Anatomical Research Of Arachnoid Structure Around Cranial Nerve Root Entry/Exit Zone And Its Significance In Patients With NVCS

Objective By observing in surgery, researching the cranial neurovascular compression syndrome (NVCS) patients’ anatomy of arachniod structure of cranial nerve root zone (Root Entry/exit Zone, REZ), and analyzing its relationship with the offending vessels, clinical, imaging and prognosis, Further investigate the pathogenesis of NVCS, to improve its treatment, improve surgical techniques and the efficacy.Methods Collected the NCS patients’clinical and imaging data who have visted the Department of Neurosurgery at the Second Hospital of LanZhou University during the period of March2011to February2014, To recorded the forms of archnoid constructed in the nerve root zone and compressing vessels and forms of oppression. To evaluate the efficacy and postoperative complications. Analyzing the relationship between the structure and responsibilities of the arachnoid vessels, forms of oppression, clinical symptoms, neuroimaging and surgical treatmentResults In the group of133cases of NVCS patients, including trigeminal neuralgia (TN)95patients,30patients of hemifacial spasm (HFS) and glossopharyngeal neuralgia (GPN)8patients.All patients were treated with retrosigmoid keyhole approach microvascular decompression(MVD), and had successfully completed surery. we have found all NVCS patients’ nerve root zone there are different degrees of arachnoid cord. Arachnoid cord exist between nerve root zone and brainstem, between nerve root zone and responsibility vessels, between nerve root zone and cerebellum, between responsibility vessels and brainstem.The arachnoid cord of nerve root zone to build forms:sparse and pulling type85cases (TN58cases,HFS21cases, GPN6cases); dense and fixed type26cases (TN18cases, HFS7cases, GPN1case); coated type14cases (TN12cases, HFS1case, GPN1case); constrained type8cases (TN7cases, HFS1case).After Statistical analysis of TN group patients, age, sex, ipsilateral, course of disease, age of onset, forms of oppression had no correlately effetion to surgery (P>0.05), while arachnoid build forms had significant correlately effction to prognosis (P<0.05).The intraoperative findings no compressing vessel in8cases(6.02%), have the compressing vessel in125cases (93.98%). In95cases TN:have showed oppression19cases (20.00%), have showed contact56cases (58.95%), have showed throughout3cases (3.16%), have showed contact and oppression5cases (5.26%), have showed contact and throughout4cases (4.21%), have only showed subarachnoid bound8cases (8.42%); In30cases HFS:have showed oppression5cases (16.67%), have showed contact16cases (53.33%), have showed throughout4cases (13.33%), have showed contact and oppression2cases (6.67%), have showed contact and throughout3cases (10.00%); In9cases GPN:have showed oppression3cases (37.50%), have showed contact3cases (37.50%), have showed contact and oppression2cases (25.00%).In TN group, The compressing vessel have showed:the superior cerebellar artery (SCA)38cases, the petrosal vein (PV)10cases, the anterior inferior cerebellar artery (AICA)18cases, posterior inferior cerebellar artery (PICA)2cases, source unknown artery (ie innominate artery)1case, mixed arteriovenous vascular responsibility type22cases, multi-joint arteries type4cases, no clear responsibility vascular8cases; In HFS group, The compressing vessel have showed:the superior cerebellar artery (SCA)3cases, the anterior inferior cerebellar artery (AICA)18cases, posterior inferior cerebellar artery (PICA)4cases, multi-joint arteries type5cases. In GPN group, The compressing vessel have showed:the superior cerebellar artery (SCA)1case, the anterior inferior cerebellar artery (AICA)1case, posterior inferior cerebellar artery (PICA)3cases, multi-joint arteries type2cases, vertebral artery1case.In the MVD for all HFS patients, we had the electrophysiological monitoring:facial muscles lateral spread response (LSR) and brainstem auditory evoked potential (BAEP). We found LSR disappeared during22patients(73.33%), did not disappear completely in8patients (26.67%); Intraoperative BAEP waveform in V wave did not change or reduced no more than50%in19patients; and reduced by50%in11patients, there were8patients gradually returned to normal after stopping operation, but3patients had not completely back to normal.Postoperative effects in all TN patients:recovery (immediate remission and complete remission within six months)71cases (74.74%), significantly remission19cases (20%), partial remission4cases (4.21%), invalid or relapse1case (1.05%); In all HFS patients:immediate remission (twitch disappeared the day postoperative)24cases (80.00%), short-term remission (twitch disappeared in the one week after surgery)4cases (13.33%), delay remission (recovery within six months postoperative)2cases. In all GPN patients:pain were instantly disappear after surgery. Postoperative complications:withdrawal syndrome appears6cases (6.32%), hearing impaired1case(1.05%), ipsilateral facial numbness14cases (11.58%) in all TN patients; hearing impaired11case(36.67%)(there were10patients gradually returned to normal after surgery, but1patients had not completely back to normal), ipsilateral facial numbness3cases (10.00%) in all HFS patients.Conclusion1. Responsibility vascular compression is the main cause of NVCS, The physiological characteristics of arachnoid build REZ area is also important. The physiological characteristics of arachnoid build REZ area can effect the direction of responsibility vascular,And pull the offending vessels and fixed to REZ area.Small number of patients solely bound and tied of arachnoid in REZ area itself may be the cause of NVCS.2. The treatment NVCS of MVD had superior efficacy, intraoperative completely release REZ area arachnoid structure is essenyial. The release of arachnoid can lift the REZ area’s stretch, and offending vessels could be reset. It may further improve the outcome.