Peripheral nerve damage (peripheral neuropathy)

The nervous system is made up of the central nervous system and the peripheral nervous system. The brain and the spinal cord make up the central nervous system. The peripheral nervous system includes all nerves outside of the brain and spinal cord. There are 3 types of nerves in the peripheral nervous system.

Sensory nerves control your ability to feel things (for example, pain, temperature sensation).

Motor nerves control movement (for example, walking, weightlifting).

Autonomic nerves control things you do that you're not conscious of (for example, breathing, your heart beating).

Sometimes cancer or its treatment can damage the nervous system. Damage to the nerves of the peripheral nervous system is called peripheral neuropathy.

Peripheral nerve damage can be caused by:

• some chemotherapy drugs such as cisplatin, docetaxel, paclitaxel (Abraxane) and vincristine
• some types of targeted therapy drugs such as bortezomib (Velcade) and thalidomide
• a tumour growing into or pressing on a peripheral nerve
• radiation therapy
• surgery
• poor nutrition
• paraneoplastic syndrome
• shingles
• some inherited neurological conditions such as Charcot-Marie-Tooth disease

You may have a higher risk of developing peripheral neuropathy if you have:

• diabetes
• kidney problems
• a thyroid that doesn't make enough thyroid hormone (called hypothyroidism)
• conditions that may slow the flow of blood through blood vessels
• certain autoimmune conditions such as rheumatoid arthritis or systemic lupus erythematosus (SLE)
• certain infections such as shingles, HIV or Lyme disease (a bacterial infection carried by ticks)
• a history of serious physical injury (for example, a car accident, a sports injury)
• a history of exposure to pesticides or heavy metals (for example, lead, mercury)
• a history of drinking large amounts of alcohol

Symptoms of peripheral neuropathy depend on which nerves are affected and how bad the injury to the nerves is. It is possible for multiple types of nerves to be affected at the same time (called combination neuropathy).

Symptoms of sensory nerve damage are usually changes in sensation. Symptoms include:

• pain

• numbness, tingling (pins and needles), itching or a burning sensation in the hands or feet

• loss of sensation or feeling in certain body parts
• feeling like your limbs are covered (such as with gloves or stockings) when they are not
• pain or discomfort when your body is touching something such as being covered by a blanket or when wearing shoes
• clumsiness or having trouble knowing where your hands and feet are in space, especially when trying to walk or pick up objects

Symptoms of motor nerve damage are usually difficulty with movement. Symptoms include:

• cramping

• muscle weakness, making it hard to do things like brush your teeth, climb up stairs, do up buttons or walk
• uncontrolled muscle twitching
• muscle and bone loss (atrophy)

Symptoms of autonomic nerve damage are usually changes to bodily functions. Symptoms include:

• digestive problems such as diarrhea or constipation

• dizziness or lightheadedness
• blurry vision
• hearing problems
• sexual problems such as erectile dysfunction
• sexual problems such as vaginal dryness
• loss of bladder control (incontinence)
• swallowing problems
• breathing problems
• an irregular heartbeat
• heat intolerance or excessive sweating

Peripheral nerve damage may be temporary but it can take a few months or even years before it goes away. Sometimes, peripheral nerve damage is permanent. In some cases, symptoms will worsen after treatment ends (known as coasting).

Tell your healthcare team if your symptoms are getting worse or don't go away. The sooner that they are aware of any problems, the sooner they can suggest ways to help you deal with them.

Your healthcare team will try to find the cause of peripheral neuropathy. If you are taking a drug or treatment that is known to cause peripheral neuropathy, they will monitor you for signs of nerve damage before each treatment.

To see how well your nerves are working, you may need to have certain tests such as:

• a neurological exam to check your reflexes and muscle strength and to see if there are any signs of numbness
• nerve conduction studies to check where and how bad the nerve damage is
• electromyography (EMG) – a test that checks the electrical signals of the nerves to the muscles
• imaging tests, including a CT scan or an MRI

Your healthcare team may also perform blood chemistry tests to check for signs of infection and measure kidney function, vitamin levels and the number of certain cells.

You may also need to do other tests to check your:

• balance and coordination
• hearing
• vision

In some cases, you will need to have a nerve biopsy to help determine the type of peripheral neuropathy.

Learn more about biopsy, CT scan, magnetic resonance imaging (MRI) and blood chemistry tests.

Your healthcare team can suggest ways to manage peripheral neuropathy based on the cause of the damage and the symptoms you’re having. If possible, they will stop or lower the dose of a drug that is causing the peripheral neuropathy to prevent permanent damage. For most people, symptoms will start to get better over time but sometimes this damage will be permanent.

If you experience pain because of peripheral neuropathy, you may be given medicines such as gabapentin, amitriptyline, lamotrigine (Lamictal), nortriptyline (Aventyl), pregabalin (Lyrica) or other pain-relieving medicines to help manage it. For peripheral neuropathy pain that is caused by chemotherapy specifically, you may also get duloxetine (Cymbalta).

When pain is extreme and other medicines have not worked, you may be given opioids to help manage your pain.

Your healthcare team may also suggest other ways to manage peripheral neuropathy, such as:

• transcutaneous electrical nerve stimulation (TENS) therapy
• scrambler therapy – a type of electrical stimulation therapy that prevents the nerves from sending pain signals by overwhelming them with other signals
• getting regular exercise
• physiotherapy or occupational therapy to help you keep your muscles strong and improve coordination and balance
• numbing creams or patches such as lidocaine cream
• steroids
• immunosuppressant drugs – medicines that decrease the activity of the immune system
• drinking plenty of fluids and eating a balanced diet rich in fibre, vitamin B and antioxidants
• medicines to help relieve constipation

Your healthcare team may also recommend the use of complementary therapies such as cannabinoids, acupuncture or acupressure therapy, massage therapy, reflexology, mindfulness and relaxation techniques to increase the effectiveness of other therapies.

If you have peripheral neuropathy, you may need to make some changes so that you are comfortable and safe.

• Be careful with sharp, hot, cold or other dangerous objects if your fingers are numb.
• Use dishes that won't break.
• Move slowly and use handrails when going up and down stairs if muscle strength or balance is affected.
• Make sure all rooms, stairways and hallways are well lit.
• Get up slowly so your body has time to adjust to a change in position.
• Remove objects that could cause you to trip or fall such as rugs or clutter.
• Use grab bars and skid-free bath mats for showers and tubs.
• Clean up any spills right away so you don’t slip.
• Make sure you can feel the steering wheel and gas and brake pedals if you drive. Be sure you can quickly move your foot back and forth between the gas and brake pedals repeatedly.
• Use a cane or walker to help keep your balance when you walk.
• Wear gloves and socks in cold weather.
• Don’t walk in bare feet. Choose shoes and socks that fit well to avoid tripping. Orthotics (a device placed in your shoe to support your foot) can make walking more comfortable.
• Consider hand or foot braces to make up for muscle weakness.
• Make sure water isn’t too hot. You can test the temperature with your elbow or use a bath thermometer. Turn the taps down to a lower setting or get a temperature control device added to your taps to keep the water cooler.
• Wear gloves when working with your hands such as when gardening or washing dishes.

Neuropathy can also increase your risk for infection and poor wound healing. Check your feet regularly for cuts or other wounds. Care for any wounds you develop to help them heal. If any wounds worsen or do not heal normally, report this to your healthcare team without waiting for your next appointment.

For some, dealing with peripheral neuropathy will lead to feelings of anger, sadness and frustration. People deal with strong emotions differently. It takes time and patience to deal with these feelings, but they should get better if you find a helpful treatment and as you adjust to these changes.

You may find it helps to share your feelings with someone close to you. You can also talk to your healthcare team to see what type of counselling or support groups are available. Spending time with your pets and with people who make you laugh, or doing something that makes you feel good, may also help to improve your mood.

You may feel different every day. Remind yourself that you are coping no matter how you feel.