The patient with acute muscular weakness

Proximal muscle weakness can present acutely or subacutely to the Acute Medical Unit. Early diagnosis of the underlying pathology is essential due to life threatening complications such as respiratory failure and cardiac disturbances as well as causing significant levels of disability. The diagnosis requires thorough history-taking and examination to discern evidence of true weakness, assess its onset, distribution and severity followed by extensive investigations including a CK level, which if high should raise suspicion of rhabdomyolysis. Assessment of respiratory function should be done promptly to identify patients with associated respiratory muscle weakness and treatment should not be delayed waiting for definitive and confirmatory investigations. Poor response to treatment is unusual when diagnosis is correct; this raises the possibility of an alternative diagnosis.