Dreaming and awareness during dexmedetomidine- and propofol-induced unresponsiveness.

BACKGROUND: Experiences during anaesthetic-induced unresponsiveness have previously been investigated by interviews after recovery. To explore whether experiences occur during drug administration, we interviewed participants during target-controlled infusion (TCI) of dexmedetomidine or propofol and after recovery. METHODS: Healthy participants received dexmedetomidine (n=23) or propofol (n=24) in stepwise increments until loss of responsiveness (LOR1). During TCI we attempted to arouse them for interview (return of responsiveness, ROR1). After the interview, if unresponsiveness ensued with the same dose (LOR2), the procedure was repeated (ROR2). Finally, the concentration was increased 1.5-fold to achieve presumable loss of consciousness (LOC), infusion terminated, and the participants interviewed upon recovery (ROR3). An emotional sound stimulus was presented during LORs and LOC, and memory for stimuli was assessed with recognition task after recovery. Interview transcripts were content analysed. RESULTS: Of participants receiving dexmedetomidine, 18/23 were arousable from LOR1 and LOR2. Of participants receiving propofol, 10/24 were arousable from LOR1 and two of four were arousable from LOR2. Of 93 interviews performed, 84% included experiences from periods of unresponsiveness (dexmedetomidine 90%, propofol 74%). Internally generated experiences (dreaming) were present in 86% of reports from unresponsive periods, while externally generated experiences (awareness) were rare and linked to brief arousals. No within drug differences in the prevalence or content of experiences during infusion vs after recovery were observed, but participants receiving dexmedetomidine reported dreaming and awareness more often. Participants receiving dexmedetomidine recognised the emotional sounds better than participants receiving propofol (42% vs 15%), but none reported references to sounds spontaneously. CONCLUSION: Anaesthetic-induced unresponsiveness does not induce unconsciousness or necessarily even disconnectedness. CLINICAL TRIAL REGISTRATION: NCT01889004.

Disentangling conscious from unconscious cognitive processing with event-related EEG potentials.

By looking for properties of consciousness, cognitive neuroscience studies have dramatically enlarged the scope of unconscious cognitive processing. This emerging knowledge inspired the development of new approaches allowing clinicians to probe and disentangle conscious from unconscious cognitive processes in non-communicating brain-injured patients both in terms of behaviour and brain activity. This information is extremely valuable in order to improve diagnosis and prognosis in such patients both at acute and chronic settings. Reciprocally, the growing observations coming from such patients suffering from disorders of consciousness provide valuable constraints to theoretical models of consciousness. In this review we chose to illustrate these recent developments by focusing on brain signals recorded with EEG at bedside in response to auditory stimuli. More precisely, we present the respective EEG markers of unconscious and conscious processing of two classes of auditory stimuli (sounds and words). We show that in both cases, conscious access to the corresponding representation (e.g.: auditory regularity and verbal semantic content) share a similar neural signature (P3b and P600/LPC) that can be distinguished from unconscious processing occurring during an earlier stage (MMN and N400). We propose a two-stage serial model of processing and discuss how unconscious and conscious signatures can be measured at bedside providing relevant informations for both diagnosis and prognosis of consciousness recovery. These two examples emphasize how fruitful can be the bidirectional approach exploring cognition in healthy subjects and in brain-damaged patients.

Non-alcoholic Wernicke's encephalopathy with cortical involvement and polyneuropathy following gastrectomy.

In this study, we present the clinical manifestations, brain magnetic resonance imaging (MRI) and concurrent polyneuropathies in two patients with non-alcoholic Wernicke's encephalopathy (WE) after gastrojejunostomy (Billroth II) anastomosis procedures. These patients developed sub-acute onset of disorientation and disturbance of consciousness following several weeks of poor intake. Peripheral neuropathy of varying severity was noted before and after the onset of WE. Brain MRI of the patients showed cerebellar vermis and symmetric cortical abnormalities in addition to typical WE changes. Electrophysiological studies demonstrated axonal sensorimotor polyneuropathy. Prompt thiamine supplement therapy was initiated and both patients gradually recovered, however mild amnesia was still noted 6 months later. We reviewed non- alcoholic WE with atypical cortical abnormalities in English language literatures and identified 29 more cases. Eight out of 31 (25.8%) patients died during follow-up. Nine patients with gait disturbance or motor paresis had showed hyporeflexia in neurological examinations. In addition to classic triad, seizure was recorded in seven patients. Dietary deprivation is a risk factor for non-alcoholic WE among elderly patients receiving gastrointestinal surgery. The prognosis is good after thiamine supplement therapy. Recognizing the MRI features and predisposing factors in patients who have undergone gastrectomy can aid in the diagnosis and management.

A mediunidade vista por alguns pioneiros da área mental / Mediumship seen by some pioneers of mental health

As vivências tidas como mediúnicas são descritas na maioria das civilizações e têm um grande impacto sobre a sociedade. Apesar de ser um tema pouco estudado atualmente, já foi objeto de intensas investigações por alguns dos fundadores da moderna psicologia e psiquiatria. Foi revisado o material produzido por Janet, James, Myers, Freud e Jung a respeito da mediunidade, com ênfase em dois aspectos: suas causas e relações com psicopatologia. Esses pesquisadores chegaram a três conclusões distintas. Janet e Freud associaram mediunidade com psicopatologia e a uma origem exclusiva no inconsciente pessoal. Jung e James aceitavam a possibilidade de um caráter não-patológico e uma origem no inconsciente pessoal, mas sem excluírem em definitivo a real atuação de um espírito desencarnado. Por fim, Myers associou a mediunidade a um desenvolvimento superior da personalidade e tendo como causa um misto entre o inconsciente, a telepatia e ação de espíritos desencarnados. Como conclusão, é apontada a necessidade de se conhecer os estudos já realizados para dar continuidade nessas investigações em busca de um paradigma realmente científico sobre a mediunidade.

[Analysis of implicit memory during propofol anesthesia]. / Análisis de la memoria implícita durante la hipnosis farmacológica con propofol.

OBJECTIVE: Consensus has not been achieved on the presence of unconscious memory of messages in general anesthesia for methodological reasons. Our objective was to apply a model of anesthesia that allows for clinical control of the level of hypnosis in order to evaluate the presence and characteristics of implicit memory in deep sedation with propofol. PATIENTS AND METHODS: We randomly assigned 48 consecutive patients undergoing lower limb surgery to two groups. In both groups subarachnoid anesthesia was with varying doses of propofol to maintain a level of hypnosis marked by inability to respond to orders, absence of movements and spontaneous ventilation. The experimental group listened to a recording of the words "banana" and "melon" for the semantic category of fruits and "white" and "black" for colors. The control group listened to a recording of environmental operating room noise. We recorded, among other variables, anxiety and age. Upon awakening, after the presence of conscious memory had been ruled out, we investigated implicit memory by comparing the percentage of correct answers in the two groups. RESULTS: The experimental group had a higher percentage of correct fruit names (p = 0.03). No differences were detected for colors. The youngest patients in the experimental group were correct more often about the fruits than were older members (p = 0.04) and those with greater anxiety were more often correct (p = 0.002). CONCLUSIONS: Implicit memory is preserved under hypnosis with propofol and is more likely to be present among those who are younger or experience greater anxiety. Concrete words with object references are more easily remembered than abstract words referring to perception. The semantic load of messages is relevant.