Effectively treating nerve damage induced by cancer therapy

A much feared side effect of many oncological treatments is chemotherapy-induced polyneuropathies. Early diagnosis and effective therapy can minimize the extent of damaged nerves.

Cancer therapy has evolved steadily in recent years. Effective immunomodulatory treatment options are now available in addition to radiotherapy and chemotherapy. However, a typical side effect of many therapeutic options is peripheral polyneuropathy. These can be manifested by both positive and negative phenomena, predominantly sensory or motor. Paresthesias, burning pain, or stocking- and glove-like deficits are most common with distally emphasized symmetric damage to peripheral nerves. As the damage progresses, pain, heat, or cold may no longer be perceived, and the numbness may lead to difficulty with fine motor, everyday activities. After cessation of neurotoxic chemotherapy, the symptoms usually subside gradually. However, after platinum-based chemotherapy, symptoms may continue to progress for up to three months.

The incidence of CIPN varies from 3% to 38% – depending on therapy. Effective preventive measures do not yet exist. However, the risk increases significantly in patients with older age, comorbidities such as diabetes mellitus or renal insufficiency, and high alcohol consumption. Regular exercise training is recommended. A Japanese study found that wearing frozen gloves and socks, and thus reducing blood flow to the hands and feet, significantly improved nerve pain. Only 27.8% of patients experienced pain. Without this measure, 80.6% perceived interference.

Recognize symptoms early

In order to exclude severe courses as far as possible, CIPN should be detected early and treated accordingly. An early warning sign of a polyneuropathy is the loss of muscle reflexes as well as a decrease in the sensation of vibration. Therefore, not only the Achilles tendon reflex but also the vibration with the Rydel-Seiffer tuning fork should be checked after each chemotherapy cycle. Sensitive deficits can be checked using a surface sensitivity test. Sticks with one end made of metal and one end made of plastic are suitable for testing the cold-warm sensation. Electroneurography can be used to measure nerve conduction velocity in the arms and legs, and electromyography measures electrical activity in the muscle.

Effective therapy of damaged peripheral nerves

Data regarding non-drug interventions are limited to date. Nevertheless, exercise therapy may be useful to improve functionality. Balance exercises, sensorimotor training, coordination and fine motor training and last but not least vibration training are recommended. Physical therapy, occupational therapy, electrotherapy or baths also help, especially with numbness in the feet or hands.

When initiating drug treatment, the choice of drug should be based on risk-benefit considerations. Antidepressants, anticonvulsants, and opioids have been shown to be effective for chemotherapy-related neuropathic pain. Plasters or ointments that act locally can also relieve the pain, albeit only to a limited extent.