Introduction and clinical case. A 38 year old woman, with no previous history of trauma, presented complaining of interscapular pain followed by pulsating headache clearly related to posture, alleviated on lying down and worse on standing up. Subsequently, she also complained of diplopia. On examination there was paresia of the left sixth cranial nerve. Low opening pressure on lumbar puncture confirmed the presence of intracranial hypotension. The protein level of the cerebrospinal fluid was slightly raised. On CT the cortical sulci and small ventricles had disappeared. Cerebral MR (without gadolinium) showed marked diffuse meningeal hyper-intensity and apparent absence of the basal cisterni. Isotopic cisternography showed a pattern compatible with hypotension, without signs of fistulas. On spinal MR no spinal meningeal defects were seen. With conservative treatment the patient improved in a few days and the headache and diplopia disappeared. The absence of traumatism or spinal operations mean that the hypotension may be considered to be spontaneous. We discuss the CSF, neuroimaging and cisternography findings characteristic of the spontaneous intracranial hypotension syndrome. Conclusion. Unawareness of this syndrome, the particular neuroimaging changes and the usual CSF anomalies may lead to confusion over diagnosis, leading to the use of invasive techniques unsuitable for a condition which often has a good prognosis and in which the symptoms resolve in a few days or weeks with conservative treatment.