Objective To explore the origin of chronic subdural heamatoma.Methods Follow-up 92 patients of acute subdural haematoma(ASDH)and 207 patients of traumatic subdural effusion(TSE)S by CT or MRI.Results None of ASDHs developed into CSDHs directly,but ASDHs could become to CSDHs via TSEs;67 cases of TSE was proved becoming to CSDHs by CT scanning or operation.Conclusions Origin of CSDH is TSE.

Objective Discuss the active mechanism of dural border layer cells in the process of subdural fluid collection developing into chronic subdural hematoma.Methods Review and analyse literature combined with one special return case whom with subdural fluid collection.Results At the same case,subdural fluid collection at left side did no change during 49 months,and that at right side developed into chronic subdural hematoma in 23rd week,and the latter was absorbed at 62rd week.Conclusion In the process of subdural fluid collection developing into chronic subdural hematoma,dural border layer cells roll on important functions.