Research Projects

Investigating Cerebral Circulation as the Physiological
Underpinning of Consciousness

A collaboration between the Beckley Foundation and the Sechenov Institute of Evolutionary Physiology and Biochemistry,
St. Petersburg, led by Prof. Yuri Moskalenko,
Amanda Feilding and Peter Halvorson

One of the projects we are most excited about at the Beckley Foundation is our collaboration with Prof. Yuri Moskalenko investigating cranial compliance. Cranial compliance is a measure of the functioning of the cranial system as a whole: the skull, the brain tissue, and all the liquids that flow through and around this complex system. Cranial compliance is determined by the interaction of all these components, and the results of our investigation so far have shown that a better understanding of these interactions is of crucial importance for healthier brains and improved cognitive functioning throughout the whole of one's life.

The Cranial System and Cranial Compliance

The circulation of blood in the brain differs from that of the other organs because the brain is encased within a nearly-rigid container, the cranium. The situation is further complicated by a second fluid system in the brain, the cerebrospinal fluid (CSF) system, which circulates in its own compartments and interacts with the blood system. These systems are interdependent such that changes in the volume, pressure and movements of one system should lead to concomitant changes in the other, consistent with the laws of fluid dynamics. The study of brain circulation has therefore evolved into the study of the bio-mechanical principles of how fluids move through soft tubes inside a closed container under pressure. There are many different configurations by which the two fluid volumes interact, and learning more about these reveals vital new information about brain circulation and its implications for health.

The concept of brain circulation from this systemic point of view, as a complex biological system, has been given the name cranial compliance or CC. Understanding CC is relevant to medical professionals as well as for each and every one of us. Changes in the elasticity of this complex system over the life span have been shown to have a direct impact on cerebral health and cognitive functioning, as our most recently completed research clearly demonstrates. To know and to manage cranial compliance is as important for the good health of the brain as knowing and managing one's blood pressure is for the heart. The good news is that our research indicates that early, proactive management of cranial compliance may counteract the diminution in brain functions considered to be an inevitable part of normal ageing.

The importance of good cerebral circulation and our intuitive understanding of this is highlighted by the long history we humans have of devising practices that improve our cerebral circulation. The benefits of yogic breathing exercises to cranial compliance, for example, indicate an appreciation that inspiration and expiration (i.e. respiratory pressure changes) are one of the driving forces of brain circulation. Indeed, the respiratory system can be considered as a third fluid system in terms of the effects it has on blood and CSF movements. Altering the extent and rhythm of breathing influences the quality and quantity of fluid movements around the brain.

As described above, to really understand cranial compliance and cerebral circulation you have to consider the brain and the cranial system as a holistic whole. The complex cranial structures that influence brain circulation are:-

1) the skull and it's membranes; 2) the vessels and their blood content; 3) the brain tissue; and 4) the cerebrospinal fluid system within all of its various compartments and convolutions. The CSF system cushions the brain and is, most importantly, responsible for the cleansing of the tissue, like a special lymphatic system just for the brain that can remove waste products too large to pass back into the blood stream.

Cranial system: Anatomical elements are the skull and its membranes, the vascular system (the blood vessels and their contents), brain tissue and the CSF system shown in yellow.

The blood and CSF systems are directly interdependent such that movements in one drives movements in the other and are themselves driven by the functional elements that influence the cranial system: 1) the cardiac cycle; 2) the respiratory cycle; and 3) the slow fluctuations resulting from auto- regulation of water and oxygen in the metabolic process (also known as Meyer oscillations - oscillations of arterial pressure occurring spontaneously in conscious subjects at a frequency lower than respiration). Cranial compliance is therefore a reflection of how these three forces drive the brain's two fluid systems within the nearly rigid cranium.

The Cranial system with its functional elements: the diagram shows the fluid systems of the brain, and gives an idea of their interaction - arterial inflow drives CSF movement, which in turn drives venous outflow.

The Moskalenko Method and the Interdependent Components of Cranial Compliance

The success of our research to date has been enabled by the unique monitoring method developed by Prof. Moskalenko. This allows for non-invasive recording of the brain's fluid movements, showing how they respond, over several minutes but on a millisecond timescale, to the driving forces of the blood and to certain functional stresses. This method permits much faster monitoring of cerebral fluid movements than MRI. Simultaneously recording data from each fluid system but by different devices enables the assessment of the interaction of the fluids moving through their respective systems, and also their specific responses to the functional stresses applied to reveal the nature and quality of cerebral circulation. The blood system is monitored by transcranial Dopplerography (TCD) and the CSF system is monitored by impedance or Rhoencephalography (REG). Recording the two systems simultaneously and then superimposing their waveforms shows distinctive interactions at three different intervals of the heartbeat. The precise characteristics of these interactions provide a good indication of the quality of cerebral circulation.

The three interdependent intervals are called 1) CCe (elasticity), 2) CCc (compensatory potential) and 3) CCo (outflow). These three intervals reflect the three different types of fluid movements that occur on a millisecond timescale with each and every heartbeat. CCe designates the elasticity of the complex system during the inflow from the beginning of the heart beat up to its maximum; CCc designates the compensatory potential of the fluids where their interaction is most active; CCo designates the outflow capacity from the system. These designations represent three distinct features of the pulse-driven movements of the blood and CSF that occur in a single heartbeat, as is depicted in the diagram below:

The Role of Arterial Pulsations And Skull Mechanics In
the Mechanism Responsible For Brain Blood Supply

The interactions are recorded and then analyzed from a systemic approach. “Interdependent components” means that a change in one component proportionally influences either one or both of the others. For example, increasing the volume of the pulse of blood during the CCe phase when blood is flowing into the brain through the arteries, directly influences the quantity of CSF movement in the next stage (CCc), when the two fluids begin to rebalance. The quantity of CSF movement during the CCc phase in turn influences the force with which the blood leaves the brain during the outflow stage (CCo), when the heart's contraction has finished.

This complex analysis of the recordings is achieved through a unique computer-aided method devised by Prof. Moskalenko et al . Recording the dynamic conditions of brain circulation in a single subject can be completed in just a few minutes with this method. Our insights into how well the cranial system is functioning is determined by the ratio of change in volume to change in pressure of the fluids within the brain, as designated by ?V/?P. This analysis method makes clear what influence the ?V/?P relationship is having on the quality of the brain circulation.

Schema of Moskalenko Method instrument array

The Relation of Cranial Compliance to Mental Health and Cognitive Functioning

The Cranial Compliance concept and the methods described above have been the basis for important investigations conducted during the collaboration between Prof. Moskalenko and the Beckley Foundation over the last two years. Recording and analysis of each of the three components of CC in an ageing human population, grouped by decades, allowed us to identify that declines in the elasticity component (CCe) of the skull and its vascular contents statistically places the individual at an increased risk of cerebral insufficiency (decreased blood flow to the brain), and a correlating decline in mental functions, by the relatively young age of 40-50.

Graph shows that the CCe component of the cranial system declines by middle age and recovers somewhat in later life.

The graph on the left shows how the time delay in CSF response increases with age during CCc (when the arterial pulse pressure is declining and CSF movement is increasing). The right-hand graph shows how CSF movements decline in middle age and are then somewhat reactivated as the brain atrophies with ageing.

This decline in CCe and CCc from middle age onwards corresponds well with the results of other researchers who have found that mild cognitive dysfunction starting around this age occurs against a backdrop of slow neural atrophy in the cortex and connective fibers. Further findings have revealed that both working memory and short-term memory are on the decline in 40-50 year olds. To our best knowledge, we are the only research group to have revealed the connection between middle-aged mental decline and a decline in cranial compliance. Although the deficit in elasticity we found in the 40-50 year group was somewhat compensated for by CSF activation due to brain atrophy during the sixth decade, we identified a directly proportional relationship between the severity of dementia symptoms and declining CCe, regardless of the specific age the dementia emerged, and despite the fact that blood flow and vascular responses remained within acceptable parameters.

The thickness of the brown arrows indicate the strength of the CSF movements, and shows that trepanation leads to increased movement of CSF around the brain and to the sub-arachnoid spaces (improving nutrient delivery and waste removal), and to less movement of CSF from the brain to the spinal column.

Additionally, our investigations have exclusively established that the increased elasticity produced by a 4 square centimetre opening in the skull does not exceed the normal limits of auto-regulation. In other words, cranial openings of this size are safe in that their effects do not exceed the normal limits of brain circulation. An artificial skull opening is a passive improvement to cerebral circulation, in the same way that Lasik eye surgery leads to a sustained improvement in vision following the procedure. A skull-opening increases the pulse-stroke volume, activates CSF movement and reduces intracranial pressure.

Compared to the normally-reduced CCe in the 40-50 year old age group, the CCe after skull opening may provide a significant improvement for that age group in the activation of their mental functions. We are continuing to study this phenomenon, and to evaluate its long-term effectiveness in maintaining elasticity of the cranial system throughout the life span.

Developing the Moskalenko Method as an Accessible Means of Assessing Intracranial Dynamics

Improving the diagnosis and treatment of age-related deteriorations in mental health is not the only medical application of this research. A very urgent direction of our efforts is to develop further the Moskalenko Method into a user-friendly package with automated readout analysis. This should enable the rapid measurement of cerebral functioning, brain circulatory dynamics and intracranial pressure (ICP) at the scene of accidents or soon after. This is of great importance as it facilitates diagnosis and application of any interventions necessary to prevent brain trauma during the time- period known as the “Golden Hour”. The “Golden Hour” refers to the first hour following an accident, during which any treatments applied have the greatest impact, and so greatly increase the chances of a patient making a full recovery. Head trauma is currently the greatest killer in the under 45 age group in the developed world, and delays in evaluating intracranial dynamics following head injuries mean that many more people die or suffer permanent brain damage than would be the case if a portable means of evaluating intracranial dynamics were more readily available to ambulance crews and to mobile medical services. The Moskalenko Method could provide just such a service, as its instrument complex is low-cost and relatively portable, and so could readily be adapted for use in emergency situations to assess cerebral dynamics. This would enable more pre-emptive interventions, and so avoid deteriorations in a patient's condition from which it is often not possible to recover. It is also a method that can be employed when access to expensive and immobile MRI technology is limited, such as en route from remote locations, on the battlefield or in much of the developing world.

The broad potential and benefits of this research mean that its continuation could prove vitally important, not only to those who are suffering a decline in cognitive ability with old age, but also to trauma patients with head injuries, those in middle age who are suffering from a decline in mental functions due to cerebral insufficiency, and to those seeking to explore and understand better the mechanics of fluid movement within the brain. To these ends, we greatly look forward to the continuation of this exciting research.

This document is a summary of some recently-completed research conducted by Prof. Yuri Moskalenko in collaboration with the Beckley Foundation. One of the research papers mentioned in this document has been accepted for publication by academic publishers and has not yet gone to press. Other papers have appeared in scientific journals in the last two years. All papers were peer-reviewed. In respect to our publishers, we reserve the right to limit duplication of this document to one copy until March 15, 2008.