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Discusses the abstract of the article "How Does EEG Burst Suppression in Anaesthesia Differ from Burst Auppression after Ischaemic Brain Damage?" by Ville Jantti and colleagues submitted at the 27th Congress of The Scandinavian Society of Anesthesiology and Intensive Care Medicine.

Primary central nervous system lymphoma (PCNSL) is an aggressive brain disease where lymphocytes invade along perivascular spaces of arteries and veins. The invasion markedly changes (peri)vascular structures but its effect on physiological brain pulsations has not been previously studied. Using physiological magnetic resonance encephalography (MREG BOLD ) scanning, this study aims to quantify the extent to which (peri)vascular PCNSL involvement alters the stability of physiological brain pulsations mediated by cerebral vasculature. Clinical implications and relevance were explored. In this study, 21 PCNSL patients (median 67y; 38% females) and 30 healthy age-matched controls (median 63y; 73% females) were scanned for MREG BOLD signal during 2018-2021. Motion effects were removed. Voxel-by-voxel Coefficient of Variation (CV) maps of MREG BOLD signal was calculated to examine the stability of physiological brain pulsations. Group-level differences in CV were examined using nonparametric covariate-adjusted tests. Subject-level CV alterations were examined against control population Z-score maps wherein clusters of increased CV values were detected. Spatial distributions of clusters and findings from routine clinical neuroimaging were compared [contrast-enhanced, diffusion-weighted, fluid-attenuated inversion recovery (FLAIR) data]. Whole-brain mean CV was linked to short-term mortality with 100% sensitivity and 100% specificity, as all deceased patients revealed higher values (n = 5, median 0.055) than surviving patients (n = 16, median 0.028) (p < .0001). After adjusting for medication, head motion, and age, patients revealed higher CV values (group median 0.035) than healthy controls (group median 0.024) around arterial territories (p ≤ .001). Abnormal clusters (median 1.10 × 10 5 mm 3 ) extended spatially beyond FLAIR lesions (median 0.62 × 10 5 mm 3 ) with differences in volumes (p = .0055)., (© 2022 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.)

Background: We report here the first population-based incidence rates and prognosis of primary central nervous system lymphoma (PCNSL) in Finland., Methods: Finnish Cancer Registry data by histological diagnosis and tumor location (2007-2017) for cases with diffuse large B-cell lymphoma., Results: During 2007-2017, 392 new cases of PCNSL were reported (195 males, 197 females). The average age-adjusted incidence was 0.68/100,000 person-years. Incidence for males was 0.74/100,000 and for females 0.63/100,000, respectively. The incidence was highest, 2.93/100,000, among people aged 75-79 years. Concerning all cases in 2007-2017 the 2-year age-adjusted relative survival rate was 33% and the corresponding 5-year survival rate was 26%. Among patients under the age of 70, the age-adjusted 5-year relative survival rate increased from 36% in 2007-2012 to 43% for 2013-2017. Among patients aged 70+ the corresponding survival rates were poor, 7 and 9%., Conclusions: PCNSL incidence in Finland is among the highest reported in the world. The annual increase in incidence was 2.4%. The prognosis is still dismal, especially in elderly patients., (© 2022. The Author(s).)

Purpose: Anesthesiologists have increasingly started to use EEG-based indexes to estimate the level and type of unconsciousness. However, the physiology and biophysics are poorly understood in anesthesiological literature., Methods: EEG was recorded from electrodes on the surface of head, including scalp, as well as DBS (deep brain stimulation) electrodes implanted deep in the brain. Mathematical modeling with a realistic head model was performed to create illustrative images of the sensitivity of electrode montages., Results: EEG pattern of anesthesia, burst-suppression, is recordable outside of scalp area as well in the depth of brain because the EEG current loops produce recordable voltage gradients in the whole head. The typical electrodes used in anesthesia monitoring are most sensitive to basal surface of frontal lobes as well as frontal and mesial parts of temporal lobes., Conclusions: EEG currents create closed-loops, which flow from the surface of the cortex and then return to the inside of the hemispheres. In the case of widespread synchronous activity like physiological sleep or anesthesia, the currents recorded with surface and depth electrodes return through the base of brain and skull.

Objectives: The aim of the study was to compare the EEG findings and haemodynamic parameters of adult male patients while undergoing mask induction with sevoflurane anaesthesia with either controlled hyperventilation (CH) or spontaneous breathing (SB)., Methods: Twenty male patients, aged 23-52 (mean 42) years were anaesthetized randomly with either spontaneous breathing or mild controlled hyperventilation via mask. EEG was recorded using a full 10-20 electrode set., Results: Anaesthesia induction with high inhaled concentrations of sevoflurane produced several epileptiform and periodic EEG patterns. CH doubled the amount of these EEG patterns compared to SB. Higher heart rate was recorded in the CH group., Conclusions: We describe a high incidence of paroxysmal EEG activity: epileptiform and generalized periodic discharges (GPDs) during rapid sevoflurane in nitrous oxide-oxygen mask induction in hyperventilated male patients. However these activities have no effect to the heart rate or the mean arterial pressure., Significance: The monitoring of GPDs and burst suppression patterns during rapid anaesthesia induction with sevoflurane provides possibility to study the effects of volatile anaesthetics in the healthy brain. In order to analyse the different sources of EEG patterns a wide-band multichannel EEG recording is necessary., (Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Chemotherapy aided by opening of the blood-brain barrier with intra-arterial infusion of hyperosmolar mannitol improves the outcome in primary central nervous system lymphoma. Proper opening of the blood-brain barrier is crucial for the treatment, yet there are no means available for its real-time monitoring. The intact blood-brain barrier maintains a mV-level electrical potential difference between blood and brain tissue, giving rise to a measurable electrical signal at the scalp. Therefore, we used direct-current electroencephalography (DC-EEG) to characterize the spatiotemporal behavior of scalp-recorded slow electrical signals during blood-brain barrier opening. Nine anesthetized patients receiving chemotherapy were monitored continuously during 47 blood-brain barrier openings induced by carotid or vertebral artery mannitol infusion. Left or right carotid artery mannitol infusion generated a strongly lateralized DC-EEG response that began with a 2 min negative shift of up to 2000 μV followed by a positive shift lasting up to 20 min above the infused carotid artery territory, whereas contralateral responses were of opposite polarity. Vertebral artery mannitol infusion gave rise to a minimally lateralized and more uniformly distributed slow negative response with a posterior-frontal gradient. Simultaneously performed near-infrared spectroscopy detected a multiphasic response beginning with mannitol-bolus induced dilution of blood and ending in a prolonged increase in the oxy/deoxyhemoglobin ratio. The pronounced DC-EEG shifts are readily accounted for by opening and sealing of the blood-brain barrier. These data show that DC-EEG is a promising real-time monitoring tool for blood-brain barrier disruption augmented drug delivery.

Primary central nervous system lymphoma (PCNSL) is a rare brain tumour with a dismal prognosis. Several phase II studies with high-dose methotrexate-based regimens have shown promising early results, but in all hospital-based data published so far, the disease outcome has been poor. Patients with relapsed or refractory disease have a dismal prognosis. We performed retrospective analysis to evaluate results and tolerabilities of BBBD therapy in combination with high-dose therapy supported by autologous stem cell transplantation. We analysed 25 patients (age range: 40-71 years) who were treated in first or second line with BBBD therapy. When we started BBBD treatment, patients had relapsed or refractory PCNSL or they did not tolerate Bonn-like therapy. In recent years, some of the patients were treated in first line. We found promising response rates. Altogether 19 (76 %) of the patients achieved a complete response (CR). Two-year progression-free survival (PFS) and overall survival (OS) rates were 61 and 57 % respectively and the five-year OS was 47 %. Patients who were treated with a five-drug therapy had a very promising prognosis. The CR rate was 100 % in first-line therapy and 60 % in relapsed cases. These findings suggest that BBBD is a promising therapy for PCNSL, especially for patients in first line, but also for patients with relapsed or refractory disease after conventional chemotherapy, who commonly have a very poor prognosis. Treatment-related toxicity was generally manageable. Thus, BBBD followed by ASCT could be a treatment of choice in transplant-eligible patients with PCNSL.

Primary central nervous system lymphoma (PCNSL) is sensitive to both chemotherapy and radiation, but the blood-brain barrier limits the usefulness of the most effective chemotherapeutic agents. On the other hand radiation therapy carries along serious long term adverse events. In BBBD-therapy the blood-brain barrier is opened with intra-arterial mannitol infusion thus permitting both the chemotherapeutics and antibodies to enter through blood-brain barrier. So far 17 patients have started the therapy in our clinics. Ten patients have reached a complete response and 8 of these responses are ongoing with follow-up times of 6-62 months.

Our aim was to explore time-varying coherence values versus spacing and referencing of electrode contacts in thalamic level from human encephalographic (EEG) data. Data has been acquired during induction of propofol anesthesia until burst-suppression level in scalp EEG. Results are shown from coherence analysis applied to EEG signals from selected depth electrode contacts pair-wise of three subjects. Alpha coherence is the most prominent behavior in all channel pairs. It is persistent throughout the time period followed and in coherence calculated between bipolar derivations in depth electrodes.

In 40-60% of cases with interictal activity in EEG, fMRI cannot locate any focus or foci with simultaneous EEG/fMRI. In experimental focal epilepsy, a priori knowledge exists of the location of the epileptogenic area. This study aimed to develop and to test an experimental focal epilepsy model, which includes dynamic induction of epileptic activity, simultaneous EEG/fMRI, and deep anesthesia. Reported results are from seven pigs (23 +/- 2 kg) studied under isoflurane anesthesia (1.2-1.6 MAC, burst-suppression EEG) and muscle relaxant. Hypo- and hypercapnia were tested in one pig. Penicillin (6000 IU) was injected via a plastic catheter (inserted into the somatosensory cortex) during fMRI (GRE-EPI, TE = 40 ms, 300 ms/two slices, acquisition delay 1700 ms) in 1.5 T (N = 6). Epileptic spikes between acquisition artifacts were reviewed and EEG total power calculated. Cross-correlation between voxel time series and three model functions resembling induced spike activity were tested. Activation map averages were calculated. Development of penicillin induced focal epileptic activity was associated with linear increase and saturation up to approximately 10-20%, in BOLD activation map average. Its initial linear increase reached 2.5-10% at the appearance of the first distinguished spike in ipsilateral EEG in all six animals. Correlated voxels were located mainly in the vicinity of the penicillin injection site and midline, but few in the thalamus. In conclusion, development of focal epileptic activity can be detected as a BOLD signal change, even preceding the spike activity in scalp EEG. This experimental model contains potential for development and testing different localization methods and revealing the characteristic time sequence of epileptic activity with fMRI during deep anesthesia.

Differences in the blood oxygen level dependent (BOLD) signal changes were studied during voluntary hyperventilation (HV) between young healthy volunteer groups, (1) with intermittent rhythmic delta activity (IRDA) (N = 4) and (2) controls (N = 4) with only diffuse arrhythmic slowing in EEG (normal response). Subjects hyperventilated (3 min) during an 8-min functional MRI in a 1.5-T scanner, with simultaneous recording of EEG (successful with N = 3 in both groups) and physiological parameters. IRDA power and average BOLD signal intensities (of selected brain regions) were calculated. Hypocapnia showed a tendency to be slightly lighter in the controls than in the IRDA group. IRDA power increased during the last minute of HV and ended 10-15 s after HV. The BOLD signal decreased in white and gray matter after the onset of HV and returned to the baseline within 2 min after HV. The BOLD signal in gray matter decreased approximately 30% more in subjects with IRDA than in controls, during the first 2 min of HV. This difference disappeared (in three subjects out of four) during IRDA in EEG. BOLD signal changes seem to depict changes, which precede IRDA. IRDA due to HV in healthy volunteers represent a model with a clearly defined EEG pattern and an observable BOLD signal change.