Recognizing an impending stroke
Study on identifying stroke in comatose patients

Date:
April 12, 2022
Source:
Charite' - Universita"tsmedizin Berlin
Summary:
Subarachnoid hemorrhage is a type of bleeding stroke which can lead
to a delayed ischemic stroke after just a few days. Researchers
have shown that massive electrochemical waves in the brain act as
a marker announcing an impending ischemic stroke. Electrodiagnostic
monitoring of these waves enables clinicians to identify the signs
of an impending stroke early, particularly in comatose patients
receiving intensive care following a subarachnoid hemorrhage.



FULL STORY ========================================================================== Subarachnoid hemorrhage is a type of bleeding stroke which can lead to a delayed ischemic stroke after just a few days. Researchers from Charite'
- - Universita"tsmedizin Berlin have shown that massive electrochemical
waves in the brain act as a marker announcing an impending ischemic
stroke.

Electrodiagnostic monitoring of these waves enables clinicians to
identify the signs of an impending stroke early, particularly in comatose patients receiving intensive care following a subarachnoid hemorrhage. The researchers' findings, which have been published in Brain, could serve
as the basis for the development of new treatments.


========================================================================== Subarachnoid hemorrhage is a type of stroke caused by bleeding into
the space between the protective membranes surrounding the brain. This
type of hemorrhagic stroke represents a neurological emergency, which
is why patients with this type of stroke require immediate intensive
care. When the brain's normal blood supply is disrupted due to an
acute blockage rather than a brain bleed, this is called an ischemic
stroke. However, an ischemic stroke can also occur as the result of a subarachnoid hemorrhage. More than half of all patients who have had a
severe subarachnoid hemorrhage will develop an ischemic stroke within
the first two weeks after their brain bleed.

Charite' researchers have identified a biomarker which indicates that
a patient is at high risk of an impending stroke post-subarachnoid
hemorrhage. "It is difficult to judge when a new stroke might be
developing, especially in patients who are in a coma and hence unable
to tell us anything about their health status," explains first author
Prof. Dr. Jens Dreier of Charite''s Center for Stroke Research. He
continues: "In our study, we have shown that electrodiagnostic monitoring
makes this moment visible. This means that treatment can be started in
time, even in comatose patients, before it is too late." The discovery
made by Prof. Dreier and his team was based on a phenomenon known as
'spreading depolarizations', massive waves of electrochemical energy
release caused by the toxic by-products of blood breakdown following hemorrhagic stroke. Affected areas of the brain require large amounts
of energy in order to restore normal conditions. In a healthy brain,
very brief periods of depolarization (a change in the membrane potential)
of nerve cells are normal and linked to blood supply: the brain can widen
blood vessels as required, thereby balancing increased energy needs with
an increase in blood flow. After a subarachnoid hemorrhage, however, pathologically massive and long-lasting spreading depolarizations can
disrupt signaling cascades between nerve cells and blood vessels,
so that the depolarization of nerve cells triggers extreme blood
vessel constriction. This in turn deprives the nerve cells of energy,
rendering them incapable of restoring normal electrochemical gradients. If depolarization persists for too long, these nerve cells will begin to
die off.

"One scientific insight from the last few years has been crucial: namely,
that the depolarization wave remains reversible up to a certain point
in time," emphasizes Prof. Dreier. He adds: "This means that cells can
recover fully if circulation, and consequently oxygen supply, is restored
in time." This was the starting point of the current clinical study,
which was conducted across five different university hospitals. In
order to take accurate measurements of spreading depolarizations, the researchers employed electrocorticography, a procedure used to measure
brain activity in neurological intensive care patients. To enable these
types of measurements, patients admitted with subarachnoid hemorrhage
had electrodes implanted under the dura mater (the brain's tough
outer membrane). The researchers also used imaging technologies such as magnetic resonance imaging (MRI) and computed tomography (CT), analyzing approximately 1,000 brain scans from 180 patients with subarachnoid
hemorrhage. The largest clinical study on spreading depolarizations to
date revealed that the average patient loses 46 milliliters of brain
tissue during the early phase after their brain bleed, i.e., by the
time they reach hospital. The average patient then loses a further
36 milliliters of brain tissue during the first two weeks after their hemorrhage, i.e., while in intensive care.

"These 36 milliliters of brain tissue are in effect salvageable," explains Prof. Dreier. He continues: "Electrodiagnostic monitoring enables us to identify developing strokes at a stage in time when the process can still
be reversed and modified. Spreading depolarizations can therefore serve
as a biomarker in real time. To an extent, this replaces an exchange with
the patient who is unable to express their symptoms and impairments as
a result of their being unconscious. This enables us to initiate early
and appropriate treatment measures in patients found to be at risk of
further stroke.

Similarly, it prevents additional medicine being given to individuals
found not to be at risk of further stroke. Potential side effects can
thus be avoided." This approach follows the principles of precision
medicine, which aims to tailor treatments to the needs of the individual patient. The researchers plan to test spreading depolarization monitoring
as an early warning system for use in routine clinical practice, where
they hope it will help to improve treatment options for people with
stroke. Artificial intelligence-based methods are likely to play a major
role in this regard. The automated analysis of electrodiagnostic data will
be necessary to ensure intensive care physicians are notified in real time
when an unconscious patient's brain tissue is at risk of further damage.


========================================================================== Story Source: Materials provided by
Charite'_-_Universita"tsmedizin_Berlin. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Jens P. Dreier, Maren K. L. Winkler, Sebastian Major, Viktor Horst,
Svetlana Lublinsky, Vasilis Kola, Coline L. Lemale, Eun-Jeung
Kang, Anna Maslarova, Irmak Salur, Janos Lu"ckl, Johannes Platz,
Devi Jorks, Ana I.

Oliveira-Ferreira, Karl Schoknecht, Clemens Reiffurth, Denny
Milakara, Dirk Wiesenthal, Nils Hecht, Nora F. Dengler, Agustin
Liotta, Stefan Wolf, Christina M. Kowoll, Andre' P. Schulte, Edgar
Santos, Erdem Gu"resir, Andreas W. Unterberg, Asita Sarrafzadeh,
Oliver W. Sakowitz, Hartmut Vatter, Michael Reiner, Gerrit Brinker,
Christian Dohmen, Ilan Shelef, Georg Bohner, Michael Scheel,
Peter Vajkoczy, Jed A. Hartings, Alon Friedman, Peter Martus,
Johannes Woitzik. Spreading depolarizations in ischaemia after
subarachnoid haemorrhage, a diagnostic phase III study. Brain,
2022; DOI: 10.1093/brain/awab457 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220412140910.htm

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