[First report in the Liege province (Belgium) of a concomitant aortic and mitral valve surgery via a minimally invasive right latero-thoracic approach]

Compared to median sternotomy, the potential benefits of minimally invasive single aortic or mitral valve surgery include reduction of blood loss, lower morbidity, and shorter intensive care unit and hospital length of stay. However, there are few reports regarding concomitant aortic and mitral valves minimally invasive surgery via mini-thoracotomy. To the authors knowledge, this is the first report in the Liege area, of a successful minimally invasive right latero-thoracic approach for aortic and mitral valve surgery in a 78-year old woman who presented severe and symptomatic aortic stenosis and mitral insufficiency. In addition to the description of the surgical approach, the authors will summarize the current literature on this approach, as well as the clinical evolution of the patient.

[Acute right heart failure]

Even though, it has long been considered as a passive channel allowing communication between the systemic and pulmonary circulations, it is now clearly established that the right ventricle plays an essential role in cardio-pulmonary couple physiology. Its failure results in a clinical presentation that reflects the systemic congestion and reduced cardiac output. It is the consequence of two pathological situations frequently encountered in intensive care including pulmonary vascular resistance increase and right ventricle contraction alteration. Mechanical ventilation, certain drugs and volume overload can also participate. The management of the acute right heart failure is based on the combination of supportive treatment and causal treatment, specific to the etiology. Supportive therapy aims to optimize filling pressures, reduce afterload and support cardiac contractibility. With the growing number of therapeutic options used according to co-morbidities, decision-making by a multidisciplinary heart team seems essential.

[Heart transplantation, indications and results at the University Hospital of Liege]

Heart transplantation remains undoubtedly the most effective treatment for end-stage heart failure, whatever its cause. Last decade has witnessed significant improvements in terms of morbidity and mortality following heart transplant. The 5-year survival rate is now beyond 70 %. However, the shortage of potential donors limits its use and requires strict criteria before listing a candidate for heart transplantation. Herein, we present a review of current indications and results of the heart transplantation program at the University hospital of Liège.

Pain assessment by pupil dilation reflex in response to noxious stimulation in anaesthetized adults

BACKGROUND

In response to noxious stimulation, pupillary dilation reflex (PDR) occurs even in anaesthetized patients. The aim of the study was to evaluate the ability of pupillometry with an automated increasing stimulus intensity to monitor intraoperative opioid administration.

METHODS

Thirty-four patients undergoing elective surgery were enrolled. Induction by propofol anaesthesia was increased progressively until the sedation depth criteria (SeD) were attained. Subsequently, a first dynamic pupil measurement was performed by applying standardized nociceptive stimulation (SNS). A second PDR evaluation was performed when remifentanil reached a target effect-site concentration. Automated infrared pupillometry was used to determine PDR during nociceptive stimulations generating a unique pupillary pain index (PPI). Vital signs were measured.

RESULTS

After opioid administration, anaesthetized patients required a higher stimulation intensity (57.43 mA vs 32.29 mA, P < .0005). Pupil variation in response to the nociceptive stimulations was significantly reduced after opioid administration (8 mm vs 28 mm, P < .0005). The PPI score decreased after analgesic treatment (8 vs 2, P < .0005), corresponding to a 30% decrease. The elicitation of PDR by nociceptive stimulation was performed without changes in vital signs before (HR 76 vs 74/min, P = .09; SBP 123 vs 113 mm Hg, P = .001) and after opioid administration (HR 63 vs 62/min, P = .4; SBP 98.66 vs 93.77 mm Hg, P = .032).

CONCLUSIONS

During propofol anaesthesia, pupillometry with the possibility of low-intensity standardized noxious stimulation via PPI protocol can be used for PDR assessment in response to remifentanil administration.

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.

[Narcolepsy-cataplexy today]

Diagnostic criteria and pathophysiology of narcolepsy-cataplexy have evolved considerably over the last 10 years. The main cause, already mentioned in a previous paper, in the Revue Médicale de Liège (65), in 2002, is based, in human beings, on a destruction of specific cells located in the lateral and posterior part of the hypothalamus (the perifornical nuclei, containing some 70,000 neurons), producing peptides which stimulate the central nervous system; they are called hypocretins or orexins. The role of autoimmunity in their disappearance becomes more evident. The treatment is simplified, but remains symptomatic. It is mainly based on Sodium Oxybate or Gamma-Hydroxybutyrate, syrup, prescribed for the night. The authors report on their own experience in this regard and on future therapeutics more targeted towards the cause of the disease.

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.

Methadone-induced toxic leukoencephalopathy: MR imaging and MR proton spectroscopy findings

We report the clinical, MR imaging, and proton MR spectroscopy findings in a middle-aged woman with proved methadone-induced toxic leukoencephalopathy. The imaging characteristics of this unusual condition have been reported only rarely in the medical literature. We show that the imaging findings in methadone-induced toxic leukoencephalopathy are similar, though not identical, to previously reported cases of neurologic deterioration due to heroin inhalation.

[Contribution of functional neuroimaging studies to the understanding of the mechanisms of general anesthesia]

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.

A cost-utility analysis of pregabalin in the management of peripheral neuropathic pain

OBJECTIVES

To assess the cost per QALY (quality-adjusted life years) of pregabalin in the management of peripheral neuropathic pain.

METHODS

We compared pregabalin on top of "usual care" with "usual care" alone. In this study, usual care was defined as a mix of drug therapies, excluding anti-epileptic drugs (AEDs), because the latter represented only 9% of current use, and clinical evidence of pregabalin was demonstrated versus usual care without anti-epileptic drugs. A Markov model was developed to simulate the evolution of a patient cohort over 1 year, and applied cycles of 4 weeks. During each cycle, patients remained in 1 out of 4 possible states: severe, moderate or mild pain, and therapy withdrawal. The health care payers perspective was taken into account. Clinical data were obtained from a trial comparing usual care plus placebo to usual care plus pregabalin, at either 150, 300, or 300/600 mg/day (the latter depending on clearance of creatinin). Resulting effects on pain were transformed into transition-probabilities between different pain levels. Cost and SF36 utility data of pain levels were obtained from a 1-month observational study in 88 patients.

RESULTS

Usual care resulted in a yearly cost of Euros 6,200 compared to Euros 5,984 for an all dose pregabalin-mix, meaning a cost saving of Euros 216 per patient. Utility increase was 0.01 for the pregabalin-mix (QALY 0.510 usual care; 0.520 pregabalin-mix). Monte Carlo analysis showed cost savings were not significant. However, the utility gain, albeit small, was statistically significant.

CONCLUSIONS

Based on this analysis, it may be concluded, that in the considered patient population, at the specialist level, pregabalin is at least cost neutral to current usual care (without AEDs) and offers a slight but significant increase in quality of life.

Molecular Pathways Involved in Apoptotic Cell Death in the Injured Cochlea: Cues to Novel Therapeutic Strategies

Most hearing loss results from lesions of the sensory cells and/or neurons of the auditory portion of the inner ear. To date, only the cochlear implantation offers long-term hearing-aid benefit, but still with limited performance and expensive cost. While the underlying causes of deafness are not clear, the death or hair cells and/or neurons and the loss of neuronal contacts are key pathological features. Pinpointing molecular events that control cell death in the cochlea is critical for the development of new strategies to prevent and treat deafness, whether in combination or not with cochlear implant therapy.

[Transient ischemic attacks: a new definition]

According to its initial definition, which dates back more than 50 years, a transient ischemic attack (TIA) is a sudden focal neurologic deficit lasting for less than 24 hours, of presumed vascular origin, and confined to an area of the brain or eye perfused by a specific artery. Recent data on the pathophysiology of cerebral ischemia and the progress made by the imaging techniques have led an American TIA Working Group to propose a new definition which states that: "A transient ischemic attack is a brief episode of neurologic dysfunction, caused by local brain or retinal ischemia, with clinical symptoms typically lasting less than one hour, and without evidence of cerebral infarction". The advantages and limitations of this new definition, the need for an emergency medical care in the presence of a TIA, the clinical signs associated with this condition, the diagnostic work up, and the differential diagnosis are briefly discussed. A clinical example illustrates the difficulties that can be encountered in a case of TIA.

Substance P protects spiral ganglion neurons from apoptosis via PKC-Ca2+-MAPK/ERK pathways

In the current study, we have investigated the ability of substance P (SP) to protect 3-day-old (P3) rat spiral ganglion neurons (SGNs) from trophic factor deprivation (TFD)-induced cell death. The presence of SP high affinity neurokinin-1 receptor (NK1) transcripts was detected in the spiral ganglion and the NK1 protein localized to SGNs both ex vivo and in vitro. Treatment with SP increased cytoplasmic Ca2+ in SGNs, further arguing for the presence of functional NK1 on these neurons. Both SP and the agonist [Sar9,Met(O2)11]-SP significantly decreased SGN cell death induced by TFD, with no effect on neurite outgrowth. The survival promoting effect of SP was blocked by the NK1 antagonist, WIN51708. Both pan-caspase inhibitor BOC-D-FMK and SP treatments markedly reduced activation of caspases and DNA fragmentation in trophic factor deprived-neurons. The neuroprotective action of SP was antagonised by specific inhibitors of second messengers, including 1.2-bis-(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM) to chelate cytosolic Ca2+, the protein kinase C (PKC) inhibitors bisindolylmaleimide I, Gö6976 and LY333531 and the MAPK/ERK inhibitor U0126. In contrast, nifedipine, a specific inhibitor of l-type Ca2+ channel, and LY294002, a phosphatidylinositol-3-OH kinase (PI3K) inhibitor, had no effect on SP trophic support of SGNs. Moreover, activation of endogenous PKC by 4 beta-phorbol 12-myristate 13-acetate (PMA) also reduced the loss of trophic factor-deprived SGNs. Thus, NK1 expressed by SGNs transmit a survival-promoting regulatory signal during TFD-induced SGN cell death via pathways involving PKC activation, Ca2+ signalling and MAPK/ERK activation, which can be accounted for by an inhibition of caspase activation.

[Statins for the brain?]

Whether cholesterol lowering decreases risk of stroke has long remained unclear. Large epidemiological studies have found only weak links between cholesterol levels and stroke. Recent studies with statins, more potent cholesterol lowering agents, have now demonstrated significant reductions of stroke incidence and total mortality when administered for secondary prevention in patients with wide ranges of cholesterol values. It remains unknown if a statin is superior to others for the secondary prevention of stroke.

[Controversies in the secondary prevention of stroke]

Stroke is the third leading cause of death and the main cause of prolonged disability of adults in industrialised countries. After a first transient ischemic attack or a first minor stroke, the risk of recurrence is 16 folds higher than in control subjects. Therefore each patient suspect of a first ischemic cerebral event should be evaluated for the presence of a specific cause which could be treated. If such a cause is not found, platelet antiaggregant medications should be started.

The anti-epileptic drug levetiracetam reverses the inhibition by negative allosteric modulators of neuronal GABA- and glycine-gated currents

1. In this study in vitro and in vivo approaches were combined in order to investigate if the anti-epileptic mechanism(s) of action of levetiracetam (LEV; Keppra) may involve modulation of inhibitory neurotransmission. 2. GABA- and glycine-gated currents were studied in vitro using whole-cell patch-clamp techniques applied on cultured cerebellar granule, hippocampal and spinal neurons. Protection against clonic convulsions was assessed in vivo in sound-susceptible mice. The effect of LEV was compared with reference anti-epileptic drugs (AEDs): carbamazepine, phenytoin, valproate, clonazepam, phenobarbital and ethosuximide. 3. LEV contrasted the reference AEDs by an absence of any direct effect on glycine-gated currents. At high concentrations, beyond therapeutic relevance, it induced a small reduction in the peak amplitude and a prolongation of the decay phase of GABA-gated currents. A similar action on GABA-elicited currents was observed with the reference AEDs, except ethosuximide. 4. These minor direct effects contrasted with a potent ability of LEV (EC(50)=1 - 10 microM) to reverse the inhibitory effects of the negative allosteric modulators zinc and beta-carbolines on both GABA(A) and glycine receptor-mediated responses. 5. Clonazepam, phenobarbital and valproate showed a similar ability to reverse the inhibition of beta-carbolines on GABA-gated currents. Blockade of zinc inhibition of GABA responses was observed with clonazepam and ethosuximide. Phenytoin was the only AED together with LEV that inhibited the antagonism of zinc on glycine-gated currents and only clonazepam and phenobarbital inhibited the action of DMCM. 6. LEV (17 mg kg(-1)) produced a potent suppression of sound-induced clonic convulsions in mice. This protective effect was significantly abolished by co-administration of the beta-carboline FG 7142, from a dose of 5 mg kg(-1). In contrast, the benzodiazepine receptor antagonist flumazenil (up to 10 mg kg(-1)) was without any effect on the protection afforded by LEV. 7. The results of the present study suggest that a novel ability to oppose the action of negative modulators on the two main inhibitory ionotropic receptors may be of relevance for the anti-epileptic mechanism(s) of action of LEV.

Levobupivacaine combined with sufentanil and epinephrine for intrathecal labor analgesia: a comparison with racemic bupivacaine

We performed a randomized, double-blinded study to compare levobupivacaine with racemic bupivacaine for labor analgesia. Eighty term parturients received either levobupivacaine 0.125% or racemic bupivacaine 0.125%, to which was added sufentanil 0.75 microg/mL and epinephrine 1.25 microg/mL. As part of a combined spinal-epidural procedure, 2 mL of this mixture was initially injected intrathecally, and the same solutions were subsequently administered epidurally. For both combinations, onset until the first painless contraction was 4 to 5 min. Most patients were pain free during the second contraction. The duration of initial spinal analgesia was 93.5 +/- 20 min and 94.7 +/- 31 min for levobupivacaine and racemic bupivacaine, respectively. The duration of analgesia for the first epidural top-up dose was also similar in the two groups. Total local anesthetic requirements during labor were not different. The only major difference observed was the absence of motor impairment in levobupivacaine-treated parturients as compared with the Racemic Bupivacaine group, in which the incidence of a Bromage-1 motor block was 34%. Other side effects and obstetric or neonatal outcomes were not different between groups. Intrathecal levobupivacaine has a similar clinical profile as racemic bupivacaine, but at equal doses it produced less motor block.

IMPLICATIONS

When used intrathecally and epidurally for labor analgesia, levobupivacaine had the same clinical profile as racemic bupivacaine, but at equal doses it produced less motor block.

Local injection of endothelin-1 produces pain-like behavior and excitation of nociceptors in rats

Neurobehavioral and neurophysiological actions of the peptide endothelin-1 (ET-1) were investigated after subcutaneous plantar hindpaw injections in adult male Sprague Dawley rats. Hindpaw flinching developed within minutes after ET-1 (8-16 nmol) injection, peaked at 30 min, lasted for 60 min, and was strongly inhibited by the endothelin-A (ET(A)) receptor antagonist, BQ-123 (3.2 m). In separate experiments, impulse activity of single, physiologically characterized sensory C-, Adelta-, and Abeta-fibers was recorded from the sciatic nerve in anesthetized rats after subcutaneous injections of endothelin-1 (1-20 nmol), alone or together with BQ-123 (3.2 m), into the plantar hindpaw receptive fields of these units. All nociceptive C-fibers (31 of 33 C-fibers studied) were excited by ET-1 (1-20 nmol) in a dose-dependent manner. For doses of 16-20 nmol, the mean latency for afferent activation after injection of ET-1 was 3.16 +/- 0.31 min, and the mean and maximum response frequency were 2.02 +/- 0.48 impulses (imp)/sec and 14.0 +/- 3.2 imp/sec, respectively. All 10 nociceptive Adelta-fibers (of 12 Adelta-fibers studied) also responded to 1-20 nmol of ET-1 in a dose-dependent manner with a mean latency of 3.5 +/- 0.12 min and mean response frequency of 3.3 +/- 2.3 imp/sec. In contrast, most Abeta-fibers (9 of 12) did not respond to ET-1. BQ-123, when coinjected with ET-1, blocked ET-1-induced activation in all C- and Adelta-fibers tested. These data demonstrate that subcutaneous administration of ET-1 to the rat plantar hindpaw produces pain-like behavior and selective excitation of nociceptive fibers through activation of ET(A) receptors.

Glycine triggers an intracellular calcium influx in oligodendrocyte progenitor cells which is mediated by the activation of both the ionotropic glycine receptor and Na+-dependent transporters

Using fluo-3 calcium imaging, we demonstrate that glycine induces an increase in intracellular calcium concentration ([Ca2+]i) in cortical oligodendrocyte progenitor (OP) cells. This effect results from a calcium entry through voltage-gated calcium channels (VGCC), as it is observed only in OP cells expressing such channels, and it is abolished either by removal of calcium from the extracellular medium or by application of an L-type VGCC blocker. Glycine-triggered Ca2+ influx in OP cells actually results from an initial depolarization that is the consequence of the activation of both the ionotropic glycine receptor (GlyR) and Na+-dependent transporters, most probably the glycine transporters 1 (GLYT1) and/or 2 (GLYT2) which are colocalized in these cells. Through this GlyR- and transporter-mediated effect on OP intrcellular calcium concentration [Ca2+]i, glycine released by neurons may, as well as other neurotransmitters, serve as a signal between neurons and OP during development.

Recent advances in the pharmacology of nerve-injury pain

Nerve injury pain remains a complex clinical challenge. Although the development of animal models of nerve injury pain has aided our understanding of potential pathophysiologic mechanisms for this condition, effective treatment still remains beyond our reach. Several classes of agents appear to block pain behavior in these animal models and humans, but they are often limited in their use by low efficacy, or undesirable side-effects. A prerequisite for the improvement of nerve injury pain includes the development of clinically-relevant animal models in which therapeutic targets can be identified.

Behavioral signs of acute pain produced by application of endothelin-1 to rat sciatic nerve

We examined whether endothelin-1 (ET-1), a potent vasoconstrictive peptide secreted in high concentration by metastatic prostate cancer cells, produces endothelin receptor-dependent pain behavior when applied to rat sciatic nerve. ET-1 (200-800 microM) applied to the epineurial surface of rat sciatic nerve produced reliable, robust, unilateral hindpaw flinching lasting 60 min. Pre-emptive systemic morphine completely blocked this effect in a naloxone-reversible manner, suggesting that this behavior was pain-related. Equipotent doses of epineurially applied epinephrine had no effect, suggesting that ET-1 effects are on tissue sites other than sciatic nerve microvessels. Prior and co-administration of BQ-123, an endothelin-A (ET(A)) receptor antagonist, also blocked ET-1-induced hindpaw flinching establishing that pain behavior induced by ET-1 application to rat sciatic nerve is ET(A) receptor mediated.

Behavioral assessment of facial pain in rats: face grooming patterns after painful and non-painful sensory disturbances in the territory of the rat's infraorbital nerve

Noxious stimulation of the rat's face evokes intense face grooming with face wash strokes almost exclusively directed to the stimulated area (e.g. Clavelou et al., Neurosci. Lett., 14 (1989) 3263-3270). Similar asymmetric face grooming behavior has been observed after transection (Berridge and Fentress, J. Neurosci., 6 (1986) 325-330) and chronic constriction of the infraorbital nerve (Vos et al., J. Neurosci., 14 (1994) 2708-2723). In the present study, the relation between unilateral facial pain and asymmetric face grooming was experimentally studied in normal, intact rats: face grooming patterns evoked by non-painful sensory disturbances in the territory of the infraorbital nerve (i.c. unilateral vibrissae clipping, anesthetic infraorbital nerve blockade, application of mineral oil on vibrissae) were compared to those evoked by noxious facial stimulation (s.c. formalin injection in mystacial pad) and those observed in unstimulated control rats, using video-analysis. Only formalin-injected rats displayed significantly more face grooming activity directed to the affected infraorbital nerve territory than unstimulated control rats. Non-painful sensory disturbances (especially mineral oil application) induced an initial bout of directed face grooming; this response was transient and short-lasting. These observations suggest that directed face grooming can be used as a sign of unilateral facial pain in freely moving rodents; unilateral non-painful facial sensory disturbances do not lead to intense and persistent directed face grooming.