Medical tests that include nerve conduction studies, needle electromyography, and neuromuscular junction testing for diagnosing motor neuron diseases, myopathies, radiculopathies, plexopathies, neuropathies, and neuromuscular junction disorders (e.g., myasthenia gravis and myasthenic syndrome). EDX studies are used to evaluate tumors involving an extremity, the spinal cord, or the peripheral nervous system.