Neuropathy
Clinic
- Disease affecting peripheral nerves which 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.
- Neuropathy may cause painful cramps, fasciculations, muscle loss, bone degeneration, and changes in the skin, hair, and nails.
Causes
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Types
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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.,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
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Mononeuritis multiplex[edit]
Autonomic neuropathy
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.