Application of a new hydrogel dural sealant that reduces epidural adhesion formation: evaluation in a large animal laminectomy model.

Object: The aim of this study was to evaluate the application and effects of a novel, nonswelling, polyethylene glycol-based hydrogel adhesion barrier and sealant in a canine laminectomy model of CSF leakage and adhesion formation.

Methods: After full-width L-2 and L-5 laminectomies, 1-cm midline durotomies were created and sutured closed, except for the last 1-2 mm on the cranial end to create spontaneous CSF leakage. All 5 control animals received no further treatment. Experimental animals received hydrogel at both durotomy sites via either the Dual Liquid applicator (5 animals) or MicroMyst gas-assisted sprayer (5 animals). Sealing of the CSF leak was confirmed by Valsalva maneuver. At 2 months, 2 animals from each group were killed to evaluate dural healing and epidural adhesion formation. The remaining animals were similarly evaluated 4 months after surgery. One animal died at 66 days due to a cause unrelated to hydrogel treatment.

Results: In hydrogel-treated animals, all leaking durotomies were sealed intraoperatively. All animals recovered uneventfully. There were no treatment-related health effects. MicroMyst hydrogel application was more controlled, slower, and significantly less thick (p = 0.0094) than Dual Liquid application. All 5 control animals developed subcutaneous CSF accumulations under the incision within days of surgery, compared with only 1 of 10 hydrogel-treated animals (p = 0.002). At 2 and 4 months, control laminectomy sites showed extensive, dense epidural adhesions blending with neodura, compared with hydrogel-treated sites (p < 0.0001 and p = 0.0234, respectively). At 2 months in hydrogel-treated animals, gel filled the epidural space and no epidural adhesions were noted (p < 0.0001 relative to controls). At 4 months, the hydrogel was absorbed. The hydrogel space was filled with scant, loosely organized connective tissue.

Conclusions: Hydrogel prevented CSF leakage and mitigated epidural scarring without affecting healing of the dura or laminectomy site. The safety profile of the hydrogel appears favorable due to its synthetic composition, polyethylene glycol chemistry, minimal local tissue response, and lack of neurological deficits. Controlled application of such hydrogel materials may reduce the incidence of postoperative leaks, prevent adhesion formation and thus improve recovery from spinal surgery, and improve identification of tissue planes for reoperations.