Asthenia

Asthenia refers to generalized physical weakness and/or a lack of energy and strength. It is not a disease, but rather, is a common sign of several acute and chronic medical conditions. Asthenia can also develop as a side effect of medications. 

Previously, the terms “weakness” and “asthenia” were both used to describe a subjective sensation of tiredness, whereas the term “fatigue” was used to describe symptoms of tiredness brought on by physical effort. In current literature, asthenia and fatigue are used interchangeably and both refer to a subjective sensation characterized by feelings of tiredness and perception of decreased capacity for physical or mental work. Asthenia may affect an individual physically, emotionally, and cognitively. Additionally, one may experience physical asthenia in specific body parts, or throughout the entire body.

Asthenia is typically caused by underlying health conditions. Causes may be acute, such as in the case of infection, (e.g., meningitis), which can lead to muscle stiffness; or cardiac decompensation (i.e., due to heart attack or stroke).  Chronic causes include natural aging; malnutrition; nutritional imbalances (e.g., vitamin B-12 deficiency); anemia; hypothyroidism; diabetes; tuberculosis; sleep apnea; and mental health conditions, such as depression.

Asthenia and generalized muscle weakness can be common in those with end-stage disease, such as chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), and cancer. A reduction of peripheral and respiratory muscle strength can occur, thereby leading to limited exercise capacity. Additionally, autoimmune diseases of the muscle, such as multiple sclerosis, can often cause asthenia. 

Finally, asthenia has been associated with certain medications, including medications prescribed to control high blood pressure (e.g., propranolol, metoprolol, methyldopa, diltiazem); antidepressants (e.g., carbidopa / levodopa, alprazolam); statins used to control high blood cholesterol (e.g., simvastatin, pravastatin); and loop diuretics used to treat symptoms of fluid overload (e.g., furosemide). It may also be caused by drug-drug interactions, such as when opiates interact with anticholinergics, antihistamines, and/or benzodiazepines. 

The signs and symptoms of asthenia include a subjective sense of physical, emotional, or cognitive tiredness that interferes with day-to-day functioning. The symptoms of weakness are typically out of proportion to the activity being performed and can be distressing and persistent. 

Asthenia can be regional, occurring in specific body parts, such as the arms or legs. Unlike paralysis, where the individual is unable to move the body part, they are still able to move the limb, however, it may feel like it takes a lot of effort. There may be associated delayed and slowed movement, muscle spasms, and tremors. Asthenia may also affect the entire body, resulting in full-body weakness and fatigue, as well as difficulty carrying out daily tasks.

Asthenia is diagnosed by a comprehensive history and physical examination performed by a clinician. The diagnosis of asthenia can be challenging since there are several potential causes and it can sometimes go undiagnosed because fatigue is considered a common symptom of many advanced diseases. The clinician may ask about the individual’s symptoms, obtain a full medical and family history, and review medications that the individual is taking. The goal is to search for reversible or treatable contributory factors, and to review all of the various organ systems potentially affected by an underlying disease. It can also be important to ascertain how the symptoms of asthenia are affecting activities of daily living and quality of life. 

A physical examination can be helpful in diagnosing the underlying cause of asthenia. For example, if the individual is experiencing localized weakness, the clinician may carry out a detailed physical examination of the affected body part. In addition, diagnostic testing such as blood tests and radiographic imaging may be needed. Clinicians may evaluate for anemia, metabolic abnormalities, malnutrition, electrolyte disturbances, and infections using blood and urine tests. A spinal tap, or lumbar puncture, allows for an analysis of the CSF fluid that surrounds the brain and spinal cord which can then be used to diagnose meningitis. Imaging using X-rays, ultrasound scans, magnetic resonance imaging (MRI) scans and computerized tomography (CT) scans can check for causes of bone, muscle, or nerve damage. Specifically, MRI can diagnose inflammation, infection, vascular irregularities that may lead to stroke and tumors that may be cancerous.

An electromyography (EMG) can be used to diagnose disorders of lower motor neurons, of muscle, and of peripheral nerves. A clinician will insert a thin needle into a muscle to assess the electrical activity during movement and at rest. Lastly, a muscle or nerve biopsy may be used to help confirm nerve disease and nerve regeneration. During this procedure, a small sample of the muscle or nerve is removed under local anesthesia and studied under a microscope.

Treatment for asthenia depends on the underlying  cause. Generally, in cases of acute asthenia caused by infection or cardiac decompensation, treatment may rapidly reverse the symptoms of asthenia. For example, asthenia that develops from a bacterial infection should subside after an individual completes a course of antibiotics. Those with asthenia may be offered medication (e.g., aspirin, thrombolytics or anticoagulants) or surgical intervention. 

Conversely, for more chronic causes of asthenia, including cancer, the treatment plan is often more multifactorial and therefore requires an interdisciplinary approach. Physical exercise is often important to enhance physical functioning and quality of life, as it has been shown to promote a sense of wellbeing, while reducing asthenia symptoms and pain. Likewise, yoga and tai chi (i.e., a traditional Chinese exercise therapy), have been shown to relieve cancer related fatigue in several studies. Maintaining proper sleep hygiene is important for reducing the symptoms of asthenia. Ensuring restful and adequate amounts of sleep by maintaining a strict sleep-wake schedule, and minimizing evening food and/or beverage intake may reduce fatigue. Additionally, cognitive-behavioral and psychosocial interventions (e.g., mindfulness-based stress reduction) have been shown to reduce fatigue and improve sleep. 

In addition to behavioral interventions, pharmacological approaches can help reduce symptoms of asthenia. Glucocorticoids (e.g., dexamethasone, prednisone, methylprednisolone) have been shown to be helpful for those with asthenia and fatigue secondary to cancer or other serious and/or life-threatening illness. Psychostimulants such as dextroamphetamine, methylphenidate, and modafinil are used to treat fatigue and depression in individuals receiving palliative care. They act rapidly and are generally well tolerated and safe. However, they are typically used with caution in individuals with heart disease or cognitive disturbances (e.g., delirium).

Lastly, in the case that the individual is experiencing asthenia as a side effect of a particular medication, altering the dose or dosing interval of a medication may substantially improve fatigue. However, the individual is encouraged to speak to their clinician before adjusting their medication dose or stop taking medication.