The three main autoregulation mechanisms of brain blood flow has been known to science until
now – myogenic, chemical-metabolic and neurogenic. It is well-known that the brain cortex and
sub cortex are functionally opposite structures. During the activation of cortex takes place
deactivating of sub cortex and on the contrary. Consequently, it must be expected dissociated
blood provision of these divisions. The described known mechanisms do not indicate to probable
existence of such a dissociated blood provision.
One of the ways of chemical-metabolic influence at blood vessels is vessel-dilating effect of
carbon dioxide. We think that the wrong interpretation of this influence have brought to an idea
that during hyperventilation in connection with reduction of blood carbon dioxide concentration
takes place spasm of vessels and ischemia of the brain. If carbon dioxide is dilating vessels, then
its absence can manifest by vessels’ spasm. It is difficult to agree with idea that absence of
something (i.e. carbon dioxide) could cause any action and we decided to analyze these
To study the hypothesis, it is important to perform eye bottom video monitoring and EEG
investigation. The eye bottom needs to be investigated at rest and after hyperventilation by speed
breath of average intensity until achievement of the clinical effect – the dizziness or slight
malaise. During the investigation of eye bottom it is important to pay attention at the color of the
disc (rose, pale, yellow, white), the condition of disc edges (clear, partially wiped, wiped, are not
seen), place of vessels’ leaving (from center, exocentric within excavation, within disc, out of
disc), the condition of veins (narrow, average diameter, vast, filled), the color of veins (bright,
slightly darkened, moderately darkened, black), the pulsation of veins (absent, scarcely visible,
moderate, expressed), the diameter of arteries (vast, moderate, narrow, very narrow), the walls of
arteries (succulent, with lateral reflex, symptom of copper and silver wires), correlation of
arteries and veins diameters (1:1, 1:2, 1:3, 1:4).
Our preliminary observations have confirmed the already evident fact that during
hyperventilation the intracranial pressure reduces. The suggestion that during hyperventilation
takes place spasm of arteries does not confirm, at least in arteries of retina where the
concentration of carbon dioxide falls too. On the contrary, usually after hyperventilation arteries
became wider.
In our opinion, the EEG waves are not the summary potentials of brain cortex’s neuron pools.
These waves reflect the electric process in intercellular space of white substance and are
registered through the cortex isolating layer. During the EEG investigation, we must pay
attention at changes of EEG parameters – amplitude and frequency before and after
hyperventilation test, tightening, detain of breathing etc. On EEG recording after

hyperventilation and other tests bringing to reduction of ICP generally occurs increasing of
amplitude and deceleration of recording. Depending on occurred changes it is possible to think
about functional state of subcortical structures of the brain.
However, it is proved, that during hyperventilation the hypoxia of the brain really occurs.
We have developed a new hypothesis about the mechanism of autoregulation of brain blood
flow. The cortical arteries pass through arachnoid shell in special liquor channels and special
connective strings pass from walls of channels to adventitial shell of artery. All arteries, before
entrance to cortex have spiral curves. According to our hypothesis in case of reduction of ICP is
decreasing the tension of arachnoid shell, relaxing the supporting strings of arteries and as a
result the arteries are falling off, the spiral curves grows and increases the resistance to blood
flow and cortex ischemia occurs. Decreasing of ICP does not accompanied with reduction of
blood quantity in internal carotid arteries. Consequently, in case of decreasing of cortical portion
of blood volume must accompany with increasing of blood flow in penetrant arteries system,
which provides with blood the subcortical system. There are no spiral curves and the
construction of arteries is segmental. In case of ICP increasing, the arachnoid caves are inflating,
the supporting strings are tightening, spiral curves become straight and blood flow resistance
decreases. The cortex hyperemia approaches. The portion of blood volume in arteries of
penetrant system decreases and, in this case, hypoxia approaches in sub cortex. Like seesaw,
approaches either ischemia or hyperemia in cortex, accordingly either hyperemia or ischemia in
sub cortex depending on degree of intracranial pressure. We named this hypothesis “hypothesis
of autoregulation of brain blood flow depending on intracranial pressure on type of seesaw”.
Practical importance of the hypothesis.
Anesthesiology: during long lasting anesthesia anesthesiologist, founding on saturation data, may
conduct the anesthesia in condition of hypoventilation. If the hypothesis is true, then the
subcortical system will be in hypoxia for all this period, which will cause inconvertible changes.
Perhaps this is the reason of such complications as diencephalic syndrome after durable
Reanimatology: the condition of sleep and awake depends on either is activated cortex, or sub
cortex. Hence, it is necessary to know how to manage adequately the brain functions to control
consciousness of the patient in intensive therapy department. It is necessary to decrease ICP if it
is required to becalm the patient. In some cases, patients are not able to wake up for a long time
though the brain did not suffer. The key tactic of treatments of such patients can become the
handling of ICP condition.
Neurology: long lasting elevation of ICP can cause the chronic ischemia of sub cortex and
hypothalamus. Hereunder it can bring to development of diencephalic tetrad – vegetative,
metabolic and hormonal disorders and neurosis. Perhaps one of the main reasons of neurosis
with all its various clinical manifestations is chronic hypoxia of hypothalamus, which develops
by the mechanism of seesaw because of ICP elevation.

Epilepsy: it is definitively clear now that the epilepsy does not exist without damaging of
subcortical specific and non-specific structures. The activities of cortex and sub cortex are
opposite. Hence, there can be an instant, when correlation of activities of these divisions
becomes optimal for development of epileptic seizures. If our hypothesis is true, the regulator for
creation of such “optimum” condition could be ICP. It is possible to take under control epileptic
seizures by manipulating the ICP.
Social hygiene, sport, education, culture: low ICP brings to drowsy, calm, passive condition. In
these cases, the cortex of the brain does not function actively. Vegetative functions of the
organism are activating. This is necessary to achieve, when we need to increase physical
possibilities, or obtain a pleasing unhooking in art. If the task is to promote education or
brainwork performance, we suppose that this cannot be achieved without elevation of ICP.
Correlations of ICP, blood provision and activity of different areas of the brain must become an
active subject in neuroscience to study.
Besides already specified methodologies of video monitoring of eye bottom and EEG, the
hypothesis is in process of study by methods of reoencephalography, myography, Doppler- and
duplex-investigations, direct and percutaneal surface and deep oximetry of the brain,
observations at open brain during neurosurgical operations.