iEMG

Intramuscular electromyography (iEMG) is a technique used to record the electrical activity of skeletal muscles by inserting fine needle electrodes directly into the muscle tissue. It is a form of EMG that provides high spatial resolution and access to activity from individual motor units, in contrast to surface EMG which uses electrodes placed on the skin.

The procedure involves sterile insertion of one or more fine electrodes into the target muscles, typically under local anesthesia. The signals are amplified and displayed for analysis during rest, voluntary contraction, or after mild electrical stimulation. Clinicians examine motor unit action potentials, recruitment patterns, firing rates, and spontaneous activity such as fibrillations or positive sharp waves to characterize neuromuscular status.

iEMG is commonly used in clinical neurophysiology to diagnose a range of neuromuscular disorders, including radiculopathies, peripheral neuropathies, myopathies, and motor neuron diseases. It can aid in assessing muscle innervation after nerve injury, guiding surgical decisions, or evaluating the effects of rehabilitation. In research settings, iEMG supports investigations of motor control, aging, and muscle adaptation, and it enables techniques such as motor unit number estimation.

Advantages of iEMG include high diagnostic specificity and the ability to isolate activity from single motor units. Limitations include its invasive nature, patient discomfort, small sampling area, and potential risks such as bleeding, infection, or nerve injury. Accurate interpretation requires trained clinicians and standardized technique.