Necrosis

Death or decay of tissue that results from loss of the blood supply and oxygen needed to keep tissue alive and healthy.

Nerve

A bundle of nerve fibers (axons). The fibers are either afferent (leading toward the brain and serving in the perception of sensory stimuli of the skin, joints, muscles, and inner organs, or efferent (leading away from the brain and mediating contractions of muscles or organs).

Nerve block

A procedure used to relieve otherwise intractable spasticity, including painful flexor spasms. An injection of phenol into the affected nerve interferes with the function of that nerve for up to 3 months, potentially increasing a person's comfort and mobility.

Nerve fibers

Slender processes of neurons, especially the prolonged axons that conduct nerve impulses.

Nervous system

Includes all of the neural structures in the body: the central nervous system consists of the brain, spinal cord, and optic nerves; the peripheral nervous system consists of the nerve roots, nerve plexi, and nerves throughout the body.

Neurodegeneration

The malfunctioning or loss of nerve cells which include neurons and axons.

Neurogenic

Related to activity of the nervous system, as in "neurogenic bladder."

Neurologist

Medical doctor (or physician) with specialized training in conditions that affect the nervous system; some have a specialized interest in MS, epilepsy, or Parkinson’s disease.

Neurology

Study of the central, peripheral, and autonomic nervous system.

Neuron

The basic nerve cell of the nervous system. A neuron consists of a nucleus within a cell body and one or more extensions called dendrites and axons.

Neuropsychologist

A doctor who does cognitive assessment and retraining of patients. Neuropsychologists specialize in brain-behavior relationships.

Neuro-psychologist

A psychologist with specialized training in the evaluation of cognitive functions. Neuro-psychologists use a battery of standardized tests to assess specific cognitive functions and identify areas of cognitive impairment. They also provide remediation for individuals with MS-related cognitive impairment. See Cognition and Cognitive impairment

Neutralizing antibodies (NAbs)

Proteins produced by the body that may block ("neutralize") the effectiveness of a drug therapy.

Non-acidic formulation

Neutral formulation of Betaseron which helps minimize stinging on injection.

Occupational therapist: A specialist in rehabilitating patients with cognitive problems. The occupational therapist focuses on restoring the patient’s ability to carry out daily tasks at home, at work, and in the community.

Oligoclonal bands: A series of distinct bands found in the immunoglobulin (a protein substance from immune cells) of the cerebrospinal fluid (CSF). The bands may be present in other conditions, but are helpful in diagnosing MS if other MS symptoms are present.

Optic atrophy

A wasting of the optic disc that results from partial or complete degeneration of optic nerve fibers and is associated with a loss of visual acuity.

Optic nerve

The bundle of over one million nerve fibers that carry visual messages from the retina to the brain.

Optic neuritis

Inflammation of the optic nerve. Also called neuropapillitis, retrobulbar neuritis.