Classification And Neuroendoscopic Managements Of Sylvian Arachnoid Cysts

Objectives Preliminary discussion on the cerebrospinal fluid circulation in the cisterns, and establish the theory of the SACs; A new type of clinical SACs is provided to guide how to select the method of operation;Methods (1) Review of related literature and selected the imaging data of the 210 cases of intracranial arachnoid cysts intracranial which come from the neurosurgery of the First Affiliated Hospital of Kunming Medical University during the May 2008 to December 2015,and summarize the cerebrospinal fluid circulation route.(2)125 cases of Sylvian arachnoid cysts in this period of time were selected; According to the relationship between the cyst and the lateral fissure cistern, a new type of Sylvian arachnoid cysts is proposed:Type I. Inner wall of SACs locating at the lateral one third part of Sylvian fissure, Type II. Inner wall locating at the middle one third part of Sylvian fissure, Type III. Inner wall stretching to the cisterna interpeduncularis. With the basis of the circulation of cerebrospinal fluid, according to different types of SACs characteristics, different operation methods are adopted in the treatment of SACs..Among them,25patients were selected for conservative observation, and others, Neuroendoscopic Cyst-Sylvian fissure fenestration was applied for Type I and II, whereas neuroendoscopic Cyst-cistern fenestration for Type high.Results (1) According to our clinical experience, We summarize two pathways of cerebrospinal fluid flow which outflow from the four ventriclee: ①Median foramen-magna cistern-superior cerebellarcistern-quadrigeminal cistern-ambient cistern-crural cistern-interpeduncular cistern-sylvian cistern-hemispheric cistern; ② Side hole-inferior cerebellopontine cistern-superior cerebellopontine cistern-prepontine cistern-interpeduncular cistern-chiasmatic cistern-olfactory cistern-carotid cistern-sylvian cistern-hemispheric cistern. The reliability of the circulation was proved by the analysis of the imaging data of 210 patients with IACs who underwent surgery.(2)Mean follow-up time was 19.8 months,25 cases of conservative observers regularly review MRI showed that there is no significant changes in the cyst, and continue to observe. Percentage of cyst deflation, clinical improvements and subdural effusion or subdural hematoma were 70%,56% and 10% for all SACs. Furthermore, Type III performed much better than the other in cyst deflation and clinical improvements (p<0.05), with much less probability of subdural effusion or subdural hematoma (p<0.05).Conclusions (1)there are two pathways of cerebrospinal fluid flow which outflow from the four ventriclee: ① Median foramen-magna cistern-superior cerebellarcistern-quadrigeminal cistern-ambient cistern-crural cistern-interpeduncular cistern-sylvian cistern-hemispheric cistern;② Side hole-inferior cerebellopontine cistern-superior cerebellopontine cistern-prepontine cistern-interpeduncular cistern-chiasmatic cistern-olfactory cistern-carotid cistern-sylvian cistern-hemispheric cistern.(2) The new type of the lateral fissure cistern can guide the selection of operation.Neuroendoscopic Cyst-cistern fenestration should be considered first for Type III SACs, while the most optimal surgical managements for Type I and Type II need more comprehensive and well-designed researches.