Percutaneous endoscopic lumbar discectomy (PELD) for migrated disc herniations is technically demanding due to the absence of the technical guideline. The purposes of this study were to propose a radiologic classification of disc migration and surgical approaches of PELD according to the classification. A prospective study of 116 consecutive patients undergoing single-level PELD was conducted. According to preoperative MRI findings, disc migration was classified into four zones based on the direction and distance from the disc space: zone 1 (far up), zone 2 (near up), zone 3 (near down), zone 4 (far down). Two surgical approaches were used according to this classification. Near-migrated discs were treated with "half-and-half" technique, which involved positioning a beveled working sheath across the disc space to the epidural space. Far-migrated discs were treated with "epiduroscopic" technique, which involved introducing the endoscope into the epidural space completely. The mean follow-up period was 14.5 (range 9-20) months. According to the Macnab criteria, satisfactory results were as follows: 91.6% (98/107) in the down-migrated discs; 88.9% (8/9) in the up-migrated discs; 97.4% (76/78) in the near-migrated discs; and 78.9% (30/38) in the far-migrated discs. The mean VAS score decreased from 7.5 +/- 1.7 preoperatively to 2.6 +/- 1.8 at the final follow-up (P < 0.0001). There were no recurrence and no approach-related complications during the follow-up period. The proposed classification and approaches will provide appropriate surgical guideline of PELD for migrated disc herniation. Based on our results, open surgery should be considered for far-migrated disc herniations.

Percutaneous endoscopic lumbar discectomy is effective for recurrent disc herniation in selected cases. The posterolateral approach through unscarred virgin tissue can prevent nerve injury and could preserve the spinal stability. Both foraminal and intracanalicular portions can be decompressed simultaneously.

The high-resolution working channel endoscope allowed us to selectively remove the cervical herniated disc. The postoperative disc height reduction was observed, with no significant effect on therapeutic success. The sagittal alignment and segmental motion were well preserved.

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Despite the successful application of percutaneous endoscopic thoracic discectomy (PETD), its technical feasibility and outcomes for symptomatic upper and midthoracic disc herniation have not been reported yet. The purpose of this article was to evaluate the feasibility of the percutaneous transforaminal endoscopic approach to remove disc herniations in the upper and midthoracic spine. Fourteen consecutive patients (mean age, 42.4 years; 12 males, 2 females) who underwent PETD were included in the analysis. The procedure was performed under local anesthesia and intravenous sedation using the standard endoscopy instrument set. The transforaminal approach combined with foraminoplasty was used to access the herniated areas. Treatment outcomes were evaluated using visual analogue scale (VAS) scores, Oswestry Disability Index (ODI) scores, and the modified MacNab criteria. Four discectomies were performed at T2–3, 5 at T3–4, and 5 at T5–6. The mean follow-up period was 43.4 months, and all patients showed statistically significant postoperative improvement (VAS: 7.3 to 2.3, ODI: 53.5 to 16.9, p<0.05 for all). No serious complications were reported during follow-up. PETD for upper and midthoracic disc herniation is a feasible and effective minimally invasive treatment option with favorable clinical results.