[Spontaneous intracranial hypotension. Radiological findings]

Spontaneous intracranial hypotension (SIH) is an uncommon condition. The main symptom is headache which appears on standing and is relieved by lying down. Diagnosis is confirmed if a CSF pressure of less than 6 cm of water is found in the absence of other causes of intracranial hypotension.

To describe the cranial MR and CT findings of 7 cases with SIH.

We studied 7 patients in whom the diagnosis had been confirmed by lumbar puncture. The findings of 5 cranial CT studies (not using contrast), 5 MR without gadolinium and 4 MR with gadolinium were studied. The CT were carried out during the first week after clinical signs appeared, and the MR at between 1 week and 4 months after onset. We reviewed previous findings in the literature.

1. Cranial CT: in one case there was an enlarged subarachnoid space; 2. MR without gadolinium: there was descent of the cerebellar tonsils in 4 patients, meningeal thickening in 5 cases and subdural collections in two patients. In no case was descent of the iter seen; 3. MR with gadolinium: aural contrast was taken up in all cases.

The CT without contrast done at the onset of the condition did not usually give data which was useful for diagnosis. The principal MR findings in our series (meningeal thickening, descent of the cerebellar tonsils, subdural collections and gadolinium uptake) in an appropriate clinical context may be sufficient for diagnosis of this condition before lumbar puncture.