CAUSESPeripheral neuropathy may have many different causes. It may be acquired or inherited. Acquired peripheral neuropathies are caused by systemic disease, e.g. tic douloureux that is caused by damage to the trigeminal nerve, or trauma, or autoimmune disorders or infections. Inherited peripheral neuropathies include several forms of Charcot-Marie-Tooth disease, peripheral neuropathy with optic atrophy, and hereditary neuropathy with liability to pressure palsies. Peripheral neuropathies without known cause are called idiopathic. 

The causes of peripheral neuropathy may be classified in the following way: 

Physical injury or trauma is the most common cause of damage to a nerve. Accidents and sports-related injuries may sever, crush, stretch, or compress one or more peripheral nerves. 

Systemic diseases, including metabolic and endocrine disorders such as diabetes, are often accompanied by peripheral neuropathies. The accumulation of toxic substances as a result of kidney disorders may often lead to peripheral neuropathy. Hormonal disorders such as acromegaly may lead to bone overgrowth that may exert pressure on nerve tissue leading to neuropathy. Alcoholism and/or vitamin deficiencies may lead to neuropathies because of a lack of vitamins E, B1, B6, or B12. Because alcoholism interferes with nutrition, it too may lead to vitamin deficiencies and neuropathies. Diseases of the blood and/or vascular system can have serious effects on nerve tissue if the oxygen supply is affected. Connective tissue disorders and chronic inflammation of nerve tissue may lead to neuropathies, and if sufficient connective tissue is destroyed the nerves become more vulnerable to compression and thus to damage as well. Cancers and benign tumors may compress nerves sufficiently to cause damage and neuropathy in disorders such as neurofibromatosis. Repetitive stress frequently leads to entrapment neuropathies such as carpal tunnel syndrome. People exposed to heavy metals and other toxins are often subject to peripheral neuropathies. 

Infections and immune disorders, especially virus infections, can cause serious nerve damage and peripheral neuropathies. Viruses causing such disorders as Epstein-Barr syndrome or herpes varicella-zoster (shingles) are often the cause of severe nerve damage and nerve pain. Human immunodeficiency virus (HIV) causes a number of different peripheral neuropathies, depending on the stage of disease. 

Inherited forms of peripheral neuropathy are the result of genetic mutations that in many instances lead to mild neuropathies, the onset of which is usually delayed to early adulthood. The more severe inherited forms, such as Charcot-Marie-Tooth disease (CMT), usually appear in childhood. In CMT disease, there are mistakes in the coding for the protective sheath (myelin sheath) that surrounds the nerve filaments.

Examples of peripheral nerve disorders include:

Guillain-Barre´ Strohl Syndrome: Since the polio vaccine came into widespread use, GBS has become the most

common remaining cause of acute neuromuscular paralysis. An acute, ascending, and progressive neuropathy

characterized by weakness, paresthesias, and hyporeflexia. In the early 1900s, Guillain, Barre´, and Strohl first

described the syndrome in 2 patients who spontaneously recovered from a progressive ascending motor

weakness with areflexia, paresthesias, sensory loss, and an elevated level of cerebrospinal fluid (CSF) protein.

Chronic Inflammatory Demyelinating Polyneuropathy (CIPD)

Polyneuropathies

Diabetic Neuropathies: Tingling in the feet may be caused by a peripheral neuropathy. Early evaluation with

laboratory studies may uncover potentially treatable disease such as diabetes and vitamin B12 deficiency.

Mononeuropathies: Isolated numbness of the hands brought on by excessive keyboard work may be identified

as Carpal Tunnel Syndrome, also a treatable problem. Ulnar neuropathies are also included as a type of

mononeuropathy.

Peripheral Nerve Injuries

Amyotrophic Lateral Sclerosis (ALS): Gehrig's disease, a disorder of the motor nerves resulting in progressive

weakness of the limbs, facial and respiratory muscles, is the most serious of the neuromuscular disorders.

Radiculopathies

Small Fiber Neuropathies

Occupational Neuropathies: Industrial and athletic injuries to nerves such as the stinger in football result in arm

weakness and tingling.

The symptoms of peripheral neuropathy are produced by disease of a single nerve

(mononeuropathy, mononeuritis), several nerves in asymmetric areas of the body (mononeuritis

multiplex), or many nerves simultaneously (polyneuropathy, polyneuritis, multiple peripheral

neuritis). These symptoms may involve sensory, motor, reflex, or blood vessel (vasomotor) function.

Lesions, usually degenerative and only rarely accompanied by signs of inflammation, may occur in

the nerve roots or peripheral nerves. 

The symptoms of peripheral nerve damage depend on the type of nerve affected. Muscle weakness,

with or without muscle cramping, uncontrolled muscle twitching (fasciculations), loss of muscle

mass, and bone erosion are usually the result of damage to a motor nerve. However, on occasion,

such changes may be due to damage to sensory or autonomic nerves as well. 

Symptoms arising from sensory nerve damage include reduced ability to touch and/or feel

vibrations, with increasing numbness in the feet and hands. Many patients feel as if their hands and

feet were covered, as if they were wearing gloves or stockings. Loss of posture sense or position

sense leads to difficulty in walking, using buttons, or maintaining balance. Associated pain varies but

may become intense and difficult to control. 

It is not unusual for patients to lose the ability to feel pain or to sense changes in temperature. Such

sensory loss may be particularly dangerous to patients with heart disease or diabetes. Patients may

fail to register the signs of an impending heart attack or to realize the degree of damage to a foot,

thus contributing to the course of preventable gangrene. 

Autonomic nerve damage generates a different set of symptoms, depending on the organ or gland

involved. Cardiovascular or pulmonary involvement may lead to life-threatening circumstances.

Other symptoms include reduced capability to sweat properly, loss of bladder control, and the

inability to control the muscles that help maintain blood pressure. Other symptoms of autonomic

nerve damage include problems related to digestion, eating and swallowing.