Motor impulsivity in Parkinson disease: associations with COMT and DRD2 polymorphisms.

Parkinson disease (PD) is an age-related degenerative disease of the brain, characterized by motor, cognitive, and psychiatric symptoms. Neurologists and neuroscientists now understand that several symptoms of the disease, including hallucinations and impulse control behaviors, stem from the dopaminergic medications used to control the motor aspects of PD. Converging evidence from animals and humans suggests that individual differences in the genes that affect the dopamine system influence the response of PD patients to dopaminergic medication. In this study, we tested the hypothesis that patients taking dopamine replacement therapy who carry candidate alleles that increase dopamine signaling, exhibit greater amounts of motor impulsivity. We examined the relation between inhibitory ability (measured by the Stop Signal Task) and polymorphisms of COMT Val158Met and DRD2 C957T in patients with idiopathic PD. On the Stop Signal Task, carriers of COMT Val/Met and Met/Met genotypes were more impulsive than Val/Val carriers, but we did not find a link between DRD2 polymorphisms and inhibitory ability. These results support the hypothesis that the Met allele of COMT confers an increased risk for behavioral impulsivity in PD patients, whereas DRD2 polymorphisms appear to be less important in determining whether PD patients exhibit a dopamine overdose in the form of motor impulsivity.

Fecal microbiota transplantation via fluoroscopy-guided nasojejunal catheter placement: indications, technique, and the role of radiology.

Clostridium difficile is a well-established cause of nosocomial gastrointestinal disease. Although antibiotics remain an effective first-line treatment for C. difficile colitis (CDC), relapse and recurrence are common. FMT has emerged as one of the safest and most effective known therapies available for recurrent or refractory CDC, which is likely due to restoration of the protective microbiotic barrier of the gastrointestinal tract. FMT varies greatly across institutions by route of delivery, dose, and protocol. We present our experience with FMT via fluoroscopic-guided nasojejunal catheter placement. The discussion will include indications and contraindications, protocol, and procedural technique, and include a case presentation incorporating original CT and fluoroscopic images. Specifically, we will address the advantages and disadvantages of image-guided FMT via the upper GI tract with respect to nasogastric-, colonoscopic-, and enema-based delivery. The efficacy of FMT for the treatment of C. difficile has been widely demonstrated in several prospective and case studies. We feel that nasojejunal FMT is an underutilized radiologic procedure which can benefit selected patients, particularly given the advantages in risk profile, cost, convenience, and lack of routine sedation.

Substantia nigra volume loss before basal forebrain degeneration in early Parkinson disease.

OBJECTIVE: To test the hypothesis that degeneration of the substantia nigra pars compacta (SNc) precedes that of the cholinergic basal forebrain (BF) in Parkinson disease (PD) using new multispectral structural magnetic resonance (MR) imaging tools to measure the volumes of the SNc and BF. DESIGN: Matched case-control study. SETTING: The Athinoula A. Martinos Imaging Center at the McGovern Institute for Brain Research, Massachusetts Institute of Technology (MIT), and the Massachusetts General Hospital/MIT Morris Udall Center of Excellence in Parkinson Disease Research. PATIENTS: Participants included 29 patients with PD (Hoehn and Yahr [H&Y] stages 1-3) and 27 matched healthy control subjects. MAIN OUTCOME MEASURES: We acquired multiecho T1-weighted, multiecho proton density, T2-weighted, and T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences from each participant. For the SNc, we created a weighted mean of the multiple echoes, yielding a single volume with a high ratio of contrast to noise. We visualized the BF using T2-weighted FLAIR images. For each participant, we manually labeled the 2 structures and calculated their volumes. RESULTS: Relative to the controls, 13 patients with H&Y stage 1 PD had significantly decreased SNc volumes. Sixteen patients with H&Y stage 2 or 3 PD showed little additional volume loss. In contrast, the BF volume loss occurred later in the disease, with a significant decrease apparent in patients having H&Y stage 2 or 3 PD compared with the controls and the patients having H&Y stage 1 PD. The latter group did not differ significantly from the controls. CONCLUSION: Our results support the proposed neuropathological trajectory in PD and establish novel multispectral methods as MR imaging biomarkers for tracking the degeneration of the SNc and BF.