Current treatment
Patients with chronic low back pain are usually initially offered conservative treatment [1;7]. This predominantly consists of painkillers, manual treatment (physiotherapy, massage, chiropractic, etc.), exercise therapy and back schools.

If the pain is permanent and disabling despite this treatment, a radiological examination will normally be carried out using conventional radiography, CT scanning and/or MR imaging.

At present, no invasive treatment is available in Denmark that is routinely initiated if conservative treatment of discogenic pain proves ineffective. (A new invasive treatment form for this patient group – the discus prosthesis – should be mentioned, but is not otherwise considered in this Health Technology Alert).

New treatment
Intradiscal electrothermal therapy (IDET) is a minimally invasive surgical procedure for the treatment of intact or slightly degenerated painful discs. The indications for the procedure have not yet been clarified. According to the literature, IDET has been offered to patients with chronic low back pain who are unresponsive to conservative treatment of at least six months duration.

The disc may only be slightly degenerated without any sign of nerve root compression, i.e. without causing pain upon lifting of a stretched leg, or other signs of nerve root compression. Prior to the procedure, discography of the affected disc is performed to provoke the pain [5;8]. Pain-provoking discography is rarely used in Denmark to identify painful discs. This is because the diagnostic value of the method is open to discussion [9–11].

With IDET, the fissured part of the disc is heated in a controlled manner under local anaesthesia. Under fluoroscopic guidance a flexible hook-shaped catheter containing a heating coil is inserted in the outer edge of the annulus fibrosus, whereafter it is heated electrically to approx. 90°C for approx. 17 minutes. The hypothesis is that the heating is completely local and should cause coagulation of the collagen tissue and destruction of the nerve endings [4;5], thereby reducing the pain. There is some uncertainty about this hypotheses, however, as mentioned below in the section on evidence [12;13].

At present there are at least three percutaneous systems for electrocoagulation and/or decompression of discs: Radionics RF Disc Catheter System® from Radionics, ArthroCare System 2000® from ArthroCare and SpineCATH® from Smith & Nephew [14;15]. The first two employ a straight catheter and are used to coagulate the nucleus of the disc (nucleoplasty). Other methods for heating discs also exist, for example ultrasound or short-wave radiation.

This Health Technology Alert solely concerns the most widespread system, SpineCATH®, for coagulation of the annulus fibrosus (annuloplasty).

The intervention can be performed on an out-patient basis, but is followed by a 6 to 8-week period of mild rehabilitation and restriction of physical strains such as sitting activities, work and motoring, among other means through the use of a back support. Greater strains must be avoided for approximately six months [16].

Use in Denmark
IDET is not yet in use in Denmark. SpineCATH® and the associated equipment bear the CE-mark, though, and can thus be marketed throughout Europe. SpineCATH® will most likely be marketed in Denmark within the immediate future [17].