Mononeuropathy
Mononeuropathy is a type of neuropathy that only affects a single nerve. It is diagnostically useful to distinguish them from polyneuropathies, because the limitation in scope makes it more likely that the cause is a localized trauma or infection.The most common cause of mononeuropathy is by physical compression of the nerve, known as compression neuropathy. Carpal tunnel syndrome is one example of this. The "pins-and-needles" sensation of one's "foot falling asleep" (paresthesia) is caused by a compression mononeuropathy, albeit a temporary one which can be resolved merely by moving around and adjusting to a more appropriate position. Direct injury to a nerve, interruption of its blood supply (ischemia), or inflammation can also cause mononeuropathy.
Mononeuritis multiplex
Mononeuritis multiplex, or mononeuropathy multiplex, is the clinical result of damage to several different nerves, either serially or concurrently.Mononeuritis multiplex typically presents with acute or subacute loss of sensory and motor function of individual peripheral nerves. The pattern of involvement is asymmetric.
Mononeuritis multiplex may also cause pain, which is characterized as deep, aching pain that is worse at night, is frequently in the lower back, hip, or leg. In people with diabetes mellitus, mononeuritis multiplex is typically encountered as acute, unilateral, severe thigh pain followed by anterior muscle weakness and loss of knee reflex.
Electrodiagnostic studies will show multifocal sensory motor axonal neuropathy.
It is caused by, or associated with, several medical conditions:
* diabetes mellitus
* vasculitides: polyarteritis nodosa, Wegener granulomatosis, and Churg-Strauss syndrome
* immune-mediated diseases like rheumatoid arthritis, lupus erythematosus (SLE), and sarcoidosis
* infections: leprosy, lyme disease, HIV
* amyloidosis
* cryoglobulinemia
* chemical agents, including trichloroethylene and dapsone
Polyneuropathy
Polyneuropathy is a pattern of nerve damage which is quite different from mononeuropathy. The term "peripheral neuropathy" is sometimes used loosely to refer to polyneuropathy. In a polyneuropathy, many nerve cells in different 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, the cell bodies of neurons remain intact, but the axons are affected in proportion to their length. 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 neurones directly. This usually picks out either the motor neurones (known as motor neurone disease) or the sensory neurones (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 on left and right sides symmetrically. As for any neuropathy, the chief symptoms include weakness or clumsiness of movement (motor); unusual or unpleasant sensations such as tingling or burning; reduction in the ability to feel texture, temperature, etc.; and impaired balance when standing or walking (sensory). In many polyneuropathies, these symptoms occur first and most severely in the feet. Autonomic symptoms may also occur, such as dizziness on standing up, erectile dysfunction and difficulty controlling urination.
Polyneuropathies are usually caused by processes that affect the body as a whole. Diabetes (or impaired glucose tolerance) is the most common cause. Other causes relate to the particular type of polyneuropathy, and there are many different causes of each type, including inflammatory diseases, 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. Sometimes this has an identifiable cause; when it does not it is often referred to as Guillain–Barré syndrome. It is important to recognize that glucose levels in the blood can spike to nerve-damaging levels after eating even though fasting blood sugar levels and average blood glucose levels can still remain below normal levels (currently typically considered below 100 for fasting blood plasma and 6.0 for HGBA1c, the test commonly used to measure average blood glucose levels over an extended period). Studies have shown that many of the cases of peripheral small fiber neuropathy with typical symptoms of tingling, pain and loss of sensation in the feet and hands are due to glucose intolerance before a diagnosis of diabetes or pre-diabetes. Such damage is often reversible, particularly in the early stages, with diet, exercise and weight loss.17
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.
Autonomic neuropathy
Autonomic neuropathy is a form of polyneuropathy which 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 spinal cord, however they have connections with the spinal cord and ultimately the brain. 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 can also cause autonomic dysfunction, such as multiple system atrophy, and therefore 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, diarrhea, constipation
* cardiovascular system: disturbances of heart rate (tachycardia, bradycardia), orthostatic hypotension, inadequate increase of heart rate on exertion
* other: 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, paresis, hypoesthesia (numbness), anesthesia, paralysis, wasting, and disappearance of the reflexes. Causes include:*Infection:
**Herpes simplex
**Shingles
**Leprosy
**Guillain-Barre syndrome
*Chemical injury
*Physical injury
*Radiation
*Underlying conditions causing localized neuritis (affecting a single nerve):
**Diphtheria
**Localized injury
**Diabetes
* Underlying conditions causing polyneuritis (affecting multiple nerves):
**Beriberi
**Vitamin B12 deficiency
**Metabolic diseases
**Diabetes
**Hypothyroidism
**Porphyria
**Infections, bacterial and/or viral
**Autoimmune disease, especially Multiple Sclerosis
**Cancer
**Alcoholism
**Wartenbergs migratory sensory neuropathy
Types of neuritis include:
*Polyneuritis or Multiple neuritis (not to be confused with multiple sclerosis)
*Brachial neuritis
*Optic neuritis
*Vestibular neuritis
*Cranial neuritis, often representing as Bell's Palsy
*Arsenic neuritis
Adapted from the Wikipedia article Peripheral neuropathy, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki
