neuritis, inflammation of a peripheral nerve, often accompanied by degenerative changes in nervous tissue. The cause can be mechanical (injury, pressure), vascular (occlusion of a vessel or hemorrhage into nerve tissue), infectious (invasion by microorganisms), toxic (metallic or chemical poisoning, alcoholism), or metabolic (vitamin deficiencies, pernicious anemia). Symptoms of neuritis that arise from involvement of sensory nerves are tingling, burning, pin-and-needle sensations, or even loss of sensation. If motor nerves are involved, symptoms may range from a slight loss of muscle tone to paralysis. Since neuritis is regarded as a condition that results from a number of disorders, rather than a disease in itself, treatment is directed first at the underlying cause. See neuralgia.

Inflammation of one or several nerves. The cause may be mechanical, vascular, allergic, toxic, metabolic, or viral. Symptoms—tingling, burning, or stabbing pains with sensory nerves and anything from muscle weakness to paralysis with motor nerves—are usually confined to the part of the body served by the inflamed nerve. In Bell palsy, facial nerve inflammation causes a characteristic facial muscle distortion. Analgesics can relieve the pain. Once the underlying cause is treated, recovery is usually rapid but may be incomplete in severe cases, with residual motor and sensory disturbances. Seealso neuralgia.

Learn more about neuritis with a free trial on Britannica.com.