RESUMEN
Spontaneous intracranial hypotension (SIH) is a rare disease with a symptom of a postural headache, which is aggravated by the erect position and relieved by the supine position. This persistent headache is dramatically improved with an epidural blood patch. C6-7 is the most common site of leakage of cerebrospinal fluid (CSF) from the subarachnoid space in SIH. The diagnosis of SIH is based on a typical history. It is supported by low CSF pressure in a lumbar puncture and diffuse dural enhancement on a brain MRI, and confirmed by a CSF leakage site on a radioisotope cisternography or on a myelography. However, we had two patients of SIH whose CSF leakage site was not found on cisternography. We tried an epidurogram just before an injection of autologous blood for an epidural blood patch, and found specific finding on the epidurogam suggesting the CSF leakage site, such as a filling defect on C6-7 during dye injection, and delayed washout of dye around the filling defect on the epidurogram performed at C7-T1/C6-7. Therefore, we suggest that an epidurogram is occasionally a useful diagnostic tool when looking for the site of CSF leakage in SIH.