LSS is caused by gradual degenerative narrowing of the spinal canal. According to a randomized controlled trial study, compared with decompression plus fusion surgery, single decompression surgery showed considerable clinical results.  The ULBD technique was first reported by Young in 1988, and it has been rapidly improved by the use of various minimally invasive techniques, such as microscopy and microendoscopy. Nevertheless, the air medium required under microscopy and microendoscopy cannot provide a clear visual field, especially in contralateral decompression procedures. [4, 5] Full endoscopic ULBD can achieve effective bilateral decompression via water medium, and several studies have reported favorable outcomes from this version of the procedure in the treatment of LSS.  However, full endoscopic ULBD has a steep learning curve and a high rate of complications.  ULBD via UBE is a relatively newly emerging technique that provides surgeons an alternative for conducting ULBD in a minimally invasive manner. Following the first report of this procedure from Egyptian and South Korean researchers, UBE-ULBD has been suggested to be a safe and effective surgery for LSS decompression. [8, 9] Nevertheless, few studies have reported the clinical outcomes of multilevel UBE-ULBD, and its efficacy and safety remain unclear. In this case, a patient with multilevel LSS underwent five-level UBE-ULBD in two stages, which is the first report to our knowledge on such a large number of ULBD procedures for one patient.
For this patient, the long segmental lumbar fusion defects, including extensive detachment of the paravertebral extensors and limited back movement, were the reasons why we chose this minimally invasive, nonfusion surgery. In addition, this patient had no obvious degenerative spinal deformity or serious back pain. All her symptoms had developed as a result of compression of nerve roots and cauda equina. Staging the procedures can reduce the duration of each process, which is beneficial for the postoperative recovery of elderly patients. The range of bone resection in conventional ULBD mainly involves the partial unilateral lamina and internal cortex of the contralateral lamina. In this patient, bone resection involved the ventral side of the superior articular process due to decompression of the nerve root in the lateral recess. This procedure is also widely used in the full endoscopic version of ULBD surgery.  Our experience with this patient demonstrates that ULBD with partial facet resection minimally damages the stability of the surgical segment, and the impairment of the paravertebral muscles was relatively limited. Additionally, the patient did not complain of obvious back pain during lumbar movement.
LSS is a very common pathological condition in elderly individuals. Complicating matters is that this pathological process frequently involves two or more levels, requiring the surgeon to attempt to balance wide-range decompression and spinal stability. UBE-ULBD could provide surgeons with a good alternative to expanded laminectomy or long segmental fusion. This minimally invasive procedure has remarkable advantages in producing early ambulation, inducing less incision pain, and requiring shorter hospital stays. All these factors could reduce the risk of postoperative complications, mortality and utilization in elderly patients. Moreover, many elderly patients who have multiple comorbidities, such as hypertension, diabetes mellitus and coronary heart disease, may have more opportunities to undergo lumbar surgery with the continuing development of minimally invasive nonfusion techniques.
UBE is an emerging minimally invasive spinal technique that can be performed for a variety of lumbar degenerative diseases, including multilevel lumbar spinal stenosis. ULBD via UBE can achieve safe and effective decompression, which may be crucial for allowing elderly patients to complete their daily activities. We presented a case of a patient who developed multilevel LSS and underwent two-stage, five-level UBE-ULBD, achieving a favorable clinical result.