Abstract
In lumbar disc herniation surgery, dural lesions seem to be the most common complication today. Studies on incidence of and outcome after a dural lesion are mainly based on retrospective studies. In a prospective study within the framework of the Swedish Spine Register, 4,173 patients operated on for lumbar disc herniation were evaluated using pre- and 1-year postoperative protocols and complication registration. Mean patient age was 41 (18–81) years and 53% of the patients were male. 93% of the operations were performed on the two lowermost lumbar levels. The incidence of dural lesions in the material was 2.7%. In patients with previous disc surgery, the incidence was doubled, 5%, a significant increase (P = 0.02). Patients with dural lesions preoperatively had more back pain and inferior scores in general health and role emotional domains of the SF-36. These factors, however, were because they had been operated on previously, not related to the dural lesion as such. The relative improvement after surgery was similar whether a dural lesion had occurred or not. It is concluded that a dural lesion is a technical complication which must be solved at the time of surgery but which does not bear any negative implications on the long-term outcome for the patient.
Keywords: Lumbar disc herniation, Complication, Surgery, Outcome
Introduction
In operations in the spinal canal, the most common untoward event is dural lesion/incidental durotomy. The proximity to the dural sac in intraspinal operations means that the risk for injuring it cannot be neglected. Previous studies have reported prevalence of dural tears varying from 1 to 17% depending on diagnosis and type of surgery performed. In a large series of spinal procedures [4], it was demonstrated that the morbidity was lower for younger patients and for disc herniation surgery. The risk factors for dural tear and the long-term outcome after such an event have been reported by several authors [1, 3, 13] but to our knowledge mainly in retrospective studies. In the large prospective SPORT study, an incidence of 4% is related [14]. Contrasting results concerning the effect of dural lesion on the long-term follow-up exist where several authors [3, 6, 10] did not report inferior outcome after this complication while in a recent pair matched study [8] the long-term outcome in lumbar disc herniation surgery was inferior in the group afflicted with an incidental durotomy.
Prospective studies should be more apt to straighten out the question marks around the dural lesion complication and the Swedish Spine Register should prove suitable for this purpose. During the last 10 years, about 80% of degenerative lumbar spine surgery in Sweden has been reported to the register which includes complication registration.
The purpose of the present study was to elucidate within the framework of the Swedish register, incidence, risk factors, and effect on outcome of an incidental dural lesion in lumbar disc herniation surgery.
Patients and methods
In total, 5,537 patients were operated on for lumbar disc herniation with microscopic or open surgery during a 5-year period. Of these, 4,173 completed the pre- as well as 1-year postoperative protocols of the Swedish Spine Register. Mean patient age was 41 years (range 18–81) and 53% of the patients were males and 47% females. The levels operated were L5-S1 51%, L4-L5 42%, L3-L4 6% and higher levels 1%.
The Swedish Spine Register, Swespine, presented elsewhere [11, 12] contains patient administered pre- and postoperative data and surgeon completed surgical data.
Preoperative data include smoking habits, working conditions, consumption of analgesics, walking distance and back as well as leg pain on the VAS scale. Further, the Oswestry Disability Index, the SF-36 questionnaire, and the EQ-5D also are completed by the patient.
Postoperatively, the same parameters are recorded as well as subjective improvement regarding leg and back pain and general satisfaction (satisfied/uncertain/dissatisfied) with outcome of surgery. The surgical data include complication registration and registration of re-operation. Further, one patient related follow-up compilation also contains complications. Comparisons of pre- and postoperative data recorded were performed by means of t tests.
Results
The results presented refer to the 4,173 patients who completed pre- and 1-year postoperative protocols. In total, 112 occasions of dural lesions were reported in these patients, corresponding to an incidence of 2.7%. Three of the patients were subjected to surgical treatment for CSF leakage before discharge from hospital. An obvious risk factor for dural lesion was previous disc surgery, which increased the incidence to 5% (P = 0.02).
Patients with dural lesions preoperatively had significantly more back pain and significantly lower outcome in the SF-36 score concerning the domains general health and role emotional (Table 1). These factors, however, were related to the fact that these patients had been operated on previously. Among other preoperative parameters, no significant differences between patients with and without dural lesions were encountered.
Table 1.
VAS back and leg pain, SF-36 and Oswestry Disability Index (ODI) in patients with and without dural lesion after lumbar disc excision
| No dural lesion | Dural lesion | P value | |
|---|---|---|---|
| VAS back pain | |||
| Preop | 46.0 | 51.2 | 0.08 |
| Postop | 25.3 | 24.7 | 0.82 |
| VAS leg pain | |||
| Preop | 66.4 | 68.0 | 0.53 |
| Postop | 22.5 | 25.0 | 0.34 |
| SF-36 | |||
| General health | |||
| Preop | 67.5 | 62.3 | 0.02 |
| Postop | 67.9 | 66.1 | 0.46 |
| Role emotional | |||
| Preop | 39.6 | 31.2 | 0.07 |
| Postop | 71.5 | 69.3 | 0.60 |
| Bodily pain | |||
| Preop | 22.2 | 22.2 | 0.96 |
| Postop | 60.1 | 59.4 | 0.81 |
| Mental health | |||
| Preop | 59.8 | 58.9 | 0.67 |
| Postop | 74.7 | 77.3 | 0.26 |
| Physical function | |||
| Preop | 37.9 | 37.7 | 0.94 |
| Postop | 72.6 | 69.5 | 0.22 |
| Role physical | |||
| Preop | 8.0 | 7.1 | 0.68 |
| Postop | 57.3 | 55.0 | 0.60 |
| Social function | |||
| Preop | 46.3 | 42.8 | 0.22 |
| Postop | 79.6 | 78.1 | 0.56 |
| Vitality | |||
| Preop | 35.1 | 35.0 | 0.95 |
| Postop | 58.2 | 60.5 | 0.40 |
| ODI | |||
| Preop | 48.7 | 50.4 | 0.44 |
| Postop | 20.2 | 21.7 | 0.48 |
At 1-year postoperatively, the improvement of back as well as leg pain, SF-36 and Oswestry scores were significant and similar for patients with and without dural lesion. Working ability was more common in patients without dural lesions (P = 0.01) but also this correlated to the fact that most patients with a dural lesion had had lumbar spine disc operations previously.
When the correlation between previous surgery, dural lesion, and outcome was analyzed, it was evident that patients with previous surgery more often sustained dural lesions and more often had an unfavorable outcome than did patients undergoing first time surgery (Table 2).
Table 2.
Satisfaction with outcome of surgery 1 year postoperatively related to previous surgery and to occurrence of a dural lesion at present surgery in percent
| Satisfied | Uncertain | Dissatisfied | |
|---|---|---|---|
| No previous operation, no dural lesion | 91 | 8 | 1 |
| No previous operation, dural lesion | 98 | 2 | – |
| Previous operation, no dural lesion | 41 | 43 | 16 |
| Previous operation, dural lesion | 92 | 8 | – |
Loss to follow-up: 1,364 patients failed to complete the 1-year follow-up questionnaire corresponding to 25%. Of these, 36 (2.6%) had sustained a dural lesion at surgery, i.e. virtually the same proportion as in those with completed 1-year follow-up. In all other preoperative demographic parameters, the group lost to follow-up was compared to those followed-up and no statistically significant differences between the two groups were recorded.
Discussion
While enhanced preoperative information to the spine surgeon (MRI, CT), improved aids in surgery (microscope, head lamp, navigation) and improved prophylaxis (antibiotics, low molecular weight heparins, early mobilization) gradually have been introduced to spine surgeons, it is difficult to demonstrate that the complication rate in lumbar spine surgery today has decreased. More complex implants, surgical techniques, and reconstructions may contrarily increase the complication rate. In the study of 18,122 hospitalizations for lumbar spine procedures in the state of Washington, Deyo et al. [4] showed young age and diagnosis for surgery to have strong influence on the complication rate. Still a complication rate during hospitalization for disc surgery of 5.7% was registered. Changes in complication rates over time are difficult to monitor and can probably only be obtained by the use of broad registration, such as national registers or complication registration according to the ICD 10 system.
Dural lesions or unintended incidental durotomies seem to be the most common complication in intraspinal surgery and figures between 1 and 14% have been presented in the literature. A dural lesion may be a minor problem treated by a suture or fibrin glue (Tisseel®) but may also be the entry point to the development or dural cutaneous fistulas, meningitis, arachnoiditis and epidural abscesses. The small but serious risk for the latter complications calls for immediate attention when dural lesion is noted during surgery. A number of treatment modalities have been presented ranging from direct closure by sutures to facial, muscular, or artificial grafts, fibrin glue and closed subarachnoid drainage [7].
The risk for CSF leakage is unquestionably lower in disc surgery than in spinal stenosis surgery and this is probably related to the less extensive procedure and the usually more voluminous spinal canal volume in disc patients.
It is obvious that previous surgery is a strong risk factor for sustaining a dural lesion. The risk increase varies between double and fivefold [5, 9] and in the paper of Cammisa et al. [3], 38% of those with dural lesions had been subjected to 1–6 procedures on the lumbar spine previously. It seems that the risk is higher for less experienced surgeons [15].
An unsolved question seems to be whether a dural lesion predisposes to an inferior long-term outcome than would be anticipated if the lesion had not occurred. Several papers in the literature point to a negative predictive outcome value of a dural lesion but others demonstrate no difference. Pair matched comparisons have been utilized to study the differences if any and Saxler et al. [8] in such a study demonstrated inferior outcome in the presence of a dural lesion. However, all reports quoted have been retrospective reviews with the associated weaknesses of this type of data collection.
The Swedish Spine Register (Swespine), has been in broad use within the nation for the last 10 years and over 80% of departments performing spine surgery in Sweden report their operations to the register. This gives a large prospective database to study questions like complications. Pre- and postoperative variables are completely patient administered while data on the operation and the postoperative course are completed by the surgeon when the patient is discharged from hospital. In total 4,173 patients subjected to lumbar disc herniation surgery and completing pre- and 1 year postoperative data were included in our study which yielded a complication rate regarding dural lesions of 2.7%. In patients with previous surgery, the incidence was doubled, 5%. The relative improvement after disc surgery was similar in patients with and without a per-operative dural lesion. The more pronounced back pain and the lower general health and role emotional of patients with dural lesions was related to the fact that these patients more often had been operated on previously. These differences to some extent remained at 1 year postoperatively but also at that time point correlated to previous surgery. Working ability was also less frequent in patients without dural lesions.
The most important aspects in dural lesion complications in our opinion are preoperative planning and prevention. Studying the preoperative MRI carefully, it is obvious where the more risky parts of the procedure will be and, in the case of repeat surgery, it seems recommendable to identify the dura in an unoperated area in the proximity of the previous operation and then carry on the dissection gently into the scarred and fibrotic area. If a dural lesion is encountered, the operating table should be adjusted with the head down and back up position to facilitate the inspection of the area and, if possible to make a suture with non-resorbable 5–0 or 6–0 sutures. It probably is wisest to do this as soon as the injury is detected but sometimes the narrow circumstances may be improved if a disc fragment is resected prior to repair. When the suture is completed, the operating table is reversed with head up and back down to test the patency of the repair. Before closing the wound, it might be advisable to cover with fibrin glue or if the suture is not tight enough a synthetic dural graft may be considered.
It is generally agreed that the patient should be recumbent after surgery, in most instances probably 24 h is used as a postoperative routine. Some surgeons, however, advocate a longer bed rest, mainly based on the histomorphological sequence of dural repair in a canine model presented by Cain et al. [2] demonstrating that it takes between 6 and 10 days to see fibroblastic bridging of the durotomy.
In conclusion, this prospective study has showed an incidence rate of 2.7% concerning dural lesion in lumbar disc herniation surgery. In patients with previous operations, the risk is doubled, 5%. Patients with previous surgery have more back pain prior to surgery and a lower quality of life, which skews this group towards inferior 1-year outcome but the difference in outcome is clearly related to previous surgery and not the dural lesion as such. A conclusion that can be drawn from this study is that a dural lesion is a technical problem which should be solved during surgery and, if so, it bears no negative implications on the 1 year postoperative outcome.
Acknowledgment
The statistical help and advice by Caddie Zhou, National Competence Center of Orthopedics Lund Sweden is gratefully acknowledged.
References
- 1.Bosacco SJ, Gardner MJ, Guille JT. Evaluation and treatment of dural tears in lumbar spine surgery: a review. Clin Orthop. 2001;389:238–247. doi: 10.1097/00003086-200108000-00033. [DOI] [PubMed] [Google Scholar]
- 2.Cain JE, Jr, Lauermann WC, Rosenthal HG. The histomorphologic sequence of dural repair: observations in the canine model. Spine. 1991;16:319–323. doi: 10.1097/00007632-199108001-00002. [DOI] [PubMed] [Google Scholar]
- 3.Cammisa FP, Girardi FP, Sangani PK, Parvataneni HK, Cadag S, Sandhu HS. Indicental durotomy in spine surgery. Spine. 2000;25:2663–2667. doi: 10.1097/00007632-200010150-00019. [DOI] [PubMed] [Google Scholar]
- 4.Deyo RA, Cherkin DC, Loeser JD, Bigos SJ, Ciol MA. Morbidity and mortality in association with operations on the lumbar spine: the influence of age, diagnosis, and procedure. J Bone Joint Surg Am. 1992;74-A:536–543. [PubMed] [Google Scholar]
- 5.Eismont FJ, Wiesel SW, Rothman RH. Treatment of dural tears associated with spinal surgery. J Bone Joint Surg Am. 1981;63-A:1132–1136. [PubMed] [Google Scholar]
- 6.Jones AA, Stambough JL, Balderston RA, Rothmann RH, Booth RE., Jr Long-term results of lumbar spine surgery complicated by unintended incidental durotomy. Spine. 1989;14:443–446. doi: 10.1097/00007632-198904000-00021. [DOI] [PubMed] [Google Scholar]
- 7.Kitchel SH, Eismont FJ, Green BA. Closed subarachnoid drainage for management of cerebrospinal fluid leakage after an operation on the spine. J Bone Joint Surg Am. 1989;71-A:984–987. [PubMed] [Google Scholar]
- 8.Saxler G, Krämer J, Barden B, Kurt A, Pförtner J, Bernsmann K. The long-term clinical sequelae of incidental durotomy in lumbar disc surgery. Spine. 2005;30:2298–2302. doi: 10.1097/01.brs.0000182131.44670.f7. [DOI] [PubMed] [Google Scholar]
- 9.Spangfort EV. The lumbar disc herniation. A computer-aided analysis of 2,504 operations. Acta Orthop Scand. 1972;43(Suppl 142):1–95. doi: 10.3109/ort.1972.43.suppl-142.01. [DOI] [PubMed] [Google Scholar]
- 10.Stolke D, Sollman WP, Seifert V. Intra- and postoperative complications in lumbar disc surgery. Spine. 1989;14:56–59. doi: 10.1097/00007632-198901000-00011. [DOI] [PubMed] [Google Scholar]
- 11.Strömqvist B, Jönsson B, Fritzell P, Hägg O, Larsson B-E, Lind B. The Swedish national register for lumbar spine surgery. Acta Orthop Scand. 2001;72:99–106. doi: 10.1080/000164701317323327. [DOI] [PubMed] [Google Scholar]
- 12.Strömqvist B, Fritzell P, Hägg O, Jönsson B. One-year report from the Swedish National Spine Register. Swedish Society of Spinal Surgeons. Acta Orthop. 2005;76(Suppl 319):1–24. doi: 10.1080/17453690510041950. [DOI] [PubMed] [Google Scholar]
- 13.Wang JC, Bohlman HH, Riew KD. Dural tears secondary to operations in the lumbar spine: management and results after a two year minimum follow-up of eighty-eight patients. J Bone Joint Surg Am. 1998;80-A:1728–1732. doi: 10.2106/00004623-199812000-00002. [DOI] [PubMed] [Google Scholar]
- 14.Weinstein J, Tosteson T, Lurie J, Tosteson A, Hanscom B, Skinner J, Abdu W, Hilibrand A, Boden S, Deyo R. Surgical vs nonoperative treatment for lumbar disk herniation. JAMA. 2006;296:2441–2450. doi: 10.1001/jama.296.20.2441. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Wiese M, Krämer J, Ernst BernsmannK, Willburger R. The related outcome and complication rate in primary lumbar microscopic disc surgery depending on the surgeon`s experience: comparative studies. Spine J. 2004;4:550–556. doi: 10.1016/j.spinee.2004.02.007. [DOI] [PubMed] [Google Scholar]