[Interest of a biopsychosocial approach in the management of a patient with chronic pain : a narrative review]. / Intérêt d'une approche biopsychosociale dans la prise en charge d'un patient souffrant de douleurs chroniques : une revue narrative.

Pain is generally perceived as a sensory, emotional and cognitive aggression by the patient who suffers from it and as the enemy that must be defeated by the physician. It may become chronic, and the passage from the acute phase to the chronic phase cannot be explained in a single way. Indeed, multiple factors come into play: biological, psychological and socio-professional. The patient's quality of life then deteriorates and places him/her in a vicious cycle of pain. The assessment of the different components of pain (sensory, emotional, cognitive and behavioural) and its maintenance factors allow for the implementation of therapeutic strategies, both physical and psychological, adapted to every patient. Due to the complexity of chronic pain management, a multidisciplinary strategy is being developed, with a global approach according to the biopsychosocial perspective, including non-pharmacological approaches, with the objective of allowing the patient to be autonomous in the management of his/her symptoms.

La douleur est généralement perçue comme une agression sensorielle, émotionnelle et cognitive par le patient qui en souffre, et comme l'ennemi que le médecin doit vaincre. Elle peut se chroniciser, et le passage de la phase aiguë à la phase chronique ne peut s'expliquer d'une façon unique. En effet, de multiples facteurs biologiques, psychologiques et socio-professionnels entrent en jeu. La qualité de vie du patient se dégrade alors et le place dans un véritable cercle vicieux de la douleur. L'évaluation des différentes composantes de la douleur (sensorielle, émotionnelle, cognitive et comportementale) et de ses facteurs de maintien permet de mettre en place des stratégies thérapeutiques, aussi bien sur le plan physique que psychologique, adaptées à chaque patient. Du fait de la complexité de la prise en charge de la douleur chronique, se développe une méthode pluridisciplinaire, dans une perspective d'approche globale selon le modèle biopsychosocial, incluant également des approches non médicamenteuses avec comme objectif, notamment, de permettre au patient une autonomie dans la gestion de sa symptomatologie.

[Intracerebroventricular infusion of morphine, bupivacaine and clonidine for the management of refractory neoplasic pain in a palliative care setting : a case report]. / Administration intracérébroventriculaire de morphine, bupivacaïne et clonidine pour la gestion de la douleur réfractaire d'origine néoplasique en soins palliatifs.

Intracerebroventricular (ICV) infusion of morphine is a well-known technique to relieve intractable neoplasic pain when conventional analgesic strategies reach their limits. Through this case report, we present indications, assets, and drawbacks of this procedure in such conditions. We also describe the adaptation of the systemic analgesic treatment to allow discharge from the hospital to home settings. Thanks to the ICV infusion of a mixture of morphine, bupivacaine and clonidine, the patient was weaned from oral opioid medications and reached an acceptable level of comfort. This allowed him to be discharged from the hospital to go back home with a specific setting of mobile palliative care structure. The patient's family followed training about the device to prevent any technical trouble and to react in case of unwanted events.

L'administration de morphine intracérébroventriculaire (ICV) est une technique bien connue pour traiter les douleurs néoplasiques insoutenables lorsqu'un traitement antalgique conventionnel atteint ses limites. A travers un cas clinique, nous présentons les indications, les atouts et les inconvénients de cette procédure dans de telles conditions. Nous décrivons aussi l'adaptation du traitement antalgique per os après implantation du cathéter. Grâce à l'infusion ICV d'un mélange de morphine, de bupivacaïne et de clonidine, le patient a été sevré totalement des dérivés opioïdes oraux et a atteint un niveau de confort acceptable pour rentrer à domicile avec une structure mobile de soins palliatifs mise en place. L'entourage du patient a bénéficié de séances d'information pour prévenir les problèmes techniques liés au dispositif et pour réagir en cas d'incident.

Propofol-induced unresponsiveness is associated with impaired feedforward connectivity in cortical hierarchy.

BACKGROUND: Impaired consciousness has been associated with impaired cortical signal propagation after transcranial magnetic stimulation (TMS). We hypothesised that the reduced current propagation under propofol-induced unresponsiveness is associated with changes in both feedforward and feedback connectivity across the cortical hierarchy. METHODS: Eight subjects underwent left occipital TMS coupled with high-density EEG recordings during wakefulness and propofol-induced unconsciousness. Spectral analysis was applied to responses recorded from sensors overlying six hierarchical cortical sources involved in visual processing. Dynamic causal modelling (DCM) of induced time-frequency responses and evoked response potentials were used to investigate propofol's effects on connectivity between regions. RESULTS: Sensor space analysis demonstrated that propofol reduced both induced and evoked power after TMS in occipital, parietal, and frontal electrodes. Bayesian model selection supported a DCM with hierarchical feedforward and feedback connections. DCM of induced EEG responses revealed that the primary effect of propofol was impaired feedforward responses in cross-frequency theta/alpha-gamma coupling and within frequency theta coupling (F contrast, family-wise error corrected P<0.05). An exploratory analysis (thresholded at uncorrected P<0.001) also suggested that propofol impaired feedforward and feedback beta band coupling. Post hoc analyses showed impairments in all feedforward connections and one feedback connection from parietal to occipital cortex. DCM of the evoked response potential showed impaired feedforward connectivity between left-sided occipital and parietal cortex (T contrast P=0.004, Bonferroni corrected). CONCLUSIONS: Propofol-induced loss of consciousness is associated with impaired hierarchical feedforward connectivity assessed by EEG after occipital TMS.

Frontal alpha-delta EEG does not preclude volitional response during anaesthesia: prospective cohort study of the isolated forearm technique.

BACKGROUND: The isolated forearm test (IFT) is the gold standard test of connected consciousness (awareness of the environment) during anaesthesia. The frontal alpha-delta EEG pattern (seen in slow wave sleep) is widely held to indicate anaesthetic-induced unconsciousness. A priori we proposed that one responder with the frontal alpha-delta EEG pattern would falsify this concept. METHODS: Frontal EEG was recorded in a subset of patients from three centres participating in an international multicentre study of IFT responsiveness following tracheal intubation. Raw EEG waveforms were analysed for power-frequency spectra, depth-of-anaesthesia indices, permutation entropy, slow wave activity saturation and alpha-delta amplitude-phase coupling. RESULTS: Volitional responses to verbal command occurred in six out of 90 patients. Three responses occurred immediately following intubation in patients (from Sites 1 and 2) exhibiting an alpha-delta dominant (delta power >20 dB, alpha power >10 dB) EEG pattern. The power-frequency spectra obtained during these responses were similar to those of non-responders (P>0.05) at those sites. A further three responses occurred in (Site 3) patients not exhibiting the classic alpha-delta EEG pattern; these responses occurred later relative to intubation, and in patients had been co-administered ketamine and less volatile anaesthetic compared with Site 1 and 2 patients. None of the derived depth-of-anaesthesia indices could robustly discrimate IFT responders and non-responders. CONCLUSIONS: Connected consciousness can occur in the presence of the frontal alpha-delta EEG pattern during anaesthesia. Frontal EEG parameters do not readily discriminate volitional responsiveness (a marker of connected consciousness) and unresponsiveness during anaesthesia. CLINICAL TRIAL REGISTRATION: NCT02248623.

Brain functional connectivity differentiates dexmedetomidine from propofol and natural sleep.

BACKGROUND: We used functional connectivity measures from brain resting state functional magnetic resonance imaging to identify human neural correlates of sedation with dexmedetomidine or propofol and their similarities with natural sleep. METHODS: Connectivity within the resting state networks that are proposed to sustain consciousness generation was compared between deep non-rapid-eye-movement (N3) sleep, dexmedetomidine sedation, and propofol sedation in volunteers who became unresponsive to verbal command. A newly acquired dexmedetomidine dataset was compared with our previously published propofol and N3 sleep datasets. RESULTS: In all three unresponsive states (dexmedetomidine sedation, propofol sedation, and N3 sleep), within-network functional connectivity, including thalamic functional connectivity in the higher-order (default mode, executive control, and salience) networks, was significantly reduced as compared with the wake state. Thalamic functional connectivity was not reduced for unresponsive states within lower-order (auditory, sensorimotor, and visual) networks. Voxel-wise statistical comparisons between the different unresponsive states revealed that thalamic functional connectivity with the medial prefrontal/anterior cingulate cortex and with the mesopontine area was reduced least during dexmedetomidine-induced unresponsiveness and most during propofol-induced unresponsiveness. The reduction seen during N3 sleep was intermediate between those of dexmedetomidine and propofol. CONCLUSIONS: Thalamic connectivity with key nodes of arousal and saliency detection networks was relatively preserved during N3 sleep and dexmedetomidine-induced unresponsiveness as compared to propofol. These network effects may explain the rapid recovery of oriented responsiveness to external stimulation seen under dexmedetomidine sedation. TRIAL REGISTRY NUMBER: Committee number: 'Comité d'Ethique Hospitalo-Facultaire Universitaire de Liège' (707); EudraCT number: 2012-003562-40; internal reference: 20121/135; accepted on August 31, 2012; Chair: Prof G. Rorive. As it was considered a phase I clinical trial, this protocol does not appear on the EudraCT public website.

Two different techniques of facial mask induction of anesthesia in children provide identical intubation conditions despite different anesthetic depth.

BACKGROUND: Sevoflurane induction in chil- dren is performed using different techniques. Constricted, centered, and symmetrical pupils (CCSP) are classically the endpoint to be achieved before laryngoscopy is performed. OBJECTIVES: We investigated whether two different inhalation induction techniques with the same clinical end- point provided similar intubating conditions and comparable depth of anesthesia as assessed by the Bispectral Index (BIS). METHODS: Following IRB approval, and informed parental consent, 20 children were recruited. They were sched- uled for general anesthesia with tracheal intubation, and randomly assigned to Group 1, where the practitioner used 6% inspired sevoflurane in 50% 02/N20, and no manually assisted ventilation, or Group 2, where inspired sevoflurane was 8% in 50% 02/N20, and ventilation was manually supported upon loss of consciousness. BIS values were blinded. Laryngoscopy was performed after CCSP. Intubation conditions scoring was based on jaw relaxation (mobile = 1, partially mobile = 2, fixed = 3), position of vocal cords (open = 1, half-closed = 2, closed = 3), and cough (no cough = 1, 1 or 2 coughing efforts = 2, persistent coughing = 3). A total score > 3 corresponded to non-optimal conditions. RESULTS: Upon CCSP, BIS values were significantly lower in Group 1 [mean (SD) : 30 (8) - 48 (18), p <0.001], despite significantly higher end-tidal sevoflurane concentration in Group 2 [mean (SD) : 5.0 (0.7) - 6.2 (0.5) ; p <0.001]. Time to CCSP was slightly shorter in Group 2. Intubation conditions were always optimal except for one patient of Group 1. DISCUSSION: Both induction techniques achieve good intubating conditions. Possible explanations for the between-group BIS difference include variable appreciation of the CCSP endpoint, different induction lengths or sevoflurane equilibration times, or sevoflurane-induced increase in electroencephalogram power. A better indicator of the best time to intubate is needed to avoid too deep anesthesia in children.

Combined minimally invasive techniques to cure accidental dural tears occurring during spine surgery: epidural blood patch associated with cerebrospinal fluid drainage and ventral bed rest.

We report the case of a 70-year-old man, with increased anesthetic risk, who beneficiated from a lumbar laminarthrectomy from lumbar vertebra 4 (L4) to sacral 1 (S1). A dural tear facing L5-S 1 levels occurred during surgery and was repaired intra-operatively. Postoperatively, back and radicular pain symptoms appeared along with a pseudo-meningocele. Successful treatment was only achieved after performing an epidural blood patch and closed subarachnoid drainage. This well-known but infrequent management was undertaken after a first epidural blood patch attempt, and after two unsuccessful surgical choking procedures. Management is here described, and discussed at the light of existing literature.

Preeclampsia: an update.

Preeclampsia was formerly defined as a multisystemic disorder characterized by new onset of hypertension (i.e. systolic blood pressure (SBP) ≥ 140 mmHg and/or diastolic blood pressure (DBP) ≥ 90 mmHg) and proteinuria (> 300 mg/24 h) arising after 20 weeks of gestation in a previously normotensive woman. Recently, the American College of Obstetricians and Gynecologists has stated that proteinuria is no longer required for the diagnosis of preeclampsia. This complication of pregnancy remains a leading cause of maternal morbidity and mortality. Clinical signs appear in the second half of pregnancy, but initial pathogenic mechanisms arise much earlier. The cytotrophoblast fails to remodel spiral arteries, leading to hypoperfusion and ischemia of the placenta. The fetal consequence is growth restriction. On the maternal side, the ischemic placenta releases factors that provoke a generalized maternal endothelial dysfunction. The endothelial dysfunction is in turn responsible for the symptoms and complications of preeclampsia. These include hypertension, proteinuria, renal impairment, thrombocytopenia, epigastric pain, liver dysfunction, hemolysis-elevated liver enzymes-low platelet count (HELLP) syndrome, visual disturbances, headache, and seizures. Despite a better understanding of preeclampsia pathophysiology and maternal hemodynamic alterations during preeclampsia, the only curative treatment remains placenta and fetus delivery. At the time of diagnosis, the initial objective is the assessment of disease severity. Severe hypertension (SBP ≥ 160 mm Hg and/or DBP ≥ 110 mmHg), thrombocytopenia < 100.000/µL, liver transaminases above twice the normal values, HELLP syndrome, renal failure, persistent epigastric or right upper quadrant pain, visual or neurologic symptoms, and acute pulmonary edema are all severity criteria. Medical treatment depends on the severity of preeclampsia, and relies on antihypertensive medications and magnesium sulfate. Medical treatment does not alter the course of the disease, but aims at preventing the occurrence of intracranial hemorrhages and seizures. The decision of terminating pregnancy and perform delivery is based on gestational age, maternal and fetal conditions, and severity of preeclampsia. Delivery is proposed for patients with preeclampsia without severe features after 37 weeks of gestation and in case of severe preeclampsia after 34 weeks of gestation. Between 24 and 34 weeks of gestation, conservative management of severe preeclampsia may be considered in selected patients. Antenatal corticosteroids should be administered to less than 34 gestation week preeclamptic women to promote fetal lung maturity. Termination of pregnancy should be discussed if severe preeclampsia occurs before 24 weeks of gestation. Maternal end organ dysfunction and non-reassuring tests of fetal well-being are indications for delivery at any gestational age. Neuraxial analgesia and anesthesia are, in the absence of thrombocytopenia, strongly considered as first line anesthetic techniques in preeclamptic patients. Airway edema and tracheal intubation-induced elevation in blood pressure are important issues of general anesthesia in those patients. The major adverse outcomes associated with preeclampsia are related to maternal central nervous system hemorrhage, hepatic rupture, and renal failure. Preeclampsia is also a risk factor for developing cardiovascular disease later in life, and therefore mandates long-term follow-up.

[The value of electroencephalography monitoring and analysis during anesthesia]. / Intérêt de la surveillance et de l'analyse de l'électroencéphalogramme au cours de l'anesthésie.

Electroencephalography (EEG) records brain electrical activity at the scalp level. As a functional and non invasive witness of brain activity, EEG has long raised the interest of researchers and practitioners, notably in the domain of anesthesia. Thanks to technical advances, this complex signal can now be dissected, and a huge amount of information can be extracted from it. This information gives the opportunity to quantify theeffects of general anesthesia on the brain, and provides a better understanding of the underlying mechanisms.

Effect of a fluid challenge on the Surgical Pleth Index during stable propofol-remifentanil anaesthesia.

BACKGROUND: The Surgical Pleth Index (SPI), derived from pulse amplitude and heartbeat interval, is proposed to monitor anti-nociception during anaesthesia. Its response to noxious stimulation can be affected by the intravascular volume status. This study investigated the effect of a fluid challenge (FC) on SPI during steady-state conditions. METHODS: After Institutional Review Board approval, 33 consenting patients undergoing neurosurgery received a 4 ml/kg starch FC over less than 5 min under stable surgical stimulation conditions and stable propofol (Ce(PPF) ) and remifentanil (Ce(REMI) ) effect-site concentrations as estimated by target-controlled infusion systems. Intravascular volume status was assessed using the Delta Down (DD). We looked at the SPI response to FC according to DD, Ce(PPF) , and Ce(REMI) . RESULTS: Following FC, SPI did not change in 16, increased in 12, and decreased in 3 patients. Ce(REMI) poorly affected the SPI response to FC. In normovolaemic patients, the probability of an SPI change after FC was low under common Ce(PPF) (0.9 to 3.9 µg/ml). A decrease in SPI was more probable with worsening hypovolaemia and lowering Ce(PPF) , while an increase in SPI was more probable with increasing Ce(PPF) . SPI changes were only attributable to modifications in pulse wave amplitude and not in heart rate. CONCLUSIONS: During stable anaesthesia and surgery, SPI may change in response to FC. The effect of FC on SPI is influenced by volaemia and Ce(PPF) through pulse wave amplitude modifications. These situations may confound the interpretation of SPI as a surrogate measure of the nociception-anti-nociception balance.

Neural correlates of consciousness during general anesthesia using functional magnetic resonance imaging (fMRI).

This paper reviews the current knowledge about the mechanisms of anesthesia-induced alteration of consciousness. It is now evident that hypnotic anesthetic agents have specific brain targets whose function is hierarchically altered in a dose-dependent manner. Higher order networks, thought to be involved in mental content generation, as well as sub-cortical networks involved in thalamic activity regulation seems to be affected first by increasing concentrations of hypnotic agents that enhance inhibitory neurotransmission. Lower order sensory networks are preserved, including thalamo-cortical connectivity into those networks, even at concentrations that suppress responsiveness, but cross-modal sensory interactions are inhibited. Thalamo-cortical connectivity into the consciousness networks decreases with increasing concentrations of those agents, and is transformed into an anti-correlated activity between the thalamus and the cortex for the deepest levels of sedation, when the subject is non responsive. Future will tell us whether these brain function alterations are also observed with hypnotic agents that mainly inhibit excitatory neurotransmission. The link between the observations made using fMRI and the identified biochemical targets of hypnotic anesthetic agents still remains to be identified.

Comparison of the surgical Pleth Index™ with haemodynamic variables to assess nociception-anti-nociception balance during general anaesthesia.

BACKGROUND: The Surgical Pleth Index (SPI) is proposed as a means to assess the balance between noxious stimulation and the anti-nociceptive effects of anaesthesia. In this study, we compared SPI, mean arterial pressure (MAP), and heart rate (HR) as a means of assessing this balance. METHODS: We studied a standard stimulus [head-holder insertion (HHI)] and varying remifentanil concentrations (CeREMI) in a group of patients undergoing neurosurgery. Patients receiving target-controlled infusions were randomly assigned to one of the three CeREMI (2, 4, or 6 ng m⁻¹), whereas propofol target was fixed at 3 µg ml⁻¹. Steady state for both targets was achieved before HHI. Intravascular volume status (IVS) was evaluated using respiratory variations in arterial pressure. Prediction probability (Pk) and ordinal regression were used to assess SPI, MAP, and HR performance at indicating CeREMI, and the influence of IVS and chronic treatment for high arterial pressure, as possible confounding factors. RESULTS: The maximum SPI, MAP, or HR observed after HHI correctly indicated CeREMI in one of the two patients [accurate prediction rate (APR)=0.5]. When IVS and chronic treatment for high arterial pressure were taken into account, the APR was 0.6 for each individual variable and 0.8 when all of them predicted the same CeREMI. That increase in APR paralleled an increase in Pk from 0.63 to 0.89. CONCLUSIONS: SPI, HR, and MAP are of comparable value at gauging noxious stimulation-CeREMI balance. Their interpretation is improved by taking account of IVS, treatment for chronic high arterial pressure, and concordance between their predictions.

Unexpected entropy response to saline spraying at the end of posterior fossa surgery: a few cases report.

The Spectral Entropy proposed to monitor the depth of anesthesia includes the State Entropy (SE) computed from the EEG (0.8-32 Hz frequency band), and the Response Entropy (RE) computed from EEG and facial muscles activity (0.5-47 Hz frequency band). We report an unexpected Entropy response to saline spraying at the end of posterior fossa surgery. Six patients undergoing scheduled functional surgery of the posterior fossa were included in this report. They were anesthetized with propofol and remifentanil using TCI and received an intubation dose of rocuronium. At the end of surgery, saline spraying, performed for hemostatic purpose and wreckage elimination, resulted in a sustained increase in RE and SE without hemodynamic modification in four patients, while no change was observed in the two other ones. In one of the responding patients, 0.1 mg kg(-1) rocuronium attenuated the Entropy response. In the two non responders, repetition of spraying or rocuronium administration did not change Entropy value. Recovery from anesthesia was comparable in all patients and none of them complained from awareness. We conclude that Entropy can increase during posterior fossa surgery in non-paralyzed patients. This response probably reflects an increase in facial muscle activity rather than a change in depth of anesthesia, as far as it can be attenuated by a small dose of rocuronium. While this hypothesis requires further investigation, these observations suggest that saline spraying may confound interpretation of Entropy during posterior fossa surgery.

Linking sleep and general anesthesia mechanisms: this is no walkover.

This review aims at defining the link between physiological sleep and general anesthesia. Despite common behavioral and electrophysiological characteristics between both states, current literature suggests that the transition process between waking and sleep or anesthesia-induced alteration of consciousness is not driven by the same sequence of events. On the one hand, sleep originates in sub-cortical structures with subsequent repercussions on thalamo-cortical interactions and cortical activity. On the other hand, anesthesia seems to primarily affect the cortex with subsequent repercussions on the activity of sub-cortical networks. This discrepancy has yet to be confirmed by further functional brain imaging and electrophysiological experiments. The relationship between the observed functional modifications of brain activity during anesthesia and the known biochemical targets of hypnotic anesthetic agents also remains to be determined.

Intravenous lidocaine infusion reduces bispectral index-guided requirements of propofol only during surgical stimulation.

BACKGROUND: I.V. lidocaine reduces volatile anaesthetics requirements during surgery. We hypothesized that lidocaine would also reduce propofol requirements during i.v. anaesthesia. METHODS: A randomized controlled study of 40 patients tested the effect of i.v. lidocaine (1.5 mg kg(-1) then 2 mg kg(-1) h(-1)) on propofol requirements. Anaesthesia was maintained with remifentanil and propofol target-controlled infusions (TCI) to keep the bispectral index (BIS) around 50. Effect-site concentrations of propofol and remifentanil and BIS values were recorded before and after skin incision. Data were analysed using anova and mixed effects analysis with NONMEM. Two dose-response studies were then performed with and without surgical stimulation. Propofol TCI titrated to obtain a BIS around 50 was kept constant. Then patients were randomized into four groups: A, saline; B, 0.75 mg kg(-1) bolus then infusion 1 mg kg(-1) h(-1); C, 1.5 mg kg(-1) bolus and infusion 2 mg kg(-1) h(-1); and D, 3 mg kg(-1) bolus and infusion 4 mg kg(-1) h(-1). Lidocaine administration coincided with skin incision. BIS values and haemodynamic variables were recorded. Data were analysed using linear regression and two-way anova. RESULTS: Lidocaine decreased propofol requirements (P<0.05) only during surgery. In the absence of surgical stimulation, lidocaine did not affect BIS nor haemodynamic variables, whereas it reduced BIS increase (P=0.036) and haemodynamic response (P=0.006) secondary to surgery. CONCLUSIONS: The sparing effect of lidocaine on anaesthetic requirements seems to be mediated by an anti-nociceptive action.

Effect of an intravenous infusion of lidocaine on cisatracurium-induced neuromuscular block duration: a randomized-controlled trial.

BACKGROUND: Intravenous lidocaine can be used intraoperatively for its analgesic and antihyperalgesic properties but local anaesthetics may also prolong the duration of action of neuromuscular blocking agents. We hypothesized that intravenous lidocaine would prolong the time to recovery of neuromuscular function after cisatracurium. METHODS: Forty-two patients were enrolled in this randomized, double-blind, placebo-controlled study. Before induction, patients were administered either a 1.5 mg/kg bolus of intravenous lidocaine followed by a 2 mg/kg/h infusion or an equal volume of saline. Anaesthesia was induced and maintained using propofol and remifentanil infusions. After loss of consciousness, a 0.15 mg/kg bolus of cisatracurium was administered. No additional cisatracurium injection was allowed. Neuromuscular function was assessed every 20 s using kinemyography. The primary endpoint was the time to spontaneous recovery of a train-of-four (TOF) ratio ≥ 0.9. RESULTS: The time to spontaneous recovery of a TOF ratio ≥ 0.9 was 94 ± 15 min in the control group and 98 ± 16 min in the lidocaine group (P=0.27). CONCLUSIONS: No significant prolongation of spontaneous recovery of a TOF ratio ≥ 0.9 after cisatracurium was found in patients receiving intravenous lidocaine.

Intracranial subdural hematoma following spinal anesthesia: case report and review of the literature.

Postdural puncture headaches represent one of the main complications of spinal anesthesia. Sometimes, they can reveal the presence of an intracerebral hemorrhage or intracranial subdural hematoma. Atypical postdural puncture headaches or secondary alterations of a typical headache, and particularly the disappearance of its postural character, must prompt to search for another cause. Early diagnosis and careful and rapid management are mandatory. We here report the case of a 53-year-old woman who presented with an intracranial subdural hematoma following spinal anesthesia for hallux valgus surgery performed 48 hours earlier. The implications of such a diagnosis are then discussed, in the light of the existing literature.

Bispectral index correlates with regional cerebral blood flow during sleep in distinct cortical and subcortical structures in humans.

The relationship between the Bispectral Index (BIS), an EEG-based monitor of anesthesia, and brain activity is still unclear. This study aimed at investigating the relationship between changes in BIS values during natural sleep and regional cerebral blood flow (rCBF) variations, as measured by Positron Emission Tomography (PET). Data were obtained from six young, healthy, right-handed, male volunteers (20-30 years old) using the H2(15)O infusion method. PET scans were performed both during waking and various stages of sleep. BIS values were monitored continuously and recorded during each PET scan. Positive correlations were detected between BIS and rCBF values in dorsolateral prefontal, parietal, anterior and posterior cingulate, precuneal, mesiofrontal, mesiotemporal and insular cortices. These areas belong to a frontoparietal network known to be related to awareness of self conscious sensory perception, attention and memory. BIS values also positively correlated with activity in brainstem and thalami, both structures known to be involved in arousal and wakefulness. These results show that BIS changes associated with physiological sleep depth co-vary with the activity of specific cortical and subcortical areas. The latter are known to modulate arousal, which in turn allows sustained thalamo-cortical enhancement of activity in a specific frontoparietal network known to be related to the content of consciousness. Thus, although mainly derived from frontal EEG, BIS could represent a wider index of cerebral activity.

[Contribution of functional neuroimaging studies to the understanding of the mechanisms of general anesthesia]. / Mécanismes de l'anesthésie générale: apport de l'imagerie fonctionnelle.

Since the early beginning of anesthesia, almost 2 centuries ago, ignorance has prevailed regarding the cerebral mechanisms of the loss of consciousness induced by general anesthesia. The recent contribution of functional brain imaging studies has allowed considerable progress in that domain. Similarly, the study of brain function under general anesthesia is currently a major tool for the understanding of conscious phenomena. This functional approach leads to conceptual changes about the functioning brain and may ultimately provide tracks for new treatments and practical applications. All these aspects are reviewed in this paper, at the light of the most recent literature.