Medical Terminology for Body Weakness
The medical term for body weakness is "asthenia," which derives from Greek meaning "absence of strength or vigor." 1
Definition and Clinical Context
Asthenia is the formal medical term used to describe a subjective feeling of weakness, lack of energy, or absence of strength. 1, 2 This term specifically refers to a static feeling of weakness that is not necessarily related to physical effort, distinguishing it from other related symptoms. 2
Important Clinical Distinctions
It is critical to differentiate asthenia from other symptoms that patients may confuse with general weakness:
- Muscle weakness: Refers to objective loss of muscle strength or function, which can be measured through physical examination (e.g., reduced grip strength, inability to rise from a chair). 3
- Dizziness: A sensation of lightheadedness or vertigo. 1
- Dyspnea: Shortness of breath or difficulty breathing. 1
- Fatigue: While often used interchangeably with asthenia, fatigue more specifically describes exhaustion that occurs with physical or intellectual effort and persists after rest. 4
Related Medical Terms
Several related terms describe specific manifestations or contexts of weakness:
- Sarcopenia: Progressive loss of skeletal muscle mass, strength, and function, typically age-related but can be secondary to disease, inactivity, or nutritional deficiency. 3
- Frailty: A state of vulnerability with reduced physiological reserve capacity, often including weakness as one of five diagnostic criteria. 3
- Myasthenia: Specifically refers to fatigable or fluctuating muscle weakness, often with ocular or bulbar involvement. 3
- Neurocirculatory asthenia: A historical term (also called Da Costa's syndrome) describing a chronic condition with fatigue, breathlessness, and other symptoms but normal physical examination. 5
Clinical Classification
Asthenia can be classified by duration:
- Prolonged fatigue: Lasting more than one month. 1
- Chronic fatigue: Duration greater than six months. 1
- Chronic fatigue syndrome: A specific diagnosis of exclusion with defined international criteria, representing 0.2-0.7% of asthenia cases. 1
- Senile asthenia syndrome: Used specifically for older adults, characterized by age-associated decrease in physiological reserve and function. 4
Clinical Significance
Asthenia is an extremely common presenting complaint, accounting for approximately 30% of ambulatory consultations. 1 Depression represents the most common underlying cause, accounting for approximately half of all cases. 1 Up to 20% of patients with asthenia remain without a definitive diagnosis despite thorough evaluation. 1