Idiopathic intracranial hypertension without intracranial hypertension

The intracranial pressure (ICP) show large daily fluctuation, mainly due to postural changes and physical activity (e.g. it goes up to 470 mmH2O under Valsalva manoeuvre1). Consequently, the dural sinus must be sufficiently rigid in order to avoid its collapse during cerebrospinal fluid (CSF) pressure peaks. Hereby, we describe a patient with collapsible dural sinus associated with an intracranial hypertension syndrome without a detectable raised ICP, suggesting that a number of crucial assumptions on idiopathic intracranial hypertension with (IIH) or without papilledema (IIHWOP) might be discussed.