Elektromiográfia

Elektromiográfia, or electromyography, is a diagnostic procedure used to assess the health of skeletal muscles and the nerves that control them. By recording electrical activity in muscles, it helps distinguish neuromuscular disorders from other conditions and can localize sites of pathology along the motor units.

EMG is performed using two main approaches: needle EMG, where fine electrodes are inserted into specific muscles to record motor unit potentials during rest and voluntary contraction; and surface EMG, where electrodes placed on the skin measure activity from larger muscle groups. For many evaluations, EMG is combined with nerve conduction studies (NCS) to assess peripheral nerve function, speed, and conduction block.

Interpretation looks at insertional activity, spontaneous activity at rest (fibrillations, positive sharp waves), motor unit action potentials during contraction, and recruitment patterns. Denervation or reinnervation changes suggest neuropathic processes, while small, short-duration, low-amplitude MUAPs and early fatigue indicate myopathies. The results are integrated with clinical findings and other tests.

Indications include unexplained weakness or numbness, muscle cramps or fasciculations, suspected radiculopathies, neuropathies, or myopathies, and assessment after nerve injury or during management of neuromuscular diseases. The procedure is generally safe but may cause brief discomfort, bleeding, or infection at insertion sites; risks are low.

Historically, electromyography developed during the 20th century, with needle EMG becoming standard practice and surface EMG expanding later for broader applications.