Abstract
Religious experiences have long
been documented in patients with epilepsy, though their exact underlying neural
mechanisms are still unclear. Here, we had the rare opportunity to record a
delusional religious conversion in real time in a patient with right temporal
lobe epilepsy undergoing continuous video-EEG. In this patient, a messianic
revelation experience occurred several hours after a complex partial seizure of
temporal origin, compatible with postictal psychosis (PIP). We analyzed the
recorded resting-state EEG epochs separately for each of the conventional
frequency bands. Topographical analysis of the bandpass filtered EEG epochs
revealed increased activity in the low-gamma range (30-40Hz) during religious
conversion compared with activity during the patient's habitual state. The
brain generator underlying this activity was localized to the left prefrontal
cortex. This suggests that religious conversion in PIP is related to control
mechanisms in the prefrontal lobe-related processes rather than medial temporal
lobe-related processes.
From the paper:
Eight hours following the last seizure, while lying in bed,
the patient abruptly “froze” and stared at the ceiling for several minutes,
stating later that he felt that God was approaching him. He then started
chanting prayers quietly, looked for his Kippa and put it on his head, chanting
the prayers more excessively. Then, abruptly, he yelled “And you are Adonai
(name of the Hebrew God) the Lord!”, stating later that god had revealed to
him, ordering him to bring redemption to the people of Israel. The patient then
stood up, detached the EEG electrodes from his skin, and went around the
department trying to convince people to follow him, stating that “God has sent
me to you”. When further questioned, he said that he does not have a concrete
plan, but he is sure that God is going to instruct him what he and his
followers should do on their way to redemption. In an in-depth psychiatric
evaluation, the patient was diagnosed as suffering from postictal psychosis
(PIP), with no other psychiatric illness. The patient was treated with
olanzapine. The psychotic state resolved within several hours…
Comparison of EEG signals recorded in resting state during
delusional religious conversion and with those during the nonpsychotic phase
using power frequency analysis, and topographical statistical comparison tests
revealed a significantly increased duration of a specific topographic FFT map
in the low-gamma band (30–40 Hz; mean ± std of 180 ± 160 ms in the PIP phase
compared with 3 ± 9 ms in the non-PIP phase; p < 0.01 after Bonferroni
correction). Notably, only the map's duration, restricted to this frequency
band, showed such a significant increased activity during religious conversion.
The neural EEG generators underlying this map were localized to the left prefrontal
cortex. No such differences were found in any other frequency band, nor in 12
control subjects in which the same analysis was conducted on two periods with
the same time interval.
The pathophysiological mechanisms of PIP are poorly
understood. As PIP occurs frequently in the framework of presurgical video-EEG
monitoring, data are, nevertheless, available in the form of both continuous
EEG recording as well as neuroimaging. With respect to EEG, several studies
have reported frequent interictal discharges in patients with PIP, suggesting
that ictal activity in the temporal lobe is directly related to this kind of
psychosis.
Postictal psychosis appears almost exclusively in patients
with temporal lobe epilepsy, predominantly with MTS . Most of the reported
patients suffered from bilateral MTS/aberrant temporal activity, though
unilateral MTS was also described . Our patient suffered from prominent right
MTS with bilateral independent interictal discharges. The similarity between
temporal lobe phenomena and psychotic symptoms does not necessarily imply
common underlying mechanisms for the two sets . Moreover, the delusion of messianic
conversion, as occurred in our patient, may be classified as beliefs of
grandeur, reference, and religious significance, similar to schizophrenic
delusions, which involve influence, persecution, and self-significance, rather
than classical semiology of TLE. Taken together, the recurrent findings over
studies of PIP revealing mesial temporal epilepsy and PFC aberrant activity
during PIP point to a disturbance of a large-scale network, which encompasses
both the PFC and the MTL. Such a network may be the default mode network (DMN),
which manages self-referenced activity and mental orientation to the
surrounding environment , and is known to be disturbed in psychosis.
Previous studies have speculated that PIP may be derived
from repeated electrical discharges or that the epilepsy and psychosis share a
common neuropathology that may be localized (with emphasis on temporal or
frontal lobe). Our study suggests an
alternative explanation of a large-scale network disturbance underlying PIP.
Courtesy of a colleague.
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