Cdk6-dependent regulation of g(1) length controls adult neurogenesis.
; Vandenbosch, Renaud ; Caron, Nicolas et al
in Stem Cells (2011), 29(4), 713-24
The presence of neurogenic precursors in the adult mammalian brain is now widely accepted, but the mechanisms coupling their proliferation with the onset of neuronal differentiation remain unknown. Here ... [more ▼]
The presence of neurogenic precursors in the adult mammalian brain is now widely accepted, but the mechanisms coupling their proliferation with the onset of neuronal differentiation remain unknown. Here, we unravel the major contribution of the G(1) regulator cyclin-dependent kinase 6 (Cdk6) to adult neurogenesis. We found that Cdk6 was essential for cell proliferation within the dentate gyrus of the hippocampus and the subventricular zone of the lateral ventricles. Specifically, Cdk6 deficiency prevents the expansion of neuronally committed precursors by lengthening G(1) phase duration, reducing concomitantly the production of newborn neurons. Altogether, our data support G(1) length as an essential regulator of the switch between proliferation and neuronal differentiation in the adult brain and Cdk6 as one intrinsic key molecular regulator of this process. STEM Cells 2011;29:713-724. [less ▲]Detailed reference viewed: 62 (34 ULg)
From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: recent advances in our understanding of disorders of consciousness.
Bruno, Marie-Aurélie ; Vanhaudenhuyse, Audrey ; Thibaut, Aurore et al
in Journal of Neurology (2011), 258(7), 1373-84
Functional neuroimaging and electrophysiology studies are changing our understanding of patients with coma and related states. Some severely brain damaged patients may show residual cortical processing in ... [more ▼]
Functional neuroimaging and electrophysiology studies are changing our understanding of patients with coma and related states. Some severely brain damaged patients may show residual cortical processing in the absence of behavioural signs of consciousness. Given these new findings, the diagnostic errors and their potential effects on treatment as well as concerns regarding the negative associations intrinsic to the term vegetative state, the European Task Force on Disorders of Consciousness has recently proposed the more neutral and descriptive term unresponsive wakefulness syndrome. When vegetative/unresponsive patients show minimal signs of consciousness but are unable to reliably communicate the term minimally responsive or minimally conscious state (MCS) is used. MCS was recently subcategorized based on the complexity of patients' behaviours: MCS+ describes high-level behavioural responses (i.e., command following, intelligible verbalizations or non-functional communication) and MCS- describes low-level behavioural responses (i.e., visual pursuit, localization of noxious stimulation or contingent behaviour such as appropriate smiling or crying to emotional stimuli). Finally, patients who show non-behavioural evidence of consciousness or communication only measurable via para-clinical testing (i.e., functional MRI, positron emission tomography, EEG or evoked potentials) can be considered to be in a functional locked-in syndrome. An improved assessment of brain function in coma and related states is not only changing nosology and medical care but also offers a better-documented diagnosis and prognosis and helps to further identify the neural correlates of human consciousness. [less ▲]Detailed reference viewed: 43 (3 ULg)
"Relevance vector machine" consciousness classifier applied to cerebral metabolism of vegetative and locked-in patients.
Phillips, Christophe ; Bruno, Marie-Aurélie ; Maquet, Pierre et al
in NeuroImage (2011), 56(2), 797808
The vegetative state is a devastating condition where patients awaken from their coma (i.e., open their eyes) but fail to show any behavioural sign of conscious awareness. Locked-in syndrome patients also ... [more ▼]
The vegetative state is a devastating condition where patients awaken from their coma (i.e., open their eyes) but fail to show any behavioural sign of conscious awareness. Locked-in syndrome patients also awaken from their coma and are unable to show any motor response to command (except for small eye movements or blinks) but recover full conscious awareness of self and environment. Bedside evaluation of residual cognitive function in coma survivors often is difficult because motor responses may be very limited or inconsistent. We here aimed to disentangle vegetative from "locked-in" patients by an automatic procedure based on machine learning using fluorodeoxyglucose PET data obtained in 37 healthy controls and in 13 patients in a vegetative state. Next, the trained machine was tested on brain scans obtained in 8 patients with locked-in syndrome. We used a sparse probabilistic Bayesian learning framework called "relevance vector machine" (RVM) to classify the scans. The trained RVM classifier, applied on an input scan, returns a probability value (p-value) of being in one class or the other, here being "conscious" or not. Training on the control and vegetative state groups was assessed with a leave-one-out cross-validation procedure, leading to 100% classification accuracy. When applied on the locked-in patients, all scans were classified as "conscious" with a mean p-value of .95 (min .85). In conclusion, even with this relatively limited data set, we could train a classifier distinguishing between normal consciousness (i.e., wakeful conscious awareness) and the vegetative state (i.e., wakeful unawareness). Cross-validation also indicated that the clinical classification and the one predicted by the automatic RVM classifier were in accordance. Moreover, when applied on a third group of "locked-in" consciously aware patients, they all had a strong probability of being similar to the normal controls, as expected. Therefore, RVM classification of cerebral metabolic images obtained in coma survivors could become a useful tool for the automated PET-based diagnosis of altered states of consciousness. [less ▲]Detailed reference viewed: 71 (15 ULg)
Attitudes towards end-of-life issues in disorders of consciousness : a European survey
Demertzi, Athina ; LEDOUX, Didier ; Bruno, Marie-Aurélie et al
in Journal of Neurology (2011)
Previous European surveys showed the support of healthcare professionals for treatment withdrawal [i.e., artificial nutrition and hydration (ANH) in chronic vegetative state (VS) patients]. The recent ... [more ▼]
Previous European surveys showed the support of healthcare professionals for treatment withdrawal [i.e., artificial nutrition and hydration (ANH) in chronic vegetative state (VS) patients]. The recent definition of minimally conscious state (MCS), and possibly research advances (e.g., functional neuroimaging), may have lead to uncertainty regarding potential residual perception and may have influenced opinions of healthcare professionals. The aim of the study was to update the end-of-life attitudes towards VS and to determine the end-of-life attitudes towards MCS. A 16-item questionnaire related to consciousness, pain and end-of-life issues in chronic (i.e., >1 year) VS and MCS and locked-in syndrome was distributed among attendants of medical and scientific conferences around Europe (n = 59). During a lecture, the items were explained orally to the attendants who needed to provide written yes/no responses. Chi-square tests and logistic regression analyses identified differences and associations for age, European region, religiosity, profession, and gender. We here report data on items concerning end-of-life issues on chronic VS and MCS. Responses were collected from 2,475 participants. For chronic VS (>1 year), 66% of healthcare professionals agreed to withdraw treatment and 82% wished not to be kept alive (P < 0.001). For chronic MCS (>1 year), less attendants agreed to withdraw treatment (28%, P < 0.001) and wished not to be kept alive (67%, P < 0.001). MCS was considered worse than VS for the patients in 54% and for their families in 42% of the sample. Respondents’ opinions were associated with geographic region and religiosity. Our data show that end-of-life opinions differ for VS as compared to MCS. The introduction of the diagnostic criteria for MCS has not substantially changed the opinions on end-of-life issues on permanent VS. Additionally, the existing legal ambiguity around MCS may have influenced the audience to draw a line between expressing preferences for self versus others, by implicitly recognizing that the latter could be a step on the slippery slope to legalize euthanasia. Given the observed individual variability, we stress the importance of advance directives and identification of proxies when discussing end-of-life issues in patients with disorders of consciousness. [less ▲]Detailed reference viewed: 252 (11 ULg)
Using human pluripotent stem cells to untangle neurodegenerative disease mechanisms
Malgrange, Brigitte ; Borgs, Laurence ; Grobarczyk, Benjamin et al
in Cellular and Molecular Life Sciences : CMLS (2011), 68(4), 635-49
Human pluripotent stem cells, including embryonic (hES) and induced pluripotent stem cells (hiPS), retain the ability to self-renew indefinitely, while maintaining the capacity to differentiate into all ... [more ▼]
Human pluripotent stem cells, including embryonic (hES) and induced pluripotent stem cells (hiPS), retain the ability to self-renew indefinitely, while maintaining the capacity to differentiate into all cell types of the nervous system. While human pluripotent cell-based therapies are unlikely to arise soon, these cells can currently be used as an inexhaustible source of committed neurons to perform high-throughput screening and safety testing of new candidate drugs. Here, we describe critically the available methods and molecular factors that are used to direct the differentiation of hES or hiPS into specific neurons. In addition, we discuss how the availability of patient-specific hiPS offers a unique opportunity to model inheritable neurodegenerative diseases and untangle their pathological mechanisms, or to validate drugs that would prevent the onset or the progression of these neurological disorders. [less ▲]Detailed reference viewed: 61 (17 ULg)
Two distinct neuronal networks mediate the awareness of environment and of self
Vanhaudenhuyse, Audrey ; Demertzi, Athina ; et al
in Journal of Cognitive Neuroscience (2011), 23(3), 570-578
Evidence from functional neuroimaging studies on resting state suggests that there are two distinct anticorrelated cortical systems that mediate conscious awareness: an "extrinsic" system that encompasses ... [more ▼]
Evidence from functional neuroimaging studies on resting state suggests that there are two distinct anticorrelated cortical systems that mediate conscious awareness: an "extrinsic" system that encompasses lateral fronto-parietal areas and has been linked with processes of external input (external awareness), and an "intrinsic" system which encompasses mainly medial brain areas and has been associated with internal processes (internal awareness). The aim of our study was to explore the neural correlates of resting state by providing behavioral and neuroimaging data from healthy volunteers. With no a priori assumptions, we first determined behaviorally the relationship between external and internal awareness in 31 subjects. We found a significant anticorrelation between external and internal awareness with a mean switching frequency of 0.05 Hz (range: 0.01-0.1 Hz). Interestingly, this frequency is similar to BOLD fMRI slow oscillations. We then evaluated 22 healthy volunteers in an fMRI paradigm looking for brain areas where BOLD activity correlated with "internal" and "external" scores. Activation of precuneus/posterior cingulate, anterior cingulate/mesiofrontal cortices, and parahippocampal areas ("intrinsic system") was linearly linked to intensity of internal awareness, whereas activation of lateral fronto-parietal cortices ("extrinsic system") was linearly associated with intensity of external awareness. [less ▲]Detailed reference viewed: 161 (23 ULg)
Disorders of consciousness: coma, vegetative and minimally conscious states
Gosseries, Olivia ; Vanhaudenhuyse, Audrey ; Bruno, Marie-Aurélie et al
in D. Cvetkovic & I. Cosic (Ed.) States of Consciousness: Experimental Insights into Meditation, Waking, Sleep and Dreams (2011)Detailed reference viewed: 47 (3 ULg)
Natalizumab to kill two birds with one stone: A case of celiac disease and multiple sclerosis.
Phan-Ba, Rémy ; LAMBINET, Nadine ; Louis, Edouard et al
in Inflammatory Bowel Diseases (2011), 17(6), 62-63Detailed reference viewed: 50 (17 ULg)
Natalizumab induces a rapid improvement of disability status and ambulation after failure of previous therapy in relapsing-remitting multiple sclerosis.
Belachew, Shibeshih ; Phan-Ba, Rémy ; et al
in European Journal of Neurology (2010), 18(2), 240-245
Background: Natalizumab (Tysabri) is a monoclonal antibody that was recently approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). Our primary objective was to analyse the efficacy ... [more ▼]
Background: Natalizumab (Tysabri) is a monoclonal antibody that was recently approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). Our primary objective was to analyse the efficacy of natalizumab on disability status and ambulation after switching patients with RRMS from other disease-modifying treatments (DMTs). Methods: A retrospective, observational study was carried out. All patients (n = 45) initiated natalizumab after experiencing at least 1 relapse in the previous year under interferon-beta (IFNB) or glatiramer acetate (GA) treatments. The patients also had at least 1 gadolinium-enhancing (Gd+) lesion on their baseline brain MRI. Expanded Disability Status Scale (EDSS) scores, and performance on the Timed 25-Foot Walk Test and on the Timed 100-Metre Walk Test were prospectively collected every 4 weeks during 44 weeks of natalizumab treatment. Brain MRI scans were performed after 20 and 44 weeks of treatment. Results: Sixty-two per cent of patients showed no clinical and no radiological signs of disease activity, and 29% showed a rapid and confirmed EDSS improvement over 44 weeks of natalizumab therapy. Patients with improvement on the EDSS showed similar levels of baseline EDSS and active T1 lesions, but had a significantly higher number of relapses, and 92% of them had experienced relapse-mediated sustained EDSS worsening in the previous year. A clinically meaningful improvement in ambulation speed was observed in approximately 30% of patients. Conclusions: These results indicate that natalizumab silences disease activity and rapidly improves disability status and walking performance, possibly through delayed relapse recovery in patients with RRMS who had shown a high level of disease activity under other DMTs. [less ▲]Detailed reference viewed: 184 (37 ULg)
The California Verbal Learning Test and other standard clinical neuropsychological tests to predict conversion from mild memory impairment to dementia.
Lekeu, Françoise ; Magis, Delphine ; et al
in Journal of Clinical and Experimental Neuropsychology (2010), 20Detailed reference viewed: 158 (17 ULg)
The Nociception Coma Scale to assess nociception in disorders of consciousness
Chatelle, Camille ; ; VANHAUDENHUYSE, Audrey et al
Poster (2010)Detailed reference viewed: 4 (0 ULg)
The Nociception Coma Scale: a first step to a better management of pain in severely brain-injured patients
Chatelle, Camille ; VANHAUDENHUYSE, Audrey ; Majerus, Steve et al
Poster (2010)Detailed reference viewed: 6 (0 ULg)
Default network connectivity reflects the level of consciousness in non-communicative brain-damaged patients.
Vanhaudenhuyse, Audrey ; Noirhomme, Quentin ; Tshibanda, Luaba et al
in Brain : A Journal of Neurology (2010), 133(Pt 1), 161-71
The 'default network' is defined as a set of areas, encompassing posterior-cingulate/precuneus, anterior cingulate/mesiofrontal cortex and temporo-parietal junctions, that show more activity at rest than ... [more ▼]
The 'default network' is defined as a set of areas, encompassing posterior-cingulate/precuneus, anterior cingulate/mesiofrontal cortex and temporo-parietal junctions, that show more activity at rest than during attention-demanding tasks. Recent studies have shown that it is possible to reliably identify this network in the absence of any task, by resting state functional magnetic resonance imaging connectivity analyses in healthy volunteers. However, the functional significance of these spontaneous brain activity fluctuations remains unclear. The aim of this study was to test if the integrity of this resting-state connectivity pattern in the default network would differ in different pathological alterations of consciousness. Fourteen non-communicative brain-damaged patients and 14 healthy controls participated in the study. Connectivity was investigated using probabilistic independent component analysis, and an automated template-matching component selection approach. Connectivity in all default network areas was found to be negatively correlated with the degree of clinical consciousness impairment, ranging from healthy controls and locked-in syndrome to minimally conscious, vegetative then coma patients. Furthermore, precuneus connectivity was found to be significantly stronger in minimally conscious patients as compared with unconscious patients. Locked-in syndrome patient's default network connectivity was not significantly different from controls. Our results show that default network connectivity is decreased in severely brain-damaged patients, in proportion to their degree of consciousness impairment. Future prospective studies in a larger patient population are needed in order to evaluate the prognostic value of the presented methodology. [less ▲]Detailed reference viewed: 102 (22 ULg)
Sleep in disorders of consciousness
Cologan, Victor ; ; LEDOUX, Didier et al
in Sleep Medicine Reviews (2010), 14(2), 97-105
From a behavioral as well as neurobiological point of view, sleep and consciousness are intimately connected. A better understanding of sleep cycles and sleep architecture of patients suffering from ... [more ▼]
From a behavioral as well as neurobiological point of view, sleep and consciousness are intimately connected. A better understanding of sleep cycles and sleep architecture of patients suffering from disorders of consciousness (DOC) might therefore improve the clinical care for these patients as well as our understanding of the neural correlations of consciousness. Defining sleep in severely brain-injured patients is however problematic as both their electrophysiological and sleep patterns differ in many ways from healthy individuals. This paper discusses the concepts involved in the study of sleep of patients suffering from DOC and critically assesses the applicability of standard sleep criteria in these patients. <br /><br />The available literature on comatose and vegetative states as well as that on locked-in and related states following traumatic or non-traumatic severe brain injury will be reviewed. A wide spectrum of sleep disturbances ranging from almost normal patterns to severe loss and architecture disorganization are reported in cases of DOC and some patterns correlate with diagnosis and prognosis. At the present time the interactions of sleep and consciousness in brain-injured patients are a little studied subject but, the authors suggest, a potentially very interesting field of research. [less ▲]Detailed reference viewed: 68 (11 ULg)
Primary diffuse leptomeningeal gliomatosis: an autopsy case and review of the literature
Somja, Joan ; Boly, Mélanie ; Sadzot, Bernard et al
in Acta Neurologica Belgica (2010), 110(4), 325-33
We report a case of primary diffuse leptomeningeal gliomatosis (PDLG) in a 76-year-old male presenting with confusion, dysarthria, diplopia, lumbal pain and headaches of recent onset. Neurological ... [more ▼]
We report a case of primary diffuse leptomeningeal gliomatosis (PDLG) in a 76-year-old male presenting with confusion, dysarthria, diplopia, lumbal pain and headaches of recent onset. Neurological examination revealed nuchal rigidity and bilateral sixth cranial nerve palsy. The cerebrospinal fluid showed a marked hyperproteinorachia (4711 mg/L) and mild cytorachia (5-10 leucocytes/mm3) with a few atypical lymphoid cells. On admission, brain CT scan and MRI demonstrated diffuse and nodular leptomeningeal contrast enhancement predominant at the skull base and several osteolytic lesions in the right parietal bone. Extensive serological studies for infectious, autoimmune or neoplastic diseases were negative. The work-up diagnosis was neurosarcoidosis or multiple meningeal and osseous metastases of an unknown primary cancer. Surgical biopsy of the right parietal bone lesion showed only fibrous tissue with no evidence of tumour or inflammation. The patient was treated with high dose corticosteroids but its neurological status progressively worsened and he died of aspiration pneumonia 35 days after admission. Post-mortem examination revealed a PDLG, a rare fatal tumour with about 60 cases reported. PDGL is characterized by the diffusion of neoplastic glial cells throughout the leptomeninges without evidence of a primary intra-parenchymal lesion. Recognition of this rare brain tumour is important as recent reports suggest that radiotherapy and chemotherapy can improve patient survival. [less ▲]Detailed reference viewed: 52 (18 ULg)
Neuroimaging after coma.
Tshibanda, Luaba ; Vanhaudenhuyse, Audrey ; Boly, Mélanie et al
in Neuroradiology (2010), 52(1), 15-24
Following coma, some patients will recover wakefulness without signs of consciousness (only showing reflex movements, i.e., the vegetative state) or may show non-reflex movements but remain without ... [more ▼]
Following coma, some patients will recover wakefulness without signs of consciousness (only showing reflex movements, i.e., the vegetative state) or may show non-reflex movements but remain without functional communication (i.e., the minimally conscious state). Currently, there remains a high rate of misdiagnosis of the vegetative state (Schnakers et. al. BMC Neurol, 9:35, 8) and the clinical and electrophysiological markers of outcome from the vegetative and minimally conscious states remain unsatisfactory. This should incite clinicians to use multimodal assessment to detect objective signs of consciousness and validate para-clinical prognostic markers in these challenging patients. This review will focus on advanced magnetic resonance imaging (MRI) techniques such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI (fMRI studies in both "activation" and "resting state" conditions) that were recently introduced in the assessment of patients with chronic disorders of consciousness. [less ▲]Detailed reference viewed: 48 (6 ULg)
Visual fixation in the vegetative state: an observational case series PET study.
Bruno, Marie-Aurélie ; Vanhaudenhuyse, Audrey ; Schnakers, Caroline et al
in BMC Neurology (2010), 10
BACKGROUND: Assessment of visual fixation is commonly used in the clinical examination of patients with disorders of consciousness. However, different international guidelines seem to disagree whether ... [more ▼]
BACKGROUND: Assessment of visual fixation is commonly used in the clinical examination of patients with disorders of consciousness. However, different international guidelines seem to disagree whether fixation is compatible with the diagnosis of the vegetative state (i.e., represents "automatic" subcortical processing) or is a sufficient sign of consciousness and higher order cortical processing. METHODS: We here studied cerebral metabolism in ten patients with chronic post-anoxic encephalopathy and 39 age-matched healthy controls. Five patients were in a vegetative state (without fixation) and five presented visual fixation but otherwise showed all criteria typical of the vegetative state. Patients were matched for age, etiology and time since insult and were followed by repeated Coma Recovery Scale-Revised (CRS-R) assessments for at least 1 year. Sustained visual fixation was considered as present when the eyes refixated a moving target for more than 2 seconds as defined by CRS-R criteria. RESULTS: Patients without fixation showed metabolic dysfunction in a widespread fronto-parietal cortical network (with only sparing of the brainstem and cerebellum) which was not different from the brain function seen in patients with visual fixation. Cortico-cortical functional connectivity with visual cortex showed no difference between both patient groups. Recovery rates did not differ between patients without or with fixation (none of the patients showed good outcome). CONCLUSIONS: Our findings suggest that sustained visual fixation in (non-traumatic) disorders of consciousness does not necessarily reflect consciousness and higher order cortical brain function. [less ▲]Detailed reference viewed: 28 (4 ULg)
La vignette diagnostique de l'etudiant: apprentissage au raisonnement diagnostique.
Moonen, Gustave ; Scheen, André
in Revue Médicale de Liège (2010), 65(1), 46-8Detailed reference viewed: 32 (7 ULg)
The nociception coma scale: A new tool to assess nociception in disorders of consciousness.
Schnakers, Caroline ; Chatelle, Camille ; Vanhaudenhuyse, Audrey et al
in Pain (2010), 148
Assessing behavioral responses to nociception is difficult in severely brain-injured patients recovering from coma. We here propose a new scale developed for assessing nociception in vegetative (VS) and ... [more ▼]
Assessing behavioral responses to nociception is difficult in severely brain-injured patients recovering from coma. We here propose a new scale developed for assessing nociception in vegetative (VS) and minimally conscious (MCS) coma survivors, the Nociception Coma Scale (NCS), and explore its concurrent validity, inter-rater agreement and sensitivity. Concurrent validity was assessed by analyzing behavioral responses of 48 post-comatose patients to a noxious stimulation (pressure applied to the fingernail) (28 VS and 20 MCS; age range 20-82years; 17 of traumatic etiology). Patients' were assessed using the NCS and four other scales employed in non-communicative patients: the 'Neonatal Infant Pain Scale' (NIPS) and the 'Faces, Legs, Activity, Cry, Consolability' (FLACC) used in newborns; and the 'Pain Assessment In Advanced Dementia Scale' (PAINAD) and the 'Checklist of Non-verbal Pain Indicators' (CNPI) used in dementia. For the establishment of inter-rater agreement, fifteen patients were concurrently assessed by two examiners. Concurrent validity, assessed by Spearman rank order correlations between the NCS and the four other validated scales, was good. Cohen's kappa analyses revealed a good to excellent inter-rater agreement for the NCS total and subscore measures, indicating that the scale yields reproducible findings across examiners. Finally, a significant difference between NCS total scores was observed as a function of diagnosis (i.e., VS or MCS). The NCS constitutes a sensitive clinical tool for assessing nociception in severely brain-injured patients. This scale constitutes the first step to a better management of patients recovering from coma. [less ▲]Detailed reference viewed: 80 (9 ULg)
Natalizumab induced freedom from disease activity after failure to previous therapy in relapsing remitting multiple sclerosis.
Belachew, Shibeshih ; ; DELVAUX, Valérie et al
Conference (2009, June)
Objectives: To analyze the efficacy of natalizumab after switching relapsing-remitting multiple sclerosis (RRMS) patients from other disease modifying treaments (DMTs). Background: Natalizumab (Tysabri ... [more ▼]
Objectives: To analyze the efficacy of natalizumab after switching relapsing-remitting multiple sclerosis (RRMS) patients from other disease modifying treaments (DMTs). Background: Natalizumab (Tysabri) is a monoclonal antibody directed against VLA4 that was recently approved for the treatment of RRMS. Due to safety concerns, the use should be restricted to highly active patients and/or patients with insufficient response to other DMTs. The pivotal trials were not designed to examine the effect of natalizumab as an escalation monotherapy. Methods: Prospective, open label, observational study. All patients initiating natalizumab had experienced at least 1 relapse in the previous year under DMTs and had at least 1 Gd-enhancing lesion on their brain MRI. Previous treatment with interferon-beta (IFN-beta) or glatiramer acetate (GA) were stopped at least one week and azathioprine or mitoxantrone at least 3 months before switching. The minimum therapy duration with natalizumab was 6 months for all patients. 21 RRMS patients were included in this analysis. The mean age of the patients was 25,5 yo with mean disease duration of 6,8 years. All patients were under IFN-beta (17) or GA (4) during at least the previous year before starting natalizumab therapy. Four patients had also received azathioprine and 1 patient mitoxantrone. Results: The mean relapse rate in the previous year was 2.15 (1-4), the mean EDSS at baseline was 3.3 (1,0-6.0), the mean number of Gd+ lesions at baseline 2,58 (1-6). Under tysabri treatment the annualized relapse rate dropped to 0,20. Eleven patients improved their EDSS (0,5 to 1,5 steps down), others remained stable at 6 months. The mean number of Gd+ T1 lesions dropped to 0,23 and the mean number of new T2 lesions was 0.25 on the control MRI at 6 months. 55% of patients were free from disease activity, i.e. had no relapses, no EDSS progression, no new T2 lesion and no Gd+ T1 lesions after 6 months of Tysabri. 5 patients experienced minor adverse events (1 zona, 2 flu-like symptoms, 1 gastroenteritis, 1 allergic reaction). Conclusion: Natalizumab was well tolerated and safe as escalation therapy when previous DMTs had failed to control disease progression in this group of highly active RRMS patients. These results suggest comparable efficacy to the phase III AFFIRM trial of natalizumab when the drug is used in a context of breakthrough disease. Although data from preliminary analyses are promising, long term investigations are warranted. [less ▲]Detailed reference viewed: 38 (0 ULg)