Surgical Treatment Of Foramen Magnum Malformation Associated With Syringomyelia In 165 Cases

Objective The surgical management of foramen magnum malformation associated with syringomyelia is controversial.The exact and perfect surgical treatment remains unclear. The purpose of this study is to review our experience with the different methods for the management of foramen magnum malformation associated with syringomyelia and to explore the better prognosis and the correct way to treatment.Methods This is a retrospective review of 165 patients (mean patient age 33.38 years ,from 7 to 61 years old) , who were treated in our hosipital from 1995 to 2004. There were 70 males and 95 females. In 5 patients who required a second operation , some forms of posterior fossa decompression had been performed . Among the total 160 cases there were 52 cases of Basilar invagination associated with syringomyelia, 151 cases of Chiari malformation associated with syringomyelia.Based on their different radiological and clinical findings ,as well as data on patient history, different operations were given,including posterior fossa decompression, resection of the dens axis,duraplasty,syringosubarachnoid shunt,resection of the tonsils.microsurgical reduction of the cerebellar tonsils,and occipitocervical fusion-stabilization. The pure posterior fossa decompression was performed in 113 patients. An additional duraplasty was conducted in 47 patients. A resection of the dens axis was performed in 5 patients, a resection of the tonsils was in 35 patients, microsurgical reduction of the cerebellar tonsils in 48, a syringe subarachnoid shunt in 25,and a occipitocervical fusion-stabilization in 11 cases. Before surgery the cerebellar tonsils were extending below the foramen magnum level in 151 patients . According to MRI images/the tip of the tonsils descended to C-1 in 79 patients, descended to C-2 in 65 patients, and descended to C-3 or lower in 7 patients. A syrinx was found in all patients.The localization and extent of syringomyelia were assessed preoperatively. By comparing the changes of clinical symptoms and MRI findings, different operational methods were evaluated the effect of surgical management and the pathogenesis was explored.Results The clinical signs and symptoms had been markedly improved in 111cases(67.27%)until patients were discharged from hospital,improved in 43 cases(26.06%),stabilized in 6 cases(3.64%),deteriorated in 3 cases(1.82%). The mortality rate of surgery was 1.21%.Of 98 patients were followed with serial MRI in 92. The mean follow-up for the series was 2.47years(range, 3 months to 8 years). After surgery, the syrinx had disappeared in 26 cases, was decreased in size in 49,was enlarged in 3, and remained unchanged in fourteen. As revealed on postoperative MRI the position of the tonsils was in remained unchanged in 3 patients.Conclution Foramen magnum malformation associated with syringomyelia is a multifactorial disease ,it can not explained by any single factor. The true pathogenesis of foramen magnum malformation associated with syringomyelia is uncertain. The long-term results of surgical treatment on foramen magnum malformation associated with syringomyelia were definite.Posterior fossa decompression combined with different operational methods is a safe and effective method for treatment of foramen magnum malformation associated with syringomyelia . Conservative treatment should be adopted in the patients with scoliosis.ln addition .follow—up MRI findings of postoperative are essential to this patients with decompressive surgery.