Re: CCSVI and CCVBP
Posted: Sun Jul 22, 2012 7:07 am
It should be noted that this paper was published in Child's Nervous System. It's actually a good paper that underscores many as yet unanswerd questions about hydrocephalus and CSF flow such as where it is absorbed. The problem is that it mixes childhood and adult hydrocephalus.
The debate regarding where CSF is absorbed is old and still not fully understoood. Most researchers still maintain that it is mostly absorbed by the archnoid granulations (AG). The AG, however, aren't formed at birth and so CSF uses other outlets until they do. The role and location of the AG in the superior sagittal sinus and CSF absorbtion is most likely due to upright posture. Regardless of where it is absorbed, once it is absorbed all CSF enters the venos system before exiting the cranial vault so that obstruction to venous outflow can effect CSF flow.
Another point is regarding compliance which is too lengthy to go into here. One point to be made, however, is that loss of vascular compliance occurs with aging and is associated with decreased blood and CSF flow. In this regard, I suspect that decreased CSF flow and production can cause the brain to sink into a pressure conus (Chiari 1) and block blood and CSF flow between the brain and cord. This will cause CSF volume to increase in the cisterns and subarachnoid space. Consequently, there is an increased incidence of Alzheimer's assoicated with circulatory degeneration due to conditions such as diabetes and heart failure which decrease blood and CSF flow in the brain.
Still another point missed in this paper is cranial (skull) compliance. The cranium in children and young adults is compliant. It gets less compliant with age as the sutures close in adults. It is my opinion that the increase in intracranial pressure in children is due to the compliance of the cranium. The closed sutures of the skull in adults resist an increase in CSF pressure.
Lastly, this paper only discusses intracranial obstructions such as aqueductal stenosis in the cause of hydrocephalus and overlooks extracranial blockages in the craniocervical junction.
While we continue to debate and research the all the nuicances of CSF production, flow and physiology, cine MRI is showing what actually happens and will continue to improve.
The debate regarding where CSF is absorbed is old and still not fully understoood. Most researchers still maintain that it is mostly absorbed by the archnoid granulations (AG). The AG, however, aren't formed at birth and so CSF uses other outlets until they do. The role and location of the AG in the superior sagittal sinus and CSF absorbtion is most likely due to upright posture. Regardless of where it is absorbed, once it is absorbed all CSF enters the venos system before exiting the cranial vault so that obstruction to venous outflow can effect CSF flow.
Another point is regarding compliance which is too lengthy to go into here. One point to be made, however, is that loss of vascular compliance occurs with aging and is associated with decreased blood and CSF flow. In this regard, I suspect that decreased CSF flow and production can cause the brain to sink into a pressure conus (Chiari 1) and block blood and CSF flow between the brain and cord. This will cause CSF volume to increase in the cisterns and subarachnoid space. Consequently, there is an increased incidence of Alzheimer's assoicated with circulatory degeneration due to conditions such as diabetes and heart failure which decrease blood and CSF flow in the brain.
Still another point missed in this paper is cranial (skull) compliance. The cranium in children and young adults is compliant. It gets less compliant with age as the sutures close in adults. It is my opinion that the increase in intracranial pressure in children is due to the compliance of the cranium. The closed sutures of the skull in adults resist an increase in CSF pressure.
Lastly, this paper only discusses intracranial obstructions such as aqueductal stenosis in the cause of hydrocephalus and overlooks extracranial blockages in the craniocervical junction.
While we continue to debate and research the all the nuicances of CSF production, flow and physiology, cine MRI is showing what actually happens and will continue to improve.