Literature References Supporting the Technique ENDOSCOPIC LASER FORAMINOPLASTY LITERATURE J Neurosurg Spine. 2003 Oct;99(3):320-3. Posterolateral percutaneous endoscopic lumbar foraminotomy for L5-S1 foraminal or lateral exit zone stenosis. Technical note. Ahn Y, Lee SH, Park WM, Lee HY. Division of Neurosurgery, Wooridul Spine Hospital, Seoul, Korea. ns-ay@hanmail.net The purpose of this study was to determine the efficacy and feasibility of posterolateral percutaneous endoscopic lumbar foraminotomy (PELF) for foraminal or lateral exit zone stenosis of the L5-S1 level in the awake patient. Twelve consecutive patients with L5-S1 foraminal stenosis and associated leg pain underwent PELF between May 2001 and July 2002. Under fluoroscopic guidance, posterolateral endoscopic foraminal decompression was performed using a bone reamer, endoscopic forceps, and a laser. Using this new technique, the authors removed part of the hypertrophied superior facet, thickened ligamentum flavum, and protruded disc compressing the exiting (L-5) nerve root. Clinical outcome was measured using the Macnab criteria. The mean follow-up period was 12.9 months. All the patients were discharged within 24 hours. Satisfactory (excellent or good) results were demonstrated in 10 patients. There was no complication. The PELF procedure provides a simple alternative for treating lumbar foraminal or lateral exit zone stenosis in selected cases. The authors found that the posterolateral endoscopic approach to the L5-S1 foramen was usually possible and that using a bone reamer to undercut the superior facet was effective. Surg Technol Int. 2003;11:255-63. Advances in endoscopic disc and spine surgery: foraminal approach. Yeung AT, Yeung CA. Arizona Institute for Minimally Invasive Spine Care, Phoenix, Arizona, USA. Endoscopic spine surgery is evolving rapidly due to improvements in surgical technique, endoscope design, and instrumentation. The current technique expands on the basic features and principles of Kambin's access to the spine through the triangular zone. A standardized method for foraminal surgery, the Yeung Endoscopic Spine System (YESS) (Richard Wolf Surgical Instrument Company, Vernon Hills, Illinois, USA) technique is proposed: (1) A protocol for optimal instrument placement by identifying the skin window, annular window, anatomic disc center, and disc inclination plane through topographical coordinates calculated by lines drawn on the skin from the C-Arm image. Adjustments in the trajectory are made to accommodate individual anatomic considerations and the pathologic disorders to be accessed. (2) Evocative Chromo-Discography (Richard Wolf Surgical Instrument Company, Vernon Hills, Illinois, USA). (3) Selective Endoscopic Discectomy (Richard Wolf Surgical Instrument Company, Vernon Hills, Illinois, USA). (4) Thermal discoplasty and annuloplasty. (5) Endoscopic foraminoplasty. (6) Accessing the epidural space in the axilla between the traversing and exiting nerve root. (7) Partially resecting the posterior annulus to get beneath the herniated fragment, if needed. This technique allows access to the epidural space from the lumbar disc as far cephalad as the middle of the vertebral body or approximately 2-3 mm caudally. The foraminal approach is routinely accessible from T-10 to L4-5. L5-S1 can be accessed with special techniques that include foraminoplasty of the lateral facet. Surgical results continue to improve, consistent with refinement of indications and techniques for specific conditions treatable by this endoscopic method. J Clin Laser Med Surg. 2001 Jun;19(3):147-57. Review of safety in endoscopic laser foraminoplasty for the management of back pain. Knight MT, Ellison DR, Goswami A, Hillier VF. The Spinal Foundation, Arbury Consulting Centre, Rochdale, United Kingdom. OBJECTIVE: The purpose of this study was to analyze the incidence and gravity of reported complications that arise in spinal surgery and assess the comparative safety, or otherwise, of endoscopic laser foraminoplasty (ELF). BACKGROUND DATA: Chemonucleolysis, decompression, discectomy, and fusion have long been cited as treatments for chronic low back pain. Over recent years newer, less invasive surgical techniques have become available, one such being ELF. Although minimally invasive, the beneficial outcome must be interpreted in relation to concerns regarding the safety of the procedure and its risks relative to those of other forms of spinal surgery. The Spinal Foundation, Rochdale has performed 958 ELFs and has collated a comprehensive database of the results of all these operations. These prospective records provided the basis for a comparison of the safety of ELF to that reported with other spinal surgical techniques. METHODS: A total of 958 procedures have been performed on 716 patients. Complications that arose during the operation and the postoperative phase of 6 weeks following the procedure were elicited from patient records. These data were correlated and compared to a meta-analysis of randomized controlled clinical trial data of complications arising during and after conventional spinal surgery. The SPSS (statistical package for social sciences) and CIA (confidence interval analysis) statistical packages were used to draw conclusions regarding the safety of ELF. RESULTS: The cohort integrity of operation and outpatient review records at 6 weeks after surgery was 100%. In 958 ELFs performed, 24 complications occurred in 23 patients. There were 9 cases of discitis (1 infective, 8 aseptic) (0.9%), 1 dural tear (0.1%), 1 deep wound infection (0.1%), 2 patients suffered a foot drop (1 transient) (0.2%), 1 myocardial infarction (0.1%), 1 erectile dysfunction (0.1%), and 1 patient who developed panic attacks post-operatively (0.1%). This amounts to an overall surgical complication rate of 1.6%. Magnetic resonance imaging (MRI) follow up of clinically symptomatic patients highlighted 8 residual disc herniations (0.8%). Meta-analysis of randomized controlled trials of conventional spinal surgery for adult onset degenerative disc disease and/or sciatic pain reported overall complication rates for fusion (11.8%), decompression (7.6%), discectomy (6.0%), and chemonucleolysis (9.6%). CONCLUSIONS: The complication rate of ELF is shown to be significantly lower than that reported following conventional spinal surgery (p < 0.01). From these results, we conclude that ELF as a treatment for chronic low back pain and sciatica presents less risk to a patient than conventional methods of spinal surgery. J Clin Laser Med Surg. 2001 Apr;19(2):73-81. Endoscopic foraminoplasty: a prospective study on 250 consecutive patients with independent evaluation. Knight MT, Goswami A, Patko JT, Buxton N. Spinal Foundation, Arbury Consulting Centre, Manchester Road, Rochdale, UK. mknight@spinal-foundation.org OBJECTIVE: This study focused on the efficacy of endoscopic decompression of the foramen guided by endoscopic aware-state pain source definition. BACKGROUND DATA: Endoscopic foraminoplasty consists of undercutting of the facet joint and endoscopic discectomy, mobilization and neurolysis of the exiting and transiting nerves, and ablation of osteophytes. This study sought the outcome of endoscopic foraminoplasty in 250 consecutive patients followed for a minimum of 2 years, reviewed and assessed by an external independent assessor. It was applied to patients with back pain and sciatica in multilevel degenerative disc disease and also to those with prior surgery. METHODS: A prospective study of endoscopic laser foraminoplasty was performed on 121 males and 129 females with an average age of 48 years (21-86 years), followed for an average period of 30 months (26-43 months). The average preoperative duration of back, buttock, or leg pain was 6.1 years (5-11 years). A total of 30% had undergone prior open spinal surgery. RESULTS: The cohort integrity at follow up was 97%. Outcome was analyzed using the percentage change in Oswestry Disability Scores and visual analogue pain scores. Clinically relevant change in pain and disability was observed in 73%. Using a percentage change in Oswestry Disability Score of 50 or more to determine good and excellent outcomes, 60% of patients exceeded this score. A total of 95% patients required no further surgical intervention. CONCLUSIONS: Endoscopic laser foraminoplasty provides a minimalist means of exploring the extraforaminal zone, the foramen, the disc, and the epidural space and performing discectomy, lateral recess decompression, osteophytectomy, and neural mobilization. Performed in the aware state, it serves to identify and localize precisely the causal source of pain in multilevel disc disease, in revision surgery, and in the infirm and elderly without open fusion or decompression. Acta Orthop Scand. 2004 Oct;75(5):610-7. Laser-induced thermal stress and the heat shock response in neural cells. Emohare O, Hafez MI, Sandison A, Coombs RR, McCarthy ID. Imperial College, Faculty of Medicine, London. BACKGROUND: The Ho: YAG laser is used extensively in orthopedic surgery. It offers a minimally invasive method of ablating tissue with precision. Previous studies have explored the effects of laser use on temperature during experimental foraminoplasty. To date, there has been limited work on the effects of thermal stress on cells in this context.Material and methods Cells were exposed either to heated medium or the Ho: YAG laser in the high-power mode. Heated medium was used as a stressor by (I) exposing groups of cells to a constant temperature of 45 degrees C for varying lengths of time: 5, 10, 15 and 20 min, and (II) exposing cells for a fixed length of time (5 min) to varying temperatures: 45 degrees C, 55 degrees C, 65 degrees C with a control treated at 37 degrees C. A third group was subjected to direct laser treatment. The effects of the treatments were assessed using trypan blue staining as a measure of viability and immunocytochemistry was used to measure changes in heat shock protein (HSP) expression. RESULTS: There was a negative correlation between cell viability and HSP expression, and between cell viability and the severity of the treatment. INTERPRETATION: Our findings suggest a possible role for the Ho: YAG laser in spinal foraminoplasty based on the high level of cell viability in the treatment regimen that most closely mirrored the clinical application of the laser. J Clin Laser Med Surg. 2002 Oct;20(5):251-5. Ablation of bone, cartilage, and facet joint capsule using Ho:YAG laser. Hafez MI, Coombs RR, Zhou S, McCarthy ID. Department of Musculoskeletal Surgery, Division of Surgery, Anaesthesia and Intensive Care, Imperial College School of Medicine, Charing Cross Hospital, London, United Kingdom. OBJECTIVE: The objective of this study was to determine of the efficiency of holmium:YAG laser for bone ablation, compared to cartilage and soft tissue of the intervertebral foramen of the lumbosacral spine. BACKGROUND DATA: The holmium:YAG (Ho:YAG) laser has been used for ablation of bulging or prolapsed discs and also has the potential for decompression of the nerve root when there is narrowing of the foraminae (foraminoplasty). It is proposed that laser ablation of bone and ligament of the intervertebral foramen for nerve root decompression using the Ho:YAG laser is able to produce sufficient bone ablation without inducing significant thermal necrosis in surrounding tissues due to its short absorption length, which could result in significant clinical advantages. MATERIALS AND METHODS: Experiments were performed on samples of laminar bone, facet joint capsule, and cartilage for quantitative and qualitative determination of the effect of Ho:YAG ablation on tissue mass loss using a range of pulse energies from 0.5 to 1.5 J/P at 15 pulses/sec. RESULTS: The results showed a significant linear correlation between the mass loss and pulse energy, and between the mass loss and radiant exposure. Electron microscopy and histology showed that the Ho:YAG ablation resulted in a very sharp and clear border with little charring. Applying 0.01 k.J of total energy at two different settings (1.5 J/p, high power, and 0.5 J/p, low power) at 15 pulses/sec, the cross-sectional area/mm(2) of the ablated bone was measured, using light microscopy and the Scion Image analysis program. The ablated areas were 2.28 +/- 0.87 and 1.16 +/- 0.43 mm(2) at high and low power, respectively (p = 0.008). Lasers Surg Med. 2001;29(1):33-7. The effect of irrigation on peak temperatures in nerve root, dura, and intervertebral disc during laser-assisted foraminoplasty. Hafez MI, Zhou S, Coombs RR, McCarthy ID. Department of Orthopaedic and Trauma Surgery, Imperial College School of Medicine, Charing Cross Campus, Fulham Palace Road, London W6 8RF. m.hafez@ic.ac.uk BACKGROUND AND OBJECTIVE: The Holmium: YAG (Ho: YAG) laser has been used for the ablation of prolapsed discs but alternative techniques are available, and this application remains controversial. It also has potential for the decompression of nerve roots within narrowed foraminae with the technique of endoscopic laser foraminoplasty. Traditional methods of decompression necessitate a major surgical procedure with potential destabilisation of the lumbar spinal segment. Nevertheless, minimally invasive techniques are attractive only if serious complications can be avoided. This study reports the peak temperatures reached in surrounding tissues with and without saline irrigation. STUDY DESIGN/MATERIALS AND METHODS: Investigation of the hypothesis was carried out in excised sheep lumbar spines. T-type thermocouples were used for the measurement of tissue temperatures during laser ablation of nerve root foraminae. The temperature was assessed in the nerve root, dura mater, and disc space. RESULTS: The Ho: YAG laser was effective in widening the foraminae by approximately 1.5 mm with a total energy of 4.60 kJ. This was statistically significant in both vertical and horizontal directions (P < 0.0003 and P < 0.00005, respectively). The mean temperature of the nerve root, dura, and disc space during the procedure was 44 +/- 3.1 degrees C, 42.8 +/- 4.7 degrees C, and 41 +/- 3.4 degrees C respectively. There were transient high peaks seen in the temperature profiles. Using saline irrigation at 27 ml/minutes these temperatures were reduced to 34.1 +/- 1.8 degrees C (P = 0.0002), 34.9 +/- 1.5 degrees C (P = 0.002), and 37.2 +/- 1.2 degrees C (P < 0.014), for nerve roots, dura, and disc space respectively. CONCLUSIONS: Laser ablation of bone and ligament for nerve root decompression using the Ho: YAG laser may offer substantial advantages, but the risk of serious complication may only be avoided if the technique is combined with saline irrigation.