Freeze-dried Amniotic Membrane For Repair Of Dural Defects

Objective:To study the probability of freeze-dried amniotic membrane (FDAM) as a dural substitue.Methods:32 guinea pigs were randomly divided into 4 groups (8 in each group).Each of the guinea pigs underwent bilateral parietal craniectomy behind the coronal suture and beside the midline to expose the dura. On the right side, a piece of dura mater was removed. The dural defect was covered with a piece of FDAM. The exposed dura on the left was cut and sutured itself as control. The animals in each group were sacrificed at 15,30,60 and 90 days after operation,respectively.The implants were harvested and stained with hematoxylin-eosin, and histologically analyzed. Blood samples were collected from guinea pigs before operation and before sacrifice. White blood cell counts were measured. Twenty-four clinical patients were chosen for the experiment,among whom 6 patients were performed the skull surgical operations of replacing the dura mater with FDAM,and 18 patients accepted the operations of replacing the dura mater with another biological artificial dura mater.The data were analyzed by SPSS 16.0 system software.Results:After operation, the behavior of all guinea pigs remained completely normal. The wound healing was achieved in all cases. No wound infection, subcutaneous effusion or cerebrospinal fluid (CSF) leakage occurred. The graft was degraded gradually and covered with a sheet of connective tissue. Dural defects repaired with FDAM showed no adhesions to the brain surface.15 days after operation, plenty of scattered fibroblasts appeared in the dural substitute.30 days after dural graft implantation, parts of the implant disappeared; meanwhile the hyperplasia of fibrous connective tissue took place in the center part of the dural substitute, without the infiltration of inflammatory cells.60 days after implantation, a majority of the dural graft was degraded, substituted by fibrous connective tissue which was of hyperplasia and low-grade degeneration, surrounded by a small quantity of giant cells.90 days after operation, colloidal degeneration happened in the dural substitute, surrounded by ossification tissue and the degenerated fibrous connective tissue. The inflammatory cells were not discovered.White blood cell counts were no significant differences before operation and before sacrifice (P>0.05).CT examinations were performed in all patients after operation.It revealed no abnormal imaging changes at the positions of dural defect which was repaired with either FDAM or another biological artificial dura mater.Post-operative complications(including infection.cerebrospinal fluid leakage and epilepsy) in two groups showed no statistical significant differences(P>0.05). All the patients who developed post-operative complications had got recovery after treatment.No physical discomfort was observed during follow-up period in all patients.Conclusion:FDAM was expected to be used widely in neurosurgery operation as a safe and applicable dural substitute.