What Is Mononeuropathy?
Neuropathy is a group of conditions that affect the nerves outside of the brain and spinal cord (the peripheral nerves). Mononeuropathy describes a condition in which only a single nerve or nerve group is damaged. This condition negatively affects the part of the body associated with that nerve or nerve group, causing a loss of sensation, movement, and/or function in that part of the body. Mononeuropathy can affect any part of the body.
There are several forms of mononeuropathy, which vary in seriousness, rarity, and symptoms. One of the more common forms of mononeuropathy is carpal tunnel syndrome. Carpal tunnel syndrome results from pressure on the median nerve in the arm, which leads to numbness, muscle damage, and weakness in the hands and fingers. There are a few forms of cranial mononeuropathy as well, which affect the nerves of the skull. Cranial mononeuropathy VI, for instance, can hinder effective eye movements and cause double vision.
Types of Mononeuropathy
When symptoms develop slowly, it is called chronic neuropathy. When symptoms come on suddenly, it is called acute neuropathy.
Neuropathy can be inherited. The most common form of hereditary neuropathy is Charcot’s joint, which affects the lower leg and foot.
Acquired neuropathy is much more common, and is usually caused by disease or injury. Nerve damage caused by diabetes is called diabetic neuropathy. When the cause is unknown, it is called idiopathic neuropathy.
Mononeuropathy can happen in any part of your body. According to the National Institute of Neurological Disorders and Stroke (NINDS), there are more than 100 types of peripheral neuropathy. (NINDS, 2011) Some of the most common are:
- axillary nerve dysfunction
- carpal tunnel syndrome
- common peroneal nerve dysfunction
- cranial mononeuropathy
- femoral neuropathy
- radial nerve dysfunction
- ulnar nerve dysfunction
- unilateral foot drop
- sciatic nerve dysfunction
- thoracic/lumbar radiculopathy
Causes of Mononeuropathy
Neuropathy occurs when nerve cells are damaged or destroyed. Injury is the most common cause of this condition. This includes accidents, falls, or repetitive motion stress.
Other causes include:
- autoimmune conditions and infections, including rheumatoid arthritis, systemic lupus erythematosus, herpes, syphilis, Lyme disease, Guillain-Barré syndrome, and human immunodeficiency virus (HIV)
- systemic diseases such as diabetes, kidney disorders, hormonal imbalances, and some types of cancer
- vascular disorders
- metabolic disorders
- improper levels of vitamins E, B1, B6, B9, B12, and niacin
- some medications, including chemotherapy
- exposure to industrial chemicals, solvents, and heavy metals like mercury and lead
Risk Factors for Developing Mononeuropathy
Anyone can get neuropathy, but your risk increases as you age. According to the Cleveland Clinic, this condition is more common in men than in women, and affects Caucasians more than other races. Activities that involve repetitive motion put you at greater risk for compression-related neuropathy. (Cleveland Clinic, 2010)
However, according to Medscape, the connection between repetitive motion and compression neuropathies is poorly understood at present. (Medscape, 2011)
Recognizing the Symptoms of Mononeuropathy
Specific symptoms depend on which nerves are affected and may include:
- loss of sensation
- tingling and burning
- lack of feeling, numbness
- lack of coordination
- loss of reflexes
- muscle twitching, cramps, or spasms
- muscle wasting
- difficulty moving, paralysis
How Mononeuropathy Is Diagnosed
If you have symptoms of nerve damage, make an appointment to see your doctor as soon as possible. Be prepared to give a complete medical history and tell him or her about any prescription and over-the-counter medications and supplements you may be taking.
Your doctor will perform a thorough medical examination. Diagnostic tests can help determine the cause of your condition. These may include:
- electromyogram (EMG), which records electrical activity in the muscles
- nerve conduction studies, which records the speed of electrical activity in the nerves
- nerve biopsy, in which your doctor will remove a small part of the nerve to look for damage
If your doctor suspects that neuropathy is being caused by an injury, or that nerve damage is a symptom of an autoimmune disorder, they may order the following tests to confirm diagnosis:
- magnetic resonance imaging (MRI)
- computed tomography (CT) scan
- antinuclear antibody panel
- C-reactive protein
- rheumatoid factor
- sedimentation rate
- blood tests
- thyroid tests
Treatment Options for Mononeuropathy
Treatment will depend on the underlying cause and the severity of nerve damage. In some cases, the affected body part may get better on its own, in which case treatment would not be required.
If a pre-existing medical condition is causing mononeuropathy, treatment will focus on managing the underlying cause in addition to treating nerve damage. For example, if nerve pain is a complication of diabetes, your doctor may recommend treatments to better control blood pressure and blood sugar levels in order to properly address the nerve damage.
Corticosteroids are commonly used to relieve swelling and pressure caused by mononeuropathy. Pain medication might be used as well to relieve symptoms.
Physical therapy can be used to help maintain muscle strength in the affected area of the body. If necessary, you may have to wear an orthopedic appliance, such as braces, splints, or special shoes.
If the neuropathy is compression-related, such as with carpal tunnel, surgery may be necessary to address the issue.
Along with whatever form of treatment is chosen, occupational therapy and potential job retraining may be necessary to address mononeuropathy’s effects on day-to-day life. Additionally, acupuncture and biofeedback may be appropriate complementary treatments for this condition.
According to the Mayo Clinic, alpha-lipoic acid may help with symptoms of peripheral neuropathy. (Mayo Clinic, 2011) It is important to note that use of this antioxidant can affect blood sugar levels. It can also cause upset stomach and skin rash. Ask your doctor before using anpha-lipoic acid.
Long-Term Outlook for Mononeuropathy
Nerve pain can sometimes last for a long time. Untreated, it can result in permanent nerve damage. Lack of feeling can make it difficult to notice a new injury, increasing the risk of further damage.
Your individual long-term outlook depends on the specific cause. Early treatment generally results in an improved long-term outlook.