Microgravity environment and compensatory: Decompensatory phases for intracranial hypertension form new perspectives to explain mechanism underlying communicating hydrocephalus and its related disorders

Abstract

The pathogenesis underlying communicating hydrocephalus has been centered on impaired cerebrospinal fluid (CSF) outflow secondary to abnormal CSF pulsation and venous hypertension. Hydrodynamic theory of hydrocephalus fares better than traditional theory in explaining the possible mechanisms underlying communicating hydrocephalus. Nonetheless, hydrodynamic theory alone could not fully explain some conditions that have ventriculomegaly but without hydrocephalus. By revisiting brain buoyancy from a fresher perspective, called microgravity environment of the brain, introducing wider concepts of anatomical and physiological compensatory–decompensatory phases for a persistent raise in intracranial pressure, and along with combining these two concepts with the previously well-accepted concepts of Monro–Kellie doctrine, intracranial hypertension, cerebral blood flow, cerebral perfusion pressure, brain compliance and elasticity, cerebral autoregulation, blood–brain and blood–CSF barriers, venous and cardiopulmonary hypertension, Windkessel phenomenon, and cerebral pulsation, we provide plausible explanations to the pathogenesis for communicating hydrocephalus and its related disorders.

Pituitary Metastasis and the Role of CSF Pulsations in Secondary Displacement after Surgery

“…Intracranial pressure varies according to the hemodynamic parameters and the central nervous system may be considered as a microcosmus with its microgravity environment [14]. This equilibrium may be altered after surgical procedures and in our case a subtotal resection of the sellar lesion probably favored the descent of the suprasellar residue because of the liberation of a space primarily filled of CSF and then by tumor.…”

A Clinical Test for a Newly Developed Direct Brain Cooling System for the Injured Brain and Pattern of Cortical Brainwaves in Cooling, Noncooling, and Dead Brain

“…The method was named D-Brain Cooling Machine simply because of the coolant fluid that goes directly into the skull. This direct cooling method was believed to cool not only the region of interest but also other brain areas that are far beyond the irrigated area through the vascular brain pulsation, which is commonly enhanced in any injured and compensated brain (Idris et al, 2014a;Kim et al, 2015Kim et al, , 2016.…”

Parenchymal pressure inconsistency in different brain areas after kaolin injection into subarachnoid space of neonatal rats

“…Although we made this comment according to mean±std error values, we observed that the pressures continued to increase in particular rats in the Kaolin groups. This observation can be explained by impaired cerebral autoregulation secondary to persistent high intracranial pressure and shifting the compensatory phase to the decompensatory phase (1,3,5,14). The damaged Windkessel phenomenon that provides and maintains constant blood flow to arterioles and capillaries during diastole under normal conditions may be attributed to this unwilling process (3,5).…”

“…And in further stages, ventriculomegaly persists with high intracranial pressure. However, if the Windkessel phenomenon is able to recover (in brains with favorable compliance capacity), ventriculomegaly may not accompany the high pressure values and may proceed to normal pressure hydrocephalus (14).…”