Full Endoscopic Anterior Cervical Discectomy and Interbody Fusion in Patients with Cervical Spondylotic Myelopathy
Authors: Lim Kang Taek 
Published: December 2022

Background:
For the surgical treatment of cervical spondylotic myelopathy (CSM), anterior decompression with fusion or posterior decompression using microscopy has been used widely as the standard procedure, depending on the location of pathology and the surgeon's preference. Endoscopic anterior cervical discectomy and interbody fusion (E-ACDF) is a minimally invasive, effective surgical option for the management of CSM. The advantages of using endoscopy for anterior cervical discectomy and interbody fusion (ACDF) are better visualization of the operative field with the possibility of changing the angle of the endoscope. This reduces the damage to the normal anatomical structure. Although long-term follow-up results are needed to evaluate fusion rate and complication, this appears to be a safe and feasible alternative to conventional ACDF for CSM. In this article, we have described the surgical technique, summarized the endoscopic process to discuss its operative strategies, and reviewed the radiographic records, pre- and postoperatively.

Material and Methods:
This retrospective review study included 36 cases aged 37 to 65 years, with CSM at one segment. All of them underwent full E-ACDF from January 2018 to April 2021. All patients were followed up for 12 months after the procedure by outpatient interviews. The clinical outcomes were evaluated based on the Visual Analog Scale (VAS) of the arm, and Japanese Orthopedic Association (JOA) score with clinical data at preoperative, 3, and 12 months after the operation. Hirabayashi method was used to assess the neurological recovery after 12 months of operation. Radiological outcomes were evaluated using plain radiography and magnetic resonance imaging, computed tomography scan to evaluate disc height, cervical lordosis (Cobb's angle), and solid fusion.

Results:
The mean operation time was 150 min (range 120–170 min) and the average length of hospital stay was 2 ± 3 days. There was one case of immediate postoperative anterior neck hematoma, which required open revision surgery. There was no case of infection or damage to the anterior visceral organ. The mean VAS scores for arm pain and mean JOA scores after endoscopic ACDF were significantly improved compared with before the operation during the follow-up period. The recovery rate, which was evaluated by the Hirabayashi method, looked good enough to indicate well recovered postoperatively. The disc height changed from 5.2 mm preoperatively to 6.2 mm after immediate postoperative and 5.9 mm after 6 months (P < 0.01). Cervical lordosis as Cobb's angle between C2 and C7 was significantly improved compared to the preoperative one during the follow-up periods also. The bone fusion rate was 100% at 6 months after the operation, and there was no segmental instability.

Conclusions:
The present study demonstrates that E-ACDF is a minimally invasive and effective surgical option for the surgical management of CSM. Based on the present study, E-ACDF may potentially enable the avoidance of various shortcomings related to surgical approaches. Through a sort of preliminary investigation, the authors confirmed the feasibility of E-ACDF and presented comparable outcome results, which might dispel the safety concern because of only one complication of wound hematoma. Better-designed randomized controlled studies with larger sample sizes in longer-term follow-ups are strongly warranted.