What it shows and when it is prescribed
The study consists of two parts. Stimulation electroneurography evaluates the speed and amplitude of an impulse along a nerve: electrodes are placed on the skin, the nerve is stimulated with weak electrical impulses, and a machine measures the muscle response. Needle electromyography records electrical activity directly in the muscle using a thin needle electrode and shows whether the muscle is suffering due to nerve damage or on its own.
The main indications are numbness and tingling in the hands and feet, weakness in the limbs, muscle atrophy, pain along the nerve. The method objectively confirms carpal tunnel syndrome and other tunnel neuropathies, assesses the degree and prevalence of polyneuropathy in diabetes mellitus, distinguishes between radicular lesions due to disc herniation and peripheral neuropathy, helps in the diagnosis of myasthenia gravis and primary muscular diseases, and also assesses the degree of nerve damage after injury and the dynamics of its recovery.
The stimulation part feels like a series of short tingles, the needle part feels like a regular injection with some discomfort when the muscle is tense. No special preparation is required, but on the day of the test you should not apply creams to your skin and should refrain from drinking coffee. Be sure to tell your doctor if you are taking anticoagulants and if you have a pacemaker.
Why do you need a direction?
Formally, most studies can be completed independently, but the information content is noticeably higher when the doctor has indicated the expected diagnosis and area of interest. The diagnostic specialist knows what to pay special attention to and includes the necessary measurements in the protocol.
Without clinical context, the study becomes a bunch of numbers, some of which may look like anomalies without having any meaning for the individual patient.
Norm and deviation
Reference values reflect the performance of most healthy people, but not all. A slight deviation may be an individual characteristic, but a result within the normal range may be a significant change for someone who previously had different numbers.
Therefore, it makes sense to keep all the protocols and bring them for repeated studies: the dynamics tell the doctor much more than a single image or recording.