Objective: To determine by cerebral venography and manometry in patients with idiopathic intracranial hypertension the cause of the previously demonstrated venous hypertension in the superior sagittal and proximal transverse sinuses.
Methods: Cerebral venous sinus pressure was measured before and immediately after C1-2 puncture with removal of 20 to 25 mL of CSF.
Results: Lowering the intracranial pressure by lateral C1-2 puncture during manometry has shown that the venous hypertension resolves immediately.
Conclusion: These studies indicate that the venous hypertension is due to compression of the transverse sinuses by raised intracranial pressure and not due to a primary obstructive process in the cerebral venous sinuses.