Spontaneous intracranial hypotension (SIH) is characterized by abnormally low intracranial pressure, which is usually caused by a CSF leak .
Incidence
The incidence of spontaneous intracranial hypotension is estimated at approximately 5/100,000[^1].
Symptoms
Patients with spontaneous intracranial hypotension develop orthostatic headaches, which worsen particularly when standing up. The headaches are generally not progressive but have a clearly defined time of onset, from which point the patients suffer from them.
Pathophysiology
The orthostatic nature of the headaches is caused by the low CSF volume resulting in sagging of the brain and, consequently, traction on the cranial nerves and dura, with the dura of the posterior cranial fossa being particularly sensitive to traction[^2].