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Electromyography (EMG)

This is an investigative method that is used to determine the functional state of the nerve roots, peripheral nerves, neuromuscular transmission and muscle.

EMG consists of two basic electro-diagnostic methods:

  1. stimulatory EMG – testing the conductivity of motor or sensory fibres of peripheral nerves,
  2. needle EMG – studying the bioelectric potentials of skeletal muscle using needle electrodes

EMG examination is conducted by a doctor-neurologist – a specialist in electromyographic issues. It is therefore necessary for the patient to have a referral for the examination. This referral must be given by a doctor, ideally a neurologist. It should include a medical history and the patient’s subjective complaints and objective findings. The referral must state clearly what the electromyographist should examine and whether they should use stimulatory EMG (e.g. on suspicion of KT syndrome or ulnar sulcus syndrome) or whether needle EMG is indicated.

Course of procedure

Stimulatory EMG is performed using registration and stimulating electrodes. The examination is performed by electrically stimulating peripheral nerves – the value varies individually, but up to 100 mA. This implies that the examination can be slightly painful. Repetitive stimulation – where there is a series of electrical impulses – is a special unit of stimulatory EMG.This examination is indicated for patients with suspected neuromuscular disorders, particularly myasthenia gravis.

Needle EMG is performed by applying a thin needle electrode into the muscle, we then receive activity from the surrounding muscle fibres through its tip.

Preparation for examination

No special preparation is required from the patient, only they should not apply cream to the examined limb in the morning. Before the examination itself they are asked to wash their hands with soap and dry them thoroughly – this is to minimize skin resistance.

EMG examination is contraindicated for patients with pacemakers. In some cases it can be performed even for these patients, but only with the consent of the cardiologist.

Needle EMG is sometimes contraindicated in patients on anticoagulant therapy (warfarin or new anticoagulants). In such cases, the individual process depends on the patient’s condition, bruising and the like.

The patient is at risk of increased bleeding and hematoma formation after examination.

The patient receives their examination report by post at their home address or the referring