Spinal radiological findings in nine patients with spontaneous intracranial hypotension.

Cranial magnetic resonance imaging (MRI) findings in spontaneous intracranial hypotension (SIH) are well known, while spinal studies have received less attention. Radiological spinal findings in nine patients with SIH are presented, looking for possible characteristic features. Five of the nine patients had histories of previous minor trauma, one of previous surgery; in three patients possible relevant preceding events were completely absent. All nine patients had cervical, seven thoracic, and four lumbar spine MRI studies; post-contrast studies were obtained in seven cases, MRI myelograms in five. Radioisotope myelocisternography was performed in four patients and myelo-CT in four. Epidural fluid collections were found in seven patients. In six cases the dural sac had collapsed, with a festooned appearance; intense epidural enhancement on post-contrast studies demonstrated marked dilatation of the epidural venous plexus. In three cases an irregular root sleeve suggested a possible point of cerebrospinal fluid (CSF) leakage. Myelo-CT demonstrated the CSF fistula in two cases, radioisotope myelocisternography in three. The pattern of spinal abnormalities is different from that seen in cranial MRI for anatomical reasons: in the spinal canal the dura is not adherent to the bone; therefore, collapse of the dural sac and dilatation of epidural venous plexus occur, rather than subdural hematomas. In most cases the search for the dural tear is difficult. Radioisotope cisternography is probably the most sensitive examination for documenting the leakage of CSF out of the subarachnoid space; myelo-CT may precisely demonstrate the point of the CSF fistula, whereas MRI may only suggest it.