Retrospective Analysis And Experience Of Surgical Treatment For Foramen Magnum Meningiomas In A Single Institute

Background:The surgical treatment of foramen magnum meningiomas(FMMs)is always a challenge for neurosurgeons.After years of exploration,a mature surgical strategy has been developed for the treatment of FMMs.Posterior midline approach was used for the treatment of posterolateral FMMs,and far-lateral approach for the treatment of anterior tumors.The approach of the anterolateral FMMs is posterior midline and far-lateral approach.However,the research on the improvement of surgical approach,therapeutic effect and the operation of important anatomic structures is still continuing.The Department of neurosurgery at Zhujiang hospital treated 20 patients with FMMs from January 2008 to December 2017,and acquired rich experience,but these cases have not been retrospective analyzed.Objectives:By reviewing 20 cases of FMMs operated between January 2008 and December 2017 at Zhujiang hospital,we attempt to summarize our experience to provide reference for the further research.Methods:We reviewed 20 cases of FMMs operated between January 2008 and December 2017 at Zhujiang hospital,including treatment process and follow-up results.And we evaluated these patients' preoperative and postoperative neurological function by Karnofsky performance scale(KPS)to analyze the therapeutic effect.Results:In this research,there were 4 males and 16 females(mean age,44.7 ±14.4 years;range 19 to 75 years).The main symptoms were numbness of the limbs(65%)and pain of neck(40%).Mean duration of symptoms was 12.3 ± 13.7 months(ranging 0.5 from to 48 months)The preoperative KPS ranged from 20 to 100(mean,78.5 ± 17.7),postoperative KPS ranged 30 to 90(mean,74.5 ± 14.7),KPS after a year ranged from 40 to 100(mean,91.5 ± 13.5).The maximum diameter of these FMMs ranged from 10 to 49 mm(mean,28.8 ± 8.8 mm),and the average diameter was 9.3-36.3 mm(mean,23.7±6.4 mm).FMMs were classified as anterior(2 cases),anterolateral(11 cases),and posterolateral(7 cases).Among them,15 cases were operated by posterior midline approach,5 cases by basic far-lateral approach,and 15 cases(75%)were totally removed,4 cases(20%)were subtotally removed,and 1 case(5%)was partly remove.No patients died.The most common complications were posterior cranial nerve injury(35%)and numbness of limbs(35%).20 patients were followed up for 12 months.17 patients could live a normal life(KPS>80).One patient had FMM recurrence.Conclusion:1.The incidence of FMMs is low,but more often in the women than the men,the incidence is higher in people between 41 to 65 years old.The main symptoms of these patients are numbness of limbs and pain of neck.Most of the patients had a long course of diseases.2.Preoperative imaging examination such as MRI and CTA should be performed in all patients,DSA should be performed before operation when the FMMs are suspected to be highly vascularized and embolization is contemplated;3.In terms of selection of surgical approach,posterior FMMs choose posterior midline approach,anterior FMMs are considered removing by far-lateral approach firstly,and anterolateral FMMs can be remove by posterior midline and far-lateral approach.4.The size of the bone window,the exposure and protection of the vertebral artery serves for acquiring space of operation.Most anterolateral and anterior FMMs don't require resection of the occipital condyle If necessary,the Medial side of occipital condyle can be removed slightly.5.Most patients come to the hospital with a large FMMs,which needs to be excised in different sections during the operation.When separating the tumor from the brain stem,traction and electrocoagulation should be avoided.Those FMMs with severe adhesion should not be totally removed with the cost of hurting important anatomic structures.6.The injury of lower cranial nerves and aspiration pneumonia are common surgical complications.Most case of injury of lower cranial nerves can be recovered within 1 year after surgery.Using Intraoperative Neurological Monitoring(IONM)during the operation,protecting the lower cranial nerves carefully as well as stem and blood vessel can lower the rate of complication.And a strict airway management is necessary after surgery can reduce morbility of aspiration pneumonia.