The function of arachnoid villi/granulations revisited.

OBJECTIVE

To establish the current viewpoint with regards to the role of arachnoid villi/granulations in cerebrospinal fluid (CSF) absorption.

DESIGN

Retrospective study.

SUBJECTS

Journal articles published between 1913 and 1993.

MAIN OUTCOME MEASURE

The contribution of arachnoid villi/granulations to CSF absorption from the subarachnoid space.

RESULTS

From available literature, it is yet to be proved that arachnoid villi/granulations are the major sites for CSF absorption from the subarachnoid space into the venous system. They may, however, play an important role in the absorption of CSF's waste products of neuronal metabolism (mainly CSF proteins) under normal physiological conditions. Furthermore, it would appear that, under pathological conditions, the absorption of CSF proteins can take place at other CSF absorption sites.

CONCLUSION

The paucity of data on the relationship between the development of arachnoid villi, the superior sagittal sinus, the superficial cortical vessels and the subarachnoid space warrants that an ontogenic study be conducted in order to achieve a better understanding of the function of arachnoid villi which is currently speculative.