What is asthenia?

What is Asthenia?

Asthenia is a subjective symptom characterized by a persistent lack of energy, vigor, or strength that is not necessarily related to physical effort and does not improve adequately with rest. 1, 2

Core Definition and Clinical Features

Asthenia represents a static feeling of weakness and exhaustion that differs fundamentally from normal fatigue because it persists despite adequate rest and occurs even with habitual levels of physical or intellectual activity. 1, 3

The term derives from Greek (a: without; esthénos: vigor, force), literally meaning "absence of strength." 1

Key Distinguishing Features

It is critical to differentiate asthenia from other symptoms that patients may confuse with it:

• Muscle weakness (objective loss of motor strength) 1
• Dizziness (vertigo or lightheadedness) 1
• Dyspnea (shortness of breath) 1

Clinical Manifestations

Asthenia typically presents with a constellation of symptoms:

• Increased fatigue and exhaustion 3
• Mood instability 3
• Increased irritability 3
• Sleep disorders 3
• Decreased physical activity 3
• Increased cognitive and mental fatigue 3

Temporal Classification

The duration of symptoms is essential for characterization:

• Prolonged fatigue: lasting more than 1 month 1
• Chronic fatigue: lasting more than 6 months 1

Epidemiology and Clinical Significance

Asthenia is an extremely common presenting complaint:

• Accounts for approximately 30% of ambulatory consultations 1
• Chronic fatigue represents up to 10% of these cases 1
• Chronic fatigue syndrome accounts for 0.2-0.7% of cases 1
• 16-64% of patients with asthenia visit primary care physicians 4

Underlying Causes

Depression is the most common cause of asthenia, representing approximately half of all cases. 1

Asthenia serves as a symptom of numerous conditions:

• Organic diseases (cardiovascular, cerebrovascular pathology) 4, 3
• Mental illnesses including stress-related neurotic disorders 4
• Somatoform disorders (panic attacks, generalized anxiety disorders) 4
• Adjustment disorders 4
• Nonpsychotic depressions 4
• Post-viral states 4
• Geriatric syndromes (senile asthenia syndrome) 3

Asthenia can be understood as a defense mechanism signaling depletion of energy resources, but may become pathological and transform into chronic fatigue syndrome, an immune-mediated disease. 5

Diagnostic Approach

Up to 20% of patients with asthenia remain without a definitive diagnosis despite thorough evaluation. 1

Chronic fatigue syndrome is a diagnosis of exclusion requiring application of the 1994 international consensus criteria. 1

Asthenia is often combined with affective and cognitive disorders, which complicates establishing the primary diagnosis. 5

Clinical Impact

The high frequency of this symptom carries enormous social and economic costs, making proper evaluation and management essential for physicians. 1