Polyneuropathy
Encyclopedia
Polyneuropathy is a neurological disorder
that occurs when many peripheral nerves throughout the body malfunction simultaneously. It may be acute and appear without warning, or chronic and develop gradually over a longer period of time. Many polyneuropathies have both motor and sensory involvement; some also involve dysfunction of the autonomic nervous system
. These disorders are often symmetric and frequently affect the feet and hands, causing weakness, loss of sensation, pins-and-needle sensations or burning pain. There are quite a few conditions that can cause polyneuropathy.
, the myelin
sheath, or the cell body.
One also needs to know what disorders are already present within the family and what diseases the patient may currently have. This is vital in forming a differential diagnosis.
Although often diseases are suggested by the physical exam and history alone, testing is still a large part of the diagnosis. Tests which may be employed include: electrodiagnostic testing using electromyography
, muscle biopsy
, serum creatine kinase
(CK), antibody
testing. Nerve biopsy is not used much, but is helpful in determining small fiber neuropathy
. Other tests may be used, especially tests for specific disorders associated with polyneuropathies.
s, autoimmune reactions, toxin
s, certain drugs, and cancer
.
Chronic polyneuropathy is often caused by diabetes mellitus
or by the excessive use of alcohol
(alcoholic polyneuropathy
), but a variety of other less common causes are known, including nutritional deficiencies, and liver
or kidney
failure.
One Danish study in 2002 suggested a link between long term exposure to statins and increased risk of polyneuropathy, although other studies have not confirmed this finding.
for polyneuropathies: vitamin deficiency, cancer
, toxins, infections (ex. Guillain-Barré Syndrome
, Lyme Disease
), liver
disease, endocrine disease (including diabetes with diabetic and pre-diabetic neuropathy
), amyloidosis
, genetic
disorders, motor neuron disorders, motor neuropathies, kidney failure, paraneoplastic, polio, porphyria
(some types), spinal muscular atrophy
, catecholamine
disorders, psychological disorders and many others.
Neurological disorder
A neurological disorder is a disorder of the body's nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord, or in the nerves leading to or from them, can result in symptoms such as paralysis, muscle weakness, poor coordination, loss of sensation, seizures,...
that occurs when many peripheral nerves throughout the body malfunction simultaneously. It may be acute and appear without warning, or chronic and develop gradually over a longer period of time. Many polyneuropathies have both motor and sensory involvement; some also involve dysfunction of the autonomic nervous system
Autonomic nervous system
The autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...
. These disorders are often symmetric and frequently affect the feet and hands, causing weakness, loss of sensation, pins-and-needle sensations or burning pain. There are quite a few conditions that can cause polyneuropathy.
Classification
Polyneuropathies can be classified in many different ways, such as by cause, by speed of progression, or by the parts of the body involved. It is also important to distinguish between classes of polyneuropathy according to which part of the nerve cell is mainly affected: the axonAxon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
, the myelin
Myelin
Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...
sheath, or the cell body.
- Distal axonopathy, or "dying-back neuropathy", is the result of some metabolic or toxic derangement of neuronNeuronA neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
s. It is the most common response of neurones to metabolic or toxic disturbances, and as such may be caused by metabolic diseases such as diabetesDiabetic neuropathyDiabetic neuropathies are neuropathic disorders that are associated with diabetes mellitus. These conditions are thought to result from diabetic microvascular injury involving small blood vessels that supply nerves in addition to macrovascular conditions that can culminate in diabetic neuropathy...
, renal failureRenal failureRenal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
, deficiency syndromes such as malnutritionMalnutritionMalnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
and alcoholismAlcoholismAlcoholism is a broad term for problems with alcohol, and is generally used to mean compulsive and uncontrolled consumption of alcoholic beverages, usually to the detriment of the drinker's health, personal relationships, and social standing...
, or the effects of toxinToxinA toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s or drugsMedicationA pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
such as chemotherapyChemotherapyChemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
. They can be further divided according to the type of axon affected: large-fiber, small-fiberSmall fiber peripheral neuropathySmall fiber peripheral neuropathy is a type of neuropathy that occurs from damage to the small unmyelinated peripheral nerve fibers. These fibers, categorized as C fibers, are present in skin, peripheral nerves and organs. The role of these nerves is to innervate the skin and help control...
, or both. The most distal portions of axons are usually the first to degenerate, and axonal atrophy advances slowly towards the nerve's cell body. If the cause is removed, regeneration is possible, though the prognosis depends on the duration and severity of the stimulus. Those with distal axonopathies usually present with sensorimotor disturbances that have a symmetrical "stocking and glove" distribution. Deep tendon reflexes and autonomic nervous systemAutonomic nervous systemThe autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...
functions are also lost or diminished in affected areas. - Myelinopathy, or "demyelinating polyneuropathy", is due to a loss of myelinMyelinMyelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...
(or of the Schwann cells that make and contain it). This demyelination slows down or completely blocks the conduction of action potentialAction potentialIn physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...
s through the axon of the nerve cell. The most common cause is acute inflammatory demyelinating polyneuropathy (AIDP, the most common form of Guillain-Barré syndromeGuillain-Barré syndromeGuillain–Barré syndrome , sometimes called Landry's paralysis, is an acute inflammatory demyelinating polyneuropathy , a disorder affecting the peripheral nervous system. Ascending paralysis, weakness beginning in the feet and hands and migrating towards the trunk, is the most typical symptom...
), though other causes include chronic inflammatory demyelinating polyneuropathyChronic inflammatory demyelinating polyneuropathyChronic inflammatory demyelinating polyneuropathy is an acquired immune-mediated inflammatory disorder of the peripheral nervous system. The disorder is sometimes called chronic relapsing polyneuropathy. CIDP is closely related to Guillain-Barré syndrome and it is considered the chronic...
(CIDP), geneticGeneticsGenetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
metabolic disorders (e.g., leukodystrophyLeukodystrophyLeukodystrophy refers to a group of disorders characterized by dysfunction of the white matter of the brain. The leukodystrophies are caused by imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fibers...
), or toxins. - Neuronopathy is the result of destruction of peripheral nervous systemPeripheral nervous systemThe peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...
(PNS) neuronNeuronA neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
s. They may be caused by motor neurone diseaseMotor neurone diseaseThe motor neurone diseases are a group of neurological disorders that selectively affect motor neurones, the cells that control voluntary muscle activity including speaking, walking, breathing, swallowing and general movement of the body. They are generally progressive in nature, and can cause...
s, sensory neuronopathies (e.g., Herpes zosterHerpes zosterHerpes zoster , commonly known as shingles and also known as zona, is a viral disease characterized by a painful skin rash with blisters in a limited area on one side of the body, often in a stripe...
), toxins or autonomicAutonomic nervous systemThe autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...
dysfunction. NeurotoxinsNeurotoxicityNeurotoxicity occurs when the exposure to natural or artificial toxic substances, which are called neurotoxins, alters the normal activity of the nervous system in such a way as to cause damage to nervous tissue. This can eventually disrupt or even kill neurons, key cells that transmit and process...
may cause neuronopathies, such as the chemotherapyChemotherapyChemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
agent vincristineVincristineVincristine , formally known as leurocristine, sometimes abbreviated "VCR", is a vinca alkaloid from the Catharanthus roseus , formerly Vinca rosea and hence its name. It is a mitotic inhibitor, and is used in cancer chemotherapy.-Mechanism:Tubulin is a structural protein that polymerizes to...
.
Evaluation
Evaluation and classification of polyneuropathies begins with a history and physical exam in order to document what the pattern of the disease process is (arms, legs, distal, proximal, symmetric), when they started, how long they've lasted, if they fluctuate, and what deficits and pain are involved. If pain is a factor, and it often is, determining where and how long the pain has been present is important.One also needs to know what disorders are already present within the family and what diseases the patient may currently have. This is vital in forming a differential diagnosis.
Although often diseases are suggested by the physical exam and history alone, testing is still a large part of the diagnosis. Tests which may be employed include: electrodiagnostic testing using electromyography
Electromyography
Electromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle...
, muscle biopsy
Muscle biopsy
In medicine, a muscle biopsy is a procedure in which a piece of muscle tissue is removed from an organism and examined microscopically. A biopsy needle is usually inserted into a muscle, wherein a small amount of tissue remains. Alternatively, an "open biopsy" can be performed by obtaining the...
, serum creatine kinase
Creatine kinase
Creatine kinase , also known as creatine phosphokinase or phospho-creatine kinase , is an enzyme expressed by various tissues and cell types. CK catalyses the conversion of creatine and consumes adenosine triphosphate to create phosphocreatine and adenosine diphosphate...
(CK), antibody
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
testing. Nerve biopsy is not used much, but is helpful in determining small fiber neuropathy
Small fiber peripheral neuropathy
Small fiber peripheral neuropathy is a type of neuropathy that occurs from damage to the small unmyelinated peripheral nerve fibers. These fibers, categorized as C fibers, are present in skin, peripheral nerves and organs. The role of these nerves is to innervate the skin and help control...
. Other tests may be used, especially tests for specific disorders associated with polyneuropathies.
Causes
Acute polyneuropathy can have various causes, including infectionInfection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
s, autoimmune reactions, toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s, certain drugs, and cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
.
Chronic polyneuropathy is often caused by diabetes mellitus
Diabetes mellitus
Diabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
or by the excessive use of alcohol
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...
(alcoholic polyneuropathy
Alcoholic polyneuropathy
Alcoholic polyneuropathy is a neurological disorder in which multiple peripheral nerves throughout the body malfunction simultaneously. It is defined by axonal degeneration in neurons of both the sensory and motor systems and initially occurs at the distal ends of the longest axons in the body...
), but a variety of other less common causes are known, including nutritional deficiencies, and liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
or kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
failure.
One Danish study in 2002 suggested a link between long term exposure to statins and increased risk of polyneuropathy, although other studies have not confirmed this finding.
Treatment
If possible, treatment focuses on the underlying disease. Further, pain medications may be given and physical therapy is used to retain muscle function.Differential
There is a large differentialDifferential diagnosis
A differential diagnosis is a systematic diagnostic method used to identify the presence of an entity where multiple alternatives are possible , and may also refer to any of the included candidate alternatives A differential diagnosis (sometimes abbreviated DDx, ddx, DD, D/Dx, or ΔΔ) is a...
for polyneuropathies: vitamin deficiency, cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
, toxins, infections (ex. Guillain-Barré Syndrome
Guillain-Barré syndrome
Guillain–Barré syndrome , sometimes called Landry's paralysis, is an acute inflammatory demyelinating polyneuropathy , a disorder affecting the peripheral nervous system. Ascending paralysis, weakness beginning in the feet and hands and migrating towards the trunk, is the most typical symptom...
, Lyme Disease
Lyme disease
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...
), liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
disease, endocrine disease (including diabetes with diabetic and pre-diabetic neuropathy
Diabetic neuropathy
Diabetic neuropathies are neuropathic disorders that are associated with diabetes mellitus. These conditions are thought to result from diabetic microvascular injury involving small blood vessels that supply nerves in addition to macrovascular conditions that can culminate in diabetic neuropathy...
), amyloidosis
Amyloidosis
In medicine, amyloidosis refers to a variety of conditions whereby the body produces "bad proteins", denoted as amyloid proteins, which are abnormally deposited in organs and/or tissues and cause harm. A protein is described as being amyloid if, due to an alteration in its secondary structure, it...
, genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
disorders, motor neuron disorders, motor neuropathies, kidney failure, paraneoplastic, polio, porphyria
Porphyria
Porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway . They are broadly classified as acute porphyrias and cutaneous porphyrias, based on the site of the overproduction and accumulation of the porphyrins...
(some types), spinal muscular atrophy
Spinal muscular atrophy
Spinal Muscular Atrophy is a neuromuscular disease characterized by degeneration of motor neurons, resulting in progressive muscular atrophy and weakness. The clinical spectrum of SMA ranges from early infant death to normal adult life with only mild weakness...
, catecholamine
Catecholamine
Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...
disorders, psychological disorders and many others.
See also
- Neuropathy
- Mononeuropathy
- PolyradiculoneuropathyPolyradiculoneuropathyPolyradiculoneuropathy describes a condition in which polyneuropathy and polyradiculopathy occur together. An example is Guillain-Barré syndrome....
- Polyneuropathy in dogs and catsPolyneuropathy in dogs and catsPolyneuropathy in dogs and cats is a collection of peripheral nerve disorders that often are breed-related in these animals. Polyneuropathy indicates that multiple nerves are involved, unlike mononeuropathy. Polyneuropathy usually involves motor nerve dysfunction, also known as lower motor neuron...
- Neuritis