Spontaneous Intracranial Hypotension and MRI

Abstract

Postural headache due to low intracranial pressure is a well-known entity and is most commonly encountered following lumbar puncture. It may occur as a consequence of a medical condition (dehydratation, uremia, etc.) but in some cases no precipitating event is apparent and the intracranial hypotension is believed to have developed spontaneously. In such cases the underlying cause of the syndrome is rarely established and treatment is non specific.

We describe three patients with spontaneous intracranial hypotension examined with MRI of the brain. Women are more commonly affected than men in the third or fourth decades of life. Schaltenbrand (1938) proposed three mechanisms by which spontaneous intracranial hypotension may be explained: diminished CSF production; CSF hyperabsorption, CSF leakage. The defect causing a CSF leak usually remains obscure. Several cases of diffuse meningeal enhancement on MRI have recently been described, probably due to meningeal hyperaemia resulting from the low CSF pressure. Subdural fluid collections have also been detected as a result of rupture of bridging veins due to the decrease in CSF volume and downward displacement of the brain.

In our cases, MRI showed a diffuse dural thickening, hyperintense in T2. Spontaneous intracranial hypotension is often a self-limiting disease, responding well to bed rest and a generous intake of oral or parenteral fluid and salt.