Diagnosing Chemotherapy-Induced Peripheral Neuropathy (CIPN)

What is chemotherapy-induced peripheral neuropathy?

Chemotherapy-induced peripheral neuropathy (CIPN) occurs when peripheral nerves are damaged following chemotherapy. CIPN is a common complication of chemotherapy and affects up to 40% of individuals that receive neurotoxic chemotherapy.

A diagnosis of CIPN is based on a medical history, physical examination, and various medical tests.

Medical history and physical examination

A medical history and physical examination can provide clues that indicate a diagnosis of CIPN. An individual's medical history can also be used to determine other possible causes for neuropathy that should be considered, such as diabetes, nutritional deficiencies, or a preexisting neuropathy.

A diagnosis of CIPN may be suspected based on the following findings from a medical history and physical examination:

• A history of receiving a chemotherapy agent known to be neurotoxic
  Forms of chemotherapy that are known to be neurotoxic include platinum drugs, taxanes, or plant alkaloids. CIPN is more likely to occur with higher doses, multiple courses, or a combination of multiple types of chemotherapy drugs.
• Timing
  Symptoms of CIPN usually begin during the first two months of treatment, progress slowly during chemotherapy treatment, and stabilize when treatment ends. While the progression of CIPN can be rapid, slow progression is more common.
• The type of symptoms
  Sensory symptoms, such as numbness, tingling and pain, are often dominant and are disproportionate to the degree of motor symptoms, such as weakness. Changes in sensing vibration, temperature and sharpness are common. Neuropathy that manifests with only motor symptoms (absent of sensory symptoms) is not likely to be caused by chemotherapy.
• The location and distribution of symptoms
  Symptoms of CIPN are usually length-dependent and symmetric. Length- dependent neuropathies start, or are worse, at the end of the longest nerves of the feet and spread upward.

Tests and studies

Based on findings from a medical history and physical exam, a variety of medical tests to confirm a CIPN diagnosis and eliminate the possibility of other health conditions may be ordered. These include, but are not limited to, the following:

• Autonomic testing measures how well the body regulates automatic functions, such as heart rate, blood pressure, and sweating.
• Electromyography (EMG) is a test in which a small needle is inserted into a muscle to measure and evaluate the electrical activity occurring in the muscle. Abnormal findings suggest damage to a nerve that controls the muscle.
• Nerve conduction study is a test in which two electrodes are placed on the skin to measure the speed of electrical impulses. This test can identify if nerves impulses are slow.
• Imaging studies, such as X-rays and MRIs, can be used to exclude other causes of neuropathic symptoms, such as structural spinal abnormalities.
• Biopsies can be used to evaluate the health of nerves. Biopsies of large-fiber nerves, such as the sural nerve in the leg, can be used to evaluate sensory and motor nerve damage. Skin biopsies can help with the identification of any changes to the cutaneous nerves that detect sensations, such as cold, warmth, and touch.