Background <p>Both thoracic ossification of the posterior longitudinal ligament (T-OPLL) and thoracic disc herniation (TDH) may cause thoracic spinal stenosis (TSS) resulting in thoracic myelopathy. Surgical decompression is the only effective treatment for symptomatic TSS. 360° Circumferential decompression, also called the “cave-in” technique, can safely and effectively treat T-OPLL; however, this procedure has not yet been performed endoscopically. Herein, we report the first case of massive T-OPLL combined with TDH that was treated endoscopically using the “cave-in” technique, with 36 months of follow-up. Further, we review the literature on this subject.</p> Case Report <p>A 76-year-old woman presented with a 2-year history of progressive numbness and weakness of both lower limbs, and pain and weakness in both lower limbs after sustaining a fall more than 1 month ago, with symptom aggravation since 1 week. Computed tomography (CT) revealed TDH combined with massive T-OPLL at the T6/7 levels. Magnetic resonance imaging (MRI) showed severe compression of the thoracic spinal cord. Two-stage endoscopic circumferential decompression was performed. During a follow-up period of 36 months, the patient recovered with no complications, and CT and MRI confirmed complete decompression of the spinal cord.</p> Conclusion <p>The endoscopic “cave-in” technique can effectively treat T-OPLL with satisfactory clinical results, and is associated with less trauma and fewer complications than conventional posterior circumferential decompression. The endoscopic “cave-in” technique can be a good surgical option for patients with T-OPLL.</p>