Asthenia/Fatigue

Asthenia and fatigue occurs in 75-90% of cancer patients and may be experienced as general lack of energy, easy tiring, generalized weakness or mental tiredness. This is the most distressing symptom in dying patients and can severely impact quality of life. Unfortunately it is frequently undiagnosed or ignored. Health care professionals have come to accept cancer related fatigue as expected and normal and they often do not screen for fatigue because they feel that there is little they can do to manage it or they are unaware of the distress that accompanies fatigue. Education of the dying person and his/her loved ones that asthenia is a frequent occurrence at the end of life may decrease unrealistic attempts at exertion and attempts to motivate the patient to achieve unrealistic goals.

COMMON CAUSES
The National Comprehensive Cancer Network (NCCN) defines fatigue as a persistent, subjective sense of tiredness related to cancer or its treatment that interferes with usual functioning.  Fatigue is a subjective experience, comparable to pain, and is best described by the person experiencing it.
Despite the fact that fatigue is so common, very little is known about its pathogenesis. 

Causes are likely multi-factorial and may include several factors such as:

  • direct tumor effects on energy consumption and supply;
  • humoral and hormonal influences;
  • paraneoplastic syndromes;
  • anemia;
  • chronic infections;
  • sleep disturbances (see Insomnia section);
  • anxiety and depression;
  • fluid and electrolyte disturbances;
  • drugs;
  • over-exertion. 

ASSESSMENT
Asthenia can be difficult to assess but there are scales that assist the patient to describe how she/he experiences fatigue. It is important to determine severity and to consider the factors that worsen or relieve fatigue, to rule out the presence of treatable causes, and to assess the impact of fatigue on daily activities and quality of life.

Some validated tools exist (Assessment Tools) for the assessment of fatigue including the Brief Fatigue Index.

Practical criteria for bedside diagnosis:
Cancer Related Fatigue: Guidelines for Evaluation and Management

MANAGEMENT
Non-Pharmacological Interventions
The key is to help families and patients to adapt activities of daily living to coincide with times of maximal energy and to develop good sleep hygiene.  If needed, arrange for help from loved ones, home care, a Community Care Access Centre (CCAC), hospice, nursing home.  Work with the patient and family to decide what is important to them, what he/she enjoys doing and develop a plan to allow them to perform and enjoy as many of these activities as possible.

Consider changing medications or time of administration to decrease drowsiness side effects during the day.

Physiotherapists and occupational therapists may provide invaluable help with assessment, teaching, and assistive devices.

Pharmacological Interventions
Asthenia is among the most difficult symptoms to treat. The most commonly used medications are 1) corticosteroids and 2) psychostimulants.

Corticosteroids:

  • mechanism of action not clear - likely due to increases in euphoria, perhaps through inhibition of tumor mediated substances;
  • benefit may decrease after 4-6 weeks;
  • in end-of-life setting the long-term side effects of morning doses of corticosteroids are not an issue;
  • Dexamethasone (Decadron). Taken orally once daily in morning.

Psychostimulants:

  • May be of benefit if asthenia is from side effect of opioid use.
  • Most experience is with methylphenidate (Ritalin):
    • short acting;
    • Extended-release formulations exist and once stable can switch to once-daily dosing;
    • Methylphenidate is safe even in people with advanced illness;
    • Side effects: tremulousness, anorexia, tachycardia, myocardial ischemia and insomnia;
  • dextroamphetamine (Dexedrine) and pemoline (Cylert) are also used.

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This page was last updated: March 9th, 2005 at 1:01pm.