Incidence and Management of Incidental Spinal Durotomies Noticed During Spinal Surgery
Ishvinder Singh Grewal1, Urpinder Singh Grewal2, *, Tom Eadsforth3, Christopher Barrett3, Robin Pillay3
Identifiers and Pagination:Year: 2019
First Page: 47
Last Page: 52
Publisher Id: TOORTHJ-13-47
Article History:Received Date: 23/10/2018
Revision Received Date: 2/1/2019
Acceptance Date: 21/1/2019
Electronic publication date: 20/02/2019
Collection year: 2019
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The aim of this study was to assess the incidence of dural tears and compare the outcomes depending on management.
A retrospective analysis of all spinal surgery over a four year period at one institution. A review of operation, and case notes to assess the intra- and post-operative management of patients suffering a dural tear and their outcomes.
3361 patients underwent invasive spinal intervention over four years. The age range was 17 to 94. The dural tear rate was higher in lumbar surgery (7.8%) compared with cervical (1.4%) and thoracic (3.8%); (p=0.000) and also in revision surgery (13.5%) compared with primary (4.8%) (p=0.000). When looking at all dural tears there was no significant difference in outcome between varying methods of dural repair and no repair at all (p=0.790). The persistent leak rate was higher in those kept in bed (17.2%) compared to those mobilised immediately (10.5%), this wasn’t statistically significant (p=0.320).
Tears occurred in 42 lumbar microdiscectomies; 93% were mobilised immediately and 79% had no dural repair, one patient developed a persistent leak. There was no difference between different repairs (p=0.964) and mobilization regimes (p=0.929). In patients undergoing bony lumbar decompression there was a difference between suture repair of the dura (9.5%) and non-suture (18%), this was not significant (p=0.304).
We advocate that patients who suffer an intra-operative dural tear should be mobilised immediately. In minimally invasive surgery such as microdiscectomy a watertight layered closure is sufficient, however, tears occurring during more invasive decompression procedures should all undergo a primary suture repair.
An incidental durotomy or dural tear is defined by ICD-10 as an accidental puncture or laceration of dura during a procedure . These procedures include spinal surgery  and interventional procedures such as epidural injection . The published incidence of incidental durotomy varies in the literature and is dependent on the procedure being performed, the experience of the surgeon, and patient factors but can range from 1% to 17% . The consequences of a dural tear to a patient can vary from nil to patient death; for example, if CSF infection  leads to sepsis . The most common manifestations of dural tear to the patient are headache, and symptoms of meningism, which are usually self-limiting . They are caused by a drop in CSF pressure leading to caudal displacement of the intracranial contents . The dural tear itself is usually healed within 10 days , unless a persistent leak develops usually indicating a CSF fluid fistula, which may result in a pseudomeningocele . It is also the second most frequently named occurrence in medical practice cases involving surgery of the lumbar spine .
The purpose of our study was to evaluate the incidence of incidental durotomies in our practice over a 4 year period, and to clarify outcomes and differences in management.
The principles of dural tear treatment have changed very little over the course of the last four decades. This consists of a primary repair; testing via Trendelenburg; watertight layered closure of muscle and fascia; and keeping the patient supine on bed rest for 4-7 days . Recent literature advises similar practice [4, 13-16].
The prolonged recumbent period itself leads to increased risk of complications such as venous thromboembolic event  and infection, as well as increased cost either to patient or hospital dependent on how treatment is financed. This is critically important as immediate mobilization has the potential for great benefits to both patient and hospital provider.
A retrospective study of all patients who underwent invasive surgical spinal intervention in a single centre recorded on MD Analyze system (Medtech Global, Australia) from January 2007 to December 2010. MD Analyze is an integrated surgical audit and outcomes database that provides prospective data tracking from diagnosis to the final outcome; and allows a retrospective audit. A keyword search was performed for operation name/description to identify all spinal cases. The operation notes were then searched for several keywords to identify cases in which durotomy occurred. These operation notes were then individually reviewed to ascertain which of these were incidental durotomies. A case note review was then performed to obtain the demographic and details of surgery. Specifically, the age and gender of the patients, whether surgery was elective or emergent; primary or revision; and what, if any repair was performed. Also assessed from the case notes, was the post-operative management; the length of hospital stay; any persistent leak or other complications; and any additional intervention required. The department was made up of twelve consultants; all of whom had been trained by the same senior consultant; and thereby all had similar surgical technique.
To ensure that ages of patients were taken at a standardized point; age recorded for purposes of the study were that at the day of surgery. Electivity of surgery was defined by planned admission via the waiting list. Method of repair was classified simply as glue; suture or both. Complications accepted were documented persistent leak; pseudomeningocele or infection. A low-pressure headache requiring no additional intervention was not counted as a complication as it was difficult to accurately quantify retrospectively and is somewhat subjective. An additional intervention was classified as any post-operative additional sutures; drains or revision surgery.
Statistical analysis of the data was then performed to assess the incidences of dural tears in various groups and compare outcomes by Fisher’s Exact Test or Pearson Chi-Square Test.
3361 patients underwent invasive spinal intervention over four years. The age of patients ranged from 17 to 94 and was normally distributed. The median patient age was 53years old. Of the 3361 interventions, 33.3% (1120 patients) were at the cervical level, 58% (1951 patients) at the lumbar level and 8.6% (290 patients) at the thoracic level (Table 1). The vast majority were primary procedures, with under 6% revision procedures (Table 2). The incidence of dural tear was noted to be 5.3% (Table 3).
The dural tear rate in revision procedures was found to be 13.5% vs 4.8% in primary procedures, this was statistically significant with a p-value of 0.005 by Fisher’s Exact Test (Table 4). The rate of dural tear varied dependent on level operated on with cervical surgery the lowest at 1.4%, followed by thoracic 3.8% and the highest rate was 7.8% in lumbar surgery. This was statistically significant by Pearson Chi-Square Test with a p-value of 0.005 (Table 5).
|Frequency||Percent||Valid Percent||Cumulative Percent|
|Frequency||Percent||Valid Percent||Cumulative Percent|
|Frequency||Percent||Valid Percent||Cumulative Percent|
|Risk Factor||% Dural Tear||p-Value|
Having established that the incidence of dural tear was most common in revision and lumbar procedures, we then analysed the difference in outcome dependent on intra- and post-operative management. Of the 179 patients who suffered a tear intra-operatively, the complete case notes were retrieved for 134.
|Level||% Dural Tear||pValue|
Intra-operatively 49.3% (66 patients) of the patients had the glue of varying brands applied, and only 5.97% (8 patients) had a suture repair. No patients had patch repairs or drains inserted. 16.4% (22 patients) had a dural repair with glue and suture and 44.8% (60 patients) had no repair of the dura. Of the patients suffering dural tear intra-operatively, 11.9% went on to develop a complication of persistent CSF leak and 9.7% required further intervention to stop this. The percentage developing persistent leaks varied from 15.9% in those glued alone, 9% in those glued and sutured, 12.5% in those sutured alone, and 10% in those with no direct dural repair. All patients had watertight layered closure of the layers above the dura. There was no significant difference (p=0.790) in the occurrence of persistent CSF leak between differing methods of closure or indeed no closure at all (Table 6).
|Repair * CSF leak Crosstabulation|
Post-operatively out of 134 patients; 29 were kept on bedrest from periods of 24-120 hours, the other 105 were mobilized immediately, for the purposes of this study that was regarded as within 24hours from surgery. The delayed mobilization group had a higher leak rate with 17.2% developing post-operative leaks, while only 10.5% of the immediately mobilized group had a persistent leak (Table 7). This was not a statistically significant difference (p=0.320).
|MOBILISATION * CSF leak Crosstabulation|
|Glue + Suture||17||1||18|
|MOBILISATION * CSF leak Crosstabulationa|
|a. Cervical or Thoracic or Lumbar = Lumbar|
We then analysed the lumbar spinal operations individually. As mentioned previously, this was by far the most common level for dural tears to occur. 152 tears were recorded intra-operatively to have occurred at this level and the complete case notes were retrieved for 113 of these. Once more, it was seen that there was no significant difference between complications and method of intra-operative repair. Those repaired with glue alone had a 15% complication rate, 5% in those repaired with glue and suture, 14% in those sutured alone and 9% in those undergoing no direct dural repair (Table 8).
Once again, post-operatively, there was no significant difference in outcome between the immediately mobilised (9%) and those kept on bed rest (15%) (Table 9).
Finally, we subdivided the lumbar surgery into those patients who had a dural tear during micro-discectomies, and those who had tear during more invasive procedures involving boney decompression.
|Suture * CSF leak Crosstabulationa|
|a. Cervical or Thoracic or Lumbar = Lumbar|
Of the 42microdiscectomies who suffered a dural tear, only 1 developed a complication (persistent CSF leak). 93% of these were mobilised immediately, and 79% had no formal dural repair. There was no significant difference in outcome between the different repairs or mobilization regimes. Of the 71 patients who suffered a tear during more invasive procedures, once more there was no significant difference between the method of repair or mobilization. There was, however, a difference between those who were sutured (9.5%) and those who weren’t (18%). This did not reach statistical significance (p=0.304) but would appear to show that when a more invasive procedure is performed there is a benefit to direct primary dural repair with sutures compared with no repair of glue alone (Table 10).
Our dural tear incidence was comparable with that shown in a prospective UK multicenter trial which also revealed that surgeons generally underestimate the regularity with which these occur . Given the aforementioned regularity of these in medicolegal cases, it is imperative that patients are accurately consented pre-operatively .
We were able to confirm what has been previously shown that the frequency of dural tears is higher in revision procedures when compared with primary procedures [16, 19-21]. The rate of dural tear was seen to be higher in lumbar spine surgery and the cervical tear rate of 1.4% in our cohort is comparable with the 1% rate seen in the series reported by Hannallah et al. .
Of greater importance was the finding that delayed mobilization and primary repair which was initially suggested by Eismont et al. in a series of only 5 patients is not as important as once believed . Most large studies since then have also advocated mandatory bed rest and primary repair with glue, suture, patch or a combination [4, 14-16, 23]. The importance of primary repair is felt to be so great that methods have been described for performing primary suture repair during microdiscectomy as this is technically difficult to achieve . There have been some small studies which have looked at early mobilization following dural tear and have all reported good results. These have, however, been relatively small [25, 26]. Khan et al. instigated a protocol of early mobilization and deemed this to be safe and effective in the treatment of dural tears .
Ours is the first study which has directly compared early versus delayed mobilization and differing methods of repair albeit retrospectively. The results clearly show there is no benefit of mandatory bed rest following dural tear, and despite not reaching statistical significance, it would appear to show that prolonged bed rest would actually appear to be detrimental and increase the risk of persistent CSF leak complications. Also, we can see that in cases of minimally invasive spinal surgery a good, watertight layered closure is sufficient without the need for direct dural repair.
Finally in cases which are more invasive and bony decompression has been performed, there would appear to be a benefit from direct primary suture repair of the tear. Despite not reaching statistical significance, it would also appear to show that the use of glue is not a substitute for direct suturing of the dura.
Our study followed up patients for up to one year post-operatively; after this patient, no patients re-presented within the 4 year time year period with later complications. It is also unlikely that patients within the study could have presented to other hospitals; as geographically, this was the only neurosurgical centre in the entire region.
However, there remains very little data on the long term sequelae of dural tears as a result of spinal surgical procedures. Therefore, further studies are required to assess long term outcomes following dural tears. For e.g., a retrospective study of patients with incidental durotomy at 10 year follow-up found that they had worse clinical outcomes in comparison to a control group . In contrast, four other comparable series to this study 189 incidental durotomies were investigated with a follow-up period from weeks to less than 5 years and no sequelae were found when the patients were treated successfully for incidental durotomies [6, 12, 15, 28]. Therefore, further studies should aim to identify prevalence of long-term sequelae and their dependence on the method of dural tear repair and mobilization status.
Currently, there is no true consensus regarding the treatment of incidental durotomies; with treatment widely varying on a surgeon by surgeon basis. Treatment modalities include primary repair with sutures, glue, muscle, fat or fascial grafts, blood or fibrin patches. Future trials should aim to randomize patients with incidental durotomies into treatment categories and then further randomize to immediate or delayed mobilization. Such trials would perhaps provide statistical clarity with regards to the gold standard treatment of incidental durotomies and mobilization status.
Limitations of this study include a limited follow-up range, absence of clinical assessment with a validated score and surgeon-to-surgeon procedural variability.
We would advocate the immediate mobilization of all patients experiencing dural tear intra-operatively and a primary suture repair of all tears occurring during invasive spinal surgery. We also believe that in minimally invasive procedures, a good layered closure is adequate and there is no benefit to technically difficult suture repair.
There are significant discrepancies between our findings and the commonly practiced approach to warrant a prospective multi-centre trial assessing early versus delayed mobilization.
ETHICS APPROVAL AND CONSENT TO PARTICIPATE
HUMAN AND ANIMAL RIGHTS
No Animals were used in this research. All human research procedures followed were in accordance with the ethical standards of the committee responsible for human experimentation (institutional and national), and with the Helsinki Declaration of 1975, as revised in 2013.
CONSENT FOR PUBLICATION
Informed consent was obtained from all individual participants included in the study.
CONFLICT OF INTEREST
The authors declare no conflict of interest, financial or otherwise.