The rate of cerebrospinal fluid leakage after spine surgery
Durotomy-induced CSF leakage is undesirable but relatively common in spine surgery, especially in cases with dural adhesion and dural ossification. The incidence varied with different procedures and different series of patients. Woff et al. observed that 1.7% of 1359 lumbar patients had CSF leakage. However, Khan et al. reported an overall CSF leakage incidence as high as 10.6% in 3183 lumbar patients, which consisted of the largest number of cases. Hannallah et al. noted that 1% of 2216 cervical spine procedures had CSF leakage. Cammisa et al. retrospectively reviewed 2144 patients, including 422 cervical surgery (338 anterior and 84 posterior), 7 posterior thoracic surgery, and 1715 lumbosacral surgery (1646 posterior and 69 anterior), and the overall incidence of CSF leakage was 3.5%. There were few reports about CSF leakage after thoracic decompression, and the incidence varied from 10–22.2%[17–19]. In this study, the incidence of CSF leak was 46.3%, which was higher than that in previous studies, and could be due to the higher rate of dural ossification (DO) (49.6%).
Repair Strategy For Dural Tear
CSF leakage induces adverse sequelae if handled improperly, such as wound non-healing, infection, CSF fistulas and meningitis [1, 14]. The treatment of CSF leakage can be classified into two treatment regimens: 1) directly close with sutures or indirectly close the dura tear with the onlay technique using dural substitute material to stop CSF leakage; 2) reduce the subarachnoid fluid and/or increase the epidural space pressure to decelerate CSF leakage.
Generally, direct repair is the best way to treat dural tear. However, it still has a failure rate of 5–9% in previous studies. In our study, one of two patients in group A had a failed direct repair of dura. Indirect closure with the onlay technique will be indicated when it is impossible to suture directly onto the edge of the dura mater or dura tear that involves the nerve root sleeve or axilla, or if dural tear lies anteriorly[2, 14]. Fat/fascia/muscle grafting, synthetic grafts, and collagen matrix/gelatin sponge can be used for this technique. Some surgeons choose not suturing if there is no breach in the arachnoid[11, 21, 22]. The rationale for this approach was that the risk of arachnoid herniation is balanced by the risk of CSF leakage through the needle holes during suturing. In addition, direct suture repair may prolong the operative time and increase surgical risk. Conservative measures in the management of dura tears included drain placement, adjustment of patient position, fluid restriction and acetazolamide to decrease CSF production[4, 23]. Although many methods for managing CSF leakage have been proposed, the optimal one remains controversial. In our study, all except two patients underwent indirect repair and subfascial wound drainage in group A due to difficulty for direct repair.
The Role Of Prolonged Wound Drain
The use of wound drains is also controversial. Some surgeons defend controlled continuous drainage to prevent meningoceles and extradural hematomas[9, 11]. For patients with CSF leakage, continuously evacuating CSF out of the wound, has been shown to facilitate sufficient healing and sealing time for the dura, soft tissue, and fascia, thereby preventing dead space and also allows the surgical wound to epithelialize and prevent the formation of CSF fistula[3, 10]. In the meantime, a tight fascial closure can increase the epidural fluid pressure, restrict CSF flow, and facilitate the dura flaps to adhere[1, 14]. Some authors counter the placement of drainage due to concern of CSF hypovolemia due to overdrainage[9, 25], which will induce headache, nausea, and vomiting. There was also a concern of complications associated with closed suction wound drains, including infection, hematoma formation, and additional neurological deficit[26, 27]. However, in the study by Niu et al., none of the 25 patients suffered from complications associated with subfascial drain after intentional durotomy. In our study, subfascial drainage was placed for all the patients to prevent extradural hematomas and evacuate the CSF to facilitate the wound to heal.
When CSF leakage occurred, the drains were left in place for a longer time than usual. The drain tubes were only pulled out when the surgeon assessed the fascia and wound closures to be well healed. However, there is no consensus about the duration of subfascial drainage. Hughes et al. proposed this time to be about 10 to 17 days postoperatively for patients without suture of durotomy. Fang et al. recommended drain tube duration of more than 7 days. Others support postoperative drainage for an average of 3 days. In the process of soft tissue repair, the inflammatory response starts in two days. Primary fibroblastic bridging occurs until postoperative day 6, and the surface is coated with inflammatory cells until postoperative day 10[27, 29]. Considering the above results, we left the wound drain in-situ for an average of 7.6 days in group A in our study. The positive results showed that none of the patients suffered from wound breakdown or fistula.
The Role Of Preventive Use Of Antibiotics For Cerebrospinal Fluid Leakage After Spine Surgery
Another risk of wound drains is ascending infection or meningitis from a tube left in place for a long time. The rate of deep wound infection could be as high as 8.1% in patients with durotomies. Although there is a consensus on the pertinence of prophylactic antibiotic therapy at induction[30, 31], the indication for prolonged antibiotic therapy, when a tear occurs, is subject to debate. Considering the risk of infection and secondary serious consequences, such as meningitis, we prolonged the time for prophylactic use of antibiotics to be 7 to 10 days, and the results showed that the rate of infection had no significant difference between the patients in group A and B.
Several limitations of this study should be noted. This was a retrospective study and had all the limitations of retrospective studies. There was no control group that had a longer duration of drainage tube without prolonged use of antibiotics. However, it is clinically not suitable to set up this control group due to the high risk of infection, and serious adverse consequences.