A total of 86 patients were enrolled in the present study and divided into NRSS-positive (n=49) and negative groups (n=37). Demographic characteristics of all patients are presented in Table 1. There were 21 males and 16 females in NRSS-negative group, with an average age of 50.27±13.25 years and an average body mass index (BMI) of 23.77±3.38 kg/m 2. In NRSS-positive group, there were 27 males and 22 females with an average age of 53.29±15.05 years old and an average BMI of 23.34±3.49 kg/m2. No significant differences in demographic parameters including gender, age, and BMI were found between the two groups. Moreover, no significant differences were found between groups with respect to the duration of disease, comorbidity, operation time, and length of hospital stay.
The incidence of positive NRSS in the different type of LDH
Radiographic characteristics between the two group are available in Table 2. LDH can be divided into central and paracentral types. There was a total of 31 patients with central LDH and 55 patients with paracentral LDH. The compressed percentage of dural sac in patients with central LDH was greater than that in patients with paracentral LDH ((31± 6) % versus (21±5) %, t=9.211, P<0.001). In addition, the compressed percentage of the dural sac between the groups showed significant differences. There were 4 patients with central type and 33 with paracentral type in the NRSS-negative group. However, there were 27 patients with central LDH and 22 patients with paracentral LDH in the NRSS-positive group. Compared to the patients with paracentral LDH, the patients with central type of LDH were more likely to get positive NRSS.
The incidence of positive NRSS in different lumbar segments
The incidence of positive NRSS in all patients was 56.98% (49/86). Further, analysis showed that the incidence of positive NRSS in different lumbar segments was different. There were 2 cases (2.33%) in L2/3 segment, 5 cases (5.81%) in L3/4 segment and 42 cases (48.84%) in L4/5 segment. The incidence of positive NRSS in L4/5 segment was significantly greater than that in L2/3 and L3/4 segments (c2=6.386, P=0.037).
The correlation between the incidence of positive NRSS and the compressed percentage of dural sac
The compressed percentage of dural sac in the present study ranged between 0 to 40%. As shown in Table 2, the incidence of positive NRSS was about 28.20% (11/39) when the compressed percentage of dural sac was less than 20%. As for the compressed percentage of dural sac more than 20%, the incidence of positive NRSS was about 80.85% (38/47).
As shown in Table 3, the preoperative clinical outcomes were evaluated by using VAS, JOA and ODI scores. The results showed that all the patients who underwent PTED had good clinical outcomes in pain relief and functional recovery. Moreover, the patients with positive NRSS had a better pain relief than those with negative NRSS, at 1 week and 1 month after surgery. However, there were no significant differences at 3 and 6 months after surgery. In terms of JOA and ODI scores, the patients with positive NRSS had a better functional recovery than those with negative NRSS at 3 and 6 months after surgery. However, no significant differences were found at 1 month after surgery between the groups.
The apparent rate of JOA scores at 6 months after surgery was 67.57% (Table 4) in the negative group and 85.71% in the positive group. The superior rate of ODI scores in the two groups at 6 months after surgery were 67.57% and 87.76%, respectively. These differences between groups were statistically significant (Table 5). The excellent and good rates of Macnab scores in the two groups at 6 months after surgery were 81.08% and 89.80%, respectively. There was no significant difference in Macnab scores between groups at 6 months after surgery (Table 6). In addition, there were no patients with complications including nerve root injury, intraspinal infection and dural sac rupture in both groups.