EEG pattern during functional tests in patients with CNS disorder


  • Irma Khachidze Faculté de médecine, Université Cadi Ayyad de Marrakech


The mechanism of EEG alterations caused by forced
breathing (hyperventilation test during functional
loading), in particular, the cause of high amplitude
slow wave activity (paroxysmal synchronization)
and development of epileptiform discharge has not
been fully clarified. Different types of pathologic
EEG reactions to hyperventilation hamper their
interpretation, while the study of these phenomena is
still of current interest. The goal of the investigation
was to study and describe the EEG response to
hyperventilation according to onset time of reaction
and the pathological type of EEG. 2186 patients,
who applied to D. Tatishvili Medical Center for
examination, were recruited according to the EEG
response to hyperventilation Based on the analysis
of the results, 3 types of pathological EEG reactions/
responses (PERH) (which have been revealed
predominantly at the first minute of functional
loading (P<0,05). The background rhythm of the
EEG was restored within 2 and /or more minutes
after the termination of loading. In 985 subjects 3
types of PERH have been revealed: First type of EEG
reaction represents disorganization of the baseline
rhythm, without paroxysmal reaction. Second type
of EEG reaction reveal generalized, high-amplitude,
monomorphic/polymorphic slow-wave paroxysmal
discharges without epileptiform activity. Thirst type
of EEG reaction reflects the epileptiform activity
with and without generalized paroxysmal discharge.
The EEG changes based on hyperventilation are
linked to hypocapnia and concurrent acute alkalosis.
It should be noted that partial pressure of carbon
dioxide reduces to a minimum 1.5-2 minutes after
hyperventilation, while pathologic changes in the EEG
(paroxysmal EEG synchronization and/or generalized
epileptiform discharges) are observed at the beginning
of forced breathing. Such time incompatibility leads
to search of alternative mechanisms that could more
adequately explain the abovementioned phenomenon.
Reasonable to consider a set of views developed by
“hormesis theory”. Since hyperventilation causes
a mild stress, it should be induce the appearance of
PERH at the beginning of forced breathing.

Biographie de l'auteur-e

Irma Khachidze, Faculté de médecine, Université Cadi Ayyad de Marrakech

Chef de service de neurologie au CHU Mohamed VI de marrakech

et professeur à la Faculté de médecine, Université Cadi Ayyad de Marrakech (Maroc).






Articles Originaux