Plasma radio-frequency-based diskectomy for treatment of cervical herniated nucleus pulposus: feasibility, safety, and preliminary clinical results

Abstract

Background and purpose: Several techniques, including chymopapain, mechanical aspiration, laser-based disk decompression, and endoscopic keyhole surgery, have been proposed as minimally invasive alternatives to fusion for treating cervical disk herniation, though none has gained wide acceptance. The purpose of this study was to assess feasibility, safety, and preliminary clinical results of percutaneous plasma-mediated radio-frequency-based diskectomy for cervical disk herniation.

Methods: Patients (N = 55) with cervical soft disk protrusion were treated over a 29-month period. They had radicular pain; 3 patients also had moderate myelopathy. The procedure was performed with the Perc-DC SpineWand by using an anterior approach. Most cases were conducted with local anesthetic on an outpatient basis. Clinical outcomes were graded by using the Macnab criteria.

Results: At 2 months, outcomes were good or excellent in 44/55 (80%) patients; the success rate was similar at 6 months, when 44 (85%) patients (n = 52/55) had good or excellent results. One clinically relevant complication (infectious diskitis) occurred within the first month postprocedure and was successfully treated. One technical complication (in situ rupture of the device tip) was observed; however, the patient remained asymptomatic during the 2-year follow-up. The 3 patients with clinical myelopathy experienced regression of cord compression symptoms; MR imaging in 2 patients showed morphologic evidence of reduction of cord compression.

Conclusions: Plasma radio-frequency-based diskectomy in the cervical spine appears to be a minimally invasive low-risk approach, which is easy to perform, associated with only minimal discomfort to the patient, and effective in the short term.

Fig 1.

A, The 19-gauge cannula with an internal mandrel is positioned against the anterior surface of the annulus fibrosus. The cannula is held by a surgical forceps to minimize x-ray exposure of the surgeon’s hand. B, Cannula placement as observed under fluoroscopy. C and D, The cannula is advanced into the disk, and the SpineWand device (D, arrow) is introduced into the nucleus pulposus via the cannula. E, The device is activated and then rotated 360°(E) to create a spheric void by means of the loop-shaped active electrode (arrow). Between 2 and 4 voids are ablated in a linear direction to create a channel. F, After the first channel into the disk is completed, the device is repositioned to a different part of the nucleus, with the placement depending on the topography of the herniation. For left-sided herniations, the first channel is made in an oblique direction, from the right anterolateral entry point toward the left posterolateral herniation; the other channel is made on the midline and directed toward the posterior profile of the disk. For a right-sided lesion, the first channel is directed obliquely toward the center of the disk; the second channel is directed toward the right paramedian, along the medial surface of the uncal process to reach the herniation in the posterior aspect of the disk. G, A schematic drawing shows the entry route, with the clinician’s fingers pushing the trachea across the midline while protecting the neurovascular bundle.

Fig 2.

A, MR imaging at baseline for a 34-year-old woman who underwent percutaneous plasma radio-frequency–based diskectomy for a disk (C6–7) herniation compressing the spinal cord and causing clinical signs of myelopathy. B, A 7-week MR imaging follow-up shows regression of both herniation and cord compression; the patient is almost asymptomatic. C, An MR image at 9-month follow-up shows almost complete regression of the disk herniation; the patient is completely asymptomatic.

Fig 3.

A, Bilateral disk herniation at C6–7 encroaching the spinal canal. The SpineWand device was placed into position by using CT-guidance and switching to direct fluoroscopy for the disk ablation procedure. This allowed activation of the plasma-field energy directly inside the herniation. B and C, The loop-shaped active electrode was inserted beyond the posterior limit of the vertebral body into the spinal canal. D, At the end of the procedure, the gas generated from the tissue excision is evident inside the disk. E, The 5-month follow-up image shows only minimal or questionable reduction of disk size; despite this, the patient reports good clinical improvement (Macnab 3) (see text for discussion).

Fig 4.

A, Lateral disk herniation compressing the nerve root. B, The cannula and SpineWand device are positioned under CT guidance and then safely and precisely directed toward the herniation. C, Note gas from tissue excision diffusing inside the herniation itself. D, A 4-month CT follow-up shows partial regression of the lesion; the patient reports a definite clinical improvement (Macnab 3).

Fig 5.

A and B, The C6–7 disk before undergoing the ablation procedure because of a mostly lateral left intraforaminal herniation (A) with the associated mild central protrusion shown in a sagittal MR image (B). C and D, MR imaging follow-up at 2 months shows hypo-T1, hyper-T2 modifications of the adjacent vertebral bodies and evidence of an inflammatory condition. E, Partial reduction of the herniation is observed at the 2-month follow-up. The patient is completely asymptomatic despite only partial reduction of the disk herniation (see text for discussion).