The Application Of In Situ Bone Flap For Skull Base Reconstruction After Endoscopic Extended Transsphenoidal Approaches

PART ONE:THE APPLICATION OF IN SITU BONE FLAP COMBINED WITH PEDICLED NASOSEPTAL FLAP FORSKULL BASE RECONSTRUCTION AFTER ENDOSCOPICEXTENDED TRANSSPHENOIDAL APPROACHESObjective: Endoscopic extended transsphenoidal approaches(EETA)for ventral skull base tumor management often cause large skull base bone and dural defects with an open cistern/ventricle,resulting in intraoperative high-flow cerebrospinal fluid(CSF)leak.Successful to reconstruct these defects is still a challenge.In this study,an in situ bone flap closure similar to transcranial surgery was proposed to reconstruct the skull base defect after EETA,and its effect was evaluated.Methods: A retrospective analysis of consecutive patients who underwent the EETAs between January 2016 and February 2019 was performed.According to whether or not to use ISBF for skull base reconstruction,these patients were divided into the ISBF group or thenon-ISBF group for comparison.Results: Of 47 patients in the ISBF group,only one patient(2.1%)developed postoperative cerebrospinal fluid(CSF)leakage,yielding a significantly lower leakage rate in the ISBF group than in the non-ISBF group(6 of 38,15.8%,P = 0.042).Besides,when only comparing cases of hydrocephalus in the two groups,the CSF leakage rate in the ISBF group was 8.3%(1/12),which was still significantly lower than that in the non-ISBF group(62.5%,6/8)(P = 0.018).Postoperative CSF leakages in both groups were successfully treated with lumbar drainage alone,and no cases of injury to the internal carotid arteries or optic nerves occurred in either group.Conclusions: The ISBF closure for EETA is feasible and safe.The ISBF closure combining with a pedicled nasoseptal flap(PNSF)has demonstrated effectiveness at facilitating a more stable and durable reconstruction and reducing CSF leaks.PART TWO:THE APPLICATION OF IN SITU BONE FLAP COMBINED WITH FREE MIDDLE TURBINATE MUCOSAL FLAP FOR SKULL BASE RECONSTRUCTION AFTER ENDOSCOPIC EXTENDED TRANSSPHENOIDAL APPROACHESObjective: To introduce the technique of in situ bone flap(ISBF)combined with the free middle turbinate mucosal flap to reconstruct the defect caused by endoscopic extended transsphenoidal approaches(EETA)and evaluate its efficiency.Method: 21 patients who underwent skull base reconstruction using ISBF combined with the free middle turbinate mucosal flap(FMTMF)after EETA between May 2019 and December 2019 at the Neurosurgery Department of the First Affiliated Hospital of Chongqing Medical University were reviewed retrospectively.The complications and the efficiency of reconstruction were analyzed by clinical and imaging follow-up.Result: Of 21 patients,19 were craniopharyngioma and 2 were suprasellar arachnoid cyst.The postoperative CT scans with sagittal and coronal images showed no displacement of the bone flap.eleven patients presented with visual improvement and no patient encountered visualimpairment.After surgery,one patient had CSF leakage complicated with intracranial infection,and two patients were suspected of intracranial infection,and these three patients were cured with lumbar drainage.No patient returned to the operating room for CSF leakage,and no death occurred.Postoperative follow-up for(4.9 ± 2.1)months(3-10 months)presented with an excellent prognosis and no intranasal discomfort existed.The CT showed well-healing of the bone flap in all cases,and contrast-enhanced MRI in 19 patients showed free mucosal flap enhancement,indicating that the mucosal flap might grow well.Conclusion: An ISBF closure combined with the FMTMF for skull base reconstruction after EETA had an excellent reconstruction results and reduce the nasal trauma and also plays a positive role in reducing the risk of the secondary operation.