Neuropathy is a condition that causes damage to the peripheral nerves, effecting sensation and, less frequently, movement. Dr Ronwyn van Eeden explains the causes and risk factors of neuropathy, and the treatments offered.
What are the causes?
Neuropathy can be caused by direct pressure or infiltration of the cancer on the nerves. More commonly, it is caused by cancer treatments; this is referred to as chemotherapy-induced peripheral neuropathy (CIPN).
These chemotherapies include taxanes commonly used in breast cancer treatment, platinum chemotherapy used across a wide variety of cancers and vinca alkaloids used for lymphoma treatment. Some newer anticancer therapies, for example, bortezomib, lenalidomide and thalidomide used in myeloma treatment, also cause neuropathies.
You’re at a higher risk of developing CIPN, if you have:
• pre-existing nervous system problems, caused from surgery or radiation.
• metabolic disorders, such as diabetes.
• nutritional deficiencies, such as vitamin B12 deficiency.
What are the symptoms?
Symptoms (see below) can be sudden or develop gradually over time, and are mostly mild and manageable. However, severe cases can be incapacitating and can severely compromise quality of life.
• Burning, numbness or tingling, generally in a “glove and stocking” distribution.
• Cold insensitivity, or not being able to feel properly and dropping things while holding them.
• Not being able to walk properly, however, this is rare.
• Experiencing ‘electric shocks’ in the body making normal touch excruciating.
• Motor symptoms can also be seen, but this is usually milder and less common.
• If internal organs are affected, bowel habits can change and diarrhoea or constipation can occur.
• Dizziness or drops in blood pressure.
CIPN is extremely difficult to treat, in that it often doesn’t respond well to painkillers or even to the current treatment recommended.
The unfortunate consequence of developing CIPN, other than affecting daily functioning and causing disability, is that it can lead to shorter survival in patients. Oncologists often have to decrease doses of treatment, or delay treatment, preventing patients from getting proper therapeutic doses and keeping to their chemotherapy schedule.
CIPN often has a cumulative effect, meaning the more chemotherapy that is administered, the more severe the neuropathy gets. This can often cause treatment to be terminated early and even permanently. The benefit of treatment has to be weighed against the risks and debilitation of the neuropathy.
Many attempts have been made to try to prevent CIPN in high-risk chemotherapy regimens. Scientists have studied several agents, such as vitamin E, calcium, magnesium, acetyl-L-carnitine and glutathione amongst others, that aid with prevention. Sadly, there is no evidence to show that any of these work. Therefore, it is not used in routine practice.
Treatment of CIPN is symptomatic, and the damage can often be permanent and irreversible. Pain is usually controlled by opioid medication, like tramadol, but often stronger opioids, like oxycodone or morphine, are needed.
When these treatments are ineffective or when the pain is severe, recommendations are antidepressant medications, such as Tryptanol or duloxetine. Antiepileptic drugs, such as Neurontin (gabapentin), Lyrica (pregabalin), lamotrigine or Tegretol can also be effective.
If there is compression of the nerves by a tumour or cancer, corticosteroids may be used. When there is neuropathic pain due to bone involvement, radiation can be used.
Local anaesthetic patches have also been shown to work.
Rehabilitation specialists, particularly physiotherapists and occupational therapists, are uniquely qualified to assess patients with CIPN and provide strategies for management. Ask your doctor for a referral.
Guidelines to help manage CIPN:
• Use pain medication as prescribed, as sometimes taking them before the pain gets severe, works best.
• Avoid very hot or cold temperatures. Don’t put your hands directly into the fridge or in front of a heater.
• Wear good-fitting shoes, socks to bed, and gloves if it is cold.
• Wear protective hand and footwear when working outdoors.
• If you have neuropathy in your feet, sit down when you’re washing dishes or brushing your teeth.
• Don’t rush to do things, give yourself extra time, or ask for help if you find certain tasks difficult, like doing up buttons or making tea.
• If you’re having difficulty walking, make use of hand rails, especially in slippery areas like the bathroom, or use a walker.
• Use a flashlight, when getting up in the dark, to avoid injuries to feet.
• Don’t drink alcohol as this can make the symptoms worse.
• Make sure your diabetes is under control as high sugar levels also damage nerves.
• If you have constipation, follow a good diet with plenty of water, fruits, vegetables and fibre. Exercise, and follow your doctor’s instructions when using laxatives.
• Talk to your doctor about the difficulties you’re experiencing, so he/she can assist with ways to make you function better.