Falls are a major source of disability in Parkinson's disease. Risk factors for falling in Parkinson's disease remain unclear. To determine the relevant risk factors for falling in Parkinson's disease, we screened 160 consecutive patients with Parkinson's disease for falls and assessed 40 variables. A comparison between fallers and nonfallers was performed using statistical univariate analyses, followed by bivariate and multivariate logistic regression, receiver-operating characteristics analysis, and Kaplan-Meier curves. 38.8% of patients experienced falls since the onset of Parkinson's disease (recurrent in 67%). Tinetti Balance score and Hoehn and Yahr staging were the best independent variables associated with falls. The Tinetti Balance test predicted falls with 71% sensitivity and 79% specificity and Hoehn and Yahr staging with 77% sensitivity and 71% specificity. The risk of falls increased exponentially with age, especially from 70 years onward. Patients aged >70 years at the onset of Parkinson's disease experienced falls significantly earlier than younger patients.

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Sirs, Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is currently the most common therapeutic surgical procedure for patients with advanced ParkinsonÕs disease (PD) and motor complications, not controlled by the pharmacological treatment. The success of the post-operative clinical outcome depends on careful patient selection and an optimal targeting of the STN. To improve the location accuracy of this nucleus, intraoperative microrecordings are performed in most centres. The standard procedure of electrodes implantation is usually carried out under local anaesthesia [1]. Experience in intraoperative microrecording of STN under general anaesthesia is scarce [2], and neuronal firing patterns are not well typified.We describe the intraoperative microrecording results obtained from a patient with advanced PD who underwent implantation of DBS electrodes in the STN under general anaesthesia using Bispectral Analysis of the Electroencephalogram (BIS). This technique allows hypnotic titration over the complete range of cortical activity. A BIS value of 65-85 is recommended for sedation and 40-65 for general anaesthesia [3]. BIS values correspond linearly to the hypnotic dose of intravenous or volatile agents [4] and, therefore, it allows changing the level of sedation and analgesia rapidly to accommodate specific requirements such as intraoperative microrecording.A 59-year-old man with a 7-year history of PD complicated with motor fluctuations and dyskinesias was scheduled for DBS of STN. General anaesthesia was used during the surgical procedure because the patient experienced a severe painful cervical dystonia which prevented positioning the stereotactic frame.Propofol 200 mg, fentanyl 150 lg and cisatracurium 10 mg were administered, then target propofol and remifentanyl concentrations were adjusted to achieve a BIS value of 60-65 during microrecordings, the lightest level of a general anaesthesia.

The aim of this study was to indentify the involvement of leptin receptors (LepR) in astrocytes in hippocampal synaptic transmission and plasticity and metabolism. To this end we used a genetic mouse model (GFAP-LepR À/À) of specific LepR ablation in GFAP positive cells and recorded excitatory postsynaptic potentials (fEPSPs) within the CA1 area. Glutamate (Glu) uptake and the expression of Glu transporters (EEAT3, GLT-1 and GLAST) and enzymes involved in Glu metabolism (glutamine synthase, GABA decarboxylase 65 and 67) were quantified. Modifications in the expression of GFAP, the glucose transporter (GLUT)-1, and the monocarboxylate transporters MCT-2 and MCT-4, were also analyzed. The results show that depletion of LepR in GFAP positive cells reduced basal synaptic transmission within the CA1 area and impaired N-methyl-D-aspartate (NMDA)evoked long-term depression (NMDA-LTD). Hippocampal slices from GFAP-LepR À/À mice displayed lower Glu uptake efficacy together with up-regulation of GLT-1, glutamine synthase, GFAP and GLUT-1. In conclusion, astrocyte LepRs are involved in the maintenance of Glu homeostasis and Glu neurotransmission within the hippocampus. Our findings support a role of hippocampal LepRs in synaptic plasticity, which could have an impact on memory and learning processes.