Neuropathy

Barachial plexopathy

Polyradiculitis

Lyc

Clinic

• Often shortened to neuropathy
• It is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord
• Damage to peripheral nerves may impair sensation, movement, gland, or organ function depending on which nerves are affected.
• Neuropathy affecting motor, sensory, or autonomic nerves result in different symptoms.
• More than one type of nerve may be affected simultaneously.
• It may be acute or chronic , and may be reversible or permanent.
• Common causes include
  • Systemic diseases (such as Diabetes or Leprosy),
  • Hyperglycemia-induced glycation,
  • Vitamin deficiency,
  • Medication (e.g., chemotherapy, or commonly prescribed antibiotics),
  • Traumatic injury, ischemia, radiation therapy, excessive alcohol consumption,
  • Immune system disease, celiac disease, Non-celiac gluten sensitivity,
  • Viral infection

Types

• Mononeuropathy
• Symmetrical polyneuropathy or simply "polyneuropathy".
• Mononeuritis multiplex
• Multifocal mononeuropathy or "multiple mononeuropathy".
• Neuropathy may cause painful cramps, fasciculations, muscle loss, bone degeneration, and changes in the skin, hair, and nails.

• Motor neuropathy may cause impaired balance and coordination or, most commonly, muscle weakness
• Sensory neuropathy may cause numbness to touch and vibration, reduced position sense causing poorer coordination and balance, reduced sensitivity to temperature change and pain, spontaneous tingling or burning pain, or allodynia (pain from normally nonpainful stimuli, such as light touch)
• Autonomic neuropathy may produce diverse symptoms, depending on the affected glands and organs, but common symptoms are poor bladder control, abnormal blood pressure or heart rate, and reduced ability to sweat normally.

Classification[edit]

Peripheral neuropathy may be classified according to the number and distribution of nerves affected (mononeuropathy, mononeuritis multiplex, or polyneuropathy), the type of nerve fiber predominantly affected (motor, sensory, autonomic), or the process affecting the nerves; e.g., inflammation (neuritis), compression (compression neuropathy), chemotherapy (chemotherapy-induced peripheral neuropathy). The affected nerves are found in an EMG (electromyography) / NCS (nerve conduction study) test and the classification is applied upon completion of the exam.

Mononeuropathy[edit]

See also: Compression neuropathy and Ulnar neuropathy

Mononeuropathy is a type of neuropathy that only affects a single nerve. Diagnostically, it is important to distinguish it from polyneuropathy because when a single nerve is affected, it is more likely to be due to localized trauma or infection.^{[citation needed]}

The most common cause of mononeuropathy is physical compression of the nerve, known as compression neuropathy. Carpal tunnel syndrome and axillary nerve palsy are examples. Direct injury to a nerve, interruption of its blood supply resulting in (ischemia), or inflammation also may cause mononeuropathy.^{[citation needed]}

Polyneuropathy[edit]

Main article: Polyneuropathy

"Polyneuropathy" is a pattern of nerve damage that is quite different from mononeuropathy, often more serious and affecting more areas of the body. The term "peripheral neuropathy" sometimes is used loosely to refer to polyneuropathy. In cases of polyneuropathy, many nerve cells in various parts of the body are affected, without regard to the nerve through which they pass; not all nerve cells are affected in any particular case. In distal axonopathy, one common pattern is that the cell bodies of neurons remain intact, but the axons are affected in proportion to their length; the longest axons are the most affected. Diabetic neuropathy is the most common cause of this pattern. In demyelinating polyneuropathies, the myelin sheath around axons is damaged, which affects the ability of the axons to conduct electrical impulses. The third and least common pattern affects the cell bodies of neurons directly. This usually picks out either the motor neurons (known as motor neuron disease) or the sensory neurons (known as sensory neuronopathy or dorsal root ganglionopathy).^{[citation needed]}

The effect of this is to cause symptoms in more than one part of the body, often symmetrically on left and right sides. As for any neuropathy, the chief symptoms include motor symptoms such as weakness or clumsiness of movement; and sensory symptoms such as unusual or unpleasant sensations such as tingling or burning; reduced ability to feel sensations such as texture or temperature, and impaired balance when standing or walking. In many polyneuropathies, these symptoms occur first and most severely in the feet. Autonomic symptoms also may occur, such as dizziness on standing up, erectile dysfunction, and difficulty controlling urination.^{[citation needed]}

Polyneuropathies usually are caused by processes that affect the body as a whole. Diabetes and impaired glucose tolerance are the most common causes. Hyperglycemia-induced formation of advanced glycation end products (AGEs) is related to diabetic neuropathy. Other causes relate to the particular type of polyneuropathy, and there are many different causes of each type, including inflammatory diseases such as Lyme disease, vitamin deficiencies, blood disorders, and toxins (including alcohol and certain prescribed drugs).

Most types of polyneuropathy progress fairly slowly, over months or years, but rapidly progressive polyneuropathy also occurs. It is important to recognize that at one time it was thought that many of the cases of small fiber peripheral neuropathy with typical symptoms of tingling, pain, and loss of sensation in the feet and hands were due to glucose intolerance before a diagnosis of diabetes or pre-diabetes. However, in August 2015, the Mayo Clinic published a scientific study in the Journal of the Neurological Sciences showing "no significant increase in...symptoms...in the prediabetes group", and stated that "A search for alternate neuropathy causes is needed in patients with prediabetes."

The treatment of polyneuropathies is aimed firstly at eliminating or controlling the cause, secondly at maintaining muscle strength and physical function, and thirdly at controlling symptoms such as neuropathic pain.^{[citation needed]}

Mononeuritis multiplex[edit]

Mononeuritis multiplex, occasionally termed polyneuritis multiplex, is simultaneous or sequential involvement of individual noncontiguous nerve trunks, either partially or completely, evolving over days to years and typically presenting with acute or subacute loss of sensory and motor function of individual nerves. The pattern of involvement is asymmetric, however, as the disease progresses, deficit(s) becomes more confluent and symmetrical, making it difficult to differentiate from polyneuropathy. Therefore, attention to the pattern of early symptoms is important.

Mononeuritis multiplex is sometimes associated with a deep, aching pain that is worse at night and frequently in the lower back, hip, or leg. In people with diabetes mellitus, mononeuritis multiplex typically is encountered as acute, unilateral, and severe thigh pain followed by anterior muscle weakness and loss of knee reflex.^{[medical citation needed]}

Electrodiagnostic medicine studies will show multifocal sensory motor axonal neuropathy.^{[citation needed]}

It is caused by, or associated with, several medical conditions:

• Diabetes mellitus
• Vasculitides: polyarteritis nodosa, granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis. This results in vasculitic neuropathy.
• Immune-mediated diseases, such as rheumatoid arthritis, systemic lupus erythematosus (SLE)
• Infections: leprosy, lyme disease, parvovirus B19, HIV
• Sarcoidosis
• Cryoglobulinemia
• Reactions to exposure to chemical agents, including trichloroethylene and dapsone^{[medical citation needed]}
• Rarely, following the sting of certain jellyfish, such as the sea nettle^{[medical citation needed]}

Autonomic neuropathy

Autonomic neuropathy is a form of polyneuropathy that affects the non-voluntary, non-sensory nervous system (i.e., the autonomic nervous system), affecting mostly the internal organs such as the bladder muscles, the cardiovascular system, the digestive tract, and the genital organs. These nerves are not under a person's conscious control and function automatically. Autonomic nerve fibers form large collections in the thorax, abdomen, and pelvis outside the spinal cord. They have connections with the spinal cord and ultimately the brain, however. Most commonly autonomic neuropathy is seen in persons with long-standing diabetes mellitus type 1 and 2. In most—but not all—cases, autonomic neuropathy occurs alongside other forms of neuropathy, such as sensory neuropathy.^{[citation needed]}

Autonomic neuropathy is one cause of malfunction of the autonomic nervous system, but not the only one; some conditions affecting the brain or spinal cord also may cause autonomic dysfunction, such as multiple system atrophy, and therefore, may cause similar symptoms to autonomic neuropathy.^{[citation needed]}

The signs and symptoms of autonomic neuropathy include the following:

• Urinary bladder conditions: bladder incontinence or urine retention
• Gastrointestinal tract: dysphagia, abdominal pain, nausea, vomiting, malabsorption, fecal incontinence, gastroparesis, diarrhoea, constipation
• Cardiovascular system: disturbances of heart rate (tachycardia, bradycardia), orthostatic hypotension, inadequate increase of heart rate on exertion
• Respiratory system: impairments in the signals associated with regulation of breathing and gas exchange (central sleep apnea, hypopnea, bradypnea).
• Skin : thermal regulation, dryness through sweat disturbances
• Other areas: hypoglycemia unawareness, genital impotence

Neuritis[edit]

Neuritis is a general term for inflammation of a nerve or the general inflammation of the peripheral nervous system. Symptoms depend on the nerves involved, but may include pain, paresthesia (pins-and-needles), paresis (weakness), hypoesthesia (numbness), anesthesia, paralysis, wasting, and disappearance of the reflexes.

Causes of neuritis include:

• Physical injury
• Infection
  • Diphtheria
  • (shingles)
  • Leprosy
  • Lyme disease
• Chemical injury such as chemotherapy
• Radiation therapy

Types of neuritis include:

• Brachial neuritis
• Cranial neuritis such as Bell's palsy
• Optic neuritis
• Vestibular neuritis
• Wartenberg's migratory sensory neuropathy
• Underlying conditions including:
  • Alcoholism
  • Autoimmune disease, especially multiple sclerosis and Guillain–Barré syndrome
  • Beriberi (vitamin B1 deficiency)
  • Cancer
  • Celiac disease
  • Non-celiac gluten sensitivity
  • Diabetes mellitus (Diabetic neuropathy)
  • Hypothyroidism
  • Porphyria
  • Vitamin B12 deficiency
  • Vitamin B6 excess

Signs and symptoms[edit]

Those with diseases or dysfunctions of their nerves may present with problems in any of the normal nerve functions. Symptoms vary depending on the types of nerve fiber involved.^{[citation needed]} In terms of sensory function, symptoms commonly include loss of function ("negative") symptoms, including numbness, tremor, impairment of balance, and gait abnormality. Gain of function (positive) symptoms include tingling, pain, itching, crawling, and pins-and-needles. Motor symptoms include loss of function ("negative") symptoms of weakness, tiredness, muscle atrophy, and gait abnormalities; and gain of function ("positive") symptoms of cramps, and muscle twitch (fasciculations).

In the most common form, length-dependent peripheral neuropathy, pain and parasthesia appears symmetrically and generally at the terminals of the longest nerves, which are in the lower legs and feet. Sensory symptoms generally develop before motor symptoms such as weakness. Length-dependent peripheral neuropathy symptoms make a slow ascent of the lower limbs, while symptoms may never appear in the upper limbs; if they do, it will be around the time that leg symptoms reach the knee. When the nerves of the autonomic nervous system are affected, symptoms may include constipation, dry mouth, difficulty urinating, and dizziness when standing.

CAP-PRI Scale for diagnosis[edit]

A user-friendly, disease-specific, quality-of-life scale can be used to monitor how someone is doing living with the burden of chronic, sensorimotor polyneuropathy. This scale, called the Chronic, Acquired Polyneuropathy - Patient-reported Index (CAP-PRI), contains only 15 items and is completed by the person affected by polyneuropathy. The total score and individual item scores can be followed over time, with item scoring used by the patient and care-provider to estimate clinical status of some of the more common life domains and symptoms impacted by polyneuropathy.^{[citation needed]}

Causes

• Ribose-5-Phosphate Isomerase Deficiency
• Surgery, chemotherapy
• Genetic diseases: Friedreich's ataxia, Fabry disease, Charcot-Marie-Tooth disease, hereditary neuropathy with liability to pressure palsy
• Hyperglycemia-induced formation of advanced glycation end products (AGEs)
• Metabolic and endocrine diseases: Diabetes mellitus, Chronic kidney failure, Porphyria, Amyloidosis, Liver failure, Hypothyroidism
• Idiopathic
• Toxic causes
• Inflammatory diseases:
  • Guillain–Barré syndrome
  • SLE
  • Leprosy
  • Sjögren's syndrome
  • Babesiosis
  • LBB
  • Vasculitis
  • Sarcoidosis
  • Multiple sclerosis
• Vitamin deficiency states: Vitamin B₁₂ (Methylcobalamin), vitamin A, vitamin E, vitamin B₁ (thiamin)
• Physical trauma: compression, automobile accident, sports injury, sports pinching, cutting, projectile injuries (for example, gunshot wound), strokes including prolonged occlusion of blood flow, electric discharge, including lightning strikes^{[medical citation needed]}

• Others: Carpal tunnel syndrome, electric shock, HIV, malignant disease, , shingles, MGUS (Monoclonal gammopathy of undetermined significance).

Diagnosis[edit]

Peripheral neuropathy may first be considered when an individual reports symptoms of numbness, tingling, and pain in feet. After ruling out a lesion in the central nervous system as a cause, diagnosis may be made on the basis of symptoms, laboratory and additional testing, clinical history, and a detailed examination.

During physical examination, specifically a neurological examination, those with generalized peripheral neuropathies most commonly have distal sensory or motor and sensory loss, although those with a pathology (problem) of the nerves may be perfectly normal; may show proximal weakness, as in some inflammatory neuropathies, such as Guillain–Barré syndrome; or may show focal sensory disturbance or weakness, such as in mononeuropathies. Classically, ankle jerk reflex is absent in peripheral neuropathy.

A physical examination will involve testing the deep ankle reflex as well as examining the feet for any ulceration. For large fiber neuropathy, an exam will usually show an abnormally decreased sensation to vibration, which is tested with a 128-Hz tuning fork, and decreased sensation of light touch when touched by a nylon monofilament.

Diagnostic tests include electromyography (EMG) and nerve conduction studies (NCSs), which assess large myelinated nerve fibers. Testing for small-fiber peripheral neuropathies often relates to the autonomic nervous system function of small thinly- and unmyelinated fibers. These tests include a sweat test and a tilt table test. Diagnosis of small fiber involvement in peripheral neuropathy may also involve a skin biopsy in which a 3 mm-thick section of skin is removed from the calf by a punch biopsy, and is used to measure the skin intraepidermal nerve fiber density (IENFD), the density of nerves in the outer layer of the skin. Reduced density of the small nerves in the epidermis supports a diagnosis of small-fiber peripheral neuropathy.

In EMG testing, demyelinating neuropathy characteristically shows a reduction in conduction velocity and prolongation of distal and F-wave latencies, whereas axonal neuropathy shows a reduction in amplitude.

Laboratory tests include blood tests for vitamin B-12 levels, a complete blood count, measurement of thyroid stimulating hormone levels, a comprehensive metabolic panel screening for diabetes and pre-diabetes, and a serum immunofixation test, which tests for antibodies in the blood.