Also referred to as peripheral neuropathy or peripheral neuritis, neuropathy occurs when illness, injury, inflammation, medication, or other factors disrupt the ability of nerves outside the spinal cord to relay messages between the brain and muscles, skin, nerves, joints, or internal organs.
Neuropathy can affect:
- Sensory nerves, which control sensation
- Motor nerves, which control movement
- Autonomic nerves, which control involuntary or semi- involuntary body functions
- Any combination of these three main types of nerves
Researchers have identified more than 100 types of neuropathy. Symptoms, which may take days, weeks, or months to develop, depend on the type or types of nerves affected and on whether neuropathy affects a single nerve or group of nerves (mononeuropathy) or more than one nerve group (polyneuropathy).
Damage to sensory nerves can reduce or intensify sensation. This can prevent patients from realizing they’ve been injured or are experiencing pains warning of heart attack or other life-threatening emergency. Or, it can make even a gentle touch extremely painful. Nerves farthest from the brain and spinal cord are usually the first to malfunction. Pain and other symptoms often appear on both sides of the body, beginning in the feet and progressing toward the center of the body. Neuropathy that affects sensory nerves also causes nerve pain, burning, tingling, and numbness. Inability to determine joint position impairs coordination.
Cramping may indicate motor nerve damage, which reduces or destroys muscle control and can result in weakness and loss of muscle. Other symptoms of muscle involvement include:
- Breathing or swallowing problems
- Absence of fine motor skills needed for such tasks as tying shoes
When autonomic nerves are damaged, diminished ability to sweat or otherwise regulate body temperature can cause heat intolerance. Vision may blur, and falling blood pressure can cause fainting or dizziness. Other symptoms include:
- Abdominal bloating
- Feeling full after eating very little
- Nausea or vomiting after meals
- Unintentional weight loss
- Urinary hesitancy or incontinence
- A sense that the bladder doesn’t fully empty