When examining nervous system function, two categories of tests can be identified, namely instrumental tests and code tests. Neurophysiological instrumental tests, belong to the group of laboratory tests, ancillary to clinical electrophysiology. These tests are performed for the purpose of verification, comparison with physical examinations and subject examinations performed previously.

Neurophysiological instrumental tests, also known as analytical tests, are based on bioelectrical signals that provide a neuromechanical image of the observed neurological symptom. These signals are recorded automatically by devices, giving a finished picture. Hence the name analytical tests, as they are in contrast to code tests, where the observed neurological symptoms are described subjectively and classified according to an arbitrary scale. Code tests are therefore called synthetic tests. Both types of tests are used and complementary, but it is instrumental neurophysiological tests that are recognised as meeting the requirements of evidence-based medicine.

Each test performed by instrumental neurological testing should be performed in a patient-friendly manner, according to a specific standard and guidelines indicating what actions should follow during the test. Of great importance for the selection of the instrumental test is the result of the subjective and physical examination, indicating a specific diagnostic hypothesis. Often, the results of instrumental examinations are the basis for decisions on the therapy to be undertaken, whether conservative or surgical, hence the importance of appropriate interpretation of the examination result, which allows very precise images to be obtained, often even of the residual function of the damaged nervous system.

There are many techniques for neurophysiological instrumental testing. Examples will be listed below. Instrumental testing techniques include classical electrodiagnostics, which involves recording the excitability of nerves and muscles to galvanic current pulses. Another test in this field is clinical electromyography (EMG), which examines the bioelectricity of skeletal muscle in diseased or traumatised states of the nervous system. Another test is polyelectromyography (PEMG), which also examines the bioelectricity of muscles, but on a global scale, i.e. a certain group of muscles over a certain period of time, which allows a picture to be obtained of their interaction. Clinical electroneurography (ENG), is a study that records the action potentials of nerve fibres, induced by stimulation of the peripheral nerve trunk with an electrical impulse. In other words, ENG is a study of nerve conduction. Tests in this field, also include the tendon reflex test, a fairly well-known test using a hammer coupled to an ENG apparatus to examine the knee reflex.