Mononeuropathy

Mononeuropathy is damage to a single nerve that causes issues like pain, abnormal sensations (paresthesia) and/or movement issues. Mononeuropathy is a type of peripheral neuropathy — it happens to nerves in your body that are outside of your brain and spinal cord.

Persistent pressure on a nerve typically causes mononeuropathy, often due to an injury or inflammation. Damage can happen to the protective covering of the nerve (myelin sheath) or part of the nerve cell (the axon), slowing or preventing signals from traveling through it.

Types

Technically, any individual nerve in your body can experience damage, leading to mononeuropathy. But it’s more likely to happen to nerves that run close to your skin or near a bone. Many of these types of mononeuropathy have their own name. Mononeuropathy can affect:

• The median nerve in your wrist (carpal tunnel syndrome)
• The sciatic nerve that runs through your pelvis down the back of your leg (sciatica)
• The ulnar nerve in your elbow (ulnar nerve entrapment)
• The radial nerve in your upper arm (radial tunnel syndrome)
• The ulnar nerve in your arm (ulnar nerve entrapment, cubital tunnel syndrome or Guyon’s canal syndrome)
• The peroneal nerve, just below your knee
• The axillary nerve in your shoulder
• The lateral femoral cutaneous nerve in your thigh

Another group of mononeuropathies is cranial mononeuropathies. They affect the 12 cranial nerves that come directly from your brain or brainstem. Bell’s palsy is one example. It affects the facial nerve (seventh cranial nerve) in your face.

You can also develop multiple mononeuropathies. This happens when you have damage to two or more nerves at the same time in different parts of your body.

Certain forms of mononeuropathy are common. For example:

• Sciatica affects about 40% of people in the U.S. at some point in their lives.
• About 1 in 60 people in the U.S. will get Bell’s palsy at some point in their lives.
• Around 3 out of every 1,000 people in the U.S. experience carpal tunnel syndrome each year.

Symptoms of mononeuropathy

Symptoms of mononeuropathy vary depending on the affected nerve. The most common symptoms are:

• Numbness in the affected area
• Pain or a burning sensation
• A feeling of “pins and needles”
• Muscle weakness in the affected area, which may result in muscle atrophy (loss of muscle bulk/size)

You should see a healthcare provider if you experience any of these symptoms.

Untreated mononeuropathy can lead to:

• Chronic pain
• Loss of sensation
• Permanent weakness or paralysis

Mononeuropathy causes

Several situations and conditions can cause mononeuropathy, including:

• Injuries
• Compression
• Health conditions

Injuries

Direct injury to a nerve is the most common cause of mononeuropathy. This can happen through:

• Repetitive motions (repetitive strain injuries)
• Overextension of a joint
• Sustained forceful muscle contractions (like tightly gripping a tool)
• Bone fractures that damage a nerve
• Trauma to a nerve, like from a knife wound or surgery
• Radiation therapy for cancer

Nerve compression

Any of the following conditions or situations can result in nerve compression (squeezing), leading to mononeuropathy:

• A tumor
• Excessive swelling (edema)
• A poorly fitted cast
• Using crutches
• Prolonged cramped postures (like while you’re gardening)
• Being confined to a bed or a single position

Health conditions

Certain health conditions can cause mononeuropathy, though they’re more likely to affect several nerves at once, not just one. Examples of health conditions that can cause mononeuropathy include:

• Alcohol use disorder
• Autoimmune and inflammatory conditions, like lupus and rheumatoid arthritis
• Certain infections, like HIV and shingles
• Diabetes
• Vitamin and nutrient deficiencies

How is mononeuropathy diagnosed?

In most cases, healthcare providers can diagnose mononeuropathy by:

• Asking about your symptoms
• Reviewing your medical history
• Doing a physical exam and a neurological exam

But because mononeuropathy has several possible causes, your provider may recommend additional testing if the cause isn’t obvious or if your symptoms are severe. Tests that can help confirm the diagnosis and/or find the underlying cause include:

• EMG (electromyography)
• Nerve conduction study
• Blood tests
• Imaging tests, like an ultrasound, an MRI scan or a CT scan

What is the treatment for mononeuropathy?

Treatment for mononeuropathy depends on several factors, like:

• The affected nerve
• The cause
• The severity
• Your symptoms

Your healthcare provider will recommend treatments based on your unique situation. Some examples of treatment include:

• Conservative treatment, like rest and taking medicines for pain management
• Splints to immobilize the area
• Steroid injections
• Physical therapy
• Treatment of any associated underlying medical condition
• Surgery to relieve pressure if the other treatments don’t work

When should I see my healthcare provider?

It’s important to see a healthcare provider if you experience symptoms of mononeuropathy, like pain, numbness and/or muscle weakness. The sooner you can get treatment, the better the outcome.

If you have a mononeuropathy diagnosis and your symptoms get worse or change, talk to your provider.

It may be helpful to ask your provider the following questions:

• What type of mononeuropathy do I have?
• What caused it?
• What are my treatment options? What do you recommend?
• How long will it take to recover from this?
• Will I have complete or partial recovery?
• How can I prevent this type of mononeuropathy from happening again?

What is the prognosis for someone with mononeuropathy?

The prognosis (outlook) for someone with mononeuropathy varies based on several factors, like the nerve that’s affected, the underlying cause and the severity of the nerve damage.

This condition can be painful and affect your ability to do everyday tasks. Some people experience long-lasting symptoms of mononeuropathy. But if your healthcare provider can find the cause of it and treatment is successful, mononeuropathy can be temporary.

What’s the difference between mononeuropathy and polyneuropathy?

Polyneuropathy happens when many nerves throughout your body malfunction at the same time. One example of acute (sudden) polyneuropathy is Guillain-Barré syndrome.

Mononeuropathy is damage to a single nerve in your body. Sometimes, it’s difficult for healthcare providers to distinguish multiple mononeuropathy from polyneuropathy.