Peripheral neuropathy classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohamadmostafa Jahansouz M.D.[2]
Overview
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).
Mononeuropathy
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.
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.
Polyneuropathy
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).
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.
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.
Mononeuritis multiplex
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 also may cause pain, which is characterized as 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.
It is caused by, or associated with, several medical conditions:
- diabetes mellitus
- vasculitides: polyarteritis nodosa, granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis
- 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.
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.
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).
- Other areas: hypoglycemia unawareness, genital impotence, sweat disturbances
Neuritis
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
- Herpes zoster (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
- Diabetes mellitus (Diabetic neuropathy)
- Hypothyroidism
- Porphyria
- Vitamin B12 deficiency
- Vitamin B6 excess
Classification
- Peripheral neuropathy may be classified according to the number and distribution of nerves affected into three groups:
- Peripheral neuropathy may be classified according to the type of nerve fiber predominantly affected into three groups:
or the process affecting the nerves; e.g., inflammation (neuritis), compression (compression neuropathy), chemotherapy (chemotherapy-induced peripheral neuropathy).
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[Disease name] may be classified into several subtypes based on:
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Based on the duration of symptoms, [disease name] may be classified as either acute or chronic.
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According to the [staging system + reference], there are [number] stages of [malignancy name] based on the [finding1], [finding2], and [finding3]. Each stage is assigned a [letter/number1] and a [letter/number2] that designate the [feature1] and [feature2].
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