Wednesday, January 8, 2014

Peripheral neuropathy

Peripheral neuropathy (PN) is damage or disease of nerves, which may affect sensation, movement, gland or organ function, and other aspects of health, depending on the type of nerve affected. Common causes include systemic diseases (such as diabetes orleprosy), vitamin deficiency, medication (e.g., chemotherapy), traumatic injury, excessive alcohol consumption, immune system disease or infection, or it may be inherited (present from birth). In conventional medical usage, the word neuropathy (neuro- + -pathy) without modifier usually means peripheral neuropathy.
Neuropathy affecting just one nerve is called "mononeuropathy" and neuropathy involving multiple nerves in roughly the same areas on both sides of the body is called "symmetrical polyneuropathy" or simply "polyneuropathy." When two or more (typically just a few, but sometimes many) separate nerves in disparate areas of the body are affected it is called "mononeuritis multiplex," "multifocal mononeuropathy" or "multiple mononeuropathy.
Peripheral neuropathy may be chronic (a long term condition where symptoms begin subtly and progress slowly) or acute (sudden onset, rapid progress and slow resolution). Acute neuropathies demand urgent diagnosis. Motor nerves (that control muscles), sensory nerves, or autonomic nerves (that control automatic functions such as heart rate, body temperature and breathing), may be affected. More than one type of nerve may be affected at the same time. Peripheral neuropathies may be classified according to the type of nerve predominantly involved, or by the underlying cause. Where the cause is unknown it is described as idiopathic neuropathy.
Neuropathy may cause painful cramps, fasciculations (fine muscle twitching), muscle loss, bone degeneration, and changes in the skin, hair, and nails. Additionally, 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 skin allodynia (severe pain from normally nonpainful stimuli, such as light touch); and 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

Peripheral neuropathy may be classified according to the number and distribution of nerves affected (mononeuropathy, mononeuritis multiplexor, polyneuropathy), the type of nerve cell affected (motor, sensory, autonomic), or the process affecting the nerves; e.g., inflammation (neuritis), compression (compression neuropathy), chemotherapy (chemotherapy-induced peripheral neuropathy).

Mononeuropathy


Mononeuropathy is a type of neuropathy that only affects a single nerve.[4] 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 and axillary nerve palsy are examples 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, 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 may also 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 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: