Objective:Toreport the MRI characteristics and clinical manifestation in 3 cases ofprimaryintracranial hypotension syndrome(PIH)and put forward the main points in its diagnosis and examination.Methods:The MRI characteristics and clinical manifestation in 3 cases diagnosed as PIH were retrospectively analyzed.Results:The brain MRI found diffuse pachymeningeal gadolinium enhancement in 2 cases

downward displacement of amygdala cerebelli and narrowing of pontine cistern and cisterna magna in 1 case.In 2 cases by spinal cord MRI

subarachnoid cavity became narrow in multi-series and multi-aspect scanning and it’s boundary became unclear;one was located on T5～T7level and the other on T8～T9level;epidural collection of fluid showed strip or comma shape.All the 3 cases had lower CSF pressure(<60 mmH2O).Conclusion:Postural headache is the most characteristic symptom clinically in PIH

and diffuse pachymeningeal gadolinium enhangcement is the common MRI manifestation.A combination of brain MRI with the common spinal cord MRI in PIH conduces to clinical diagnosis.