Electromyography (EMG) is a key diagnostic test to study nerve and muscle function. It is required for the investigation and strudy of neuromuscular disorders, thus when symptoms are suspected to be related to altered nerve transmission or muscle suffering.
In particular, EMG is useful to clarify:
- Sensitivity disturbances such as tingling, numbness, or a "shaking" sensation;
- Loss of strength or motor difficulties that cannot be explained by other investigations;
- Persistent muscle pain or frequent cramping;
- Suspected herniated disc or nerve compression (e.g., carpal tunnel syndrome);
- Possible neuromuscular diseases (myopathies, neuropathies, radiculopathies).
The conditions for which the examination is most frequently requested are peripheral nerve compressions, such as carpal tunnel syndrome, and all forms of pain affecting the spine such as low back pain, cervicobrachialgia, and others.
Another category of pathology for which electromyographic investigation is required is peripheral neuropathies, which cause motor difficulties and/or sensory abnormalities.
Less frequent, but equally important, is the diagnostic role in the acute form of polyradiculonevritis, known as Guillain-Barré syndrome; in hereditary and degenerative neuro-muscular diseases (e.g., myopathies and amyotrophic sclerosis larethralis); in diseases of nerve transmission such as myasthenia gravis; and in traumatic nerve trunk injuries.
The examination is divided into two parts:
- in a first step, an Electroneurography (ENG) is performed , which is a noninvasive test that involves placing recording electrodes on the skin and administering electrical stimulation along the path of the nerves. In this way, the technician studies the responses to these stimuli and the speed and conduction efficiency of the nerves themselves are measured.
- the second phase is that proper toElectromyography (EMG), which is performed using a disposable needle-electrode, and evaluates the electrical activity generated by the muscle, both at rest and during contraction.
The investigation may cause mild discomfort, similar to an electric shock or a puncture, but it is short-lived, has no contraindications, and no preparation is needed.
The examination is performed by a neurophysiopathology technician and then reported by a specialist who will be able to figure out precisely whether the disorder originates in a nerve, a muscle, or their connection so that the most appropriate treatment can be set up.
