Intracranial pressure and veins.

This review summarizes the relationship between intracranial pressure and the venous system as far as ultrasound methods are concerned. Although the pressure in cortical veins is tightly and linearly coupled to the intracranial pressure, venous flow velocities in the basal veins are not. However, venous flow velocities reflect better the local cerebral blood flow than measurements in arteries. Therefore, they correlate better with clinical outcome in head trauma and subarachnoid hemorrhage. Transorbital sonography with measurement of the optic nerve sheath diameter and optic disk elevation has evolved to a valuable point of care diagnostic tool in idiopathic intracranial hypertension. In cerebral vein and sinus thrombosis ultrasound is at best a supplementary diagnostic tool, which may have a value in patient follow-up.