New concept of cerebrospinal fluid dynamics in cerebral venous sinus thrombosis

Cerebral venous sinus thrombosis develops as a consequence of sinus obstruction, leading to hindering of venous drainage, gradual edema and increased intracranial pressure (ICP). Intracerebral hemorrhage occurs, of which the symptoms may be alleviated by cerebrospinal fluid (CSF) drainage. Clinical brain function improvement may be directly attributed to the effect of the decreased ICP, or to the decreased pressure on the venous sinus which alleviates venous blood flow and sinus thrombosis. However, worsening, rather than improvement of symptoms are occasionally observed in patients after CSF drainage, and therefore it is as yet difficult to determine the precise indications for CSF drainage. The authors of this study suggest that external CSF drainage of sagittal sinus thrombosis may accelerate the sinus thrombosis and aggravate symptoms in such a patient. In other words, the sagittal sinus differs from other sinuses in that when sinus thrombosis develops, CSF absorption is impeded from the early stages, leading to a higher likelihood of ventricular dilatation, because most of the CSF are normally absorbed through the arachnoid villi and drain into the sagittal sinus. External CSF drainage and subsequently decreased ICP will improve sinus thrombosis after implementation of CSF drainage of the sagittal sinus thrombosis, but on the other hand, this decreased CSF drainage leads to decreased venous sinus blood flow, both of which may result in aggravation of the sinus thrombosis. However, it is also suggested that CSF drainage may be accomplished safely on the unilateral lateral sinus thrombosis because CSF drainage may alleviate venous sinus obstruction, and does not influence the sinus blood flow. We, authors of this study suggest that caution should be taken when external CSF drainage of the sagittal sinus thrombosis is performed to prevent further aggravation of intracranial pressure elevation.