Validity of the finger tapping test in Parkinson’s disease,elderly and young healthy subjects: Is there a role for central fatigue?

Objective

The main goal of this work is to evaluate the validity of the finger tapping test (FT) to detect alterations in rhythm formation.

Methods

We use FT to study the alterations in motor rhythm in three different groups: Parkinson’s patients, elderly healthy controls, and young healthy control subjects (HY). The test was performed in COMFORT and FAST tapping modes and repeated on two different days.

Results

For the variables analyzed (frequency and variability) both modes were repeatable in all groups. Also, intra-class correlation coefficients showed excellent levels of consistency between days. The test clearly differentiated the groups in both FAST and COMFORT modes. However, when fatigue was analyzed, a decrease in the tapping frequency was observed in HY during the FAST mode only. The amplitude of motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) was early-potentiated but not delayed-depressed, both for COMFORT and FAST modes. This suggests that fatigue was not of cortico-spinal origin. Other forms of central fatigue are discussed.

Conclusions

FT at FAST mode is not a valid test to detect differences in rhythm formation across the groups studied; fatigue is a confounding variable in some groups if the test is performed as fast as possible.

Significance

COMFORT mode is recommended in protocols including the FT for evaluating rhythm formation.     

A critical appraisal of sedation, analgesia and delirium in neurocritical care

Administering analgesics, sedatives and antipsychotics is challenging in the Neurological Intensive Care Unit (NICU). We reviewed this literature and our current practice to better inform the critical care practitioner and to identify gaps for future research. We electronically searched observational, intervention and outcome studies addressing sedation, analgesia and delirium in the NICU, and their bibliographies. Practice patterns were assessed in three critical care units with specialized neurological care in Montreal. Bedside pain assessment tools are psychometrically validated in the neuro-critically ill but sedation and delirium tools are not. Rigorous pain and sedation assessments appear feasible; delirium screening has not been tested. Publications addressing outcomes and responses to pharmacologic treatment lack consistency, rigor or both. In daily practice, pharmacologic management varies greatly. Clearly, little information exists on analgesia, sedation and delirium in the NICU. Systematic evaluation of pain improves outcome. No evidence-based therapeutic recommendations can be proffered.     

Neurocognitive-genetic and neuroimaging-genetic research paradigms in schizophrenia and bipolar disorder

Studies examining intermediate phenotypes such as neurocognitive and neuroanatomical measures along with susceptibility genes are important for improving our understanding of the neural basis of schizophrenia (SZ) and bipolar disorder (BD). In this paper, we review extant studies involving neurocognitive-genetic and neuroimaging-genetic perspectives and particularly related to catechol-O-methyltransferase (COMT), brain-derived neurotrophic factor (BDNF) and neuregulin-1 (NRG1) genes in SZ and BD. In terms of neurocognitive-genetic investigations, COMT and BDNF are the two most studied candidate genes especially in patients with SZ. Whereas BDNF Met carriers perform worse on verbal working memory, problem solving and visuo-spatial abilities, COMT Met carriers perform better in working memory, attention, executive functioning with evidence of genotype by diagnosis interactions including high-risk individuals. In terms of genetic-structural MRI studies, patients with SZ are found to have reductions in the frontal, temporal, parietal cortices, and limbic regions, which are associated with BDNF, COMT, and NRGI genes. Genetic-functional MRI studies in psychotic disorders are sparse, especially with regard to BD. These neurocognitive and neuroimaging findings are associated with genes which are implicated in functional pathways related to neuronal signaling, inter-neuronal communication and neuroplasticity.     

Impact of quetiapine on resolution of individual delirium symptoms in critically ill patients with delirium: a <Emphasis Type="Italic">post-hoc</Emphasis> analysis of a double-blind,randomized, placebo-controlled study

Introduction  

We hypothesized that delirium symptoms may respond differently to antipsychotic therapy. The purpose of this paper was to retrospectively compare duration and time to first resolution of individual delirium symptoms from the database of a randomized, double-blind, placebo-controlled study comparing quetiapine (Q) or placebo (P), both with haloperidol rescue, for critically ill patients with delirium.     

Special Article Toronto critical care medicine symposium report

Critical care provides constant challenges to the practitioner whose attempt to remain up to date is made more difficult by the breadth and amount of new information available. This critical care symposium aptly captured bench-to-bedside areas of interesting new basic research, reviewed clinical trials with potential practical impact on day-to-day practice, and revisited older scientific questions (such as steroids in sepsis) which are now being re-evaluated in a new light.