Dopamine denervation in the functional territories of the striatum: a new MR and atlas-based 123I-FP-CIT SPECT quantification method.

Current quantification methods of 123I-FP-CIT SPECT rely on anatomical parcellation of the striatum. We propose here to implement a new method based on MRI segmentation and functional atlas of the basal ganglia (MR-ATLAS) that could provide a reliable quantification within the sensorimotor, associative, and limbic territories of the striatum. Patients with Parkinson's disease (PD), idiopathic rapid eye movement sleep behavioral disorder (iRBD), and healthy controls underwent 123I-FP-CIT SPECT, MRI, motor, and cognitive assessments. SPECT data were corrected for partial volume effects and registered to a functional atlas of the striatum to allow quantification in every functional region of the striatum (nucleus accumbens, limbic, associative, and sensorimotor parts of the striatum). The MR-ATLAS quantification method is proved to be reliable in every territory of the striatum. In addition, good correlations were found between cognitive dysexecutive tests and the binding within the functional (limbic) territories of the striatum using the MR-ATLAS method, slightly better than correlations found using the anatomical quantification method. This new MR-ATLAS method provides a robust and useful tool for studying the dopaminergic system in PD, particularly with respect to cognitive functions. It may also be relevant to further unravel the relationship between dopaminergic denervation and cognitive or behavioral symptoms.

On the Relationship between Mechanical Properties and Crystallisation of Chemically Post-Processed Additive Manufactured Polylactic Acid Pieces.

Nowadays, improvement of the surface finish of parts manufactured by fused deposition modelling is a well-studied topic. Chemical post-treatments have proven to be the best technique in terms of time consumption and smoothness improvement. However, these treatments modify the structure of the material and, consequently, its mechanical properties. This relationship was studied in this work. In this case, on the basis of a previous study on crystallisation, polylactic acid pieces were subjected to different post-treatments to evaluate their effects on the sample's mechanical properties, i.e., tensile strength and hardness. Models were obtained according to their percentage of crystallisation, which was related to the different treatments, as well as immersion time. Dramatic changes were obtained within a wide range of material behaviour with some treatments. Specifically, changes were obtained in the maximum stress (from 55 to 20 MPa), in elongation (from 3% to 260%), and in the hardness scale (Shore D to A).

[Obsessive-compulsive disorder as seen by those who are confronted with it: A survey of patients, relatives and clinicians]. / Le trouble obsessionnel compulsif vu par ceux qui y sont confrontés : enquête auprès de patients, de proches et de cliniciens.

INTRODUCTION: Obsessive compulsive disorder (OCD) is one of the most disabling mental health disorders due to its negative impact on the patient's quality of life as well on that of her living caregivers. This disorder generates an additional burden for relatives, which may in turn affect the family dynamics and impair the evolution of the disease. Along with medications, cognitive behavioral therapy (CBT) represents a well-validated first line of treatment for OCD. However, therapeutic responses across patients are uneven with often residual symptoms and limited quality of life improvements. In total, OCD is a severely debilitating disease with repercussions on both personal, social and professional lives of patients and their relatives even after clinically-delivered treatments. The mutual identification of points of convergence and divergence in social representations is a factor that contributes to satisfactory interpersonal relationships. In the care relationship in general and particularly in the field of mental health, taking account of these different representations and expectations is essential for improving the care process: upstream of the care in the choice the therapeutic strategy and in strengthening the therapeutic alliance. Although less studied, the relationship with relatives of patients also depends on representations of each which have a significant impact on clinical outcomes and experience of the disease. OBJECTIVE: To carry out the first study of cross-representations of OCD in three groups of people affected by it: those who suffer, their families and clinicians. HYPOTHESIS: Considering the experiences and knowledge of patients, relatives and clinicians, we assumed that their representations related to OCD would partially overlap. Specifically, we assumed that the positioning of each population compared to the other two would differ depending on the investigated dimensions: nosology, etiology, therapy and psychiatric disability. METHODS: From 2010 to 2011 we conducted an online survey among self-declared OCD-patients (n=86), OCD-patients' relatives (n=38) and clinicians (n=79). The questionnaire included both closed questions regarding the nosology, etiology, therapy and psychiatric disabilities and open questions probing the representations of the disorder and its evolution, its impact on personal, social and professional domains, and on the quality of life. In particular, we investigated how each population conceived the role and involvement of the relatives in the care process and how they dealt daily with the disorder. RESULTS: Confirming our hypothesis, our results showed that representations of OCD converge on the DSM-based definition of the disorder conveyed by patient associations and mass media. The three populations also recognize the burden and the handicap associated with OCD considerably restrict their daily functioning. However, patients and relatives differ from clinicians in their view of the etiology and their expectations of the therapeutic process. Unexpectedly, patients do not report frequent stigmatization although this may reflect their attempt to hide their disorder as a form of self-stigmatization. Patients focus on care modalities (alternative therapies) motivated by quality of life improvement rather than symptom reduction put forward by clinicians. Relatives ask for being involved in the care process. CONCLUSION: Our study emphasizes the importance for health professionals to take into account the expectations of patients and their relatives in order to maximize the therapeutic alliance and efficiency of treatment.

Deafferentation in thalamic and pontine areas in severe traumatic brain injury.

PURPOSE: Severe traumatic brain injury (TBI) is characterized mainly by diffuse axonal injuries (DAI). The cortico-subcortical disconnections induced by such fiber disruption play a central role in consciousness recovery. We hypothesized that these cortico-subcortical deafferentations inferred from diffusion MRI data could differentiate between TBI patients with favorable or unfavorable (death, vegetative state, or minimally conscious state) outcome one year after injury. METHODS: Cortico-subcortical fiber density maps were derived by using probabilistic tractography from diffusion tensor imaging data acquired in 24 severe TBI patients and 9 healthy controls. These maps were compared between patients and controls as well as between patients with favorable (FO) and unfavorable (UFO) 1-year outcome to identify the thalamo-cortical and ponto-thalamo-cortical pathways involved in the maintenance of consciousness. RESULTS: Thalamo-cortical and ponto-thalamo-cortical fiber density was significantly lower in TBI patients than in healthy controls. Comparing FO and UFO TBI patients showed thalamo-cortical deafferentation associated with unfavorable outcome for projections from ventral posterior and intermediate thalamic nuclei to the associative frontal, sensorimotor and associative temporal cortices. Specific ponto-thalamic deafferentation in projections from the upper dorsal pons (including the reticular formation) was also associated with unfavorable outcome. CONCLUSION: Fiber density of cortico-subcortical pathways as measured from diffusion MRI tractography is a relevant candidate biomarker for early prediction of one-year favorable outcome in severe TBI.

Basal ganglia dysfunction in OCD: subthalamic neuronal activity correlates with symptoms severity and predicts high-frequency stimulation efficacy.

Functional and connectivity changes in corticostriatal systems have been reported in the brains of patients with obsessive-compulsive disorder (OCD); however, the relationship between basal ganglia activity and OCD severity has never been adequately established. We recently showed that deep brain stimulation of the subthalamic nucleus (STN), a central basal ganglia nucleus, improves OCD. Here, single-unit subthalamic neuronal activity was analysed in 12 OCD patients, in relation to the severity of obsessions and compulsions and response to STN stimulation, and compared with that obtained in 12 patients with Parkinson's disease (PD). STN neurons in OCD patients had lower discharge frequency than those in PD patients, with a similar proportion of burst-type activity (69 vs 67%). Oscillatory activity was present in 46 and 68% of neurons in OCD and PD patients, respectively, predominantly in the low-frequency band (1-8 Hz). In OCD patients, the bursty and oscillatory subthalamic neuronal activity was mainly located in the associative-limbic part. Both OCD severity and clinical improvement following STN stimulation were related to the STN neuronal activity. In patients with the most severe OCD, STN neurons exhibited bursts with shorter duration and interburst interval, but higher intraburst frequency, and more oscillations in the low-frequency bands. In patients with best clinical outcome with STN stimulation, STN neurons displayed higher mean discharge, burst and intraburst frequencies, and lower interburst interval. These findings are consistent with the hypothesis of a dysfunction in the associative-limbic subdivision of the basal ganglia circuitry in OCD's pathophysiology.