Percutaneous electrothermal treatment of the intervertebral disc annulus for low back pain and sciatica

Catheter breakage was reported in 19 patients (involving 20 tips which fractured and separated) in a case series of 1675 patients treated by Intradiscal Electrothermal Therapy (IDET). Two broken tips were retrieved using percutaneous methods, 1 was removed surgically, 16 were left in the disc and 1 was left in subcutaneous tissues. None of the cases were associated with any morbidity. A case report of 1 patient treated by IDET described paraesthesia and dysaethesia in the left leg, 6 months after a procedure in which 3 different catheters had to be used because of catheter breakage. On the third attempt, the tip of the catheter broke off inside the disc space and was not retrieved. When the patient reported dysaesthetic symptoms, the tip was surgically removed and the patient reported no symptoms 3 months after removal.

Transient radiculopathy, which lasted for less than 6 weeks, was reported in 11% (4 of 38) of patients in the IDET group and 5% (1 of 19) of patients in the sham procedure group in a randomised controlled trial of 57 patients.

Bladder dysfunction was reported in 1 patient in the case series of 1675 patients treated by IDET. During IDET the treating physician noted that the catheter was positioned in the extra‑discal space. No further details were provided.

Type 1 complex regional pain syndrome was reported at 3‑month follow‑up in a case report of 1 patient treated by Percutaneous Intradiscal Radiofrequency Thermocoagulation (PIRFT) of the annulus. The patient reported that their back pain decreased after receiving PIRFT but both feet became extremely painful and swollen. The patient was treated by medical therapy and a computer tomography‑guided lumbar sympathetic trunk block.

Increased axial back pain was reported in a case report of 1 patient treated by IDET. Magnetic resonance imaging at 3‑month follow‑up revealed diffuse 'marrow oedema' of the L2 vertebral body consistent with osteonecrosis; this resolved at 12‑month follow‑up.

In a systematic review of 17 studies that included patients treated by IDET, 11 studies (486 patients) reported the incidence of adverse events. Meta‑analysis revealed an adverse event rate of 0.8% (95% confidence interval 0.2% to 1.4%). Adverse events included:

• A burning sensation in the leg of 1 patient; this resolved.

• Paraesthesia and numbness in the thighs of 2 patients; both resolved.

• Foot drop in 1 patient; this resolved.

• Increasing lower leg pain in 1 patient; the patient was subsequently lost to follow‑up.

• Increasing back and thigh pain in 1 patient; this was treated by spinal fusion.

• Headache in 1 patient; this resolved.

• Increasing radicular pain in 5 patients; pain resolved in 4 patients, 1 patient needed surgery.

• Device failure in 1 patient due to scar tissue around the treatment site; the patient was treated by inter‑body fusion.

• Increasing low‑back pain in 1 patient; this was treated by spinal fusion.

• Nerve root injury in 1 patient; this resolved.

• Increased disc herniation in 2 patients; both were treated by spinal fusion.

• Decreased anal sphincter tone and faecal incontinence in 1 patient; this resolved.

• Non‑dermatomal leg pain in 2 patients; both resolved.

• Discitis in 1 patient; this was treated by spinal fusion.

• Anterolisthesis in 1 patient; this was treated by spinal fusion.

In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers listed the following anecdotal adverse events: catheter misplacement through the disc to the retroperitoneum and visceral/vascular injury. They considered that the following were theoretical adverse events: excessive bleeding, spinal instability and paralysis.