosis depends on the type and location of the tumor. Tumor marker tests and imaging may be used; some tumors can be seen (for example, tumors on the exterior of the skin) or felt (palpated with the hands).
Twitching: : Involuntary contractions of groups of muscle fibers. Also known as fasciculations. Fasciculations can occur in normal individuals without an associated disease or condition and can also occur as a result of illness, such as muscle cramps, nerve diseases, and metabolism imbalances.
Unilateral: Having, or relating to, one side. For example, a unilateral rash is one that is only on one side of the body.
Viral: Of or pertaining to a virus. For example, if a person has a viral rash, the rash was caused by a virus.
Viral infection: Infection caused by the presence of a virus in the body. Depending on the virus and the person's state of health, various viruses can infect almost any type of body tissue, from the brain to the skin. Viral infections cannot be treated with antibiotics; in fact, in some cases the use of antibiotics makes the infection worse. The vast majority of human viral infections can be effectively fought by the body's own immune system, with a little help in the form of proper diet, hydration, and rest. As for the rest, treatment depends on the type and location of the virus, and may include anti-viral or other drugs.
Virus: A microorganism that is smaller than a bacterium that cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations); this ability to mutate is responsible for the ability of some viruses to change slightly in each infected person, making treatment difficult. Viruses cause many common human infections and are also responsible for a number of rare diseases. Examples of viral illnesses range from the common cold, which can be caused by one of the rhinoviruses, to AIDS, which is caused by HIV. Viruses may contain either DNA or RNA as their genetic material. Herpes simplex virus and the hepatitis B virus are DNA viruses. RNA viruses have an enzyme called reverse transcriptase that permits the usual sequence of DNA-to-RNA to be reversed so that the virus can make a DNA version of itself.
RNA viruses include HIV and hepatitis C virus. Researchers have grouped viruses together into several major families, based on their shape, behavior, and other characteristics. These include the herpes-viruses, adenoviruses, papovaviruses (including
the papillomaviruses), hepadnaviruses, poxviruses, and parvoviruses, among the DNA viruses. On the RNA virus side, major families include the picorna-viruses (including the rhinoviruses), calciviruses, paramyxoviruses, orthomyxoviruses, rhabdoviruses, filoviruses, and retroviruses. There are dozens
of smaller virus families within these major classifications. Many viruses are host specific, capable of infecting and causing disease in humans or specific animals only.
