Muscle Weakness

CLINICAL DIAGNOSTIC MANUAL

Muscle weakness is a condition in which muscles lack the strength to perform daily tasks. This weakness may be generalised or localised and can affect both proximal and distal muscles.

The causes of muscle weakness vary and may include bone, joint, or adjacent muscle diseases, lower motor neuron injuries, and muscle disorders. Identifying the underlying cause is crucial to providing appropriate treatment and improving the patient’s quality of life.

Condition	Clinical Symptoms and Signs	Suspected Diagnosis	Confirmatory Diagnosis
Bone, joint, or adjacent muscle disease	Joint or bone pain, swelling, limited movement, muscle weakness associated with the affected region	Clinical history, physical exam, signs of inflammation or bone deformity	X-rays, MRI, blood tests (inflammatory markers)
Lower motor neuron injury	Weakness, muscle atrophy, fasciculations, hypotonia, diminished reflexes	Clinical history, neurological exam	EMG, nerve conduction studies
Muscle disease	Progressive muscle weakness, difficulty climbing stairs or lifting objects, muscle atrophy, possible muscle pain	Clinical history, physical exam, signs of myopathy	Elevated CPK, muscle biopsy, genetic studies