Electrodiagnosis of radiculopathy

While nerve conduction studies are an important part of the electrodiagnostic examination (EDX), the diagnosis of a radiculopathy rests mainly on the needle electrode examination (NEE) findings. Myotomal spontaneous activity and neurogenic motor unit potential (MUP) changes are the key abnormalities seen. To optimize the rate of identifying a radiculopathy, selection of appropriate muscles for the NEE is paramount. Myotomal charts derived from anatomic, radiographic, and EDX studies may help guide development of the NEE protocol for radiculopathy and increase the diagnostic yield. As recommended by a number of studies, the suggested minimum NEE protocol should consist of at least five proximal and distal limb muscles. NEE of paraspinal muscles should also be included routinely, but several limitations preclude reliance on isolated findings for establishing a diagnosis of radiculopathy. In addition to the NEE, the preservation of sensory nerve action potentials is also important in localizing the lesion to the nerve root. In some cases, they may be absent due to age or technical factors, confounding the diagnosis. Finally, various patterns of EDX findings may be seen in specific nerve root disorders that can help expedite diagnosis and clinical management.