ObjectiveTo summarize the clinical features of and prognosis factors for spontaneous intracranial hypotension (SIH). MethodsWe continuously registered hospitalized patients diagnosed with SIH from December 1st, 2010 to February 1st, 2014. Etiology information and clinical features were collected at the first day of admission. Routine blood test and lumbar puncture were done as soon as possible. Every patient got position and fluid infusion therapy. During the one-week follow-up, headache level was evaluated with Visual Analogue Scale (VAS). ResultsThere were 110 patients included, and among them, 39(35.5%) were male and 71(64.55%) were female. The age of onset was between 17 and 91 years old with a mean onset age of (42.0±12.4). Besides postural headache, common signs were nausea (68 cases, 61.8%), vomiting (63 cases, 57.3%), dizziness (40 cases, 36.4%), neck pain (27 cases, 24.5%), and tinnitus (23 cases, 20.9%). VAS at baseline was (7.46±0.86), and at the last follow-up, VAS was (3.45±2.17), with an average improvement of 53.75%. Patients with ANA marker positive had better prognosis. ConclusionSIH can accompany serious brain stem and cerebellum signs, and even meningeal irritation. Cerebrospinal fluid (CSF) changes are similar to virus infection with negative serum virus screening. If CSF leak cannot be found on imaging, patients can improve through fluid infusion therapy and postural treatment.