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Dural Repair and Patch Techniques: Anterior and Posterior

The gold standard for treatment of all CSF leaks is primary repair of the dural defect with 5-0 or 6-0 Prolene or Neurilon. There are certain pathologic situations and intraspinal locations for which primary repair may be technically formidable or impossible and require patch techniques (Fig. 80.1). This includes a durotomy in the setting of anterior cervical or lumbar diskectomy, en bloc removal of tumor with adherent dura, resection of an intradural tumor, microdiskectomy with adherent nerve root sleeve, adherent stenotic ossification of the posterior longitudinal ligament (OPLL) or ligamentum flavum, and traumatic bony laceration of dura.

Fig. 80.1 Type A tear can be repaired primarily, whereas type B opening requires patch technique. Types C and D tears should be considered for fat, fibrin glue, or collagen matrix onlay bailout.

Contraindications

Do not attempt primary dural repair if under tension secondary to a large defect or constraining adhesions. Pinhole high-pressure leaks are better treated with enlargement and primary suture closure. A patch repair cannot be performed if a dural edge cannot be circumferentially exposed. Management of durotomy in the setting of an acute infection is a challenge.

Special Considerations

There is a published association of dural tears with smoking, diabetes, more than three epidural steroid injections 6 months prior to surgery, trauma, and revision surgery. Preoperative planning enables the surgeon to be prepared for dural repair with a choice of graft. Patients must be informed of the nature, purpose, risks, benefits, and alternatives of autograft (fascia lata, lumbodorsal fascia, or fat), allograft (cadaveric dura or pericardium), xenograft (bovine pericardium), or synthetic (Gore-Tex or DuraGen [Integra Life Sciences Corp., Plainsboro, NJ] collagen matrix suture or sutureless) patch grafts.

Special Instructions, Position, and Anesthesia

A surgical microscope or loupes can enhance the evaluation and repair of durotomies. The availability of specialized instruments such a watchmaker’s or knot-tying forceps, microscissors, microneedle holder, and knot-pusher can mitigate the technical difficulty of a small workspace.

If autograft fascia lata is to be used for patch repair, then the patient’s lateral thigh should be available, prepped, and draped at the start of the procedure. Anesthesia personnel will have to perform Valsalva maneuver to test the repair or sometimes identify the pinhole tear.

Tips, Pearls, and Lessons Learned

Local erector spinae fascia or fat is readily available without increased risks. Collagen matrix onlay can be successful with limited technical or time demands but adds to material costs. Autograft fascia lata has the best handling characteristics and does not pose the risk of disease transmission but requires separate incision with associated morbidity including possible weakness of leg abduction.

Placement of an intradural lumbar drain for 3 to 5 days reduces CSF pressure on the repair; however, the surgical and nursing staff must be extremely diligent in monitoring the flow (<10 cc/hr) and position (ear or shoulder level). Remember to continue prophylactic antibiotics until the drain is discontinued. If CSF appears cloudy or turbid, then fluid should be sent for Gram stain and cultures. We recommend placing a skin stitch upon drain removal to minimize leakage. If there is persistent drain-site leakage, then place a pressure dressing and institute bed rest for 2 to 3 more days.

Strategies to reduce perioperative intrathecal pressure include decreasing central venous pressure if a central line is present, smooth reversal of anesthesia to decrease tracheal irritation and coughing, Foley catheter for 2 to 5 days to facilitate bed rest, curbing narcotic use or providing stool softeners or laxatives to decrease constipation, antitussives, and locking the head of bed to <30 to 45 degrees. One should also avoid postoperative steroids if possible to promote physiologic augmentation of the primary or patch dural repair.

If using DuraGen collagen matrix onlay (sutureless) technique, then a local drain is required (Fig. 80.2). With other techniques, however, local drains may pose the risk of repair breakdown or encourage formation of CSF fistula. If a local drain is preferred, then we recommend draining off the suction. Although a Gore-Tex synthetic graft is readily available, it is relatively stiff and requires special needles and suture, which makes it challenging in a narrow workspace. Patch suturing does leave pinholes from the suture needle that can be sealed with fibrin glue.

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