What is neuropathy?
Neuropathy is a general term for any disorders of the central and peripheral nervous system. It encompasses the conditions of
- Polyneuropathy: In which the same process affects many nerves, especially peripheral nerves;
- Mononeuropathy: Which is isolated involvement of a single nerve due to trauma, compression, or entrapment (e.g., carpal tunnel syndrome);
- Mononeuropathy multiplex: Referring to more than one nerve trunk involvement, usually due to compression or an inflammatory vascular cause.
Diseases of the central nervous system (malignancy, stroke, or spinal lesion) can present with similar symptoms, making diagnosis difficult.
Causes of Neuropathy
- Kidney disease (uremia)
- HIV infection
- Vitamin deficiencies (B12, folate)
- Lyme disease
- Autoimmune diseases (Guillain-Barré Syndrome)
- Toxicity (alcohol, chemotherapy, metals)
- Hereditary (Charcot-Marie-Tooth disease
- Mechanical injury (vibration-induced, e.g., construction jack-hammers, etc.)
- Prolonged cold exposure
Signs and Symptoms
Signs and symptoms of neuropathy include sensory loss, usually distally–hands, feet, fingers, toes, and burning sensation, pain, or weakness. Weakness and sensory loss can occur simultaneously when the nerves involve have mixed motor and sensory functions. In many neuropathies, the longer nerves are affected first, which is why nerves of the feet may offer the first presentation of neuropathy. The neuropathy related to the longest nerves can present as a “stocking and glove” distribution pattern, which can then extend when severe.
Depending on the cause, neuropathy can stabilize and even improve, but typically progresses slowly over years. Acute neuropathy from toxic exposure can worsen over a few weeks, stabilize, and then recover slowly over months.
The speed of conduction of some nerves depends on an insulating coating (myelin), and when a neuropathy involves destruction of this coating, nerves for movement are mostly involved, presenting as weakness. Chronic injury related to length of the nerves, such as in diabetes, will present with sensory loss and paresthesia’s (tingling, numbness, burning) first, then motor symptoms of weakness.