Muscle weakness

What it means

Reduced strength of muscles.

It is important clinical to distinguish between muscle weakness, fatigue, and asthenia. Fatigue describes the inability to continue performing a task after multiple repetitions; in contrast, a patient with primary weakness is unable to perform the first repetition of the task. Asthenia is a sense of weariness or exhaustion in the absence of muscle weakness. Conditions that result in intrinsic muscle weakness can be divided into several main categories: infectious, neurologic, endocrine, inflammatory, rheumatologic, genetic, metabolic, electrolyte-induced, or drug-induced.

Rare diseases that can present with this248

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 2 diseases where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category