Alcoholic polyneuropathy is a

neurological disorder Neurological disorders represent a complex array of medical conditions that fundamentally disrupt the functioning of the nervous system. These disorders affect the brain, spinal cord, and nerve networks, presenting unique diagnosis, treatment, and ...

in which peripheral

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...

s throughout the body malfunction simultaneously. It is defined by

axon An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences) is a long, slender cellular extensions, projection of a nerve cell, or neuron, ...

al degeneration in

neuron A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural net ...

s of both the

sensory Sensory may refer to: Biology * Sensory ecology, how organisms obtain information about their environment * Sensory neuron, nerve cell responsible for transmitting information about external stimuli * Sensory perception, the process of acquiri ...

and

motor system The motor system is the set of central nervous system, central and peripheral nervous system, peripheral structures in the nervous system that support motor functions, i.e. movement. Peripheral structures may include skeletal muscles and Efferen ...

s and initially occurs at the

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

ends of the longest axons in the

body Body may refer to: In science * Physical body, an object in physics that represents a large amount, has mass or takes up space * Body (biology), the physical material of an organism * Body plan, the physical features shared by a group of anim ...

. This

nerve damage Nerve injury is an injury to a nerve. There is no single classification system that can describe all the many variations of nerve injuries. In 1941, Herbert Seddon introduced a classification of nerve injuries based on three main types of nerve ...

causes an individual to experience pain and motor weakness, first in the feet and hands and then progressing centrally. Alcoholic polyneuropathy is caused primarily by chronic alcoholism; however,

vitamin deficiencies Vitamin deficiency is the condition of a long-term lack of a vitamin. When caused by not enough vitamin intake it is classified as a ''primary deficiency'', whereas when due to an underlying disorder such as malabsorption it is called a ''seconda ...

are also known to contribute to its development. This

disease A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...

typically occurs in chronic alcoholics who have some sort of nutritional deficiency. Treatment may involve nutritional supplementation, pain management, and abstaining from alcohol.

Signs and symptoms

An early warning sign (

prodrome In medicine, a prodrome is an early sign or symptom (or set of signs and symptoms, referred to as prodromal symptoms) that often indicates the onset of a disease before more diagnostically specific signs and symptoms develop. More specifically, it ...

) of the possibility of developing alcoholic polyneuropathy, especially in a chronic alcoholic, would be weight loss because this usually signifies a nutritional deficiency that can lead to the development of the disease. Alcoholic polyneuropathy usually has a gradual onset over months or even years, although axonal degeneration often begins before an individual experiences any

symptom Signs and symptoms are diagnostic indications of an illness, injury, or condition. Signs are objective and externally observable; symptoms are a person's reported subjective experiences. A sign for example may be a higher or lower temperature ...

s. The disease typically involves sensory issues and motor loss, as well as painful physical perceptions, though all sensory modalities may be involved. Symptoms that affect the sensory and motor systems seem to develop symmetrically. For example, if the right foot is affected, the left foot is affected simultaneously or soon becomes affected. In most cases, the legs are affected first, followed by the arms. The hands usually become involved when the symptoms reach above the ankle. This is called a stocking-and-glove pattern of sensory disturbances.

Sensory

Common manifestations of sensory issues include numbness or painful sensations in the arms and legs, abnormal sensations like "pins and needles," and

heat intolerance Heat intolerance is a symptom characterized by feeling overheated in warm environments or when the surrounding environment's temperature rises. Typically, the person feels uncomfortably hot and sweats excessively. Compared to heat illnesses lik ...

Pain Pain is a distressing feeling often caused by intense or damaging Stimulus (physiology), stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sense, sensory and emotional experience associated with, or res ...

experienced by individuals depends on the severity of the polyneuropathy. It may be dull and constant in some individuals while being sharp and lancinating in others. In many subjects, tenderness is seen upon the palpitation of muscles in the feet and legs. Certain people may also feel

cramp A cramp is a sudden, involuntary, painful skeletal muscle contraction or overshortening associated with electrical activity. While generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the aff ...

ing sensations in the muscles affected and others say there is a burning sensation in their feet and calves.

Motor

Sensory symptoms are gradually followed by motor symptoms. Motor symptoms may include muscle cramps and weakness,

erectile dysfunction Erectile dysfunction (ED), also referred to as impotence, is a form of sexual dysfunction in males characterized by the persistent or recurring inability to achieve or maintain a Human penis, penile erection with sufficient rigidity and durat ...

in men, problems urinating,

constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The Human feces, stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the ...

, and

diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

. Individuals also may experience muscle wasting and decreased or absent

deep tendon reflex Deep or The Deep may refer to: Places United States * Deep Creek (Appomattox River tributary), Virginia * Deep Creek (Great Salt Lake), Idaho and Utah * Deep Creek (Mahantango Creek tributary), Pennsylvania * Deep Creek (Mojave River tributary) ...

es. Some people may experience frequent falls and gait unsteadiness due to

ataxia Ataxia (from Greek α- negative prefix+ -τάξις rder= "lack of order") is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in e ...

. This ataxia may be caused by

cerebellar The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or e ...

degeneration, sensory ataxia, or distal muscle weakness. Over time, alcoholic polyneuropathy may also cause difficulty swallowing (

dysphagia Dysphagia is difficulty in swallowing. Although classified under " symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right. It may be a sensation that suggests difficulty in the passage of solids or l ...

), speech impairment ( disarthria),

muscle spasms A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ, such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a musc ...

, and

muscle atrophy Muscle atrophy is the loss of skeletal muscle mass. It can be caused by immobility, aging, malnutrition, medications, or a wide range of injuries or diseases that impact the musculoskeletal or nervous system. Muscle atrophy leads to muscle weakne ...

. In addition to alcoholic polyneuropathy, the individual may also show other related disorders such as

Wernicke–Korsakoff syndrome Wernicke-Korsakoff syndrome (WKS), colloquially referred to as wet brain syndrome, is the combined presence of Wernicke encephalopathy (WE) and Korsakoff syndrome. Due to the close relationship between these two disorders, people with either ar ...

and cerebellar degeneration that result from alcoholism-related nutritional disorders.

Severity

Polyneuropathy spans a large range of severity. Some cases are seemingly

asymptomatic Asymptomatic (or clinically silent) is an adjective categorising the medical conditions (i.e., injuries or diseases) that patients carry but without experiencing their symptoms, despite an explicit diagnosis (e.g., a positive medical test). P ...

and may only be recognized on careful examination. The most severe cases may cause profound

physical disability A physical disability is a limitation on a person's physical functioning, mobility, dexterity or stamina. Other physical disabilities include impairments which limit other facets of daily living, such as respiratory disorders, blindness, epilepsy ...

Causes

The general cause of this disease appears to be prolonged and heavy consumption of

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

accompanied by a nutritional deficiency. However, there is ongoing debate over the active mechanisms, including whether the main cause is the direct

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

effect of alcohol itself or whether the disease is a result of alcoholism-related

malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues a ...

. A 2019 metastudy found that the relationship between ethanol toxicity and neuropathy remained unproven.

Effects due to nutritional deficiency

Frequently alcoholics have disrupted social links in their lives and have an irregular lifestyle. This may cause an alcoholic to change their eating habits including more missed meals and a poor dietary balance. Alcoholism may also result in loss of

appetite Appetite is the desire to eat food items, usually due to hunger. Appealing foods can stimulate appetite even when hunger is absent, although appetite can be greatly reduced by satiety. Appetite exists in all higher life-forms, and serves to reg ...

, alcoholic

gastritis Gastritis is the inflammation of the lining of the stomach. It may occur as a short episode or may be of a long duration. There may be no symptoms but, when symptoms are present, the most common is upper abdominal pain (see dyspepsia). Othe ...

, and vomiting, which decrease food intake. Alcohol abuse damages the lining of the

gastrointestinal system The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...

and reduces absorption of nutrients that are taken in. The combination of all of them may result in a nutritional deficiency that is linked to the development of alcoholic polyneuropathy. There is evidence that providing individuals with adequate vitamins improves symptoms despite continued alcohol intake, indicating that vitamin deficiency may be a major factor in the development and progression of alcoholic polyneuropathy. In experimental models of alcoholic polyneuropathy utilizing

rats Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' (pack rats), '' Bandicota'' (bandicoot ...

and monkeys no convincing evidence was found that proper nutritional intake along with alcohol results in polyneuropathy. Thiamine pyrophosphate V2

In most cases, individuals with alcoholic polyneuropathy have some degree of nutritional deficiency. Alcohol, a

carbohydrate A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...

, increases the

metabolic Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the ...

demand for

thiamine Thiamine, also known as thiamin and vitamin B1, is a vitamin – an Nutrient#Micronutrients, essential micronutrient for humans and animals. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosp ...

(vitamin B1) because of its role in the metabolism of glucose. Thiamine levels are usually low in alcoholics due to their decreased nutritional intake. In addition, alcohol interferes with intestinal absorption of thiamine, thereby further decreasing thiamine levels in the body. Thiamine is important in three reactions in the metabolism of glucose: the

decarboxylation Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is ...

pyruvic acid Pyruvic acid (CH3COCOOH) is the simplest of the keto acids, alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate acid, conjugate base, CH3COCOO−, is an metabolic intermediate, intermediate in several m ...

, d-ketoglutaric acid, and

transketolase Transketolase (abbreviated as TK) is an enzyme that, in humans, is encoded by the ''TKT'' gene. It participates in both the pentose phosphate pathway in all organisms and the Calvin cycle of photosynthesis. Transketolase catalyzes two important r ...

. A lack of thiamine in the cells may therefore prevent neurons from maintaining necessary

adenosine triphosphate Adenosine triphosphate (ATP) is a nucleoside triphosphate that provides energy to drive and support many processes in living cell (biology), cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known ...

(ATP) levels as a result of impaired

glycolysis Glycolysis is the metabolic pathway that converts glucose () into pyruvic acid, pyruvate and, in most organisms, occurs in the liquid part of cells (the cytosol). The Thermodynamic free energy, free energy released in this process is used to form ...

. Thiamine deficiency alone could explain the impaired nerve

conduction Conductor or conduction may refer to: Biology and medicine * Bone conduction, the conduction of sound to the inner ear * Conduction aphasia, a language disorder Mathematics * Conductor (ring theory) * Conductor of an abelian variety * Condu ...

in those with alcoholic polyneuropathy, but other factors likely play a part. The malnutrition many alcoholics experience deprives them of important cofactors for the oxidative metabolism of glucose. Neural tissues depend on this process for energy, and disruption of the cycle would impair cell growth and function.

Schwann cell Schwann cells or neurolemmocytes (named after German physiologist Theodor Schwann) are the principal glia of the peripheral nervous system (PNS). Glial cells function to support neurons and in the PNS, also include Satellite glial cell, satellite ...

s produce myelin that wraps around the sensory and motor nerve axons to enhance

action potential An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly ri ...

conduction in the periphery. An energy deficiency in Schwann cells would account for the disappearance of myelin on peripheral nerves, which may result in damage to axons or loss of nerve function altogether. In peripheral nerves, oxidative enzyme activity is most concentrated around the

nodes of Ranvier Nodes of Ranvier ( ), also known as myelin-sheath gaps, occur along a myelinated axon where the axolemma is exposed to the extracellular space. Nodes of Ranvier are uninsulated axonal domains that are high in sodium and potassium ion channels ...

, making these locations most vulnerable to cofactor deprivation. Lacking essential cofactors reduces myelin impedance, increases current leakage, and slows signal transmission. Disruptions in conductance first affect the peripheral ends of the longest and largest peripheral nerve fibers because they suffer most from decreased action potential propagation. Thus, neural deterioration occurs in an accelerating cycle: myelin damage reduces conductance, and reduced conductance contributes to myelin degradation. The slowed conduction of action potentials in axons causes segmental demyelination extending proximally; this is also known as retrograde degeneration. Many of the studies conducted that observe alcoholic polyneuropathy in patients are often criticized for their criteria used to assess nutritional deficiency in the subjects because they may not have completely ruled out the possibility of a nutritional deficiency in the genesis of the polyneuropathy. Many researchers favor the nutritional origin of this disease, but the possibility of alcohol having a toxic effect on the peripheral nerves has not been completely ruled out.

Effects due to alcohol ingestion

The consumption of alcohol may lead to the buildup of certain toxins in the body. For example, in the process of breaking down alcohol, the body produces

acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...

, which can accumulate to toxic levels in alcoholics. This suggests that there is a possibility

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

(or its metabolites) may cause alcoholic polyneuropathy. There is evidence that polyneuropathy is also prevalent in well-nourished alcoholics, supporting the idea that there is a direct toxic effect of alcohol. The metabolic effects of liver damage associated with alcoholism may also contribute to the development of alcoholic polyneuropathy. Normal products of the liver, such as

lipoic acid Lipoic acid (LA), also known as α-lipoic acid, alpha-lipoic acid (ALA) and thioctic acid, is an organosulfur compound derived from caprylic acid (octanoic acid). ALA, which is made in animals normally, is essential for aerobic metabolism. It i ...

, may be deficient in alcoholics. This deficiency would also disrupt glycolysis and can alter metabolism, transport, storage, and activation of essential nutrients.

Acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...

is toxic to peripheral nerves. There are increased levels of acetaldehyde produced during

metabolism. If the acetaldehyde is not metabolized quickly the nerves may be affected by the accumulation of acetaldehyde to toxic levels.

Pathophysiology

The

pathophysiology Pathophysiology (or physiopathology) is a branch of study, at the intersection of pathology and physiology, concerning disordered physiological processes that cause, result from, or are otherwise associated with a disease or injury. Pathology is ...

of alcoholic polyneuropathy is unclear.

Diagnosis

Alcoholic polyneuropathy is very similar to other axonal degenerative polyneuropathies and therefore can be difficult to diagnose. When alcoholics have sensorimotor polyneuropathy as well as a nutritional deficiency, a diagnosis of alcoholic polyneuropathy is often reached. To confirm the diagnosis, a physician must rule out other causes of similar clinical syndromes. Other neuropathies can be differentiated on the basis of typical clinical or laboratory features. Differential diagnoses to alcoholic polyneuropathy include

amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States—Lou Gehrig's disease (LGD), is a rare, Terminal illness, terminal neurodegenerative disease, neurodegenerative disorder that results i ...

beriberi Thiamine deficiency is a medical condition of low levels of thiamine (vitamin B1). A severe and chronic form is known as beriberi. The name beriberi was possibly borrowed in the 18th century from the Sinhalese phrase (bæri bæri, “I canno ...

, Charcot-Marie-Tooth disease, diabetic lumbosacral plexopathy, Guillain Barre Syndrome,

diabetic neuropathy Diabetic neuropathy includes various types of nerve damage associated with diabetes mellitus. The most common form, diabetic peripheral neuropathy, affects 30% of all diabetic patients. Studies suggests that cutaneous nerve branches, such as the s ...

mononeuritis multiplex Peripheral neuropathy, often shortened to neuropathy, refers to damage or disease affecting the nerves. Damage to nerves may impair sensation, movement, gland function, and/or organ function depending on which nerve fibers are affected. Neuropa ...

and

post-polio syndrome Post-polio syndrome (PPS, poliomyelitis sequelae) is a group of latent symptoms of poliomyelitis (polio), occurring in more than 80% of polio infections. The symptoms are caused by the damaging effects of the viral infection on the nervous syst ...

. To clarify the diagnosis, medical workup most commonly involves laboratory tests, though, in some cases,

imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image). Imaging technology is the application of materials and methods to create, preserve, or duplicate images. ...

nerve conduction studies A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called ...

electromyography Electromyography (EMG) 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 electromyo ...

, and vibrometer testing may also be used. A number of tests may be used to rule out other causes of peripheral neuropathy. One of the first presenting symptoms of

diabetes mellitus Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...

may be peripheral neuropathy, and

hemoglobin A1C Glycated hemoglobin, also called glycohemoglobin, is a form of hemoglobin (Hb) that is chemically linked to a sugar. Most monosaccharides, including glucose, galactose, and fructose, spontaneously (that is, enzyme, non-enzymatically) bond with h ...

can be used to estimate average blood glucose levels. Elevated blood

creatinine Creatinine (; ) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass). Biological relevance Serum creatinine (a blood measurement) is an impor ...

levels may indicate

chronic kidney disease Chronic kidney disease (CKD) is a type of long-term kidney disease, defined by the sustained presence of abnormal kidney function and/or abnormal kidney structure. To meet criteria for CKD, the abnormalities must be present for at least three mo ...

and may also be a cause of peripheral neuropathy. A heavy metal toxicity screen should also be used to exclude lead toxicity as a cause of neuropathy. Alcoholism is normally associated with nutritional deficiencies, which may contribute to the development of alcoholic polyneuropathy.

Thiamine Thiamine, also known as thiamin and vitamin B1, is a vitamin – an Nutrient#Micronutrients, essential micronutrient for humans and animals. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosp ...

, vitamin B-12, and

folic acid Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...

are vitamins that play an essential role in the

peripheral A peripheral device, or simply peripheral, is an auxiliary hardware device that a computer uses to transfer information externally. A peripheral is a hardware component that is accessible to and controlled by a computer but is not a core compo ...

and

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

and should be among the first analyzed in laboratory tests. It has been difficult to assess thiamine status in individuals due to difficulties in developing a method to directly

assay An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity ...

thiamine in the blood and urine. A

liver function test Liver function tests (LFTs or LFs), also referred to as a hepatic panel or liver panel, are groups of blood tests that provide information about the state of a patient's liver. These tests include prothrombin time (PT/INR), activated partial ...

may also be ordered, as alcoholic consumption may cause an increase in liver enzyme levels.

Management

Although there is no known cure for alcoholic polyneuropathy, there are a number of treatments that can control symptoms and promote independence.

Physical therapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

is beneficial for strength training of weakened muscles, as well as for gait and balance training.

Nutrition

To best manage symptoms, refraining from consuming alcohol is essential. Abstinence from alcohol encourages proper diet and helps prevent progression or recurrence of the neuropathy. Once an individual stops consuming alcohol it is important to make sure they understand that substantial recovery usually isn't seen for a few months. Some subjective improvement may appear right away, but this is usually due to the overall benefits of alcohol detoxification. If alcohol consumption continues, vitamin supplementation alone is not enough to improve the symptoms of most individuals. Nutritional therapy with

parenteral In pharmacology and toxicology, a route of administration is the way by which a drug, fluid, poison, or other substance is taken into the body. Routes of administration are generally classified by the location at which the substance is applied. ...

multivitamins is beneficial to implement until the person can maintain adequate nutritional intake. Treatments also include

vitamin Vitamins are Organic compound, organic molecules (or a set of closely related molecules called vitamer, vitamers) that are essential to an organism in small quantities for proper metabolism, metabolic function. Nutrient#Essential nutrients, ...

supplementation (especially

). In more severe cases of nutritional deficiency 320 mg/day of

benfotiamine Benfotiamine ( rINN, or ''S''-benzoylthiamine ''O''-monophosphate) is a synthetic, fat-soluble, ''S''-acyl derivative of thiamine (vitamin B1) that is approved in some countries as a medication or dietary supplement to treat diabetic sensorimoto ...

for 4 weeks followed by 120 mg/day for 4 more weeks may be prescribed in an effort to return thiamine levels to normal.

Pain

Painful dysesthesias caused by alcoholic polyneuropathy can be treated by using

gabapentin Gabapentin, sold under the brand name Neurontin among others, is an anticonvulsant medication primarily used to treat neuropathic pain and also for partial seizures of epilepsy. It is a commonly used medication for the treatment of neuropath ...

amitriptyline Amitriptyline, sold under the brand name Elavil among others, is a tricyclic antidepressant primarily used to treat major depressive disorder, and a variety of pain syndromes such as neuropathic pain, fibromyalgia, migraine and tension headac ...

in combination with over-the-counter pain medications, such as

aspirin Aspirin () is the genericized trademark for acetylsalicylic acid (ASA), a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic. Specific inflammatory conditions that aspirin is ...

ibuprofen Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that is used to relieve pain, fever, and inflammation. This includes dysmenorrhea, painful menstrual periods, migraines, and rheumatoid arthritis. It can be taken oral administration, ...

, or

acetaminophen Paracetamol, or acetaminophen, is a non-opioid analgesic and antipyretic agent used to treat fever and mild to moderate pain. It is a widely available over-the-counter drug sold under various brand names, including Tylenol and Panadol. Parac ...

Tricyclic antidepressants Tricyclic antidepressants (TCAs) are a class of medications that are used primarily as antidepressants. TCAs were discovered in the early 1950s and were marketed later in the decade. They are named after their chemical structure, which contains ...

such as

, or

carbamazepine Carbamazepine, sold under the brand name Tegretol among others, is an anticonvulsant medication used in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other medications and as ...

may help stabbing pains and have central and peripheral

anticholinergic Anticholinergics (anticholinergic agents) are substances that block the action of the acetylcholine (ACh) neurotransmitter at synapses in the central nervous system, central and peripheral nervous system. These agents inhibit the parasympatheti ...

and sedative effects. These agents have central effects on pain transmission and block the active reuptake of norepinephrine and serotonin. Anticonvulsant drugs like

pregabalin Pregabalin, sold under the brand name Lyrica among others, is an anticonvulsant, analgesic, and anxiolytic amino acid medication used to treat epilepsy, neuropathic pain, fibromyalgia, restless legs syndrome, opioid withdrawal, generalized anx ...

block the active reuptake of

norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic compound, organic chemical in the catecholamine family that functions in the brain and human body, body as a hormone, neurotransmitter and neuromodulator. The ...

and

serotonin Serotonin (), also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter with a wide range of functions in both the central nervous system (CNS) and also peripheral tissues. It is involved in mood, cognition, reward, learning, ...

and have properties that relieve neuropathic pain. However, these medications take a few weeks to become effective and are rarely used in the treatment of

acute pain Pain is a distressing feeling often caused by intense or damaging Stimulus (physiology), stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sense, sensory and emotional experience associated with, or res ...

. Topical analgesics like

capsaicin Capsaicin (8-methyl-''N''-vanillyl-6-nonenamide) (, rarely ) is an active component of chili peppers, which are plants belonging to the genus ''Capsicum''. It is a potent Irritation, irritant for Mammal, mammals, including humans, and produces ...

may also relieve minor aches and pains of muscles and joints.

Prognosis

Alcoholic polyneuropathy is not life-threatening but may significantly affect one's quality of life. Effects of the disease range from mild discomfort to severe disability. It is difficult to assess the

prognosis Prognosis ( Greek: πρόγνωσις "fore-knowing, foreseeing"; : prognoses) is a medical term for predicting the likelihood or expected development of a disease, including whether the signs and symptoms will improve or worsen (and how quickly) ...

of a patient because alcohol dependence results in difficulty maintaining abstinence from drinking alcohol. It has been shown that a good prognosis may be given for mild neuropathy if the person has abstained from drinking for 3–5 years.

Early stage

During the early stages of the disease the damage appears reversible when people take adequate amounts of vitamins, such as thiamine. If the polyneuropathy is mild, the individual normally experiences a significant improvement and symptoms may be eliminated within weeks to months after proper nutrition is established. When those people diagnosed with alcohol polyneuropathy experience a recovery, it is presumed to result from regeneration and collateral sprouting of the damaged axons.

Progressed disease

As the disease progresses, the damage may become permanent. In severe cases of thiamine deficiency, a few of the positive symptoms (including neuropathic pain) may persist indefinitely. Even after the restoration of a balanced nutritional intake, those patients with severe or chronic polyneuropathy may experience lifelong residual symptoms.

Epidemiology

In 2020 the NIH quoted an estimate that in the United States 25% to 66% of chronic alcohol users experience some form of neuropathy. The rate of incidence of alcoholic polyneuropathy involving sensory and motor polyneuropathy has been stated as from 10% to 50% of alcoholics depending on the subject selection and diagnostic criteria. If electrodiagnostic criteria are used, alcoholic polyneuropathy may be found in up to 90% of individuals being assessed. The distribution and severity of the disease depends on regional dietary habits, individual drinking habits, as well as an individual's

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...

. Large studies have been conducted and show that alcoholic polyneuropathy severity and incidence correlates best with the total lifetime consumption of alcohol. Factors such as nutritional intake, age, or other medical conditions are correlate in lesser degrees. For unknown reasons, alcoholic polyneuropathy has a high incidence in women. Certain alcoholic beverages can also contain congeners that may also be bioactive; therefore, the consumption of varying alcohol beverages may result in different health consequences. An individual's nutritional intake also plays a role in the development of this disease. Depending on the specific dietary habits, they may have a deficiency of one or more of the following:

(vitamin B1),

niacin Nicotinic acid, or niacin, is an organic compound and a vitamer of vitamin B3, an essential human nutrient. It is produced by plants and animals from the amino acid tryptophan. Nicotinic acid is also a prescription medication. Amounts f ...

(vitamin B3),

pantothenic acid Pantothenic acid (vitamin B5) is a B vitamin and an essential nutrient. All animals need pantothenic acid in order to synthesize coenzyme A (CoA), which is essential for cellular energy production and for the synthesis and degradation of prote ...

(vitamin B5),

pyridoxine Pyridoxine (PN) is a form of vitamin B6 found commonly in food and used as a dietary supplement. As a supplement it is used to treat and prevent pyridoxine deficiency, sideroblastic anaemia, pyridoxine-dependent epilepsy, certain metaboli ...

(vitamin B6) and

biotin Biotin (also known as vitamin B7 or vitamin H) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. ...

(vitamin B7),

vitamin B12 Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. One of eight B vitamins, it serves as a vital cofactor (biochemistry), cofactor in DNA synthesis and both fatty acid metabolism, fatty acid and amino a ...

, and

vitamin A Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most not ...

Acetaldehyde

It is also thought there is perhaps a genetic predisposition for some alcoholics that results in increased frequency of alcoholic polyneuropathy in certain ethnic groups. During the body's processing of alcohol, ethanol is oxidized to acetaldehyde mainly by

alcohol dehydrogenase Alcohol dehydrogenases (ADH) () are a group of dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of nicotinamide adenine dinucleotide (NAD+) to N ...

; acetaldehyde is then oxidized to acetate mainly by aldehyde dehydrogenase (ALDH).

ALDH2 Aldehyde dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the ''ALDH2'' gene located on chromosome 12. ALDH2 belongs to the aldehyde dehydrogenase family of enzymes. Aldehyde dehydrogenase is the second enzyme of the majo ...

is an isozyme of ALDH and ALDH2 has a polymorphism (ALDH2*2, Glu487Lys) that makes ADLH2 inactive; this allele is more prevalent among Southeast and East Asians and results in a failure to quickly metabolize acetaldehyde. The neurotoxicity resulting from the accumulation of acetaldehyde may play a role in the pathogenesis of alcoholic polyneuropathy.

History

The first description of

s associated with alcoholic polyneuropathy were recorded by John C. Lettsome in 1787 when he noted

hyperesthesia Hyperesthesia is a condition that involves an abnormal increase in sensitivity to stimuli of the senses. Stimuli of the senses can include sound that one hears, foods that one tastes, textures that one feels, and so forth. Increased touch sensi ...

and

paralysis Paralysis (: paralyses; also known as plegia) is a loss of Motor skill, motor function in one or more Skeletal muscle, muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory d ...

in legs more than arms of patients. Jackson has also been credited with describing polyneuropathy in chronic alcoholics in 1822. The clinical title of alcoholic polyneuropathy was widely recognized by the late nineteenth century. It was thought that the polyneuropathy was a direct result of the toxic effect alcohol had on peripheral nerves when used excessively. In 1928, George C. Shattuck argued that the polyneuropathy resulted from a vitamin B deficiency commonly found in alcoholics and he claimed that alcoholic polyneuropathy should be related to

. This debate continues today over what exactly causes this disease, some argue it is just the alcohol toxicity, others claim the vitamin deficiencies are to blame and still others say it is some combination of the two.

Research directions

In 2001 research directions included the effect that an alcoholics' consumption and choice of alcoholic beverage might have on their development of alcoholic polyneuropathy. Some beverages may include more nutrients than others (such as thiamine), but the effects of this with regards to helping with a nutritional deficiency in alcoholics is yet unknown. Research also continued on reasons for the development of alcoholic polyneuropathy. Some argue it is a direct result of alcohol's toxic effect on the nerves, but others say factors such as a nutritional deficiency or chronic liver disease may play a role in the development as well. Multiple mechanisms may be present.

References

External links

{{Psychoactive substance use Health effects of alcohol Peripheral nervous system disorders