3 The procedure
3.1 Percutaneous electrothermal treatment aims to relieve back pain and sciatica by applying thermal energy to the annulus of a damaged intervertebral disc in order to stiffen the annulus and disrupt nerve endings within it. Thermal treatment of the annulus can be performed using a variety of techniques which use radiofrequency energy. These include Intradiscal Electrothermal Therapy (IDET), biacuplasty, and Percutaneous Intradiscal Radiofrequency Thermocoagulation (PIRFT). PIRFT can be used to treat the intervertebral disc annulus and/or the disc nucleus. This guidance considers only thermal treatment of the annulus.
3.2 Percutaneous electrothermal treatment is usually done with the patient under sedation and using local anaesthesia. The damaged disc is identified by lumbar discography. If the patient feels pain when contrast is injected into the disc (provocative discography), this is usually taken as evidence that the disc is symptomatic. Under fluoroscopic guidance, 1 or 2 introducer needles are inserted into the disc. If 1 introducer needle is used, a monopolar electrode or catheter is then passed into the disc and positioned next to its posterior wall. If 2 introducer needles are used, bipolar electrodes are inserted through each introducer into contralateral sides of the disc. Once in position, electrodes heat the annulus for 2–15 minutes, depending on the technique being used. The aim is to contract collagen fibres and promote closure of any tears and cracks. In addition, treatment may destroy nociceptive pain fibres.