Radiofrequency ablation is well suited to small neural targets that can be identified by radiologic (x-ray, computed tomography scan, ultrasound, etc.) and/or functional (electrical stimulation) means. Such targets include sympathetic and dorsal root ganglia, the gasserian ganglion, and medial branches of the posterior primary rami of spinal nerves (for zygapophyseal joint denervation). Larger peripheral nerves are often not considered candidates for ablation, as the resulting sensory and motor dysfunction could disable the patient. Radiofrequency thermal lesions are produced by exciting ions within a field of alternating electric current at 500,000 Hz.