Abstract

Background: The incidence of cerebrospinal fluid (CSF) leaks/dural tears (DT) occurring during anterior cervical diskectomy and fusion (ACDF) are typically relatively low. However, this frequency markedly increases when anterior corpectomy and fusion (ACF) are performed to address ossification of the posterior longitudinal ligament (OPLL).

Methods: The reported frequencies of CSF leaks/DT occurring during elective ACDF (i.e. exclusive of trauma), ranges from 0.24% to 1.7%. Notably, this incidence substantially rises for multilevel ACF addressing anterior OPLL, markedly varying from 3.4 - 44.7%.

Results: The classical risks of anterior cervical CSF leaks/DT with anterior cervical surgery may be minimized utilizing an operating microscope. For OPLL, careful evaluation of preoperative non-contrast CT studies is critical, especially to document whether any of the 3 signs of dural penetrance is present. Here, posterior operative choices should be strongly considered in the presence of sufficient lordosis and/or a Positive K Line (+ K Line) as this will avoid an anterior cervical CSF leak/dural fistula. Alternatively, for patients with kyphosis and a Negative K Line (- K Line), preoperative anticipation and planning to treat an intraoperative anterior CSF leak/DT (i.e. direct anterior primary dural graft repair with 7-0 Gore-Tex sutures, microdural staples, microfibrillar collagen, wound-peritoneal shunt, and lumbar drain or lumboperitneal shunt) are essential in the course of performing direct anterior OPLL resection.

Conclusion: The incidence of anterior cervical CSF leaks/DT is relatively low (i.e. range 0.24 - 1.7%) where ACDF is performed for disc disease/spur/spondylosis exclusive of OPLL. However, where ACF is performed for multilevel OPLL, the risk of CSF Leaks/DT is substantially higher (i.e. range 4.3-44.7%).

Keywords: Anterior Cervical Diskectomy/Fusion (ACDF), Anterior Corpectomy Fusion (ACF), Ossification Posterior Longitudinal Ligament (OPLL), Radiculopathy, Myelopathy, Cervical Cerebrospinal Fluid (CSF) Leaks, Dural Tears (DT), Repair Stragies CSF Fistulas

INTRODUCTION

The frequencies of anterior cervical CSF leaks/dural tears (DT) occurring during anterior cervical surgery vary markedly dependent upon the pathology; relatively low rates are observed for anterior cervical diskectomy/fusion (ACDF)[ 1 , 3 , 4 , 12 , 18 , 19 ] vs. much higher frequencies for anterior corpectomy and fusion dealing with ossification of the posterior longitudinal ligament (OPLL)[ 1 , 6 , 11 , 14 , 17 ] [ Table 1 ].[ 1 - 20 ] Routinely using an operating microscope, the range of frequencies for cerebrospinal fluid (CSF) leaks/dural tears (DT) occurring during anterior cervical diskectomy and fusion (ACDF) are relatively low (i.e. 0.24% (3048/1, 261,140 ACDF),[ 12 ] 0.45%,[ 19 ] 0.8% ACDF,[ 1 ] 1%,[ 18 ] and 0.5-1.7%).[ 1 , 4 , 12 , 18 , 19 ] However, the frequency increases markedly with anterior corpectomy and fusion (ACF) addressing ossification of the posterior longitudinal ligament (i.e. 4.3%,[ 15 ] 8.7% (7 DT out of 11 with dural ossification,[ 6 ] 27.5%,[ 11 ] 42%,[ 17 ] and and 44%)).[ 6 , 11 , 14 , 15 , 17 ] In summary, the incidence of anterior cervical CSF leaks/DT is relatively low for ACDF, but markedly increases in OPLL patients.

Table 1:

Clinical data for cerebrospinal fluid leaks/dural tears occurring during anterior cervical surgery.

Case Summary

A middle-aged patient had previously undergone a C6-C7 ACDF [ Figure 1 ]. The patient newly presented after significant cervical trauma with cervical radiculopathy/myelopathy. When the MR documented a new large central disc herniation at the C56 level filling over 50% of the spinal canal, an ACDF at the C56 level was performed using a PEEK cage [ Figure 2 ]. At surgery, we found the C56 acute disc herniation was accompanied by an irregular limbus vertebral fracture that had lacerated the dura; this DT was initially treated with microfibrillar collagen. However, within one postoperative week, the patient developed an MR-documented anterior fluid collection at the disc space level [ Figure 3 ]. At the second surgery, the anterior dural leak was directly repaired by sewing in a dural patch graft with 7-0 Gore-Tex sutures, supplemented with 1.4 mm microdural staples between the sutures, and with the placement of microfibrillar collagen. To avoid anterior cord compression, the anterior interbody graft, utilized without a plate, was deliberately replaced anteriorly in the disc space over the repair construct. Several weeks later, due to concern regarding the stability of the C56 graft, the patient underwent a posterior cervical C5-C7 instrumented fusion. AP and Lateral cervical X-rays obtained 2 months and 2 years postoperatively confirmed the stability of both the anterior (C56 ACDF) and posterior instrumentation (C5-C7 fusion) [ Figure 4 ]. Additionally, the patient remained asymptomatic over this interval.

Figure 1:

(a) Preoperative Anteroposterior (AP) and (b) Lateral Cervical X-rays. The AP (a) and Lateral (b) preoperative cervical X-rays documented a C67 anterior cervical diskectomy and fusion (ACDF) previously performed utilizing an anterior cervical plate/screws with an interbody graft.

Figure 2:

(a) Preoperative Axial and (b) Sagittal MR of the Cervical Spine. The preoperative Cervical Axial (a) and Sagittal (b) MR documented a large central disc herniation at the C56 level above the prior C67 anterior cervical diskectomy and fusion (ACDF). This disc herniation filled over 50% of the ventral spinal canal causing marked cord compression (i.e. as confirmed by the high intramedullary cord signal consistent with edema).

Figure 3:

(a) Postoperative Axial and (b) Sagittal Cervical MR 5 Days Following the C56 ACDF. The initial C56 anterior cervical diskectomy and fusion (ACDF), performed under the microscope, required the removal of a large disc herniation and placement of microfibrillar collagen over a cerebrospinal fluid (CSF) fistula attributed to a traumatic limbus vertebral fracture. (i.e. occurring secondary to the history of trauma). A Polyetheretherketone (PEEK) cage was placed. However, 5 days later, fluid accumulated in the wound, and the follow-up Axial (a) and Sagittal (b) MR scans documented a ventral hyperintense fluid collection consistent with a CSF leak/DT in the anterior epidural disc space. The second surgery, also performed utilizing an operating microscope, included teatment of the anterior CSF leak/DT by direct suturing in an anterior dural graft with 7-0 Gore-Tex Sutures, placement of 1.4 mm microdural staples between the sutures, and the application of microfibrillar collagen.

Figure 4:

No Change in the (a) Anteroposterior (AP) and (b) Lateral Cervical X-rays Obtained 2 Months and 2 Years Following the C56 Anterior Cervical Diskectomy and Fusion (ACDF) and Posterior C5-C7 Instrumented Fusion. The AP (a) and Lateral (b) Cervical X-rays obtained 2 months and 2 years following the C56 ACDF and C5-C7 posterior instrumented fusion showed no changes in the location of the anterior (C56 ACDF) or posterior (C5-C7 fusion) instrumentation.

Lessons Learned From This Case

In this patient, who sustained a traumatic cervical disc herniation, the first lesson was that we should have obtained a preoperative cervical CT scan in addition to the MR. This would likely have documented the attendant limbus vertebral fracture responsible for the ventral cerebrospinal fluid (CSF)/DT, enabling the surgeon to better anticipate the need for a complex anterior cervical dural repair. Second, surgery for traumatic cervical disc herniations require not only the routine use of an operating microscope, but also the ready availability of 7-0 Gore-Tex sutures, microdural staples (1.4 mm), and microfibrillar collagen in case a CSF leak is encountered.

Range of Incidence of CSF Leaks For Elective ACDF Surgery

The risk of CSF leaks/DT occurring during ACDF surgery ranges from 0.24-1.7% [ Table 1 ].[ 1 , 4 , 12 , 18 , 19 ] Syre et al. (2014) identified 13 (1%) of 1223 cervical trauma patients undergoing ACDF as having CSF leaks/DT (3 surgeons); notably, 9 patients underwent direct intraoperative repairs, and 4 of the 9 additionally received lumbar drains.[ 18 ] For these 9 patients undergoing primary repairs, 1 required no further intervention, 3 required additional surgery for failed dural repairs, and 3 needed shunts (i.e. including one ventriculoperitoneal shunt for newly developed hydrocephalus). Based on a Nationwide Inpatient Sample (NIS), the incidence of DT for Yoshihara et al. (2015) was 0.45% (855 patients) out of 190,021 patients undergoing cervical surgery; notably, the risk of DT increased 58.4-fold with OPLL, and anterior DT markedly increased the frequency of hospital adverse events (AE).[ 19 ] Adamson et al. (2016) performed 1000 ACF (i.e. single level vs. 2 level procedures in a 2:1 ratio) in an ambulatory surgical center (ASC), and compared the incidence of CSF leaks/DT and other AE occurring in the ASC vs. 484 control inpatients; 8 (0.8%) of the 1000 ASC patients had postoperative AE that included 1 CSF leak/DT, 3 transfers to the hospital for pain, 2 transfers for EKG changes, 1 postoperative clot, and 1 case of new postoperative weakness requiring additional surgery. [ 1 ] Of interest, there were no deaths among ASC patients, and the 30-day readmission rate was 22%. Epstein (2019) found the overall range of rates for AE following ACDF was 13.2-19.3%; CSF leaks/DT comprised 0.5-1.7% of these AE, while the reoperation rate was 11.1%, the readmission rate at 30 days was 5.1%, and the readmission rate at 90 postoperative days was 7%.[ 4 ] Kapadia et al. (2019) found 3048 (0.24%) CSF leaks/DT out of a Nationwide Inpatient Sample of 1,261,140 patients undergoing ACDF; most leaks occurred in older (i.e. over 70), non-white patients exhibiting obesity, and/or hypertension.[ 12 ] Notably, the length of stay was increased from 2.1 days to 6 days for patients with intraoperative dural fistulas.

Incidence of Anterior Cervical CSF Leaks/DT for Patients Undergoing ACDF For Trauma

Two studies, one case report and another small case series, discussed performing anterior cervical dural repairs of CSF leaks following traumatic injuries [ Table 1 ].[ 8 , 13 ] In Goodwin et al. (2016), a 21-year-old male sustained a traumatic C56 subluxation with a spinal cord injury resulting in quadriplegia following a motor vehicle accident.[ 8 ] One week postoperatively, he developed fevers, retropharyngeal air, and pneumocephalus. The esophagram documented a perforation at the C56 level that was repaired, while the ventral CSF fistula was simultaneously closed. In Lee et al. (2014), the incidence of CSF leaks/DT for those undergoing ACDF for trauma was 13.2% (i.e. 7 patients) of 53 total patients; these DT were typically recognized intraoperatively, and repairs usually including the utilization of fibrin glues.[ 13 ] Notable, was that most fibrin glue/fibrin sealant package inserts warn, as a direct contraindication, against the use of these products in the anterior cervical spine.[ 5 ]

Single Case Reports or Small Series of Patients Developing Cervical CSF Leaks/DT Following ACDF Performed in the Absence of Trauma

Single case reports and small series recounted varying rates of CSF leaks/DT occurring following non-traumatic injuries requiring ACDF.[ 2 , 7 , 10 ] Elder et al. (2016) reported 14 OPLL patients undergoing 1-2 level ACDF who experienced CSF leaks/DT; DT repairs included fibrin glue, a synthetic dural substitute, and 5 lumbar drains.[ 2 ] In Halayqeh et al. (2023), a 43-year-old female with Ehlers-Danlos Syndrome presented 1 year following an ACDF with positional headaches; diagnostic studies showed inferior displacement of the cerebellar tonsils, anterior plate subsidence, and an anterior CSF leak/DT.[ 10 ] Here, surgery required repair of the DT, and replacement of the plate (i.e. adequate replacement confirmed on postoperative studies).[ 10 ] Also, in 2023, Gazzeri et al., applied TachoSil, a fibrin sealant, to treat 7 anterior intraoperative CSF leaks/DT following ACDF where there was significant calcification of the anterior dura.[ 7 ] Again, note that most manufacturers’ package inserts cite a direct contraindication for placing fibrin sealants/fibrin glues during anterior cervical surgery due to the risks of increased swelling and resultant significant cord compression contributing to neurological deficitis.

Large Series Summarizing Risks and Management of CSF Leaks/DT in OPLL Patients

Epstein, in 2014, looked at 3 CT signs of OPLL penetrating the anterior cervical dura [ Table 1 ].[ 3 ] These findings markedly increase the risks of an anterior cervical CSF leak/DT occurring when choosing to perform anterior cervical surgery in OPLL patients [ Table 1 ].[ 3 ] The frequency of risks for anterior cervical CSF leaks/DT with OPLL varied widely; 4.3-32%,[ 15 ] 8.7% (DO 63.6% no DO 3.5%),[ 6 ] 19.6%,[ 11 ] 42%[ 17 ] and 44.7%.[ 6 , 11 , 14 , 15 , 17 ] Mazur et al. (2011) reviewed 11 studies that identified 4.3 to 32% frequencies for CSF leaks/DT occurring following anterior cervical OPLL surgery; direct dural repairs were preferred over other ajunctive measures, including drains/shunts.[ 15 ] Lei et al. (2012) encountered 21 (44.7%) CSF leaks/DT occurring with anterior OPLL surgery (i.e. positively correlated with segmental OPLL of over 5 mm, and > 50% canal stenosis); 15 occurred intraoperatively, 5 were observed postoperatively, while a 6^th involved a partial dural tear with intact arachnoid.[ 14 ] For such leaks they recommended primary suturing/repair of dural defects without the addition of shunts. Fengbin et al. (2015) found the overall incidence of anterior cervical CSF leaks/DT was 8.7% out of 126 OPLL patients; 7 (63.6%) of 11 with dural ossification developed DT vs. a lesser 4 (3.5%) instances occurring out of 115 patients without dural ossification (DO).[ 6 ] Of the 11 repairs, consisting of gelatin foam/fibrin glue, bed rest, and lumbar drains, 3 CSF leaks/DT resolved within 5 postoperative days, while 8 persisted, requiring pressure bandages, aspiration, and/or lumbar drainage. In Odate et al. (2017), 19 patients first underwent laminoplasty for OPLL followed secondarily by ACDF (revision surgery); 8 (42%) patients developed CSF leaks/DT (i.e. 8 with + K line (meaning pathology anterior to the K line allowed for anterior, posterior, or circumferential surgery) vs. 11 with - K line (pathology posterior to the K line required anterior cervical surgery)).[ 17 ] Jang et al. (2023) found 14 (19.6%) CSF leaks/DT out of 51 OPLL patients undergoing anterior cervical surgery, and discussed using a; “pump-regulated lumbar drain” to treat these fistulas while avoiding over-drainage and prolonged bed rest”.[ 11 ]

One Small Case Series and One Case Report on Treatment of CSF Leaks/DT in OPLL Patients Undergoing Anterior Cervical Surgery

One small case series and one case report discussed the presentation/management of CSF leaks/DT occurring due to OPLL and/or other pathologies [ Table 1 ].[ 9 , 16 ] Mitchell et al. (2016) discussed repairing 8 consecutive CSF leaks/DT in patients undergoing anterior cervical surgery for OPLL, intradural disc herniations, and/or dural ectasias; initial treatment included covering dural defects with dural substitutes, application of fibrin sealant, placement of an “undersized interbody anterior graft”, a low-pressure drain, and/or an additional wound drain.[ 16 ] All 8 repairs were successful (i.e. no postoperative wound dehiscence, no residual cord compression, no new neurological deficits, no meningitis, no headaches, and no need to replace lumbar drains). Guppy et al. (2017) presented 2 older OPLL patients and added 1 case of a 56-year-old female with OPLL who presented with a new C56 anterior cervical Myelo-CT-documented CSF leak/DT secondary to a prior ACDF 7 years ago; she successfully underwent detethering of the cord and repair of the C56 anterior dural defect.[ 9 ]

Case Report of Anterior Cervical CSF Leak/DT in OPLL Patient Treated with Contraindicated DuraSeal Resulting in Quadriplegia

Epstein (2021) noted that the package insert for the fibrin sealant DuraSeal (Integra LifeSciences Princeton NJ) states that it’s use is contraindicated for treating anterior cervical CSF fistulas/DT due to the risk of cord swelling/cord compression (i.e. the hydrogel swells 12% “in all directions”) [ Table 1 ].[ 5 ] Further, it should not be applied over unrepaired leaks, and should only be used as an adjunct over “sutured dural repairs” (i.e. and should not be applied for gaps of > 2 mm). In this case report, following C4 and C5 anterior corpectomies and C3-C6 anterior fusion for OPLL, the surgeon placed Duraseal over the massive, unrepaired anterior dural defect. When the postoperative MR demonstrated marked anterior cord compression due to the DuraSeal, he then performed the wrong second operation; a laminectomy/posterior fusion. No further postoperative MR studies were performed for several weeks, leaving the patient quadriplegic due to the continued anterior cord compression from DuraSeal.

CONCLUSION

The incidence of anterior cervical CSF leaks/DT is relatively low (i.e. 0.24% to 1.7%) for ACDF performed to address disc disease/spur/spondylosis exclusive of OPLL [ Table 1 ].[ 1 , 4 , 12 , 18 , 19 ] However, for OPLL patients, performing single/multilevel ACF markedly increases the risks of CSF leaks/DT (i.e. 4.3-44.7%) [ Table 1 ].[ 6 , 11 , 14 , 15 , 17 ]

Ethical approval

Institutional Review Board approval is not required.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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