Objective
This study aimed to describe the surgical technique in patients with cervical herniated disc treated with unilateral biportal endoscopic spinal surgery.
Materials and Methods
Working and viewing portals were created in each unilateral paravertebral area at the target disc level. Under exploring by endoscopic view, effective decompression was possible via safe access to the medial foramen with minimal laminectomy and facetectomy. We evaluated 27 patients, and clinical outcome was analyzed using the visual analogue scale (VAS), Neck disability index (NDI), Macnab criteria, and motor function of involved upper extremity, all assessed before and 3, 6 months post procedure.
Results
The VASs for axial neck pain and upper extremity pain decreased from 6.8 to 1.9 and 7.7 to 1.5, respectively, at 6 months post procedure. The NDIs were improved from 45.5 to 13.0 at 6 months post procedure. According to the Macnab criteria, an ‘Excellent’ , ‘Good’ , and ‘Fair’ result was obtained in 55.6%, 29.6%, and 14.8% subjects, respectively. The motor power of involved upper extremity improved as an approximately one grade on average at 6 months post procedure; 3.9±0.8 to 4.8±0.4.
Conclusions
Unilateral biportal endoscopic spinal cervical surgery can be an efficient and safe intervention in patients with cervical herniated disc.

Background
Owing to its new introduction, there are few documents on pit-falls of biportal endoscopic spine surgery (BESS) clinically. The authors reported etiologies in need of early exploration after BESS for lumbar degenerative diseases and strategies to overcome them.
Methods
BESS were performed for lumbar spine diseases (LSDs) by two spine surgeons from December 2013 to March 2016. Postoperative MRI was checked for all cases and following-up MRIs in the case in need of revision surgery within six months after the first surgery due to pain intolerable, sustained or recurred. The complicated cases were reviewed and classified as radiographic and operative findings to reveal the main reasons for early explorations.
Results
The 562 cases (M:295, F:267, Age 58.5±14.1 yrs, 20~88 yrs) included lumbar disc herniation (LDH) (255 cases), extraforaminal disc herniation (22 cases), spinal stenosis (218 cases), degenerative spondylolisthesis (27 cases), revision surgery after recurred disc herniation or restenosis after open surgery (24 cases), juxtafacet cyst (11 cases), adjacent segment stenosis with fusion surgery (3 cases), and spondylolytic spondylolisthesis (2 cases). Early explorations were needed in 43 cases (7.7%) at 26.1±31.5 days after the initial operations. Causative etiologies were listed as recurred LDH (12 cases, 27.9%), remnant stenosis (7 cases, 16.3%), remained ruptured disc fragment (6 cases, 14.0%), root edema (5 cases, 11.6%), synovitis (4 cases, 9.3%), hematoma (3 cases, 7.0%), dura tear (2 cases, 4.7%), recurred stenosis (2 cases. 4.7%), wrong level (1 case, 2.3%) and postoperative fungal infection (1 case, 2.3%). Thirty-one cases (72.1%) were revised within 4 weeks and most conditions (40 cases, 93.0%) were improved after early exploration using BESS. Two cases of dura tear were conversed to open repair. One case of fungal infection was suspected to related with the patient’s medical illness including long-term steroid use for chronic lung disease with pulmonary fibrosis and Diabetes mellitus.
Conclusions
Preoperative planning should be prepared carefully to decrease early exploration. It was helpful to comparing MRIs immediately postoperative and early following-up to find the reasons. Don’t hesitate to explore the operated site again using BESS, because most etiologies are supposed to be controlled by early exploration without need of converting to open surgery except in the case of dura tear in need of dural repair.

Extreme lateral interbody fusion (XLIF) and direct lateral interbody fusion (DLIF) are novel minimally invasive transpsoas approaches to the lumbar spine for performing fusions. Advantages of DLIF include easier technique, faster recovery, minimal complication, high fusion rate, and possibility of achieving better alignment. Many previous reports have evaluated outcomes of DLIF. The authors described surgical procedure of DLIF and reviewed clinical outcomes, radiological outcomes, and complications from various literatures. In conclusion, the DLIF seems to be a valuable minimally invasive surgical tool for the fusion in patients with various diseases, including degenerative disc disease, instability, stenosis, scoliosis, tumor, infection, and adjacent segment degeneration.