In this study, we retrospectively analyzed the clinical data and surgical results of ACDF and PEPCD in the treatment of single-segment CSR. Our study found that PEPCD treatment of single-segment CSR was similar to ACDF in terms of early and mid-term effects. Both of which can effectively remove nerve root compression to relieve symptoms, which is similar to previous findings [21, 23, 26, 27]. Compared with ACDF, PEPCD can significantly reduce the surgical trauma (reduced blood loss, shortened hospital stay), to promote postoperative rehabilitation (Back to work / Full activity), reduce economic and social burden (lower hospitalization costs) [20, 31]. We found that the ACDF and PEPCD can significant improve C2-7 lordosis, and the C2-7 lordosis improved more in the ACDF group when compared with that of PEPCD. In the PEPCD group, 2 patients due to intraoperative or postoperative symptoms did not significantly alleviate, thus changing the surgical procedure. There were no cases of revision surgery due to recurrence of symptoms. The failure rate PEPCD were significantly higher than those of ACDF group.
With the changes in modern life and working style, the incidence of neck and shoulder pain and other diseases caused by degenerative intervertebral discs is increasing [32]. CSR is a common cause of neck pain and upper limb pain [33]. Through the control of neck activities, physical therapy, analgesic, dehydration, neurotrophic drug therapy, symptoms can be alleviated [3, 34]. For long-term, severe CSR patients, surgical treatment is required. With the development of minimally invasive endoscopic surgery in recent years, more and more people have reported the application of PEPCD in the treatment of cervical spondylosis [21, 26, 27, 35, 36]. PEPCD surgery not only have advantages of cervical posterior keyhole surgery and MED surgery, but also has a smaller trauma, better visual field, more accurate decompression positioning, surgical operation more accurate and so on. With the further optimization of endoscopic devices, surgical operation is more simple. The cervical lamina is relatively flat and there is a natural lamina intervertebral space, which helps to locate and place the endoscopic channel during operation. It is very practical.
In this study, patients with PEPCD were treated with a customized plaster bed based on the size of the patient. On one hand, the plaster bed was convenient for intraoperative X-ray fluoroscopy. On the other hand, the plaster bed, which was customized according to the patient's body, was convenient for regulating the position of the patient and preventing intraoperative pressure. In the course of surgery, the patient's position is the head side raised 20–30° prone position. The aim is to reduce the pressure in the spinal canal venous plexus, thereby reducing intraoperative bleeding [37]. The patient's cervical spine is in a slightly flexed position, widening the gap between the vertebrae and enlarging the operating space. Disc herniation, especially the prominent below the nerve root, will increase the nerve root tension. When the patient in general anesthesia, the neck muscles will be in a relaxed state. If the cervical spine in the excessive flexion, nerve root will be excessive traction, which may increase the rate of iatrogenic injury. The double needle technique and the "K" point are used to determine the position of the target segment and the working channel. During the operation, according to the position of the double needle and the K point in the X-ray anteroposterior radiograph, the position of the endoscope working channel of the K point can be accurately positioned by adjusting the needle 1–2 times. The lamina gap is located by clearing the soft tissue around the K point.
Hemorrhage during the PEPCD is an important factor affecting the success of surgery. There are 3 types of bleeding in chief, one is the soft tissue around the vertebral column, one is the spinal cord venous plexus bleeding, the other is the upper and lower vertebral lamina of cancellous bone. Radiofrequency electrocoagulation can effectively stop the bleeding of soft tissue around the lamina. The vertebral vein venous hemorrhage can be decreased through the position adjustment to reduce venous plexus pressure. In our clinical practice, we found that increased saline pressure can reduce the intraoperative spinal canal venous plexus bleeding. Bleeding from the upper and lower vertebral cancellous bone is difficult to deal with. In this study, there was one case of intraoperative vertebral hemorrhage, which seriously affected the surgical field of vision, and we had to change the operation plan finally. There are some ways to decrease bleeding in the literature. Using controlled hypotension [38, 39], local vasoconstrictor [40] and new hemostatic biological materials [41] can reduce bleeding. It had been reported that the use of hot saline irrigation can effectively reduce the bleeding of functional endoscopic sinus surgery (FESS) [42]. Whether thermal saline can reduce the bleeding in PEPCD surgery, and thermal saline effect on spinal cord need further study.
For the upper and lower lamina decompression range, we believed that to minimize the destruction of the articular process while ensuring adequate decompression of the nerve root. In open surgery, biomechanical studies had shown that removal of more than 50% of articular processes can cause cervical instability [43]. PEPCD surgery reduced the stripping of ligaments and muscles around the spine, so the probability of cervical instability was reduced. In this study, three-dimensional reconstruction of CT showed that with the prolongation of time, the area of the cervical vertebral plate was gradually decreased. The results showed that the bited lamina had the trend of fracture healing under the influence of biomechanics and internal microenvironment. This healing can further enhance the stability of the vertebral body and prevent the occurrence of postoperative vertebral instability. Therefore, we believe that the first element in the PEPCD procedure is sufficient laminectomy to achieve adequate decompression. Facet joint resection should be controlled within 50%, in the course of surgery it may be appropriate to enlarge the standard according to decompression.
The essence of PEPCD operation is the further optimization and extension of keyhole and MED. The technique of endoscopic technique is used to remove the small joints and the prominent nucleus pulposus through a more minimally invasive and more accurate technique, so as to achieve the purpose of nerve root canal enlargement and nerve root decompression. In this study, we confirmed that the clinical effect of PEPCD in the treatment of CSR is equivalent to that of ACDF, and the surgical trauma is smaller and the postoperative recovery is faster. PEPCD surgery is limited by its own technical characteristics, adapted to cervical disc herniation and small joint hyperplasia induced intervertebral foramen stenosis; contraindications include central cervical disc herniation, cervical spondylotic myelopathy, posterior longitudinal ligament ossification or cervical unstable and so on [20, 44]. However, with the development of endoscopic techniques, PEPCD has also been applied to multi-segment cervical spondylosis [27], cervical spondylotic myelopathy, and achieved good early postoperative effect. In this study, the number of samples and the follow-up time were limited, and no re-protrusion was observed. However, there was reports that the re-protrusion of PEPCD was 3.4% for 2 years fellow-up [21]. Re-herniation after minimally invasive surgery has been a problem for spine surgeons. As surgery only removed the prominent nucleus pulposus, intervertebral disc rupture still exists, so the residual nucleus pulposus can still re-herniation through intervertebral disc rupture. It had been reported that the use of polymethyl methacrylate (PMMA) closure in the surgery can significantly reduce the probability of postoperative re-herniation [45]. Due to the limitations of material technology and lack of long-term follow-up, clinical application is not extensive. Due to the steep learning curve of PEPCD surgery, and the requirement of the ability of understanding the three-dimensional anatomical structure during PEPCD, the development of the operation is limited.