Dural Repair in MISS and CSF Leak Management

13 Dural Repair in MISS and CSF Leak Management

Ramin A. Morshed, Young M. Lee, and Dean Chou

Summary

Durotomies are intraoperative complications that can significantly impact a patient’s postoperative recovery and are difficult to repair during minimally invasive spine surgery (MISS). In this chapter, we review management approaches for intraoperative durotomies during MISS as well as repair techniques.

Keywords: dural tear durotomy cerebrospinal fluid leak minimally invasive spine surgery repair

13.1 Introduction

Dural tears are intraoperative complications that can significantly impact a patient’s postoperative recovery and clinical course after spine surgery. Symptoms of a cerebrospinal fluid (CSF) leak include positional headaches, dizziness, and visual impairment, but consequences may be as severe as the formation of a subdural hematoma or hygroma due to intracranial hypotension. CSF leakage from an incision may cause wound breakdown or a surgical site infection, necessitating reoperation. Furthermore, herniation of nerve roots through a pseudomeningocele may cause neurological deficits. Nandyala et al reported longer hospitalization and greater incidence of perioperative complications including high rates of neurological injury in patients with incidental durotomies during spine surgery.1

Although reportedly less frequent than in open procedures, dural tears occur in up to 1.6 to 6.6% of minimally invasive spine surgeries (MISS).²^,³^,⁴^,⁵ However, primary dural closure in these cases can be challenging given the narrow surgical working area during MISS. Thus, novel techniques for dural closure are needed. Here, we review several intraoperative techniques for management of CSF leaks in MISS as well as postoperative management considerations.

Repair of an intraoperative CSF leak is possible in MISS despite limitations placed on surgeons by the tube-retractor system. Conversion to open surgery is usually not necessary. Small openings with only CSF leakage can be repaired with dural sealants. If there are nerve roots extruded, this requires careful reinsertion and primary closure.

13.2 Techniques for Repair (Video 13.1)

Video 13.1 CSF-leak MIS dural repair.

The following steps for repair are summarized in Table 13.1. When a CSF leak is identified intraoperatively, the extent of injury must be adequately assessed immediately before proceeding with the remainder of the operation. In order to allow for better visualization, the surgical corridor may be expanded using larger diameter tubes, the intraoperative microscope may need to be brought in if not already used, and adequate lighting of the area may be achieved through the use of a fiberoptic light source. If intrathecal elements (e.g., nerve rootlets) are noted to have herniated through the dural defect, care must be taken to push these gently back intradurally. Positioning techniques such as placing the patient in Trendelenburg position may allow for relaxation of the thecal sac to allow for more facile dural edge approximation. In some instances, additional bone may need to be removed in order to completely expose the entirety of the defect.

Table 13.1 Surgical steps for management of CSF leak in MISS

1.Identification of leak	•Determine the extent and location of leak to see if primary closure is possible •Identify the size of dural opening
2.Obtain adequate exposure	•Expand surgical corridor with larger diameter tubes •Remove excess ligament or bone to better isolate area of leak and expose edges of the dura to allow closure
3.Protect critical structures	•Consider placement of paddies to cover and reduce any herniating nerve roots through the dural defect •Place patient in Trendelenburg position to allow for relaxation of thecal sac to aide in reducing any herniating nerve roots
4.Small dural defect	•Consider applying adhesive sealant •Perform Valsalva maneuver check to ensure no further leakage after repair
5.Large dural defect (nerve root sticking out)	•Drain CSF and reinsert nerve roots •Patch technique •Apply self-closing U-clips •Primary closure with suture with appropriate surgical instrumentation; consider adjuvant adhesive sealant and paraspinal muscle •Perform Valsalva maneuver check to ensure no further leakage after repair
6.Postoperative management	•Recommend bedrest for 2 to 5 days depending on size of leak •Patient positioning: Upright positioning is recommended for cervical durotomies; flat positioning is recommended for lumbar durotomies •Consideration of a lumbar drain at the time of surgery if there is high suspicion that primary closure will fail. May consider percutaneous lumbar drain placement at a later time if patient continues to have ongoing symptoms of a CSF leak or develops bogginess around the incision. The drain must be placed at a lumbar level that was not involved in the operation. We would recommend drainage of 10 to 15 mL of CSF per hour with a lower rate if patients develop low-pressure headaches •Obtain a head CT if patient develops severe, worsening headaches or a focal neurological deficit
Abbreviations: CSF, cerebrospinal fluid; CT, computed tomography; MISS, minimally invasive spine surgery.

The technique used for repair depends on the size of the defect and whether primary repair is possible based on location. Often, for small dural tears with slow rates of CSF leakage, adhesive sealant closure with agents such as fibrin glue or polyethylene glycol-based hydrogel products may be attempted with postapplication observation to ensure that the leak is not ongoing. Of note, rare reports demonstrate expansion of hydrogels after applications resulting in spinal cord or cauda equina compression.6^,⁷ With larger tears associated with more brisk flow of CSF, application of adhesive sealant may not be sufficient and primary closure must be attempted.

For slightly larger dural tears, various techniques have been reported in the literature. Shibayama et al described a patch technique using bioabsorbable polyglactin 910 and fibrin glue. Small squares of 3 to 10 mm in size were soaked in fibrinogen solution and placed over the defect, sometimes in multiple layers. Thrombin was then applied reacting with the fibrinogen to seal the defect. This technique was used in seven patients with adequate closure of the dural defect with no evidence of a CSF leak postoperatively on MRI and no need for reoperation.⁸ Other groups have used self-closing U-clips for closure of small defects, and Ferroli et al reported no evidence of persistent CSF leakage in seven patients with intraoperative durotomy using this device.⁹^,¹⁰ These devices will approximate the dural edges together to achieve closure, but it is critical to choose the correct size to ensure the edges are tightly approximated.

However, primary closure with sutures may be required for CSF leaks due to dural injury. In MISS, the use of a Castroviejo needle driver is limited because opening and closing of this microinstrument may be impaired with the additional limitation of inadequate needle rotation to throw sutures at the correct angle. Instead, a micropituitary rongeur can be used as a needle driver, a technique adapted from arthroscopic surgery.¹¹ We typically use a 5–0 prolene suture to perform a figure-of-eight suture over the tear. Other sutures that could be used include neurolon or Gore-Tex (Ethicon).¹² The suture can then be tied completely outside the wound and pushed down using a laparoscopic knot pusher. Tan et al reported primary dural closure on intended durotomies with specialized MIS Scanlan instruments (Scanlan International, St. Paul, Minnesota) with adjuvant fibrin glue with no patients having a pseudomeningocele and no patient requiring revision surgery. For more information about the specific instruments and management of CSF leaks via MIS Scanlan instruments, please refer to Chapter 11, Fig. 11.6. In this report, a Scanlan dural repair kit was used which included a special curved needle holder, Jacobson needle holder, Chitwood knot pusher, and modified suture scissors.¹² To bolster an irregular, nonlinear defect, a small piece of paraspinal muscle may be harvested and used to plug the dural defect in between a figure-of-eight stitch. Some groups advocate for adjuvant adhesive sealant application over the suture line, regardless of whether it is watertight after repair.¹³ Finally, if the dural tear is very large and primary closure through the tube is not possible despite the abovementioned techniques, conversion to an open procedure with more exposure may be needed. A summary of reports addressing dural closure in MIS cases can be found in Table 13.2 with Fig. 13.1 providing an illustration of these techniques.