Analysis Of Surgical Efficacy And Prognosis For Chiari Malformation Type Ⅰ Combined With Syringomyelia

Objective: Posterior fossa decompression combined with duraplasty and resection or cauterization of tonsils is widely accepted as an effective treatment for patients with Chiari malformation type I combined with syringomyelia.However,few studies have evaluated the effect of the two methods of management of the cerebellar tonsils.At the same time,postoperative clinical outcomes and prognostic factors of syringomyelia are unclear.The purpose of this study was to evaluate the efficacy of two types of treatment modalities of cerebellar tonsillar in patients with Chiari malformation type I combined with syringomyelia and the factors influencing the prognosis of syringomyelia.Methods: We retrospectively analyzed the demographic and disease characteristics of patients with Chiari malformation type I with syringomyelia who underwent posterior fossa decompression combined with duraplasty and resection or cauterization of tonsils and in our hospital from January 2017 to December 2020,and collected radiological results at 3 months after surgery and clinical outcomes at least 1 year later.The patients were divided into two groups according to the different treatment methods of the cerebellar tonsillar: Posterior fossa decompression with duraplasty(PFDD)and resection of tonsils vs.PFDD and cauterization of tonsils.The prognosis of syringomyelia was classified into 3 categories according to radiological results of 3 months after surgery: improvement: cavity shrinkage rate > 20%;Stability: cavity shrinkage rate: 0-20%;deterioration: cavity enlargement.The Tator score(excellent,good,or poor)and the Chicago Chiari Outcome Scale(CCOS,4-16)were used to assess prognosis and surgical outcome.Results: A total of 68 patients were enrolled in the current study,including 22 males and 46 females,with an average age of 46.6±8.3 years.tonsils cauterization was performed in 34 patients,tonsils resection was performed in the rest.The operation time of cauterization group was significantly shorter than that of resection group(p=0.003).There were no statistically significant differences in CCOS score(p=0.673),symptom improvement(p=0.457)and cavity reduction rate(p=1.000)between the two groups.There was also no significant difference in postoperative complications(p>0.05).Regression analysis showed that small preoperative cavity diameter(p=0.008)and C1-C2 facet malalignment(p=0.045)predicted poor prognosis of syringomyelia,while shorter clivus length(p=0.040)and Wackenheim’s line disjoint with the odontoid(p=0.032)were associated with better symptom improvement.Patients with preoperative headache(p=0.046)and shorter clivus(p=0.044)had higher CCOS scores.Conclusions: In patients with CM-I complicated with syringomyelia,cauterization and resection of tonsil have achieved similar short-term clinical efficacy and cavity resolution rates,and there is no significant difference in postoperative complications.However,the operation time of cauterization group was significantly shorter than that of resection group.C1-C2 facet alignment and a larger preoperative cavity diameter were associated with better syrinx prognosis.Patients with a shorter clivus and Wackenheim’s line disjoint with odontoid had higher symptom improvement rate,and patients with headache and a shorter clivus had higher CCOS scores.According to the specific situation of the patient,we can choose the appropriate surgical methods and predict the prognosis.