Neurological side effects
Neurological side effects of cancer treatment occur through direct or indirect damage to the central nervous system, peripheral nervous system, cranial nerves or any combination of the three. Damage is drug specific. Out of the three, the peripheral nervous system is the most commonly affected.
Neuropathy (nerve damage)
Peripheral Neuropathy
Peripheral Neuropathy is becoming a more common occurrence with the advent of new drugs. It results from irritation or damage to sensory and motor nerves outside the central nervous system. In addition to cancer treatment, there are other factors that increase a person’s risk for developing peripheral neuropathy. These include a history of diabetes, other disease processes such as AIDS, heavy use of alcohol, malnutrition, history of bone fractures, medications such as steroids, as well as certain cancers themselves, in particular lung cancer.
Peripheral neuropathy can be a serious complication of cancer treatment if not addressed at the onset of symptoms. It generally presents as numbness and tingling in the fingers and toes; you may also experience weakness or pain in the hands/arms/feet/legs, and abnormal sensations such as burning, tickling, prickling or tingling. Sometimes instead of a certain sensation you may only notice difficulty picking up objects and buttoning clothing, dropping things or stumbling when you walk.
The nerves of the large intestines may also be affected, causing decreased motility of the bowel resulting in constipation and sometimes obstruction of the intestines. It is important that you report any changes in sensations in your fingers/toes, changes in ability to perform normal activities or changes in bowel habits (constipation) to us promptly.
At this time there are no reliable treatments for peripheral neuropathy and care is centered on preventing the worsening of symptoms and treating pain. Sometimes this may include changing your cancer treatment or decreasing the dosage of the drugs you are receiving. Pain is generally managed with drugs. Recovery is a slow process but your physician or nurse can discuss some of the approaches used to encourage regeneration of damaged nerves.
Eye and vision problems
Cancer treatment may affect your eyes. Causes of eye problems, also referred to as ocular toxicity, are multiple. Damage to the eye or eye structures may occur through the distribution of chemo drugs in tears, irritation caused by loss of eyelashes, infections and other disease processes.
Visual impairment related to treatment may occur during chemotherapy and up to several weeks after its completion. The risk for developing eye problems is related to specific drugs. Symptoms of eye problems are: cloudy vision, blurred vision, sensitivity to light, eye pain, changes in vision, dry/gritty eyes, red and irritated appearing eyes, drainage from the eyes, increased and bothersome tearing and changes in vision.
Treatment of eye problems depends on the specific problem and its’ severity. It is important that you talk to your physician or nurse if you are experiencing any of the symptoms described below.
Conjunctivitis (pink eye) occurs secondary to the effect of chemotherapy on your immune system, as well as through direct effect on the cells of the conjunctiva. Chemotherapy drugs associated with conjunctivitis include Capecitabine (Xeloda), Epirubicin (Ellence) and Methotrexate. Conjunctivitis may also be viral, bacterial or allergic. If the conjunctivitis is related to a bacterial infection the doctor may prescribe antibiotic eye drops. If it is viral or allergic application of warm moist washcloths to the eyes and the use of an over-the-counter decongestant eye drop may help. Protect your eyes with sunglasses when out in the sun and try to avoid substances known to cause conjunctivitis such as dust and pollen. Practice good hand hygiene to avoid infections and do not share towels or washcloths with other family members. Never share eye makeup with anyone.
Dry eyes can occur when there is a decrease in an important chemical that is present in tears which helps to lubricate your eyes. Your eyes may feel dry and gritty or you may actually have an excess of tearing. The use of artificial tears may be helpful and cool compresses can relieve some of the irritation. Dry eyes generally resolve after completion of therapy, although some problems such as changes in tear production may become permanent.
Watery eyes can be a result of blockage in the eyes’ drainage system or you may be producing too many tears. Although there are several treatment drugs that can contribute to this problem, including Fluorouracil, Doxorubicin (Adriamycin) and Capecitabine (Xeloda), it is often related to environmental issues such as dust, pollen, smoke or other pollutants. Treatment of excessive tearing will be dependent upon the cause. The application of a warm compress to the eyes is sometimes helpful in coping with the discomfort. If possible try to eliminate environmental irritants from your work or home environment. Practice good hand hygiene to avoid infections.
Photophobia or sensitivity to light can be caused by injury to the cornea or inflammation of the uveal tract. When your eyes are exposed to light the pupils constrict and if there is any swelling present this may cause pain. This most commonly occurs when the eyes are exposed to sunlight. While photophobia can be caused by some chemotherapy drugs, it can also be caused by other disease processes as well as infections of the eye. Treatment will be dependent upon the cause.
Cataracts are cloudy areas in the lens of the eye. They usually occur in one eye and are generally a result of aging. However, some of the supportive medications used in cancer treatment such as Tamoxifen, Prednisone and Dexamethasone may contribute to the development of cataracts. In addition, exposure to radiation or long-term exposure to sunlight may also contribute to the development of cataracts. Symptoms of cataracts may include: blurry or cloudy vision, difficulty see in the dark, change in colors, appearance of a halo around lights, frequent changes in eyeglass prescription or double vision. Treatment of cataracts is generally surgical.
It is crucial that you let us know about any changes in your vision immediately. Visual symptoms could also occur because of disruption of ocular blood supply or cancer spread to the eyes or nervous system, and have to be attended immediately.
Inner ear problems
Our inner ear contains nerves which are responsible for hearing and balance. Toxicity to inner ear nerves, also called ototoxicity, can occur in up to 30% of patients receiving platinum-based cancer treatment. Patients with certain pre-existing hearing problem are at a greater risk for developing ototoxicity.
Ototoxicity may lead to temporary or permanent hearing loss, ringing in the ears (tinnitus) and/or dizziness. It may present as sounds appearing muffled, nausea/vomiting associated with dizziness, or ringing/strange sounds in the ear. You may notice that you have to turn the TV or radio up more than usual to hear or have difficulty hearing conversation when there is external noise present. It is important to report any of these symptoms to your physician or nurse promptly. The best way to avoid serious damage is changing to a different chemotherapy agent at first signs of the problem. Although specific symptoms such as dizziness or nausea/vomiting can be treated, there are no known treatments for damaged nerves.
If your inner ear has suffered, here are some things that you can do to help manage:
If you are experiencing ringing in the ears, try using a quiet radio, TV or other low level sound when you are trying to rest. This background noise may help you ignore the ringing and make it easier to rest.
Avoid stress and anxiety as these may worsen the symptoms.
Drink plenty of water and other non-caffeinated and non-alcoholic fluids to prevent dehydration. Dehydration can cause dizziness.
Avoid loud noise to prevent additional damage.
If you are experiencing dizziness, change positions slowly to give your body time to adapt to the change.
If dizziness can’t be controlled through medications we may need to refer you to a therapist to teach “vestibular exercise” to help control your dizziness.
Dizziness
Dizziness is frequently described as feeling lightheaded, woozy or faint. Most people notice dizziness when they change positions (such as changing from a lying to sitting position or sitting to standing position) or move their heads. Another symptom often categorized by patients as dizziness is vertigo. Vertigo is a different problem and has different causes. Any symptoms of dizziness or vertigo (feel like the room is spinning) should be reported to your physician or nurse promptly as both can be signs of more serious problems.
Dizziness and lightheadedness in cancer patients have many causes which are related to treatment only indirectly. It can result from anemia, dehydration due to nausea, vomiting, diarrhea or decreased appetite, use of blood pressure medications, to name a few. Dizziness and imbalance could also be due to cancer itself when it invades the brain.
Treatment for dizziness is dependent on the underlying cause. But some things you can do to help yourself are:
- Stay hydrated. Drink plenty of fluids – between 2-3 liters a day (if you are not on fluid restriction). This can include fruit juices, water, non-caffeinated drinks and nonalcoholic drinks.
- Change positions slowly. You need to allow your body time to adapt to changes in position. When changing from a sitting position to standing do not immediately begin to walk. Give yourself a few seconds to allow your blood pressure to adapt to the change.
- Walk slowly and with assistance (walker/cane) if dizziness is moderate to severe.
- Take anti-nausea medications as prescribed to decrease risk of nausea and vomiting.
- Report any symptoms you are experiencing that may be interfering with your ability to take in fluid (mouth sores, difficulty swallowing, etc).
- Try to avoid medications that have caused you dizziness in the past.
Remember, dizziness can be a fleeting symptom easy to resolve or the sign of a more serious problem. It is important to speak with your physician or nurse if you are experiencing this problem. Sudden severe ear pain, sudden loss of vision, falls or loss of consciousness associated with your dizziness should be reported immediately.
Chemotherapy can also cause dizziness directly, although it does not happen often. Damage to the inner ear nerves responsible for balance can occur with a drug called Cisplatin (see Hearing problems). Another, very rare, toxic side effect of chemotherapy is called Cerebellar Toxicity. It occurs via a direct effect of chemotherapy on the cerebellum, a part of the brain involved in coordination, and is primarily associated with high doses of the drugs cytarabine and 5-FU. Risk factors for developing cerebellar toxicity include: increased age, history of treatment with other medications toxic to the central nervous system, liver dysfunction and treatment infusions lasting over one hour. Persons experiencing this side effect may have an unsteady gait, have jerky movements or hand tremors when reaching for objects, changes in speech such as slurred speech, unusual pauses between words, double vision or difficulty writing. Treatment for cerebellar toxicity usually involves stopping the drug either temporarily or completely.