BRAIN COOLING IN HUMANS - ANATOMICAL CONSIDERATIONS

Vascular arrangements allowing a bulky transfer of venous blood from t he skin of the head and from nasal and paranasal mucous membranes to t he dura mater provide an excellent anatomical basis for the convection process of cooling, caused by evaporation of sweat or mucus. The dura mater, with its extraordinarily high vascularization controlled by a potent vasomotor apparatus, may transmit temperature changes to the ce rebrospinal fluid (CSF) compartment. Temperature gradients of the CSF may in turn influence the temperature of brain parenchyma(1) directly, along the extensive contact area between the cerebrocortical surface and the CSF-compartment, or (2) indirectly, via brain arteries that ex tend over long distances and arborize within the subarachnoid space be fore entering the pial vascular network and brain parenchyma. Numerous subarachnoid and pial arterial branches exposed to the CSF have diame ters in the range of the vessels of the retia mirabilia of animals in which selective brain cooling has been clearly established experimenta lly. It is also shown that the arrangements of venous plexuses within the vertebral canal provide anatomical preconditions for a cooling of the spinal cord via the CSF. The possibility of spinal cord and spinal ganglia cooling by temperature convection via venous blood cooled in the venous networks of the skin of the back flowing through numerous a nastomoses to the external and internal vertebral plexuses and, finall y, into the vascular bed of the spinal dura is discussed on the basis of anatomical facts.