Percutaneous Transforaminal Endoscopic Discectomy

Background: Percutaneous transforaminal endoscopic discectomy (PTED) is a minimally invasive technique for the treatment of symptomatic lumbar disc herniation (LDH) that is growing in popularity. The procedure involves the insertion of a transforaminal spinal endoscope for direct access and removal of intra and extra-foraminal disc fragments 1 . Description: The patient is preferably placed in a prone position. A spinal needle is advanced under fluoroscopic guidance into the foramen to the medial border of the inferior pedicle. A guidewire is introduced through the needle cannula, and sequential dilators are advanced into the foramen. A partial facetectomy/foraminotomy is performed so that a 10-mm working cannula and spinal endoscope can be introduced. Endoscopic pituitary rongeurs are utilized to remove the extruded disc material. Once the extruded fragments are no longer visualized, a probe is utilized to verify that no remaining disc material is present, and a diagnostic endoscopy is performed. The cannula is removed, and the incision is closed in a standard fashion. Alternatives: Nonoperative alternatives to PTED include activity modification, nonsteroidal anti-inflammatory drugs and/or acetaminophen, physical therapy, and epidural steroid injections 2 . When surgical intervention is indicated, alternative techniques for decompression include conventional microdiscectomy, tubular microdiscectomy, and unilateral biportal endoscopic discectomy 3 , as well as lumbar fusion techniques. Rationale: PTED shares similar indications as open and tubular discectomy, including soft LDH confirmed on imaging, persistent radiculopathy, new sensory/motor neurologic deficits, and failed nonoperative treatment of >6 weeks 1 . Compared with open and tubular discectomy, PTED offers several advantages, including a smaller skin incision, feasibility under local anesthesia, direct visualization, avoidance of muscle retraction, minimal bone removal and neural manipulation, preservation of spine stability and adjacent anatomy, decreased intraoperative blood loss, and shorter operative times 4–11 . In patients with a far lateral or foraminal LDH, PTED may avoid the need for fusion 12 . Considerations for PTED include the narrow working corridor, representing a risk of iatrogenic injury or incomplete decompression, and the associated learning curve 13,14 . Relative contraindications include recurrent LDH, paracentral LDH, extruded LDH, sequestration of the disc, significant obesity, isthmic spondylolisthesis, and severe canal stenosis 11 . Additionally, accessing the lower lumbar levels via a transforaminal approach may be difficult in patients with a high iliac crest. Expected Outcomes: PTED is a safe procedure that has been shown to improve patient-reported outcomes and functional status. In a recent meta-analysis, Gadjradj et al. reported a pooled complication rate of 4.6% (range, 0% to 8.6%) for PTED 8 . Hoogland et al. reported 85% excellent/good satisfaction in patients who underwent PTED, compared with 8% poor satisfaction, as well as improvements in visual analogue scale back and leg pain scores of 6.0 and 5.6, respectively, at 2-year follow-up. Chen et al. found that PTED resulted in similar patient-reported outcomes with similar rates of complications, recurrence, and reoperation and shorter in-bed times and lengths of stay compared with open discectomy 5 . Important Tips: The exiting nerve root is at risk during the approach. The foramen is entered at the furthest point from the nerve root by targeting the superior-most portion of the inferior pedicle (anteroposterior view) and the posterior-inferior corner of the disc (lateral view). For procedures performed with the patient under awake anesthesia, the patient should be monitored for nerve-root injury by asking them to report pain and move their feet. When a patient is fully anesthetized, neuromonitoring should be utilized. Neuromonitoring is especially important to remove fragments in difficult-to-access locations. Because of the narrow corridor, it may be difficult to confirm full decompression. Thoroughly reviewing the patient imaging to understand the fragment location is necessary. Postoperatively, it is important to evaluate patients to identify cases of incomplete decompression. The dorsal root ganglion is sensitive to irritation. Prior to closure, we irrigate the working cannula with a steroidal solution. The learning curve for PTED has been shown to be 31 cases, which is longer than traditional microdiscectomy techniques 14 . Acronyms and Abbreviations: PTED = percutaneous transforaminal endoscopic discectomy LDH = lumbar disc herniation AP = anteroposterior PSH = past surgical history MRI = magnetic resonance imaging OR = operating room PACU = post-anesthesia care unit