Peripheral Neuropathy & Chemotherapy

The peripheral nervous system sends signals between the central nervous system (the brain and spinal cord) to all other parts of the body. Peripheral neuropathy happens when peripheral nerves are damaged, resulting in pain, numbness, tingling, weakness or balance problems among other symptoms. These symptoms usually develop in the legs, feet, arms or hands, but can appear anywhere in the body.

Why does peripheral neuropathy occur in cancer patients?

Cancer patients are at risk for peripheral neuropathy because of the cancer itself and related treatments.

Cancer: Depending on its location, cancer can cause neuropathy. It is possible for cancer to move into the nerves. Cancerous tumors can also press on nerves and cause damage.

Chemotherapy: Chemotherapy can also cause severe nerve damage. Approximately 30-40% of cancer patients experience some form of neuropathy during or after chemotherapy treatment. Often, the hands and feet are the most affected areas.

Other cancer treatments: Surgeries to remove tumors may cause damage to nearby nerves. Also, radiation therapy used to kill cancer cells can impact the nerves in the treatment area. Neuropathy from radiation may not occur until months or even years after treatment.

Other causes of peripheral neuropathy

Peripheral neuropathy can also result from traumatic injuries, infections, metabolic problems and exposure to toxins. One of the most common causes is diabetes. Other causes can include:

• Benign tumors
• Medications
• Alcohol use disorder
• Vitamin/nutrient deficiency
• Inflammatory and autoimmune disease
• Heredity

Peripheral neuropathy symptoms

The symptoms of peripheral neuropathy vary based on the number of nerves involved, the location of the nerves and the severity of damage. There are different types of nerves in your nervous system:

• Sensory nerves send signals to the brain that allow for taste, smell and the sensation of pain.
• Autonomic nerves regulate unconscious processes in your body such as blood pressure, digestion and body temperature.
• Motor nerves carry messages from the brain that tell your muscles to move.

Peripheral neuropathy symptoms for different nerves can include the following:

Sensory nerves

• Numbness
• Tingling
• Lack of balance
• Burning
• Buzzing sensation
• Shocking sensation

Autonomic nerves

• Intolerance of heat
• Excessive sweating
• Loss of bladder control
• Diarrhea or constipation
• Dizziness after standing up

Motor nerves

• Twitching
• Muscle cramps
• Abnormal reflexes

Peripheral neuropathy diagnosis

It is important to diagnose peripheral neuropathy accurately. Some of the following information and tests may be used to find out if you have peripheral neuropathy.

• Medical history: Your health care team will ask you a series of questions about social habits, exposure to toxins, alcohol use, medical treatments and family history of neurological conditions.
• Physical and neurological exams: The doctor will look for signs of peripheral neuropathy and test your coordination, muscle strength and reflexes.
• Blood tests: These can detect exposure to harmful chemicals/toxins and immune system problems.
• Genetic tests: These are typically performed in the form of lab tests.
• EMG (electromyogram):  This is a diagnostic test that measures the health of nerves and the muscles they control.
• NCV (nerve conduction velocity): This test measures how fast an electrical impulse moves through your nerves.
• Diagnostic imaging: MRI and CT scans may reveal certain causes of neuropathy such as tumors, herniated disks and abnormalities in veins or arteries.

Stages of peripheral neuropathy

Staging is a way of classifying a condition by symptoms and how the body is affected when it is diagnosed. The stages of peripheral neuropathy are:

• Stage I: Sporadic pain and numbness
  • You may notice symptoms occasionally, but not constantly. Often symptoms are easily overlooked during this stage.
• Stage II: Persistent pain and numbness
  • Pain and numbness are more constant and increasingly difficult to ignore. Addressing symptoms by this stage is critical to preventing further nerve damage.
• Stage III: Debilitating pain and numbness
  • The pain and numbness in stage III are so severe that activity is greatly affected. Walking will become difficult, and you may be unable to balance. Severe numbness increases risk of injuries such as cuts and burns and resulting infections can be life threatening.
• Stage IV: Complete numbness
  • Walking is almost impossible due to severely damaged and deadened nerves. The risk of amputations and complications is highest at this stage.

Treating peripheral neuropathy

While it cannot be cured, there are several options to treat peripheral neuropathy and prevent it from worsening. It is important to discuss your options with your health care team.

Ways to address peripheral neuropathy include:

• Correction of the underlying cause (Examples: Stop smoking, address any vitamin deficiencies, and avoid alcohol and toxic agents)
• Medications
  • Anticonvulsants: Anticonvulsants have been found effective in managing neuropathy due to their ability to block electrical signals in the nervous system.
  • Antidepressants: Certain antidepressants can treat peripheral neuropathy pain. Often, antidepressants are used in combination with other methods such as anticonvulsants.
  • Opioids: Opioids may be used for pain that cannot be managed with other treatments. This is generally not recommended due to limited data and the risk of dependence or addiction.
• Topical agents: These include gels, lotions and patches often available over the counter.
• Surgery: Occasionally, surgery can be performed to alleviate painful pressure on nerves.
• Plasma exchange and intravenous immunoglobulin (IVIg): Patients suffering from certain inflammatory conditions may find relief using plasma exchange or immune globulin therapy.
• Transcutaneous electrical nerve stimulation (TENS): A small unit sends low-level electrical impulses though the skin using small adhesive patches; the impulses block the sensation of pain from reaching the brain.
• Physical therapy: With the help of a physical therapist, patients can learn exercises to improve muscle strength. The physical therapist may recommend devices such as canes and walkers.
• Lifestyle modifications (Examples: Avoid alcohol, stop smoking, exercise regularly and eat a well-balanced diet that supports nerve health).
• Alternative medicine: Acupuncture and massage may help patients with peripheral neuropathy.

Peripheral neuropathy safety tips

There are several steps patients can take to limit the impact of peripheral neuropathy. These include:

• When running water, start with a cold temperature then gradually shift to warmer.
• Use gloves for protection when exposed to cold temperatures and while performing activities such as yard work.
• Wear socks.
• Inspect your hands and feet regularly for cuts and injuries.
• Do not drive a vehicle if you are unable to feel the brakes or gas pedal.
• Take steps to prevent falling, including:
  • Both indoors and outdoors, wear shoes that fit properly and have a rubber sole.
  • Avoid walking on surfaces that are uneven.
  • Keep your living area well lit.
  • If advised, use a cane or walker.
  • Consider installing grab bars in the shower/bathtub and stairway railings at home.
  • Keep floors clear of things that could cause you to trip such as electrical cords or rugs.