Surgical Approach And Technique For Endoscopic Endonasal Surgery Of Knosp Grade 4 Pituitary Adenoma,Anatomical Study And Clinical Application

Part I:Further investigation of the lateral approach for the resection of Knosp grade 4 pituitary adenomas in endoscopic endonasal surgeryBackground: The endoscopic endonasal lateral-approach is used to remove the tumor in the lateral compartment of the cavernous sinus(CS)of Knosp grade 4pituitary adenoma(KG4PAs).However,the present lateral approach is difficult to achieve safe and effective resection of KG4 PAs,resulting in a low gross total resection(GTR)rate of KG4 PA.Objective: Further in-depth study of the lateral compartment by endoscopic endonasal approach(EEA)to improve safety and efficacy of the lateral approach.Methods: Sixteen cadaveric specimens were used for endonasal endoscopic dissection,and the lateral compartment of the CS was exposed to observe the neurovascular and fiber structures within the lateral compartment.A subclassification of the lateral approach based on further knowledge of the lateral compartment was proposed.Results: The authors identified multiple fibers that anchored the horizontal segment of internal carotid artery(ICA)to the abducens nerve.The fibers,the sympathetic nerve,and the inferior lateral trunk(ILT)form a partition-like structure in the lateral compartment named the abducens nerve-ICA complex(AIC),and the lateral compartment can be divided into the superolateral and inferolateral compartments by AIC.Accordingly,the lateral approach was subclassified into superior lateral(SL)approach and anterior inferior(AI)approach;the SL approach is mainly used to resect type A KG4 PAs,the AI approach is used to resect type B KG4 PAs,and the combination of the two is used for type AB KG4 PAs.Conclusion: This study revealed that the lateral compartment was divided by the AIC into the superolateral and inferolateral compartments,avoiding the misconception that the lateral compartment was an up-and-down communication.Therefore,the lateral approach was subclassified into the SL approach and the AI approach for resection of KG4 PAs,which significantly improved the safety in the surgical treatment of KG4 PAs.Part II:A novel technique to manage internal carotid artery injury in endoscopic endonasal skull base surgery in the premise of proximal and distal controlsObjective: Intraoperative internal carotid artery injury is one of the most daunting complications in endoscopic skull base surgery.This study aimed to propose a novel technique to manage ICA injury after proximal and distal controls.Methods: The appropriate block sites together with the proximal and distal controls of ICA were demonstrated in six injected cadaveric specimens.The surgical outcomes of five patients with intraoperative ICA injury and managed with this concept were retrospectively reviewed.Results: Five block sites for vascular control could be identified in all six specimens,including(1)distal to the distal dural ring,(2)proximal to the proximal dural ring,(3)anterior genu of the parasellar ICA,(4)the upper third of the paraclival ICA,and(5)just above the foramen lacerum.Both proximal and distal controls of ICA were achieved by using the block sites in combination.Gross tumor resection was achieved in all five cases after the intraoperative ICA injury was successfully managed.Three coping techniques were used,including direct coagulation to seal(three cases),endoscopic suture(one case),and coagulation to sacrifice(one case).Focal brainstem infarction occurred in one case,one patient died of intracranial infection,and the other three cases had no sequelae.No pseudoaneurysm occurred in all patients.Except the sacrificed ICA,the other ICA was intact during follow-up.Conclusions: It is technically feasible to manage ICA injuries after proximal and distal controls during EEA surgeries.The surgical outcomes from our case series supported the use of this novel technique.Part III:Outcomes and Complications of Aggressive Resection Strategy for Pituitary Adenomas in Knosp Grade 4 With Transsphenoidal EndoscopyObjective: Surgery for pituitary adenomas(PAs)with cavernoussinus(CS)invasion in Knosp grade4 is a great challenge and whether to adopt a conservative or aggressive surgical strategy is controversial.The aim of this study is to provide the outcomes and complications of an aggressive resection strategy for Knosp grade 4PAs with transsphenoidal endoscopic surgery.Methods: Outcomes and complications were retrospectively analyzed in 102 patients with Knosp grade 4 PAs.Results: Among them,53 cases were females and 49 males,primary PAs were seen in 60 patients and recurrent Pas were seen in 42 cases.Gross total resection(GTR)of the entire tumor was achieved in 72 cases(70.6%),subtotal tumor resection(STR)in 18 cases(17.6%),and partial tumor resection(PTR)in 12 cases(11.8%).Additionally,GTR of the tumor within the CS was achieved in 82 patients(80.4%),STR in 17 patients(16.7%),and PTR in 3 patients(2.9%).40 cases(39.2%)were classified as functional PAs,and hormone remission was seen in 29 of these 40patients(72.5%),postoperatively.The GTR rates of the entire lesion and the CS lesion in the primary tumor were 80% and 91.7%,respectively.Statistical analyses showed that both recurrent tumors and firm consistency tumors were adverse factors for complete resection(P<0.05).Patients with GTR of the entire tumor were more likely to have favorable endocrine and visual outcomes than those with incomplete resection(P<0.05).Overall,the most common surgical complication was new cranial nerve palsy(n=7,6.8%).The incidence of internal carotid artery(ICA)injury and postoperative cerebrospinal fluid(CSF)leakage was 2.0%(n=2)and 5.9%(n=6),respectively.Six patients(5.9%)experienced tumor recurrence postoperatively.Conclusions: For experienced neuroendoscopists,an aggressive tumor resection strategy via transsphenoidal endoscopic surgery may be an effective and safe option for Knosp grade 4 PAs.