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Lumbar Endoscopic Discectomy for the Treatment of Back and Leg Pain: Short and Intermediate Term Results Utilizing the Inside-Out Transforaminal and Interlaminar Techniques 2014

Category Interventional George Rappard, MD
Purpose The Inside-out transforaminal and interlaminar endoscopic technique is a percutaneous method of performing lumbar discectomy. This paper reviews the short and intermediate term results of this procedure in a population of patients with discogenic back pain and radiculopathy. Materials & Methods 14 consecutive patients were treated in 2013 by a single operator (GR). Patients were considered candidates for surgery if they possessed disc herniations resulting in back or leg pain. Both contained and extruded herniations were treated. Migrated herniations were excluded from consideration of endoscopic discectomy. Intra-operative discography and elicitation of concordant findings was performed in all transforaminal cases. Pre-operative discography was performed in interlaminar cases if multi-level and adjacent disc abnormalities were noted on MRI. Discography of a normal MRI appearing disc was never performed. All procedures were performed in an ambulatory surgery center. Discectomy was performed either via a posterolateral transforaminal approach, utilizing the inside-out technique, or via an interlaminar approach. In the inside-out transforaminal approach, a 7mm cannula is inserted posterolateraly through the foramen and into the posterior disc. Intra-discal discectomy is carried out. The cannula is then withdrawn under endoscopic guidance and the ventrolateral epidural space and foramen is inspected. Additional removal of migrated or extruded disc is carried out. The transforaminal approach is performed under sedation. Intra-operative discography and elicitation of concordant findings was performed in all transforaminal cases. The skin incision is approximated with a single absorbable suture. In the interlaminar approach, an 8mm cannula is inserted via a paramedian interlaminar approach. Muscle dissection and a ligamentum flavum window is performed endoscopically. The cannula is endoscopically advanced into the posterior epidural space and the traversing nerve roots and thecal sac are retracted medially to expose the disc herniation. Discectomy is then carried out. The interlaminar approach is performed under general anesthesia. The skin incision is approximated with a single absorbable suture. After October 2013, the interlaminar approach was utilized on all posterior L5/S1 disc herniations. Whichever the interventional and surgical approach, all discectomies were followed by thermodiscoplasty. In thermodiscoplasty a bipolar radiofrequency probe is inserted into the disc and the posterior inner annular segment is cauterized, akin to a visualized IDET. All patients were discharged home the same day, within 2 hours of surgery. Patients were scheduled to return for follow up at 1 week, 2 months, 3 months, and at 6 months. The data recorded and presented is as of the last follow up date. At the pre-operative and each post-operative visit Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) data was obtained. ODI was measured via the use of a standardized questionnaire. VAS scores were measured by measuring the patient’s response to a linear 100mm scale. VAS scores were felt be significant if >30mm on the 100mm scale. Results The majority of the patients in this series, 11/14 (79%), suffered accident related injuries, resulting in post-traumatic lumbar disc herniation. The other 3 patients sustained work related or activity related injuries. The mean follow up period was 86 days. Follow up is available at 6 months in 2/14 patients, 3 months in 4/14 patients, 2 months in 1/14 patients and 1 month in 6/14 patients. Therefor, 3 month follow up was available in 6/14 (43%) of patients. In 6/14 patients (43%) back pain was the predominant presenting symptom, with little or no leg pain. In all other patients, leg and back pain were both significant. The mean Pre-operative ODI was 44%, consistent with severe disability with limitation of activities of daily living. At last follow up, ODI scores had decreased to a mean of 28%, consistent with moderate disability affecting social life. This was a 36% improvement. The mean pre-operative back pain VAS was 56. This reduced to a mean post-operative score of 21, representing a 63% improvement. The mean pre-operative leg pain VAS was 33. This reduced to a mean post-operative score of 13, representing a 61% improvement. 2/14 (14%) of patients had transient worsening of radicular leg pain following transforaminal discectomy, all resolving by the 12 week follow up. No one had worsening of their back pain during the follow up period. 3/14 (21%) of patients had significant (greater than 40/100) back or leg pain at follow up. 1 of these cases was noted to have symptomatic sacroiliac joint disease. The other 2 were suffering from multiple disc injuries and have not yet completed treatment at all injured levels. 1/14 (7%) suffered a transient motor deficit after surgery, resolving by the 4 week follow up. This was a previously injured nerve and was noted to be atrophic at surgery. There were no hemorrhagic complications, no infections and no CSF leaks. Conclusion Endoscopic lumbar discectomy, whether by the inside-out transforaminal approach or the interlaminar approach, is an effective and safe means to treat discogenic back pain or radiculopathy secondary to herniated disc. Not surprisingly, endoscopic discectomy was very effective in reducing radicular symptoms. Only 2/14 (14%) patients had persistent significant (>30mm on VAS score) symptoms at follow up and both of these had untreated post-traumatic herniations. This is in keeping with the generally reported results of open or micro-discectomy. Surprisingly, endoscopic discectomy proved to be very effective in the treatment of patients presenting with predominantly back complaints. 100% of these patients had their back pain reduced to below significant levels on follow up. The significant improvement in discogenic back pain was felt to be due to the addition of thermodiscoplasty as a means of ablating intra-annular innervation. References None