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Biomedical subjects

Marie-Elisabeth Faymonville

Publications and source records attributed to Marie-Elisabeth Faymonville.

9 recordsLinked to original sources
PubMed2006

Functional neuroanatomy of the hypnotic state.

The neural mechanisms underlying hypnosis and especially the modulation of pain perception by hypnosis remain obscure. Using PET we first described the distribution of regional cerebral blood flow during the hypnotic state. Hypnosis relied on revivification of pleasant autobiographical memories and was compared to imaging autobiographical material in "normal alertness". The hypnotic state was related to the activation of a widespread set of cortical areas involving occipital, parietal, precentral, premotor, and ventrolateral prefrontal and anterior cingulate cortices. This pattern of activation shares some similarities with mental imagery, from which it mainly differs by the relative deactivation of precuneus. Second, we looked at the anti-nociceptive effects of hypnosis. Compared to the resting state, hypnosis reduced pain perception by approximately 50%. The hypnosis-induced reduction of affective and sensory responses to noxious thermal stimulation were modulated by the activity in the midcingulate cortex (area 24a'). Finally, we assessed changes in cerebral functional connectivity related to hypnosis. Compared to normal alertness (i.e., rest and mental imagery), the hypnotic state, significantly enhanced the functional modulation between midcingulate cortex and a large neural network involved in sensory, affective, cognitive and behavioral aspects of nociception. These findings show that not only pharmacological but also psychological strategies for pain control can modulate the cerebral network involved in noxious perception.

Brain↗
PubMed2006

Brain response to one's own name in vegetative state, minimally conscious state, and locked-in syndrome.

BACKGROUND: A major challenge in the management of severely brain-injured patients with altered states of consciousness is to estimate their residual perception of the environment. OBJECTIVE: To investigate the integrity of detection of one's own name in patients in a behaviorally well-documented vegetative state (VS), patients in a minimally conscious state (MCS), and patients with locked-in syndrome. DESIGN: We recorded the auditory evoked potentials to the patient's own name and to 7 other equiprobable first names in 15 brain-damaged patients. RESULTS: A P3 component was observed in response to the patient's name in all patients with locked-in syndrome, in all MCS patients, and in 3 of 5 patients in a VS. P3 latency was significantly (P<.05) delayed for MCS and VS patients compared with healthy volunteers. CONCLUSIONS: These results suggest that partially preserved semantic processing could be observed in noncommunicative brain-damaged patients, notably for the detection of salient stimuli, such as the subject's own name. This function seems delayed in MCS and (if present) in VS patients. More important, a P3 response does not necessarily reflect conscious perception and cannot be used to differentiate VS from MCS patients.

Acoustic Stimulation↗
PubMed2005

The cognitive modulation of pain: hypnosis- and placebo-induced analgesia.

Nowadays, there is compelling evidence that there is a poor relationship between the incoming sensory input and the resulting pain sensation. Signals coming from the peripheral nervous system undergo a complex modulation by cognitive, affective, and motivational processes when they enter the central nervous system. Placebo- and hypnosis-induced analgesia form two extreme examples of how cognitive processes may influence the pain sensation. With the advent of modern brain imaging techniques, researchers have started to disentangle the brain mechanisms involved in these forms of cognitive modulation of pain. These studies have shown that the prefrontal and anterior cingulate cortices form important structures in a descending pathway that modulates incoming sensory input, likely via activation of the endogenous pain modulatory structures in the midbrain periaqueductal gray. Although little is known about the receptor systems involved in hypnosis-induced analgesia, studies of the placebo response suggest that the opiodergic and dopaminergic systems play an important role in the mediation of the placebo response.

Analgesia↗
PubMed2005

The locked-in syndrome : what is it like to be conscious but paralyzed and voiceless?

The locked-in syndrome (pseudocoma) describes patients who are awake and conscious but selectively deefferented, i.e., have no means of producing speech, limb or facial movements. Acute ventral pontine lesions are its most common cause. People with such brainstem lesions often remain comatose for some days or weeks, needing artificial respiration and then gradually wake up, but remaining paralyzed and voiceless, superficially resembling patients in a vegetative state or akinetic mutism. In acute locked-in syndrome (LIS), eye-coded communication and evaluation of cognitive and emotional functioning is very limited because vigilance is fluctuating and eye movements may be inconsistent, very small, and easily exhausted. It has been shown that more than half of the time it is the family and not the physician who first realized that the patient was aware. Distressingly, recent studies reported that the diagnosis of LIS on average takes over 2.5 months. In some cases it took 4-6 years before aware and sensitive patients, locked in an immobile body, were recognized as being conscious. Once a LIS patient becomes medically stable, and given appropriate medical care, life expectancy increases to several decades. Even if the chances of good motor recovery are very limited, existing eye-controlled, computer-based communication technology currently allow the patient to control his environment, use a word processor coupled to a speech synthesizer, and access the worldwide net. Healthy individuals and medical professionals sometimes assume that the quality of life of an LIS patient is so poor that it is not worth living. On the contrary, chronic LIS patients typically self-report meaningful quality of life and their demand for euthanasia is surprisingly infrequent. Biased clinicians might provide less aggressive medical treatment and influence the family in inappropriate ways. It is important to stress that only the medically stabilized, informed LIS patient is competent to consent to or refuse life-sustaining treatment. Patients suffering from LIS should not be denied the right to die - and to die with dignity - but also, and more importantly, they should not be denied the right to live - and to live with dignity and the best possible revalidation, and pain and symptom management. In our opinion, there is an urgent need for a renewed ethical and medicolegal framework for our care of locked-in patients.

Consciousness↗
PubMed2004

Auditory processing in severely brain injured patients: differences between the minimally conscious state and the persistent vegetative state.

BACKGROUND: The minimally conscious state (MCS) is a recently defined clinical condition; it differs from the persistent vegetative state (PVS) by the presence of inconsistent, but clearly discernible, behavioral evidence of consciousness. OBJECTIVE: To study auditory processing among patients who are in an MCS, patients who are in a PVS, and healthy control subjects. METHODS: By means of (15)O-radiolabeled water-positron emission tomography, we measured changes in regional cerebral blood flow induced by auditory click stimuli in 5 patients in an MCS, 15 patients in a PVS, and 18 healthy controls. RESULTS: In both patients in an MCS and the healthy controls, auditory stimulation activated bilateral superior temporal gyri (Brodmann areas 41, 42, and 22). In patients in a PVS, the activation was restricted to Brodmann areas 41 and 42 bilaterally. We also showed that, compared with patients in a PVS, patients in an MCS demonstrated a stronger functional connectivity between the secondary auditory cortex and temporal and prefrontal association cortices. CONCLUSIONS: Although assumptions about the level of consciousness in severely brain injured patients are difficult to make, our findings suggest that the cerebral activity observed in patients in an MCS is more likely to lead to higher-order integrative processes, thought to be necessary for the gain of conscious auditory perception.

Acoustic Stimulation↗
PubMed2003

Increased cerebral functional connectivity underlying the antinociceptive effects of hypnosis.

The neural mechanisms underlying the antinociceptive effects of hypnosis are not well understood. Using positron emission tomography (PET), we recently showed that the activity in the anterior cingulate cortex (midcingulate area 24a') covaries with the hypnosis-induced reduction of affective and sensory responses to noxious thermal stimulation [Faymonville et al., Anesthesiology 92 (2000) 1257-1267]. In the present study, we assessed changes in cerebral functional connectivity related to the hypnotic state, compared to simple distraction and the resting state. Nineteen highly hypnotizable right-handed volunteers were studied using H2(15)O-PET. The experimental conditions were hot noxious or warm non-noxious stimulation of the right hand during resting state, mental imagery and hypnotic state. Using a psychophysiological interaction analysis, we identified brain areas that would respond to noxious stimulations under the modulatory action of the midcingulate cortex in, and only in, the hypnotic state. Hypnosis, compared to the resting state, reduced pain perception by 50%. Pain perception during rest and mental imagery was not significantly different. Analysis of PET data showed that the hypnotic state, compared to normal alertness (i.e., rest and mental imagery), significantly enhanced the functional modulation between midcingulate cortex and a large neural network encompassing bilateral insula, pregenual anterior cingulate cortex, pre-supplementary motor area, right prefrontal cortex and striatum, thalamus and brainstem. These findings point to a critical role for the midcingulate cortex in the modulation of a large cortical and subcortical network underlying its influence on sensory, affective, cognitive and behavioral aspects of nociception, in the specific context of hypnosis.

Adult↗
PubMed2002

Brain function in the vegetative state.

Positron emission tomography (PET) techniques represent a useful tool to better understand the residual brain function in vegetative state patients. It has been shown that overall cerebral metabolic rates for glucose are massively reduced in this condition. However, the recovery of consciousness from vegetative state is not always associated with substantial changes in global metabolism. This finding led us to hypothesize that some vegetative patients are unconscious not just because of a global loss of neuronal function, but rather due to an altered activity in some critical brain regions and to the abolished functional connections between them. We used voxel-based Statistical Parametric Mapping (SPM) approaches to characterize the functional neuroanatomy of the vegetative state. The most dysfunctional brain regions were bilateral frontal and parieto-temporal associative cortices. Despite the metabolic impairment, external stimulation still induced a significant neuronal activation (i.e., change in blood flow) in vegetative patients as shown by both auditory click stimuli and noxious somatosensory stimuli. However, this activation was limited to primary cortices and dissociated from higher-order associative cortices, thought to be necessary for conscious perception. Finally, we demonstrated that vegetative patients have impaired functional connections between distant cortical areas and between the thalami and the cortex and, more importantly, that recovery of consciousness is paralleled by a restoration of this cortico-thalamo-cortical interaction.

Cerebral Cortex↗
PubMedDate not supplied

Cerebral processing of auditory and noxious stimuli in severely brain injured patients: differences between VS and MCS.

We review cerebral processing of auditory and noxious stimuli in minimally conscious state (MCS) and vegetative state (VS) patients. In contrast with limited brain activation found in VS patients, MCS patients show activation similar to controls in response to auditory, emotional and noxious stimuli. Despite an apparent clinical similarity between MCS and VS patients, functional imaging data show striking differences in cortical segregation and integration between these two conditions. However, in the absence of a generally accepted neural correlate of consciousness as measured by functional neuroimaging, clinical assessment remains the gold standard for the evaluation and management of severely brain damaged patients.

Acoustic Stimulation↗