INCIDENTAL DURAL FISSURES DURING DEGENERATIVE SPINE SURGERY

Transcription

1 ORTHOPAEDICS INCIDENTAL DURAL FISSURES DURING DEGENERATIVE SPINE SURGERY Mohamed EL HUSSEINI 1*, Mehde EL AFFI 1, Khalil HAIDAR 2 El Husseini M, El Affi M, Haidar K. Incidental dural fissures during degenerative spine surgery. J Med Liban 2018 ; 66 (4) : El Husseini M, El Affi M, Haidar K. Brèche fortuite de la duremère durant la chirurgie du rachis dégénératif. J Med Liban 2018 ; 66 (4) : ABSTRACT Dural sac tear is an infrequent, but well recognized complication of spine surgery in which the thin layer over the spinal cord is cut by the neurosurgeon during lumbar spine operations for degenerative disorders. Its incidence varies depending on several risk factors and regarding the intra- and postoperative management. This study included 134 patients who were operated for recurrences over two years interval. Intraoperative dural fissures were repaired through suture, by applying muscle and fat grafts. One case presented a cerebrospinal fluid (CSF) fistula which was repaired at reintervention. Dural tears occurred in 10 cases representing 67.7% of all cases. Risk factors include older age, female sex, obesity, surgeon s experience, previous operation at the same level. All incidental dural fissures during operations for degenerative lumbar disorders must be diagnosed and immediately repaired to prevent complications such as CSF fistula, osteodiscitis and increased costs of the treatment. Dural sac tears can be prevented, identified and treated, respecting a precise surgical technique and a standardized treatment protocol. Unintended durotomies were associated with fewer complications than previously reported in open spinal operations. Keywords : dural sac tear; dural fissure; CSF fistula RÉSUMÉ La brèche durale est une complication bien connue en chirurgie du rachis où la fine enveloppe recouvrant la moelle épinière est coupée par le neurochirurgien durant la chirurgie du rachis lombaire dans les pathologiesdégénératives. Son incidence varie en fonction de plusieurs facteurs de risque ainsi qu à la prise en charge per- et postopératoire. C est une étude sur deux ans qui a inclus 134 patients opérés pour récidives. Les brèches durales peropératoires ont été traitées par suture renforcée par greffes de muscle et de graisse. Un cas de fistule de liquide céphalorachidien (LCR) a été traité par reprise chirurgicale. Les déchirures du sac dural ont survenu dans 10 cas représentant 67,7% du total des cas. Les facteurs de risque comprennent entre autres l âge avancé, le sexe féminin, l obésité, l expérience du chirurgien ainsi qu une intervention antérieure au même niveau. Toutes les fissures durales accidentelles lors des interventions chirurgicales sur le rachisme lombaire dégénératif doivent être diagnostiquées et traitées immédiatement pour prévenir des complications telles que fistule de LCR, osteodiscitis et une augmentation du coût du traitement. Les brèches durales peuvent être prévenues, identifiées et traitées en respectant une technique chirurgicale précise et un protocole de traitement standardisé. Des durotomies non intentionnelles ont été associées à un taux plus bas de complications que ceux rapportés antérieurement dans les chirurgies à ciel ouvert du rachis. Mots-Clés : brèche durale; fistule de LCR INTRODUCTION Incidental injury of lumbar dura during surgery for lumbar herniated disc or lumbar spinal stenosis represents a serious problem which needs to be promptly recognized and immediately repaired to prevent further complications. The occurrence of cerebrospinal fluid (CS) fistula increases the hospitalization period and also the costs of a second surgical intervention. The dural tear may occur in various situations: following a myelography or spinal puncture, an aggression caused by a bone fragment, an inappropriate tool maneuver or excessive traction of the 1 Department of Neurosurgery, Dar Al Amal Hospital, Baalbeck, Lebanon. 2 Department of General Surgery, Hôpital Libano-Français, Zahle, Lebanon. * Corresponding author: Mohamed El Husseini, MD. drhusseiny@yahoo.com root. The incidence of unintentional durotomy during spinal operations was estimated in different series between 1.6% to 17.4%, depending on the complexity of the operation, the surgeon s experience, the type of operation primary or reintervention, the patient s age [1-5]. Several consequences of inadequately treated dural tears have been reported [6-9]. If the dural tear is not properly closed or unrecognized, patients can present with postural headaches, vertigo, posterior neck pain and/or stiffness, nausea, diplopia, photophobia, tinnitus, meningitis and blurred vision [7,10,11]. Signs and symptoms of incidental durotomy are directly related to the continuous leakage of CSF and the loss of dural turgor. Severe postural headache is a classic symptom of CSF overdrainage and dural injury. Decreased CSF pressure leads to a caudal displacement 226 Lebanese Medical Journal 2018 Volume 66 (4)

2 of neural contents, which stretches the meninges, thus resulting in a severe headache [9]. Incidental durotomy has been demonstrated to be associated with intracranial hypotension, tonsillar herniation, subdural hematoma or hygroma formation. The aim of this study is to evaluate the incidence of unintentional durotomy during operations for degenerative lumbar spinal disorders as well as the intraoperative and postoperative management of this complication. MATERIAL AND METHODS The subjects of this retrospective study were 134 patients operated during in the Dar Al Amal Hospital by two neurosurgeons and a smaller number by an orthopedic surgeon. Every patient with lumbar disc herniation presented with radicular leg pain, paresthesia and the following neurological signs: straight leg raising pain under 45, external or internal popliteal sciatic nerve paresis, depressed/ asymmetric reflexes. For all cases magnetic resonance imaging (MRI) was performed. The symptoms had persisted for more than six weeks and did not respond to conservative therapy. The patients with lumbar spinal stenosis presented with neurogenic claudication. Some patients treated previously with laminectomy in other hospitals during the period were admitted for reoperation and diagnosed with lumbar disc herniation/lumbar spinal stenosis at two or three levels Surgical treatment Primary surgery for lumbar disc herniation consisted of interlaminar approach at the herniation site, followed by discectomy. For spinal stenosis, we performed bilateral interlaminarar approach in case of foraminal stenosis, and laminectomy in case of central spinal stenosis. There were cases with previous lumbar herniation operated by laminectomy, readmitted with recurrence of herniation associated with spinal stenosis. In these cases we tried to identify normal dura mater at the extremities of the laminectomy, in order to resect as much as possible from the fibrous scar and to remove the herniated disc. When incidental dural tear occurred, we tried to close the dural breach by primary suture if possible with 4-0 silk. The suture was covered with gel foam, fat graft and muscle graft. In other cases with small dural breach, when the suture was unnecessary or impossible, we applied muscle graft, fat graft, gel foam and fibrin glue. Subfascial drains were used according to the surgeon s preference. We also used vancomycine which was placed in the epidural space at the end of the operation. Postoperative management Patients received antibiotics IV (cefazolin) for three days. They remained at bed rest in prone position for two to three days, depending on the length of the durotomy and the quality of dural repair. RESULTS This study included 134 patients operated for lumbar degenerative diseases. Dural fistulas occurred in 10 cases, with an overall incidence of 7.4%, in patients aged between 45 and 69 years, with a peak in the sixth decade. This peak corresponds to the decade of appearance and operation on patients with herniated disc, representing 67.7% of all cases. Dural leaks occurred more frequently during reinterventions (23%), compared with the primary approaches for herniated disc (3.5%) or spinal stenosis (6.13%). The extremely large number of dural leaks in cases of resurgery is due to the fact that in many of these patients, laminectomy was performed at 1 or 2 levels. Some of them were also operated for lumbar instrumentation and at radiological control we discovered the vicious position of screws. The postoperative scars were extensive and adherent. Reintervention was performed for recurring hernia at the same level or adjacent levels, trying to remove the fragment of the herniated disc and the epidural scar or replacing the screws. While studying the operation protocols, we observed that the dura mater was described as thin, translucent, even in cases without dural rupture. In such cases, if an adjustment of the superior articular facet after removing its internal third is not performed, puncture dural fissures could occur after closing the operative wound due to dural friction on the irregular surface of the vertebra. The most common locations of the dural injury were the lateral lesions (84.7%). The risk of fistula increases in cases with imperfect suture of aponeurosis or skin [2]. Because the tension inside dura is higher at lumbar level, especially in orthostatic position, the mechanisms permitting the closure do not realize their purpose. This liquid in tension forces its way out and realize an external fistula [12]. The most common locations of dural injury were the lateral lesions (84.7%), followed by injuries of the root sheath and root axilla. Primary dural repair was made by suturing the dura in seven cases, supplemented by applying fat and muscle grafts. In some cases, the suture of the dura was not necessary because the breach was punctuated and we used autologous fat and muscle to cover the dural defect. The epidural drain was used in five cases. In other cases it was considered that epidural bleeding promotes breach closure, but blood can also be M. HUSSEINI et al. Incidental dural fissures Lebanese Medical Journal 2018 Volume 66 (4) 227

3 a good culture medium and can lead to secondary infection. The patient with intraoperative CSF leak remained at bed rest in prone position for three days and received antibiotics to prevent infection; some authors questioned the antibiotic prophylaxis, recommending instead an epidural blood patch [13]. In two cases, the dural leak was not recognized intraoperatively during the primary surgery and its repair was performed during reintervention by dural suture. Another postoperative complication, osteodiscitis, occured in one patient who had no epidural drainage after surgery. In the case of one patient who was operated without any dural tear and infection, a wound dehiscency appeared when the stitches were removed. DISCUSSION Incidental durotomy was reported in several series of patients operated for degenerative spinal injuries and is a common complication of spinal surgery, even when performed by surgeons with high professional qualifications. It is often underreported by hospitals and thus may be more common than previously thought [14]. Incidental tearing of the dura mater in spinal surgery is encountered in 10% of the primary interventions and twice as much in relapses. The incidence of dural tears is variable according to the indications, the type of procedures and the different studies. The reported incidence varies between 1.6% and 17.4%. Williams BJ et al. examining over 108,000 spine surgery patients found 1.6% of them experienced a dural tear [15]. Stolke D et al. revealed in 1989 a 17.4% incidence rate of dural tears in a study population of 481 patients who underwent back surgery [16]. In the US, the Coordination and Maintenance Committee (ICD-CM) found that 57% of the hospitals they scrutinized underreported the incidence of dural tears. The committee asserted that 46% of the 2,446 hospitals reported no dural tears at all [15]. A peek at patient records found that dural tears were presented more often in people who experienced poor outcomes from spine surgery in which a synovial cyst was removed. According to the authors, it looks as though the dural tear foreshadowed the poor surgical outcomes [16]. According to Klessinger et al., dural tears tend to happen most often at the L5/S1 level. They also state that when only part of the cyst is removed, the patient is not at risk for a dural tear [17]. Morgan-Hough et al. reported 46 (8.7%) complications in 2003, with 29 dural tears (5.5%) in 531 operations for lumbar disc herniation [18]. Our study reported an incidence of 7.4% located towards the lower limit of the incidence reported in current literature. Regarding operations for recurrent disc herniations, we can confirm that there is indeed a significantly higher incidence of unintentional dural tear than reported previously [4,5,19,20]. The higher incidence in revision operations can be explained by the fact that, in the past, the approach used for disc herniations was laminectomy, which left behind an extensive epidural scar at the levels of the dura and the nerve roots. We removed the entire epidural scar and the disc herniation. If the dissection in the epidural space was lateral, at the level of the herniated disc, leaving scar on the posterior dural sac, the incidence rate of incidental durotomy decreased. In our study, durotomy did not associate with damage to the spinal nerves and has not created new neurological deficits postoperatively. Use of high speed drills, decompression for ossification of the posterior longitudinal ligament and spine surgery revision procedures are associated with an increase risk for incidental durotomies. Discussing risk factors studied previously we can mention older age [21-25], female sex [22,23], experience level of the surgeon [25], elevated surgical invasiveness [22], lumbar surgery [20], revision surgery [21,22], pre-existing conditions such as degenerative spondylolisthesis [2,24], ossification of the posterior longitudinal ligament (OPLL) [26], and synovial cysts [24]. Dural leaks are more common in obese patients, in old patients in whom disc herniation reoccurs and occur more often with less experienced surgeons. Irregular bone surfaces in interluminar approach could explain the occurrence of CSF fistula in cases when any dural break was not notified and the dura was thin, translucent. Among the comorbidities, only obesity can be a risk factor regarding a miniopen approach like the interluminar approach, the depth of the lesion can create the condition of an unintentional dural rupture. All patients were operated under general anesthesia. When operations were occasionally performed under spinal anesthesia, we found that when the patient coughs during the operation a displacement and a swelling of the dura occur due to increased intracanial pressure, which is why we do not advise spinal anesthesia because, during discectomy, sudden mobility may favor dural breaking. Two previous reports have described female sex as a risk factor for incidental durotomy [27,28]; however, neither explained the reasons for this finding. Hong et al. analyzed the dural sac thickness in the human spine and concluded that it tended to be thinner in women than in men [29]. Incidental durotomy was also found less likely to occur in discectomy than in lumbar spinal decompression [30,31]. Regarding the postoperative consequences of dural injuries, Wang et al., Jones et al. and Cammisa et al. concluded similarly: dural tears do not have deleterious effects in outcomes, do not increase the risk of other 228 Lebanese Medical Journal 2018 Volume 66 (4) M. HUSSEINI et al. Incidental dural fissures

4 perioperative morbidities or later outcome [4,5,7]. Saxler et al. had different results: 41 lumbar discectomy patients with intraoperative dural tear presented a poorer outcome after surgery [32]. Dural sac tears can lead to cerebrospinal fluid leakage, meningitis, nerve problems and more serious conditions [33]. Dural tear is detected intraoperatively by the presence of CSF in the epidural space. In punctiform dural tear, CSF is in small quantity, mixed with blood, and dural fissure can remain unrecognized. Anterior, small dural sac rupture is difficult to observe. In this case, a postoperative MRI can reveal the site of dural lesion [34]. Even after dural suture, CSF can be observed leaking in the epidural space through the repaired defect while performing Valsalva maneuver. Some treatment strategies have shown a promising effect toward: 1) creating watertight dural closure to stop CSF leak with the help of dural substitute material; and 2) retarding CSF leak by changing pressure difference, including reducing the subarachnoid fluid pressure, increasing the epidural space pressure and both [33]. To decrease intradural pressure of CSF when the dura mater was very thin or during the dural suture, we used the Trendelenburg position and blocked CSF with a cottonoid in the superior pole of the approach. Primary repair of durotomies, once recognized, should always be done to prevent the complications. In small punctiform durotomies, fat graft, muscle graft or a simple blood patch can be effective, but larger dural tears must be sutured. In all cases fibrin glue is recommended. Recent studies showed that polyethylene glycol (PEG) is the hydrogelof choice [34,35]. Kim compared the efficacy of PEG hydrogel sealant and fibrin glue as an adjuvant repair. It was found that the successful rate in watertight closure is 91.2% vs 63.6% [36]. But there is a warning of potential expansion up to 50%. Two cases of cervical cord compression by hydrogel were reported [37]. Autologous fat graft as an excellent water sealant is a good alternative for muscle graft. It can revascularize, prevent scar formation, and does not adhere to the neural elements [38]. In 2016, a low-swell PEG hydrogel as a modified form was developed and proved to have a significantly higher rate of watertight closure than fibrin glue (98.6% vs 79.2%) [39]. In 2018, a fast-resorbing polymer mesh-supported reconstruction technique was described for dural tear [40]. The methods to reduce subarachnoid fluid pressure include inhibiting the formation of CSF, adjusting patient s position, and CSF shunting by subarachnoid catheter. In a randomized clinical trial on 28 patients, a dose of 25 mg/kg/day of acetazolamide was administered in the first 48h. After treatment, the CSF leak stopped in all patients [41]. Another issue such as the use of drains is controversial. We used it in five patients. Wang et al. placed a drain in all cases [5]. Eismont et al. do not recommend drain, arguing it could favor the formation of CSF fistula [42]. Cammisa et al. used a drain in case of adequate tear repair [4]. A tight fascial closure can increase the epidural fluid pressure, delay CSF flow and facilitate the dural flaps to adhere. In the meantime, subfascial drain and discharging excessive CSF will eliminate the dead space [43]. A good repair of dural tear can be accompanied by postoperative bed rest. Patients from our study remained in bed rest for 3-5 days, in prone position. The length of bed rest required was determined by the surgical procedure, the size of durotomy, the quality of primary repair and postoperative symptoms. In other series, postoperative bed rest was used for a similar period of time but in supine position [4,5]. Hodges et al. reported that 75% of the patients who had dural tears repaired during surgery did not need bed rest [44]. In case of dural tear and intraoperative dural repair, postoperative bed rest and prolonged postoperative antibiotic prophylaxis were recommended to prevent complications. We had one case with discitis and one case with dehiscent wound. Weinstein et al. reported an overall infection rate of 2.1% and 8.1% deep normal infection rate in durotomy cases [45]. We were not able to demonstrate a specific spinal location in which dural tears tend to happen more frequently. Although our study included a large number of patients, there was no region of the spine that was significantly more represented in terms of number of dural tears. This may be due to the fact that dural tears happened for different reasons and many tears are due to adhesions and scarring that can appear in different regions across the dural sac. CONCLUSION Incidental injury of the dural sac is a relatively frequent intraoperative occurrence of spinal surgery. The incidence of dural tear was higher in patients who underwent laminectomy than in those who underwent microdiscectomy and revision surgery. Obesity and revision surgery are risk factors for incidental durotomy. In order to prevent or to minimize the incidental dural injury, spinal surgeries should be performed by experienced spine surgeons and respect a strict protocol. Suture remains the best way to treat dural tears. Nevertheless, long-term follow-up is needed to assess long-term outcome. Spine surgeons should discuss the risks and complications preoperatively. M. HUSSEINI et al. Incidental dural fissures Lebanese Medical Journal 2018 Volume 66 (4) 229

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