[Clinical and neuroradiological features of spontaneous intracranial hypotension: report of two cases].

We report two patients with spontaneous intracranial hypotension (SIH) showing bilateral subdural hematoma. One of the two patients was a 32-year-old woman, and the other was a 27-year-old healthy woman. Both patients presented chronic, intractable, orthostatic headache with dizziness and nausea. In both patients, both general and neurological examinations were normal, and routine laboratory tests were all normal, except for dry taps of the lumbar puncture. Brain CT scans and MRI revealed thin, bilateral subdural hematomas. RI-cisternography and CT-myelography disclosed multiple extraspinal CSF leakages along the nerve root sheathes of the cervical segments and early bladder filling of the radionucleotides in both patients. These findings support an emerging hypothesis that the extraspinal CSF leakage may play a role for inducing SIH. Anatomical fragility around the nerve sheath, especially that of the lower cervical segments, may contribute to the pathophysiological mechanism underlying SIH. For making a prompt diagnosis of SIH and for the better understanding of the pathophysiological mechanism of SIH, RI-cisternography of the whole spinal segments is important.