Side Effect: Muscle Twitching and Muscle Spasms

Muscle twitching and muscle spasms are two different conditions, although they are often used interchangeably.

• Muscle twitching refers to the involuntary contraction of a small group of muscles or muscle fibers. These twitches can be visible or felt under the skin and usually last only a few seconds.
• On the other hand, muscle spasms, also known as muscle cramps, are painful and involuntary contractions of a larger group of muscles. They can last several minutes and can cause severe discomfort.

Muscle twitching can look like small, rapid, flickering-like movements under the skin. It can occur in any muscle in the body and can be triggered by fatigue, stress, caffeine, or certain medications.

Muscle spasms typically involve larger muscle groups, such as the legs, back, or abdomen. They can cause sudden, intense pain, stiffness, and limited mobility.

Patients with cancer are at risk of developing muscle twitching and muscle spasms due to several factors, including:

• cancer-related fatigue
• dehydration
• electrolyte imbalances
• or other underlying medical conditions.
• medications that are used to treat bone loss (bisphosphonates, denosumab) or to increase your white blood cell count (filgrastim, peg-filgrastim) can also cause muscle cramps.

Cancer treatments that can increase the risk of muscle spasms include:

• Chemotherapy - docetaxel (Taxotere®), ixabepilone (Ixempra®), paclitaxel (Taxol®), vincristine (Vincasar®)
• Aromatase inhibitors - anastrozole (Arimidex®), exemestane (Aromasin®), letrozole (Femara®)
• Hormonal therapy - fulvestrant (Faslodex®), raloxifene (Evista®), tamoxifen (Soltamox®), and toremifene (Fareston®)
• Targeted therapy – trastuzumab, ado-trastuzumab emtansine (Kadcyla®)

Things you can do to help prevent muscle twitching or muscle spasms include:

• stretching exercises
• staying hydrated
• avoiding triggers such as caffeine or alcohol.

Treating muscle twitching or muscle spasms can involve a range of approaches, depending on the underlying cause and severity of symptoms.

• Acupuncture, massage therapy, yoga, hot and cold packs, and over the counter pain relievers can help to alleviate muscle pain.
• More severe cases may require medications such as muscle relaxants or antispasmodics, physical therapy, or nerve blocks.
• In some cases, treating the underlying cancer may also help alleviate muscle twitching or spasms.