Peripheral neuropathy history and symptoms
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Saumya Easaw, M.B.B.S.[2]
Signs and symptoms
Symptoms are related to the type of affected nerve and may be seen over a period of days, weeks, or years. Muscle weakness is the most common symptom of motor nerve damage. Other symptoms may include painful cramps and fasciculations (uncontrolled muscle twitching visible under the skin), muscle loss, bone degeneration, and changes in the skin, hair, and nails. These more general degenerative changes also can result from sensory or autonomic nerve fiber loss.
Sensory nerve damage causes a more complex range of symptoms because sensory nerves have a wider, more highly specialized range of functions. Larger sensory fibers enclosed in myelin (a fatty protein that coats and insulates many nerves) register vibration, light touch, and position sense. Damage to large sensory fibers lessens the ability to feel vibrations and touch, resulting in a general sense of numbness, especially in the hands and feet. People may feel as if they are wearing gloves and stockings even when they are not. Many patients cannot recognize by touch alone the shapes of small objects or distinguish between different shapes. This damage to sensory fibers may contribute to the loss of reflexes (as can motor nerve damage). Loss of position sense often makes people unable to coordinate complex movements like walking or fastening buttons, or to maintain their balance when their eyes are shut.
Neuropathic pain is difficult to control and can seriously affect emotional well-being and overall quality of life. Neuropathic pain is often worse at night, seriously disrupting sleep and adding to the emotional burden of sensory nerve damage. Neuropathic pain is usually perceived as a steady burning and/or "pins and needles" and/or "electric shock" sensations and/or tickling. The difference is due to the fact that "ordinary" pain stimulates only pain nerves, while a neuropathy often results in the firing of both pain and non-pain (touch, warm, cool) sensory nerves in the same area, producing signals that the spinal cord and brain do not normally expect to receive.
Smaller sensory fibers without myelin sheaths transmit pain and temperature sensations. Damage to these fibers can interfere with the ability to feel pain or changes in temperature. People may fail to sense that they have been injured from a cut or that a wound is becoming infected. Others may not detect pains that warn of impending heart attack or other acute conditions. (Loss of pain sensation is a particularly serious problem for people with diabetes, contributing to the high rate of lower limb amputations among this population.) Pain receptors in the skin can also become oversensitized, so that people may feel severe pain (allodynia) from stimuli that are normally painless (for example, some may experience pain from bed sheets draped lightly over the body).
Symptoms of autonomic nerve damage are diverse and depend upon which organs or glands are affected. Autonomic nerve dysfunction can become life threatening and may require emergency medical care in cases when breathing becomes impaired or when the heart begins beating irregularly. Common symptoms of autonomic nerve damage include an inability to sweat normally, which may lead to heat intolerance; a loss of bladder control, which may cause infection or incontinence; and an inability to control muscles that expand or contract blood vessels to maintain safe blood pressure levels. A loss of control over blood pressure can cause dizziness, lightheadedness, or even fainting when a person moves suddenly from a seated to a standing position (a condition known as postural or orthostatic hypotension).
Gastrointestinal symptoms frequently accompany autonomic neuropathy. Nerves controlling intestinal muscle contractions often malfunction, leading to diarrhea, constipation, or incontinence. Many people also have problems eating or swallowing if certain autonomic nerves are affected.
Numbness is an abnormal sensation called dysesthesias and allodynias that occur either spontaneously or in reaction to external stimuli, and a characteristic form of pain, called neuropathic pain or neuralgia, that is qualitatively different from the ordinary nociceptive pain one might experience from stubbing a toe or hitting a finger with a hammer.
Those with diseases or dysfunctions of their peripheral nerves can present with problems in any of the normal peripheral nerve functions.
In terms of sensory function, there are commonly loss of function (negative) symptoms, which include numbness, tremor, and gait imbalance.
Gain of function (positive) symptoms include tingling, pain, itching, crawling, and pins and needles. Pain can become intense enough to require use of opiate drugs (i.e., morphine, oxycontin).
Skin can become so hypersensitive that patients are prohibited from having anything touch certain parts of their body, especially the feet. People with this degree of sensitivity cannot have a bed sheet touch their feet or wear socks or shoes, and eventually become housebound.
Motor symptoms include loss of function (negative) symptoms of weakness, tiredness, heaviness, and gait abnormalities; and gain of function (positive) symptoms of cramps, tremor, and fasciculations.
There is also pain in the muscles (myalgia), cramps, etc., and there may also be autonomic dysfunction.
During physical examination, those with generalized peripheral neuropathies most commonly have distal sensory or motor and sensory loss, though those with apathology (problem) of the peripheral nerves may be perfectly normal; may show proximal weakness, as in some inflammatory neuropathies likeGuillain-Barré syndrome); or may show focal sensory disturbance or weakness, such as in mononeuropathies, radiculopathies and plexopathies.
Common disorders of the peripheral nerves include focal entrapment neuropathies (e.g., carpal tunnel syndrome), generalized peripheral neuropathies(e.g., diabetic neuropathy), plexopathies (e.g., brachial neuritis) and radiculopathies (e.g., of cranial nerve VII; Facial nerve).