Many reports, including retrospective, prospective, meta-analyses and randomized controlled studies, have indicated that PCN is a long-term safe and effective modality for treating contained CHIVD.7,13,14,21 The effectiveness of PCN has been reported as not inferior to anterior cervical discectomy (ACD) or PCD.10,12,13 However, Epstein et al. reported that CT could achieve similar improvements as PCN.22 Our study found that the PCN group had significantly superior outcomes compared with the CT. group, including earlier recovery from pain and functional limitations for as long as 6 months (Figure 2). Unlike lumbar HIVD, less spontaneous regression was identified with CHIVD, reducing the effectiveness of CT for cervical discogenic pain.23,24 Our results also indicated that the extension of the CT period for more than 6 months can only gain limited effects and is less efficient than receiving PCN for patients suffering from symptomatic contained CHIVD. These findings suggested that early PCN intervention after 6 months’ invalid CT should be considered to achieve prompt and long-term satisfactory results. On the other hand, with regard to safety, only some rare complications, such as inferior thyroid artery injury or spondylodiskitis, have been described.25,26
Cervical disc degeneration and reduced disc height are potential risk factors for the prediction of neck pain in patients.27 However, some studies have reported that larger or optimal interbody implants do not achieve better clinical outcomes in the case of increased disc height.28,29 In addition, the acceleration of disc degeneration has been reported as a potential drawback of PCN.15,30 The present study attempted to identify temporal evidence of imaging changes after PCN. We noted a significant decrease in cervical disc height among PCN patients that could be detected as early as 3 months after surgery (Table 2). But no correlation was detected between changes in disc height and PCN outcomes (Figure 3), indicating that decreased disc height after PCN cannot be used as an indicator of poor outcome. At our center, we performed the standard three-point circular coblation technique for PCN (at 1/4, 2/4, and 3/4) in each cervical disc space (Figure 4).31 We propose that some amount of decrease in disc height following PCN may represent an acceptable trade-off for apparent symptom improvements. However, whether the use of fewer circular coblation points would reduce the decrease in disk height or provide similar efficacy for pain relief and functional improvements remain unknown. Further large-scale studies and longer follow-up periods remain necessary to determine whether the observed decrease in disc height will result in symptom progression, which may contribute to the eventual necessity of ACDF or ADR. In our series, all patients who received PCN tolerated the whole course well, and no complications were reported. The imaging parameters, such as ROM, Cobb’s angle, and the SVA, did not change, indicating that the PCN-induced decrease in disc height did not alter the sagittal or axial balance of the patients.
Klessinger reported the data for 133 PCN patients, which was associated with a 19.5% re-surgery rate, and concluded that PCN represents a poor replacement for conventional open surgery.32 In contrast to their data, 90 PCN patients were recruited in our series, and only one patient received ADR three months after PCN due to a lack of improvement. Another three patients received a second PCN after 11, 14, and 43 months. Our re-surgery rate was approximately 4.44% (4/90) within an average of 30.44 ± 24.36 months after surgery. This drastic difference in results between studies may be due to patient selection.31,33 The decision making for performing PCN should be based on several parameters which including the patients’ age, symptoms, signs and the image characteristics. Despite the disc degeneration that can progress with age, the most optimal stepwise therapeutic policies should be adopted in accordance to this reason. PCN is a simple, safe, time-saving, outpatient clinical surgery that possesses good value for symptomatic contained CHIVD, especially after short-term failure to respond to CT, too early to receive open surgery, or general anesthesia are contraindicated due to complicated medical problems.10,11 We believed that PCN does not represent an alternative to PCD, ACD and ADR, but may be used to postpone or to decrease the need for eventual-step cervical fusion surgery to treat degenerative cervical disc disease.13
Although this study was designed to conduct follow-up X-rays of the cervical spine, some patients did not come to the clinic for these final imaging analyses, resulting in loss to follow-up, which may result in some inconsistencies in the total number of cases included in the analysis. In addition, the present study also featured a number of additional limitations, such as the limited number of cases, the lack of randomization, the insufficient length of follow-up, and the use of only two-dimensional follow-up images. However, we believe that these preliminary data can provide a new and useful clinical understanding of the effectiveness of PCN.