Jørgen Alving

Increased dopamine tone during meditation-induced change of consciousness

This is the first in vivo demonstration of an association between endogenous neurotransmitter release and conscious experience. Using 11C-raclopride PET we demonstrated increased endogenous dopamine release in the ventral striatum during Yoga Nidra meditation. Yoga Nidra is characterized by a depressed level of desire for action, associated with decreased blood flow in prefrontal, cerebellar and subcortical regions, structures thought to be organized in open loops subserving executive control. In the striatum, dopamine modulates excitatory glutamatergic synapses of the projections from the frontal cortex to striatal neurons, which in turn project back to the frontal cortex via the pallidum and ventral thalamus. The present study was designed to investigate whether endogenous dopamine release increases during loss of executive control in meditation. Participants underwent two 11C-raclopride PET scans: one while attending to speech with eyes closed, and one during active meditation. The tracer competes with endogenous dopamine for access to dopamine D2 receptors predominantly found in the basal ganglia. During meditation, 11C-raclopride binding in ventral striatum decreased by 7.9%. This corresponds to a 65% increase in endogenous dopamine release. The reduced raclopride binding correlated significantly with a concomitant increase in EEG theta activity, a characteristic feature of meditation. All participants reported a decreased desire for action during meditation, along with heightened sensory imagery. The level of gratification and the depth of relaxation did not differ between the attention and meditation conditions. Here we show increased striatal dopamine release during meditation associated with the experience of reduced readiness for action. It is suggested that being in the conscious state of meditation causes a suppression of cortico-striatal glutamatergic transmission. To our knowledge this is the first time in vivo evidence has been provided for regulation of conscious states at a synaptic level.

Standardized computer-based organized reporting of EEG: SCORE.

The electroencephalography (EEG) signal has a high complexity, and the process of extracting clinically relevant features is achieved by visual analysis of the recordings. The interobserver agreement in EEG interpretation is only moderate. This is partly due to the method of reporting the findings in free‐text format. The purpose of our endeavor was to create a computer‐based system for EEG assessment and reporting, where the physicians would construct the reports by choosing from predefined elements for each relevant EEG feature, as well as the clinical phenomena (for video‐EEG recordings). A working group of EEG experts took part in consensus workshops in Dianalund, Denmark, in 2010 and 2011. The faculty was approved by the Commission on European Affairs of the International League Against Epilepsy (ILAE). The working group produced a consensus proposal that went through a pan‐European review process, organized by the European Chapter of the International Federation of Clinical Neurophysiology. The Standardised Computer‐based Organised Reporting of EEG (SCORE) software was constructed based on the terms and features of the consensus statement and it was tested in the clinical practice. The main elements of SCORE are the following: personal data of the patient, referral data, recording conditions, modulators, background activity, drowsiness and sleep, interictal findings, “episodes” (clinical or subclinical events), physiologic patterns, patterns of uncertain significance, artifacts, polygraphic channels, and diagnostic significance. The following specific aspects of the neonatal EEGs are scored: alertness, temporal organization, and spatial organization. For each EEG finding, relevant features are scored using predefined terms. Definitions are provided for all EEG terms and features. SCORE can potentially improve the quality of EEG assessment and reporting; it will help incorporate the results of computer‐assisted analysis into the report, it will make possible the build‐up of a multinational database, and it will help in training young neurophysiologists.

Diagnostic usefulness and duration of the inpatient long-term video-EEG monitoring: Findings in patients extensively investigated before the monitoring

Inpatient long-term video-EEG monitoring (LTM) is an important diagnostic tool for patients with seizures and other paroxysmal behavioural events. The main referral categories are diagnosis (epileptic versus non-epileptic disorder), seizure classification and presurgical evaluation. The diagnostic usefulness of the LTM varies considerably (19-75%) depending on how this was defined and on the selection of the patients. The purpose of this study was to assess the diagnostic usefulness and the necessary duration of the LTM for the referral groups, in patients extensively investigated before the monitoring. An LTM was considered diagnostically useful when it provided previously not reported, clinically relevant information on the paroxysmal event. For the presurgical group, reaching a decision concerning surgery was an additional requirement. We reviewed data from 234 consecutive LTM-sessions (221 patients) over a 2-year period. In 44% of the cases the LTM was diagnostically useful. There were no significant differences concerning diagnostic usefulness among the main referral groups: diagnostic (41%), classification (41%) and presurgical (55%). Diagnostic usefulness did not differ among the age groups either. The duration of the successful LTM-sessions was significantly longer in the presurgical group (mean: 3.5 days) than in the diagnostic and classification groups (2.4 and 2.3 days, respectively). We conclude that LTM is a valuable diagnostic tool even in patients extensively investigated before the monitoring, and is equally effective in the referral and age groups. However, patients referred for presurgical evaluation need considerably longer LTM, and this should be taken into account when planning the resources and calculating the costs.

Beyond the double banana: Improved recognition of temporal lobe seizures in long-term EEG

Purpose: To investigate whether extending the 10-20 array with 6 electrodes in the inferior temporal chain and constructing computed montages increases the diagnostic value of ictal EEG activity originating in the temporal lobe. In addition, the accuracy of computer-assisted spectral source analysis was investigated. Methods: Forty EEG samples were reviewed by 7 EEG experts in various montages (longitudinal and transversal bipolar, common average, source derivation, source montage, current source density, and reference-free montages) using 2 electrode arrays (10-20 and the extended one). Spectral source analysis used source montage to calculate density spectral array, defining the earliest oscillatory onset. From this, phase maps were calculated for localization. The reference standard was the decision of the multidisciplinary epilepsy surgery team on the seizure onset zone. Clinical performance was compared with the double banana (longitudinal bipolar montage, 10-20 array). Results: Adding the inferior temporal electrode chain, computed montages (reference free, common average, and source derivation), and voltage maps significantly increased the sensitivity. Phase maps had the highest sensitivity and identified ictal activity at earlier time-point than visual inspection. There was no significant difference concerning specificity. Conclusions: The findings advocate for the use of these digital EEG technology–derived analysis methods in clinical practice.

Diagnostic yield of five minutes compared to three minutes hyperventilation during electroencephalography

PURPOSE To investigate whether hyperventilation (HV) for 5min increases the diagnostic yield of electroencephalography (EEG) compared to 3min HV. METHODS data were evaluated from 1084 consecutive patients, from three European centres, referred to EEG on suspicion of epilepsy. Seizures and interictal EEG abnormalities precipitated during the first 3min and during the last 2min of the HV period (totally 5min) were determined. RESULTS Eight hundred seventy-seven patients (81%) completed 5min HV. Seizures were precipitated during the first 3min of HV in 21 patients, and during the last 2min in four more patients. Interictal EEG abnormalities were precipitated in the first 3min of HV in 16 patients, and during the last 2min in 7 more patients. Psychogenic nonepileptic seizures occurred in eight patients during the first 3min of HV and in two more patients during the last 2min. No adverse events occurred during the last 2min of HV, but eight patients (1%) stopped HV during the last 2min because they were not able to hyperventilate further. CONCLUSION 16% of seizures and 30% of interictal EEG abnormalities triggered by HV occurred during the last 2min of HV, suggesting the clinical usefulness of prolonged hyperventilation for 5min. The vast majority of patients (99%) who are able to hyperventilate for 3min can complete 5min HV, without additional adverse events.

Epileptic prodromes: Are they nonconvulsive status epilepticus?

PURPOSE The aim of this study was to assess how frequently prodromes occur in an adult patient group from a tertiary referral epilepsy centre and to investigate the EEG changes during the prodromes. METHODS 578 consecutive patients were interviewed on subjective phenomena, experiences heralding the seizures, for at least 30min before the start of the seizure. EEGs were recorded during the prodromes. RESULTS Ten out of 490 included patients had prodromes (2%). We were able to record EEG during prodromes in 6 patients. Three patients had EEG changes corresponding to nonconvulsive status epilepticus. Three patients had unrevealing EEG recordings during prodromes. CONCLUSION Our results suggest that at least in a part of the patients, the prodromes are actually ictal phenomena, and should be treated as nonconvulsive status epilepticus.

Effect of medication withdrawal on the interictal epileptiform EEG discharges in presurgical evaluation

Medication withdrawal (MW) is an important method of provoking seizures and activating epileptiform EEG activity during the diagnostic work-up of patients evaluated for epilepsy surgery. Previously it was suggested that MW might influence the seizure-type and activate cortical areas otherwise not producing epileptiform discharges, leading to a false localization of the irritative zone. In order to investigate this we reviewed 42 consecutive cases of MW, of 36 patients, during a 3-year period. We compared seizure frequency, seizure-types and the localization of interictal epileptiform discharges before and after MW. Seizure frequency was significantly higher after MW. In the whole group we found an increase in seizure propagation: the proportion of the complex partial seizures and secondarily generalised seizures increased, while the proportion of the simple partial seizures decreased following MW. In one-third of the patients the interictal EEGs after the MW were different from those recorded before the MW. However, in these discordant cases the EEG findings after the MW (and not before the MW) were concordant with the seizure onset zone and the lesional zone. We conclude that MW is an effective and reliable seizure provoking method, and it does not lead to false localization of the irritative zone.

How long shall we record electroencephalography

The duration of electroencephalography (EEG) recordings varies widely among laboratories. Although several recommendations had been published, there are no previous studies directly addressing this.

Do patients need to stay in bed all day in the Epilepsy Monitoring Unit? Safety data from a non-restrictive setting

PURPOSE To assess whether injuries occur more often in an Epilepsy Monitoring Unit (EMU) where portable EEG amplifiers are used, and where patients can freely move within a large area during the monitoring. METHODS Patients were monitored at the Danish Epilepsy Center, in an EMU specifically designed for this purpose, and they were under continuous surveillance by personnel dedicated to the EMU. Adverse events (AEs) - including injuries, were prospectively noted, as part of the safety policy of the hospital. Other data were retrospectively extracted from the electronic database, for a 5-year period (January 2012-December 2016). RESULTS 976 patients were admitted to the EMU. Falls occurred in 19 patients (1.9%) but none of them resulted in injury. Only one serious AE occurred: a patient had a convulsive status epilepticus, which did not respond to first-line treatment in the EMU and was transferred to the intensive care unit. The rate of AEs were similar or lower than previously reported by other centers, where the mobility of the patients had been restricted during monitoring. CONCLUSION In an EMU specially designed for this purpose, where patients are under continuous surveillance by personnel dedicated to the EMU, injuries can be avoided even when the mobility of the patients is not restricted.

Postictal inhibition of the somatosensory cortex

Transient suppression of the motor cortex and of the speech areas cause well-described postictal phenomena following seizures involving the respective cortical areas. Pain is a rare symptom in epileptic seizures. We present a patient with painful tonic seizures in the left leg. The amplitude of the cortical component of the somatosensory evoked potential following stimulation of the left tibial nerve was reduced immediately after the seizure. Our findings suggest that the excitability of the sensory cortex is transiently reduced following a seizure involving the somatosensory area.