Physiatrists offer a broad spectrum of medical services. They do not perform surgery. Some perform procedural pain techniques such as joint/tendon injections and acupuncture and all get training in electrodiagnostic studies (studies of nerves). Some physiatrists have sub-specialty training in other advanced procedural techniques like trigger point injection (TPI), epidural steroid injection (ESI), facet injection, intradiscal electrothermal techniques (IDET), spinoscopy and other diagnostic and therapeutic blockades. A physiatrist may prescribe drugs or assistive devices such as bracing or artificial limbs. They may utilize therapies such as thermal, electrotherapies, massage, acupuncture, biofeedback, manual medicine and often therapeutic exercise.