Symptomatic post-discectomy pseudocyst after endoscopic lumbar discectomy

Abstract

Objective: The objectives of this study were to determine the frequency of symptomatic postdiscectomy pseudocyst (PP) after endoscopic discectomy and to compare the results of surgical and conservative management of them.

Methods: Initial study participants were 1,503 cases (1,406 patients) receiving endoscopic lumbar discectomy by 23-member board of neurosurgeons from March 2003 to October 2008. All patients' postoperative magnetic resonance imaging (MRI) scans were evaluated. On the postoperative MRI, cystic lesion of T2W high and T1W low at discectomy site was regarded as PP. Reviews of medical records and radiological findings were done. The PP patients were divided into two groups, surgical and conservative management by treatment modality after PP detection. We compared the results of the two groups using the visual analogue scale (VAS) for low back pain (LBP), VAS for leg pain (LP) and the Oswestry disability index (ODI).

Results: Among 1,503 cases of all male soldiers, the MRIs showed that pseudocysts formed in 15 patients, about 1.0% of the initial cases. The mean postoperative interval from surgery to PP detection was 53.7 days. Interlaminar approach was correlated with PP formation compared with transforaminal approach (p=0.001). The mean VAS for LBP and LP in the surgical group improved from 6.5 and 4.8 to 2.0 and 2.3, respectively. The mean VAS for LBP and LP in the conservative group improved from 4.4 and 4.4 to 3.9 and 2.3, respectively. There was no difference in treatment outcome between surgical and conservative management of symptomatic PP.

Conclusion: Although this study was done in limited environment, symptomatic PP was detected at two months' postoperative period in about 1% of cases. Interlaminar approach seems to be more related with PP compared with transforaminal approach.

Keywords: Endoscopic discectomy; Herniated disc; Lumbar; Postoperative complication; Pseudocyst.

Fig. 1

MRIs of Case 3, who underwent right L5/S1 endoscopic discectomy via interlaminar approach. A and B : Lumbar MRIs on Day 30 shows a pseudocyst (arrow) compressing the neural structures at the discectomy site. C and D : Lumbar MRIs on Day 70 shows complete resolution (arrow) of the right L5/S1 pseudocyst and epidural decompression at the right S1 root.

Fig. 2

Case illustration of symptomatic PP, detected 5 months after endoscopic discectomy via the interlaminar approach (used with the permission of Dr. Hoon Kim). A and B : A 17 mm cystic mass, between dura and posterior longitudinal ligament, at L5/S1-level compressing the left S1 root. C : Intraoperative finding shows cystic mass beneath left S1 root being compressed. D : Microscopic view of cystic wall shows fibrous tissue with some inflammatory cells, indicating an inflammatory reaction with some hemorrhages.