Management of postoperative complications: general approach.

The goal of postoperative management is to promote early mobility and avoid postoperative complications, recognizing the potentially devastating impact of complications on elderly patients with hip fracture. The recommended approach involves early mobilization; freedom from tethers (indwelling urinary catheters and other devices); effective pain control; treating malnutrition; preventing pressure ulcers; reducing risk for pulmonary, urinary, and wound infections; and managing cognition. This carefully structured and patient-centered management provides older, vulnerable patients their best chance of returning to their previous level of functioning as quickly and safety as possible.

Training stroke patients with continuous tracking movements: evaluating the improvement of voluntary control.

We report on a pilot study of robot therapy with stroke patients. Patients were requested to track a continuously moving target according to a figure-of-eight. Assistance was provided by an attractive force field, whose magnitude was regulated according to a principle of minimal assistance and a principle of consolidation of the learned memory trace. From the analysis of the assistive forces, we show that subjects improve their degree of voluntary control.

Activity, tolerability and efficacy of levetiracetam on cerebellar symptoms in multiple sclerosis patients: a pilot kinematic study.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate the activity measured by kinematic analysis, tolerability and efficacy of levetiracetam (LEV) in multiple sclerosis (MS) patients affected by cerebellar symptoms, in a randomized single-blind, placebo-controlled cross-over study. METHODS: Eight MS subjects with cerebellar signs (five female and three male; mean EDSS: 4.77; mean disease duration 9.2) performed a reaching task on a digitizing tablet and their trajectories went through a kinematic analysis. The subjects were assessed at baseline, after 21 days of treatment, after wash-out period (day 35) and after 21 days of treatment (day 56). LEV was used at the maximum dosage of 1500 mg daily. The primary outcome was the modification on smoothness (JERK) whilst aiming error (AAI) and centripetal acceleration (CA) were considered as secondary outcomes. RESULTS: Two subjects were excluded from the final analysis. Primary outcome (i.e. JERK) was significantly affected by the administration of LEV overtime (nine arms in active treatment versus three arms in placebo decreased the mean values of their JERK). Regarding secondary outcomes CA was significantly affected by the administration of LEV. No statistical significant results were found comparing clinical scales during the four assessments. DISCUSSION: The results indicate that LEV was able to modify kinematic parameter so the medication was active but no improvement in clinical scales was observed. LEV needs to be tested in a larger group of subjects designed to verify treatment efficacy using higher dosage of the medication.

Subtle upper limb impairment in asymptomatic multiple sclerosis subjects.

We evaluated upper limb function in multiple sclerosis (MS) subjects (11 clinically definite MS patients and seven clinically isolated syndrome (CIS) subjects), with a normal upper limb standard neurological examination. Subjects performed center-out reaching movements under visual control, with and without vision of the hand. Their movements were recorded through a digitizing tablet. Motor performance was also related to lesion load, estimated from magnetic resonance imaging (MRI). We found that in MS and CIS subjects, under the hand vision condition, movements were significantly less smooth, and had a less symmetric speed profile. However, the observed impairment did not correlate with MRI findings. This result may be interpreted as evidence of a compensatory strategy, elicited by subtle alterations in sensorimotor control.

Connecting neurons to a mobile robot: an in vitro bidirectional neural interface.

One of the key properties of intelligent behaviors is the capability to learn and adapt to changing environmental conditions. These features are the result of the continuous and intense interaction of the brain with the external world, mediated by the body. For this reason "embodiment" represents an innovative and very suitable experimental paradigm when studying the neural processes underlying learning new behaviors and adapting to unpredicted situations. To this purpose, we developed a novel bidirectional neural interface. We interconnected in vitro neurons, extracted from rat embryos and plated on a microelectrode array (MEA), to external devices, thus allowing real-time closed-loop interaction. The novelty of this experimental approach entails the necessity to explore different computational schemes and experimental hypotheses. In this paper, we present an open, scalable architecture, which allows fast prototyping of different modules and where coding and decoding schemes and different experimental configurations can be tested. This hybrid system can be used for studying the computational properties and information coding in biological neuronal networks with far-reaching implications for the future development of advanced neuroprostheses.

Connecting brains to robots: an artificial body for studying the computational properties of neural tissues.

We have created a hybrid neuro-robotic system that establishes two-way communication between the brain of a lamprey and a small mobile robot. The purpose of this system is to offer a new paradigm for investigating the behavioral, computational, and neurobiological mechanisms of sensory-motor learning in a unified context. The mobile robot acts as an artificial body that delivers sensory information to the neural tissue and receives command signals from it. The sensory information encodes the intensity of light generated by a fixed source. The closed-loop interaction between brain and robot generates autonomous behaviors whose features are strictly related to the structure and operation of the neural preparation. We provide a detailed description of the hybrid system, and we present experimental findings on its performance. In particular, we found (a) that the hybrid system generates stable behaviors, (b) that different preparations display different but systematic responses to the presentation of an optical stimulus, and (c) that alteration of the sensory input leads to short- and long-term adaptive changes in the robot responses. The comparison of the behaviors generated by the lamprey's brain stem with the behaviors generated by network models of the same neural system provides us with a new tool for investigating the computational properties of synaptic plasticity.

Computational implications of modeling grasping as a form of (multiple-parallel) reaching.

Although it is true that the specific research on grasping has been dominated in recent years by the canonical transport + grip model originally formulated by Jeannerod (1984), still one can find in the research on reaching a number of links and anticipations to the new view on grasping made explicit by the authors of the target article. This paper reviews some of the relevant concepts and outlines a modeling framework that aims at biological plausibility.

Can non-linear muscle dynamics explain the smoothness of handwriting movements?

The paper addresses the issue of the role of non-linear muscle dynamics in determining the smoothness and invariance of handwriting trajectories. In particular, a specific neuromuscular control model is described that has recently been shown to explain the detailed time course of hand stiffness during arm reaching movements. In the paper the model is applied to more complex handwriting trajectories, with the purpose of verifying to which extent the load compensation capabilities of the periphery can subserve motor equivalence. Simulations show the power of the mechanism for movements of "normal" speed. For quicker movements periphery alone is not enough and a central load compensation action is clearly required.

Are complex control signals required for human arm movement?

It has been proposed that the control signals underlying voluntary human arm movement have a "complex" nonmonotonic time-varying form, and a number of empirical findings have been offered in support of this idea. In this paper, we address three such findings using a model of two-joint arm motion based on the lambda version of the equilibrium-point hypothesis. The model includes six one- and two-joint muscles, reflexes, modeled control signals, muscle properties, and limb dynamics. First, we address the claim that "complex" equilibrium trajectories are required to account for nonmonotonic joint impedance patterns observed during multijoint movement. Using constant-rate shifts in the neurally specified equilibrium of the limb and constant cocontraction commands, we obtain patterns of predicted joint stiffness during simulated multijoint movements that match the nonmonotonic patterns reported empirically. We then use the algorithm proposed by Gomi and Kawato to compute a hypothetical equilibrium trajectory from simulated stiffness, viscosity, and limb kinematics. Like that reported by Gomi and Kawato, the resulting trajectory was nonmonotonic, first leading then lagging the position of the limb. Second, we address the claim that high levels of stiffness are required to generate rapid single-joint movements when simple equilibrium shifts are used. We compare empirical measurements of stiffness during rapid single-joint movements with the predicted stiffness of movements generated using constant-rate equilibrium shifts and constant cocontraction commands. Single-joint movements are simulated at a number of speeds, and the procedure used by Bennett to estimate stiffness is followed. We show that when the magnitude of the cocontraction command is scaled in proportion to movement speed, simulated joint stiffness varies with movement speed in a manner comparable with that reported by Bennett. Third, we address the related claim that nonmonotonic equilibrium shifts are required to generate rapid single-joint movements. Using constant-rate equilibrium shifts and constant cocontraction commands, rapid single-joint movements are simulated in the presence of external torques. We use the procedure reported by Latash and Gottlieb to compute hypothetical equilibrium trajectories from simulated torque and angle measurements during movement. As in Latash and Gottlieb, a nonmonotonic function is obtained even though the control signals used in the simulations are constant-rate changes in the equilibrium position of the limb. Differences between the "simple" equilibrium trajectory proposed in the present paper and those that are derived from the procedures used by Gomi and Kawato and Latash and Gottlieb arise from their use of simplified models of force generation.

A dynamic biomechanical model for neural control of speech production.

A model of the midsagittal plane motion of the tongue, jaw, hyoid bone, and larynx is presented, based on the lambda version of equilibrium point hypothesis. The model includes muscle properties and realistic geometrical arrangement of muscles, modeled neural inputs and reflexes, and dynamics of soft tissue and bony structures. The focus is on the organization of control signals underlying vocal tract motions and on the dynamic behavior of articulators. A number of muscle synergies or "basic motions" of the system are identified. In particular, it is shown that systematic sources of variation in an x-ray data base of midsagittal vocal tract motions can be accounted for, at the muscle level, with six independent commands, each corresponding to a direction of articulator motion. There are two commands for the jaw (corresponding to sagittal plane jaw rotation and jaw protrusion), one command controlling larynx height, and three commands for the tongue (corresponding to forward and backward motion of the tongue body, arching and flattening of the tongue dorsum, and motion of the tongue tip). It is suggested that all movements of the system can be approximated as linear combinations of such basic motions. In other words, individual movements and sequences of movements can be accounted for by a simple additive control model. The dynamics of individual commands are also assessed. It is shown that the dynamic effects are not neglectable in speechlike movements because of the different dynamic behaviors of soft and bony structures.

Teaching managed care : philosophy and technique.

The authors describe a case-oriented seminar on managed care designed to teach psychiatric residents and medical students the principles of cost containment and delivery of quality care. The participants engage in role-play (reviewer, provider, appeal arbitrator) to elucidate the process. The response of the participants indicates that this seminar is a useful teaching model. Salient points regarding the content and process of the seminar are discussed in some detail.

GHB: a home brew.

Gamma-hydroxybutyric acid is an allegedly benign illicit substance that is gaining increasing recognition and attention among substance abusers and athletes. Alongside foreign-made brands, the compound is also easily available, at low cost because of the facility with which it can be produced in one's kitchen. Named by some "Nature's Quaalude" or sold as a health product, it is often used with a false sense of security as it may cause serious and disabling complications, as illustrated by this clinical vignette.

A control model of human tongue movements in speech.

Tongue movements during speech production have been investigated by means of a simple yet realistic biomechanical model, based on a finite elements modeling of soft tissues, in the framework of the equilibrium point hypothesis (lambda-model) of motor control. In particular, the model has been applied to the estimation of the "central" control commands issued to the muscles, for a data set of mid-sagittal digitized tracings of vocal tract shape, recorded by means of low-intensity X-ray cineradiographies during speech. In spite of the highly non-linear mapping between the shape of the oral cavity and its acoustic consequences, the organization of control commands preserves the peculiar spatial organization of vowel phonemes in acoustic space. A factor analysis of control commands, which have been decomposed into independent or "orthogonal" muscle groups, has shown that, in spite of the great mobility of the tongue and the highly complex arrangement of tongue muscles, its movements can be explained in terms of the activation of a small number of independent muscle groups, each corresponding to an elementary or "primitive" movement. These results are consistent with the hypothesis that the tongue is controlled by a small number of independent "articulators", for which a precise biomechanical substrate is provided. The influence of the effect of jaw and hyoid movements on tongue equilibrium has also been evaluated, suggesting that the bony structures cannot be considered as a moving frame of reference, but, indeed, there may be a substantial interaction between them and the tongue, that may only be accounted for by a "global" model. The reported results also define a simple control model for the tongue and, in analogy with similar modelling studies, they suggest that, because of the peculiar geometrical arrangement of tongue muscles, the central nervous system (CNS) may not need a detailed representation of tongue mechanics but rather may make use of a relatively small number of muscle synergies, that are invariant over the whole space of tongue configurations.

Retrospective study of 2,200 involuntary psychiatric admissions and readmissions.

OBJECTIVE: The authors describe demographic data, the distribution of diagnoses, and comorbid psychoactive substance use in a large sample of patients involuntarily admitted to a psychiatric hospital from multiple crisis centers and explore the relative roles these variables may play in service utilization and admission rates. METHOD: Data on demographic characteristics and comorbid psychoactive substance use in 2,200 consecutive involuntary hospital admissions of 1,755 psychiatric patients were gathered. Pertinent demographic and comorbidity data at first admission for the 1,755 patients, 314 of whom were admitted more than once, were analyzed; then the data for the 1,441 single-admission patients and the data at first admission for the 314 patients who had multiple admissions were compared. Finally, the diagnostic distribution and comorbid psychoactive substance use in all 2,200 admissions were investigated, with attention to a subgroup of 88 high-risk patients (those with three or more admissions) who represented a total of 307 admissions. RESULTS: Specific demographic characteristics were represented in the patient group at a high level of statistical significance. The diagnosis of schizophrenia was significantly overrepresented. Schizophrenia and psychosis not elsewhere classified clustered in the subgroup with a high risk of readmission. CONCLUSIONS: The results suggest a specific profile for the patient with heightened risk of hospital admission: a young, unmarried, African American male who has schizophrenia without comorbid substance abuse. An effect size data analysis identified marital status and a diagnosis of schizophrenia as the variables associated with the greatest likelihood of admission. Unexpectedly, the impact of comorbid psychoactive substance use was relatively modest and showed a uniform distribution among diagnostic groups.

Gender differences among civilly committed schizophrenia subjects.

The authors describe a sample of 815 acutely ill schizophrenia patients hospitalized under a petition for involuntary inpatient treatment and illustrate how this group of patients can be considered as more representative of involuntary commitment status than more traditional "involuntary" patients drawn from State hospitals' wards. Available demographics of the general population from which the sample was drawn are also presented for comparison. The authors then report the gender distribution of several variables--age, marital status, psychoactive substance use, comorbidity, length of stay, and frequency of readmissions--among the study sample and discuss the relevance of these findings.

Providers and reviewers teach informed managed care.

Two utilization review case studies are summarized, with discussion of both the provider's and the reviewer's perspective. This interface between managed care organizations and behavioral health care professionals offers some instructive guidelines on how to best approach the utilization review process.

Comorbid substance abuse and recovery from acute psychiatric relapse.

OBJECTIVE: The study investigated whether chronic mentally ill patients whose psychiatric relapse was complicated by active substance abuse recovered from relapse at a different rate than similar patients with no comorbid substance abuse. METHODS: A total of 401 patients involuntarily hospitalized on a short-term psychiatric treatment unit received a urine toxicology screen on admission; the severity of their psychiatric symptoms was rated on the fifth day of hospitalization using the Brief Psychiatric Rating Scale (BPRS). Differences in scores between patients who had positive screens and those who had negative screens were evaluated for various diagnostic groups. RESULTS: Patients who had a positive screen and a primary discharge diagnosis of psychoactive substance abuse had a BPRS total score indicating less psychopathology than similarly diagnosed patients with negative screens. Patients who had positive screens and a diagnosis of personality disorder had some BPRS subscale scores indicating greater psychopathology than their counterparts with negative screens. No other significant differences in recovery rates between the two groups were found, although comparisons indicated trends toward faster recovery in some areas of functioning by schizophrenic patients with positive screens and affective disorder patients with negative screens. CONCLUSIONS: Results suggest that use of a urine toxicology screen and the BPRS early in treatment may aid in assessing the acute course of several psychiatric disorders and the effect of comorbidity.

Neurocomputing aspects in modelling cursive handwriting.

This paper describes a distributed modelling framework of the motor control processes that underly the planning of cursive handwriting. The model, that focuses on the hypothetical functions of the posterior parietal cortex combines a paradigm of self-organization (for building robust and coherent maps of the different motor spaces) with relaxation dynamics (for run-time incorporation of task constraints) and non-linear integration (for a smooth integration between via-points).

Reported prevalence of drug abuse comorbidity in a city-wide emergency rooms system.

Frequency and results of urine toxicology screens in a state-guided system of emergency rooms in a large city were compared with frequency and results of the same tests in the same population at a university-run intensive treatment psychiatric unit. Differences both in prevalence and in results were noted, with the emergency rooms testing significantly less patients than the intensive treatment unit and documenting a significantly lower rate of active substance abuse comorbidity to psychiatric disorders. Possible explanations for these differences are discussed, including clinical, attitudinal, and cost containment factors. These findings have a definite impact on treatment decision making, diagnostic precision, and validity of epidemiologic reports.