Application Of Electromyography (EMG) Together With A Nerve Conduction Study(NCS)
EMG helps to identify the reason when one has signs and symptoms such as muscle weakness, tingling, involuntary muscle twitching, numbness, certain types of limb pain, muscles’ pain and cramping, or other abnormal sensations that points out a nerve or muscle disorder and determine the presence-duration of the problem. As the EMG may be done with a nerve conduction study (NCS) in the case of some purely primary myopathic conditions or without an NCS, both tests are usually performed together to differentiate if one has a muscle or a nerve disorder. Spinal nerve injury does not cause neck, mid or low back pain, and for this reason, evidence has not shown EMG or NCS to be helpful in diagnosing causes of axial lumbar pain, thoracic pain, or cervical spine pain.
Hence, EMG discovers nerve compression or injury, nerve root injury and other problems of the muscles or nerves in both adults and children. A normal muscle at rest does not emit any detectable electric current, but in motion, the abnormal muscle emits electric impulses. In other words, an EMG can detect problems with muscles during rest or action. The electric impulses can be amplified and analysed through the sonic and oscilloscopic patterns they create that are different and helps to distinguish simple atrophy of disuse from the denervation that may be associated with it.
EMG serves much the same function as myelography with comparable accuracy and with greater safety and simplicity. Depending on the symptoms and a doctor's examination, he or she might use EMG to test one muscle or several to detect the disorder. EMG and NCS results have a variety of clinical and biomedical applications. Both can aid in ruling out or diagnose a variety of conditions that helps the doctor to determine the underlying cause of these symptoms. These two are used to monitor specific conditions like progressive muscular disorders such as Muscular dystrophy and Polymyositis, neuromuscular disorders such as Myasthenia gravis, Lambert-Eaton syndrome and Guillain-Barré syndrome, motor neurons’ disorder such as Amyotrophic Lateral Sclerosis (ALS), peripheral nerve disorders such as Peripheral neuropathy and Carpal tunnel syndrome, nerve root disorders such as Sciatica, Radiculopathy and Herniated disc. For example, one of the applications of EMG is entrapment neuropathy. In most of the common entrapments like Carpal tunnel syndrome and Peroneal nerve lesions at the fibular head, NCS is usually-used principal diagnostic technique.
However, not all entrapments are manageable to diagnose using NCS and thus an EMG must be performed to identify the specific distribution of abnormality. The Carpal tunnel syndrome can be distinguished by EMG of the pronator teres, finger and wrist flexors, and abductor pollicis brevis. As for the Peroneal nerve lesions, EMG is the best technique to distinguish sciatic lesions from S1 lesions by displaying in the latter EMG signs of denervation in the muscles innervated by the superior and inferior gluteal nerves. Next, brachial plexus lesions. EMG can illustrate the upper limb muscles in order to discover the distribution of denervation changes and identify whether they accord to the root, cord, trunk, and nerve innervation to supply the localisation of brachial plexus lesions. As the same principles are employed in clinical examination, EMG has its own specialty of displaying the abnormality in clinically unaffected muscles.
