Abstract

The classical microsurgical approach in the treatment of herniated nucleus polposus (HNP) has been substituted over the years both by endoscopic approach in which it is possible to practice via endoscopy a laser thermo-discoplasty, both by percutaneous laser disc decompression and nucleotomy. Percutaneous laser disc decompression and nucleotomy have been done worldwide in more than 60000 cases of HNP. Because water is the major component of the intervertebral disc, and in HNP pain is caused by disc protrusion pressing against the nerve root, a 980 nm Diode (Biolitec AG –Germany) laser introduced via a 21G needle under X-ray or CT-scan guidance and local anesthesia, vaporizes a small amount of nucleous polposus with a disc shrinkage and a relief of pressure on nerve root. Most patients get off the table pain free and are back to work in 5 to 7 days. Nine hundred patients suffering for relevant symptoms therapy-resistant 6 months on average before consulting our department, have been treated. Five hundred-eighty five (65%) males and three hundred-fifteen (35%) females had a percutaneous laser disc decompression and nucleotomy. The average age of patients operated was 46 years (18 – 60). In 62 cases the procedure has been performed after an unsuccessful conventional surgical approach with a relapse of the disc herniation. Results: The sucess rate at a mean follow-up of 48 months was 85% with a complication rate of 0.5%.

Introduction

Several treatments over the years have been performed in disc herniation. At the moment, the gold standards, in order to reduce the complications seem to be all the miniinvasive techniques, permitting not only the best solution for the patient, but also a fast , sure and effective postoperative recovery time. The percutaneous laser disc decompression and nucleotomy is based on a reduction of volume in a closed hydraulic space, resulting in a great fall of pressure. Because water is the major component of the intervertebral disc, and in disc herniation pain is caused by the disc protrusion pressing against the nerve root, by vaporizing and shrinking the nucleus polposus, the result is an immediate decompression on the nerve root (1).

Since the first application (2), several types (Nd:YAG 1064nm, 1320nm; KTP 532nm; CO2 10.6?m; Ho:YAG 2100nm, Diode 940nm, 810nm) of lasers over the years have been employed.

The Authors believe that 980nm is the optimal wavelength for laser disc decompression and nucleotomy, because 980nm is 10 times more absorbent than 810nm and 5 times more absorbent than 1064nm, requiring less laser energy; this implies less heat diffusion in surrounding tissues and no undesirable side effects.

Materials And Methods

Results

A retrospective evaluation at an average follow-up of 48 months has been performed, after performing MRI or CT scan at 12 weeks, VAS (Visual Analogue Scale) and by applying the Macnab's criteria (Table 1) on a total of 900 patients.

The Excellent/Good results according to Macnab were 70%, the Fair results were 16%, and the Poor results were 14%. The VAS decreased from a preoperative 8.5 to a postoperative 2.3. MRI or CT scan showed a disc herniation reduction at 12 weeks in only 70% of Excellent/Good results, because a disc shrinkage of less than 1.5 – 2 ml has not MRI or CT scan detectable (5,6). (Figg.2 – 4). No significant difference in outcome (p < 0.05) related to sex, age, disc level, previous microdiscectomy, and symptoms duration was found. A statistically significant difference (p > 0.05) was found in non contained discs' results in the cases performed under CT-Scan Guidance, with a success rate of 86.5%. The cases performed under C-arm had a successful rate of 67%. Fair and Poor results correlate (p > 0.05) with non contained disc herniation (transannular extrusion), with microsurgery performed after 1-3 months in 40% of cases treated under C-arm.

In 65% of Excellent/Good results there was an immediate pain relief with a normal straight leg raising (SLR), in 19% after 72 hours and in 16% after 3-7 days; neurological signs improvement (motor weakness and reflex depression) was recorded by 1 month in 58% of cases, 3 months in 32% and 3-6 months in 10% of cases.

Discussion

Percutaneous Laser Disc Decompression and Nucleotomy has been performed at moment worlwide on more than 60000 patients. The more used lasers were KTP 532nm, Ho:YAG 2100nm, Nd: YAG 1064nm. Their combined success rate (excellent/good to fair) according to Macnab and Oswestry score were more than 80%, with a complication rate of less than 1.5%(7,8,9). In order to obtain a good result it is very important not only a proper selection of the patients, but also a good choice of the laser used.

With regard the use of the Diode 980nm, we believe to be the best and more advanced laser in the treatment of disc herniation, related to the optimal water absorption. Because 980nm is 10 times more absorbent than 810nm and 5 times more absorbent than 1064nm, requiring less laser energy; this implies less heat diffusion in surrounding tissues and no undesirable side effects. A first introduction of Diode 940nm in disc herniation treatment has been performed in 1998 by Hellinger (10) in a prospective randomized study versus Nd: YAG 1064nm. The overall success rate (90%) confirm the proper use of Diode in order to decompress the nerve root by disc herniation. Nakai (11) also confirmed in an experimental study with a Diode 810nm, that Diode is less aggressive in the surrounding tissue, preserving the end plate and the vertebral body from any damage. No secondary changes on the intervertebral disc and adiacent vertebral body after Diode laser disc irradiation were detected.

Experimental studies performed both on human and specimen lumbar discs using the Biolitec-AG Diode laser 980nm showed an absorption of laser light of 90.27% in the disc and a retraction of about 55% (+/- 1.7) On 2.7mmq of the tissue after laser treatment (12).

For these reasons the Authors believed using the specially designed and optimised Diode 980nm Laser (Biolitec-AG Diode laser 980nm) in the treatment of disc herniation, confirming the overall success rate of the literature (7,8,9,13,14), without any complications related to heat diffusion in surrounding tissues (aseptic discitis and spondilytis, bladder injuries, vascular injuries to the abdominal cavity, abdomen injuries).

Conclusion

In conclusion the procedure appear to be nowdays a safe and valid alternative to the microsurgery, particularly under CT-Scan guidance, in order to visualize the nerve root and also apply energy on several points of disc herniation. This permits to have a shrinking concentrated in a bigger area, realizing a minimal invasiveness on the spine to be treated, and avoiding the potential complications related to the microdiscectomy (recurrence rate of more than 8-15%, peridural scar in more than 6-10%, dural sac tear, bleeding, iatrogenic microinstability), and does not preclude microsurgery, if needed.

Figure 1a:Diode 980nm laser (Bioliteck AG)

Figure 1b: disposable 360µm Silica Fiber Optic

Figure 1e: C-ARM guidance, LL view

Figure 1f: C-ARM guidance AP view

Figure 1g: CT view of foraminal disc erniation

Figure 1h: CT guidance view

Figure 1i: CT-Scan Guidance and 3D Reconstruction

Figure 2a: 27yrs female L5-S1 HNP

Figure 2b: after laser 980nm

Table 1: Macnab's criteria

- Excellent/Good : Resumed preop function, occasional backache, no objective signs of nerve root involvement

- Fair: Intermittent episodes of mild lumbar pain and/or low back pain, no objective signs of nerve root involvement

- Poor: Subjiective: no productivity, continued pain, inactive, objective signs of nerve root involvement

Correspondence to

Pier Paolo M. Menchetti, M.D., F.R.C.S. (US) Villa Cherubini Clinic, Via Cherubini, 8 – 50132 Florence – Italy Fax : +39 055 2347266; e-mail: ppm.menchetti@libero.it

References