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National Cancer Institute

the US government agency for cancer research and information.

near point of accommodation

the closest point in front of the eyes that an object may be clearly focused.

near point of convergence

the maximum extent the two eyes can be turned inward.

needle aspiration (of the breast)

uses a thin needle and syringe to collect tissue or drain a lump after using a local anesthetic.

needle biopsy

biopsy procedure in which a small sample of tissue is removed through a hollow needle.

neoadjuvant therapy

chemotherapy given before surgery or radiation therapy.

nephrectomy

surgical removal of the kidney.

nephropathy

diabetic kidney disease

nerve conduction test

procedure to determine nerve impulse generation.

nerve sparing technique

a surgical technique often used during a radial prostatectomy in which one or both of the neurovascular bundles controlling erections are spared.

Nerve Stimulator

A nerve stimulator supplies electrons to depolarise a nerve. The number of electrons supplied per stimulus equals the current. To make sure that the nerve is completely depolarised we keep winding up the stimulating current until the muscular response does not increase any more, then we add another 10%. This is called the supra-maximal stimulus. At this point we assume that the nerve supplying the muscle is completely depolarised. As a result the muscle must be maximally stimulated by the nerve. The muscle contraction that results must also be maximal. (The contraction is also called a twitch). The muscle response to the stimulus is called a twitch. The amount or strength of movement is called the twitch height. (From the height of the trace on a recorder.) To allow comparison of twitches it is essential that this current remains constant to ensure the nerve is always completely depolarised.

neural mobilization

- techniques by which neural tissues are moved, either by movement relative to their surroundings or by tension development.

neural plasticity

ability of the brain and/or certain parts of the nervous system to change in order to adapt to new conditions, such as an injury.

neural prostheses

devices that substitute for an injured or diseased part of the nervous system to enhance the function.

neural stimulation

to activate or energize a nerve through an external source.

neural tube defect

type of birth defect, such as spina bifida, that results from failure of the spinal cord or brain to develop normally in a fetus.

neuralgia

a painful condition caused by disorders of the nervous system.

neuritis

inflammation of a nerve or nerves

neurofibromatosis (Von Recklinghausen’s)

a group of inherited disorders in which noncancerous tumors grow on several nerves that may include the hearing nerve.

neurogenic

of nerve origin

neurogenic communication disorder

inability to exchange information with others because of hearing, speech, and/or language problems caused by impairment of the nervous system.

neuron

a cell specialized to conduct and generate electrical impulses and to carry information from one part of the brain to another.

neuropathology

the study of the nervous system

Neurosurgery

A surgical specialty for the treatment of diseases and disorders of the brain, spinal cord, and peripheral and sympathetic nervous system.

neurotransmitters

chemical substances that carry impulses from one nerve cell to another; found in the space (synapse) that separates the transmitting neuron's terminal (axon) from the receiving neuron's terminal (dendrite).

Nissen fundoplication

operation to sew the top of the stomach (fundus) around the esophagus; used to stop stomach contents from flowing back into the esophagus (reflux) and to repair a hiatal hernia.

noise-induced hearing loss

hearing loss that is caused either by a one-time or repeated exposure to very loud sound(s).

non-insulin-dependent diabetes

see type 2 diabetes.

noninvasive procedures

a diagnostic effort or treatment that does not require entering the body or puncturing the skin.

non-steroidal anti-inflammatory drugs (NSAIDs)

medications that produces antipyretic, analgesic, and anti-inflammatory effects.

nonsyndromic hereditary hearing impairment

hearing loss or deafness that is inherited and is not associated with other inherited clinical characteristics.

nontropical sprue

see celiac disease

nonulcer dyspepsia

constant pain or discomfort in the upper gastrointestinal tract.

norepinephrine

a neurotransmitter found mainly in areas of the brain that are involved in governing autonomic nervous system activity, especially blood pressure and heart rate.

Norwalk virus

virus that may cause gastrointestinal (GI) infection and diarrhea. (See also gastroenteritis.)

nuclear medicine

a specialized area of radiology that uses very small amounts of radioactive substances to examine organ function and structure.

nutrients

proteins, carbohydrates, fats, vitamins, and minerals provided by food and necessary for growth and the maintenance of life.

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