Objective: Spinal dural arteriovenous fistula (SDAVF) is a frequently encountered spinal vascular malformation but also an under-diagnosed entity with frequent misdiagnosis. Some patients who had received methylprednisolone pulse treatment (MPPT) were reported to have dramatic fluctuations. We want to evaluate the specific effects of MPPT on SDAVF patients. Methods: We collected the medical records of 11 patients (13 case-times) who had received MPPT before surgery, taking the other 215 contemporary cases in the database as control. We quantified the clinical history of each MPPT patient by ALS scores and depict the changing processes by "Time-ALS" lines based on clinical documents and detailed personal interview. Results : In comparison to the control group, most of the subject patients (92.3%) showed markedly sharp aggravation immediately after MPPT. Though there were fluctuations after the peak of aggravation, 91.7% could not recover to previous status. MPPT accelerated the whole clinical course and resulted in poor long-term prognosis. Conclusion: SDAVF patients tend to have a remarkably acute and irreversible aggravation after MPPT. Attention should be paid to this unacquainted cause of progressive myelopathy in clinical practice and steroids treatment should be avoided before clarifying the diagnosis.