Possible role of the cavernous sinus veins in cerebrospinal fluid absorption

Abstract

The purpose of this investigation was to enhance our understanding of cerebrospinal fluid (CSF) absorption pathways. To achieve this, Microfil (a coloured silastic material) was infused into the subarachnoid space (cisterna magna) of sheep post mortem, and the relevant tissues examined macroscopically and microscopically. The Microfil was taken up by an extensive network of extracranial lymphatic vessels in the olfactory turbinates. In addition however, Microfil also passed consistently through the dura at the base of the brain. Microfil was noted in the spaces surrounding the venous network that comprises the cavernous sinus, in the adventitia of the internal carotid arteries and adjacent to the pituitary gland. Additionally, Microfil was observed within the endoneurial spaces of the trigeminal nerve and in lymphatic vessels emerging from the epineurium of the nerve. These results suggest several unconventional pathways by which CSF may be removed from the subarachnoid space. The movement of CSF to locations external to the cranium via these routes may lead to its absorption into veins and lymphatics outside of the skull. The physiological importance of these pathways requires further investigation.

Topographic study on nerve-associated lymphatic vessels in the murine craniofacial region by immunohistochemistry and electron microscopy

“…Application of immunohistochemistry for LYVE-1 to such specimens as tissue sections and blocks is useful for demonstrating the cranial lymphatic system in the murine cranium. The present histochemical findings in the nasal region indicate a possible drainage route for cerebrospinal fluid along the olfactory nerves in the mouse, as reported in the other mammals including sheep (9), pig (12), lamb (27) and rat (12,25). Our immunohistochemical examination further disclosed the lymphatic vessels in the dura mater on the cribriform plate within the murine neurocranium, thus implying that the cerebrospinal fluid drainage from the subarachnoidal space to the nasal lymphatics might-at least partly-commence with the intracranial dural lymphatics.…”

“…Several reports have described the lymphatic vessels associated with optic and olfactory nerves in the viscerocranial region of some mammals. The studies using injections of a silastic material such as Mirofil ® (MV-122; Flow Tech Inc., Carver, MA) and/or dyes into the subarachnoidal space have demonstrated the nasal lymphatic vessels, and this implies the cerebrospinal fluid drainage route along the olfactory nerves into the nasal lymphatics (9,12,25,27). Additionally in the optic nerve, the lymphatic vessels have been shown in the dura mater of the nerve sheath and thought to serve as drainage pathway of cerebrospinal fluid (5,6,11,14).…”

The translaminar pressure gradient in sustained zero gravity, idiopathic intracranial hypertension, and glaucoma

“…Some CSF drainage occurs via arachnoidal granulations into the cerebral venous system, so an elevation in venous pressure leads to a rise in CSFp also [38]. Additional CSF drainage occurs into olfactory and optic nerve meningeal lymphatics in animals and humans [39][40][41][42]. The meningeal lymphatics are particularly dense around the termination of the ONSAS [42].…”

Cine Phase-Contrast MR Images Failed to Predict Clinical Outcome Following ETV

“…beyond the basal cisterns and CMJ. [21][22][23] Those CSF absorption devices declined possibly due to lengthy intracranial hypertension, especially in the patient with CSF diversion. 17,20,24 In other words, the previous ETV-treated OHCP might already coexist with "communicating HCP" due to the decrease in CSF absorption even before initial ETV.…”