George V. Kondraske

Quantification of lumbar function part 3: Preliminary data on isokinetic torso rotation testing with myoelectric spectral analysis in normal and low-back pain subjects

A prototype isokinetic torso rotation unit and an EMG signal processing system were utilized to obtain preliminary information on torso rotation. In Study 1, range-of-motion was found to be surprisingly uniform between low-back pain patients and normal subjects, although there was a significant strength variation between them at all isokinetic speeds tested. Both female patients and normal females showed approximately 70%–75% of the strength (torque/body weight) levels relative to their male counterparts. The decrement in trunk strength at high speeds was proportional for both patients and controls and was not nearly as dramatic as the decrement seen in the sagittal plane. In Studies 2 and 3, anatomic relationships evaluated by EMG testing of obliques and erector spinae showed that the contralateral abdominal obliques were the most consistent muscles providing a significant torsional moment to the spine.

Assessment of basic human performance resources predicts operative performance of laparoscopic surgery

BACKGROUND Interest in laparoscopic surgery has prompted development of educational programs designed to teach and assess laparoscopic skills. Although these programs are beneficial, because of the inherent demands imposed by laparoscopy some aspects of operative performance might not improve with practice. This suggests that innate ability could predict level of operative skill. Assessment of operative and technical potential to date has relied largely on subjective rather than objective criteria. In this study, the relationships between objective measures of human basic performance resources (BPRs) and laparoscopic performance were evaluated using Nonlinear Causal Resource Analysis (NCRA), a novel predictive and explanatory modeling approach based on General Systems Performance Theory. STUDY DESIGN Twenty urology residents were voluntary enrolled. Thirteen validated BPRs were measured and analyzed relative to operative laparoscopic performance (assessed by two experts) of two porcine laparoscopic nephrectomies (LN). The laparoscopic procedure, representing a High Level Task (HLT), was evaluated using a modified Global Rating of Operative Performance Scale. NCRA models were devised to predict performance of the HLT laparoscopic nephrectomies based on BPRs and to determine the limiting performance resource. RESULTS NCRA models predicted excellent agreement with actual operative performance, suggesting that measures of innate ability (or BPRs) predicted performance of laparoscopic nephrectomy. In 65%, the prediction by NCRA was near identical to the expert rating on the HLT. In 25% of cases, NCRA overpredicted performance; in 10%, NCRA underpredicted performance of the HLT compared to the subjective ratings. Neuromotor channel capacity was the most common performance-limiting resource. CONCLUSIONS Preliminary findings suggest objective prediction of laparoscopic performance with limiting resource diagnostics for an individual surgeon is possible and practical using appropriate new measurement and modeling methods. Selection of surgical candidates, training, and educational curriculum could be positively affected.

Network-based infrastructure for distributed remote operations and robotics research

The establishment of a unique infrastructure for distributed robotics and remote operations research within an educational environment is reported. The distributed laboratory consists of sites at four universities and NASAs Johnson Space Center. The distributed laboratory configuration provides the opportunity to quantitatively study the effects of various system components and technologies on overall telerobotic task performance. The ability to execute representative inspection and manipulation tasks with multiple control, robot, and performance/workload monitoring sites simultaneously connected has been demonstrated. Operations are carried out on a routine basis. During the process, needs for hardware and software standards development have been identified. The current implementation provides a basis for linking government, industrial, and university facilities to realize a truly collaborative research and development environment, enabling graduate students to experience educational opportunities that would otherwise not be possible. >

Surgeon workload and motion efficiency with robot and human laparoscopic camera control

AbstractsBackground: Surgeons are now being assisted by robotic systems in a wide range of laparoscopic procedures. Some reports have suggested that robot-assisted camera control (RACC) may be superior to a human driver in terms of quality of view and directional precision, as well as long-term cost savings. Therefore, we setout to investigate the impact of RACC of surgeon motion efficiency. Methods: Twenty pigs were randomized to undergo a standardized laparoscopic Nissen fundoplication with either a human or RACC system, the AESOP 2000. All procedures were performed by the same surgical fellow. Time was recorded for dissection and suture phases. Inertial motion sensors were used to monitor both the surgeons hands and the camera. Digitized data were analyzed to produce summary measures related to overall motion. Results: The operative times were slightly longer with RACC (mean 80.2 ± 20.6 vs 73.1 ± 15.4 min, not significant). With regard to operative times and surgeon motion measures, the only statistically significant differences were for setup and breakdown times, which contributed <15% to the total time for the procedure. Conclusion: In terms of impact on surgeon motion efficiency and operative time under normal surgical conditions, RACC is essentially the same as an expert human driver. However, careful planning and structuring of the surgical suite may yield some small gains in operative time.

Olanzapine: Interaction study with imipramine

Olanzapine is an “atypical” antipsychotic agent with a high affinity for serotonin 5HT2A/C, 5HT3, 5HT6, and dopamine D1, D2, D3, D4 receptors. Depressed patients with psychotic disorders frequently require treatment with concomitant antipsychotic and antidepressant medications. Imipramine pharmacokinetics serve as a marker for hepatic CYP2D6, CYP1A2, CYP3A activity. An open‐label, three‐way randomized crossover study was done to determine the safety, pharmacokinetics, and potential for a drug interaction between olanzapine (5 mg) and imipramine (75 mg). Each drug was administered alone and in combination. Nine healthy men, ages 32 to 54 years, enrolled in the study. Psychomotor performance capacities, plasma olanzapine, imipramine, desipramine concentrations, and clinical laboratory tests were measured. Pharmacokinetic variables, vital signs, subjective tests for liveliness, and psychomotor outcomes were analyzed using a two‐way ANOVA. Olanzapine was safe. Sedation, postural hypotension, and minor vital sign alterations occurred during all treatments. On the liveliness questionnaire, patients generally reported poorer (less lively) scores with olanzapine alone or coadministered with imipramine versus baseline scores. These effects disappeared within 24 hours after administration. Olanzapine alone and in combination decreased motor‐speed tasks (finger tapping and visual‐arm random reach) compared with baseline or imipramine treatment. Peak 6‐hour changes were statistically significant but clinical importance was only marginal. Olanzapine concentrations were <19% greater than with imipramine. But olanzapine did not affect the kinetics of imipramine or desipramine and, therefore, did not show a metabolic drug interaction involving CYP2D6. J Clin Pharmacol 1997;37:971–978.

Functional near-infrared spectroscopy maps cortical plasticity underlying altered motor performance induced by transcranial direct current stimulation

Abstract. Transcranial direct current stimulation (tDCS) of the human sensorimotor cortex during physical rehabilitation induces plasticity in the injured brain that improves motor performance. Bi-hemispheric tDCS is a noninvasive technique that modulates cortical activation by delivering weak current through a pair of anodal–cathodal (excitation–suppression) electrodes, placed on the scalp and centered over the primary motor cortex of each hemisphere. To quantify tDCS-induced plasticity during motor performance, sensorimotor cortical activity was mapped during an event-related, wrist flexion task by functional near-infrared spectroscopy (fNIRS) before, during, and after applying both possible bi-hemispheric tDCS montages in eight healthy adults. Additionally, torque applied to a lever device during isometric wrist flexion and surface electromyography measurements of major muscle group activity in both arms were acquired concurrently with fNIRS. This multiparameter approach found that hemispheric suppression contralateral to wrist flexion changed resting-state connectivity from intra-hemispheric to inter-hemispheric and increased flexion speed (p<0.05). Conversely, exciting this hemisphere increased opposing muscle output resulting in a decrease in speed but an increase in accuracy (p<0.05 for both). The findings of this work suggest that tDCS with fNIRS and concurrent multimotor measurements can provide insights into how neuroplasticity changes muscle output, which could find future use in guiding motor rehabilitation.

Evidence for cortical dysfunction in spasmodic dysphonia: Regional cerebral blood flow and quantitative electrophysiology☆

Cortical function was evaluated in 26 subjects with spasmodic dysphonia. Quantitative topographic electrophysiologic mapping (QTE) was employed to provide quantitative analyses of EEG spectra and auditory and visual long-latency evoked potentials. Single-photon emission computed tomography (SPECT) of the cerebral transit of Xenon-133 was used to evaluate regional cerebral blood flow. Left hemispheric abnormalities in cortical function were found by both techniques in 10 subjects and by at least one technique in 18 subjects. Right hemispheric abnormalities were observed by both techniques in 8 subjects and by at least one technique in 18 subjects. Most patients with cortical dysfunction in one hemisphere had cortical dysfunction in the other, while only 4 subjects had unilateral lesions as found by one of the two techniques. Eight subjects were normal by all measurements. Underlying structural abnormalities were detected by magnetic resonance imaging in 5/24 subjects. However, functional abnormalities (SPECT or QTE) were not observed at sites of structural abnormalities. SPECT and QTE were significantly related in identification of left hemispheric dysfunction (p = .037) with a trend in the right hemisphere (p = .070), and a significant congruence of SPECT and QTE findings occurred in the left anterior cortical quadrant (p = .011). These findings indicate that dysfunction of cortical perfusion and/or cortical electrophysiology is associated with spasmodic dysphonia in the majority of subjects studied.

Temporal characterization of myoelectric spectral moments changes: analysis of common parameters

To investigate the validity of common spectral shift parameterizations, two closely related studies were conducted. Simple linear and exponential regression models were applied to the time-series myoelectric mean power frequency and median power frequency data of two normal subjects as well as a single subject over multiple trials. Statistical analyses were applied to test the hypothesis that no significant differences in extracted features (measurands) exist between different epochs of spectral parameter data. Statistically significant differences were found to exist in both studies, implying that the trial duration can significantly influence the obtained measurement values, and that neither linear nor simple exponential regression models adequately characterize the time-dependent changes. It is concluded that parameterization techniques based on statistical curve-fitting strategies should be supplemented with physiologic models to gain insight into the functional nature of the time dependency. Results are discussed in this context.<<ETX>>

Multichannel electromyographic observations in spasmodic dysphonia patients and normal control subjects.

Spasmodic dysphonia is primarily a disorder of vocalization. Increasing evidence, however, suggests that individuals with this disorder comprise a heterogeneous population characterized by abnormal motor control throughout the vocal tract. Multichannel simultaneous electromyography was performed on 11 spasmodic dysphonia patients and 10 normal awake subjects to investigate both the distribution of neuromotor abnormality within the vocal tract (eg, intrinsic and extrinsic laryngeal muscles, tongue, and palate) and the contribution of activation of higher central nervous system centers to observed abnormality. Experimental tasks ranged from vegetative (quiet breathing) to simple linguistic (short sentences). Digitized electromyographic signals were analyzed to compute the amplitude envelope and extract a set of parameters that represent amplitude characteristics. Electrode insertions were cross-validated by quantitative analysis of patterns of activation across selected reference tasks and by traditional qualitative methods. Between-group differences were found for measures of normalized median and peak token amplitudes. These differences are both task- and measure-dependent. Results highlight the complex and interactive effects of muscle, task, and quantitative measures on between-group differences.

Performance theory based outcome measurement in engineering education and training

An approach is presented to improve engineering education that is based on new concepts of systems performance and classic feedback theory. An important aspect is the use of general systems performance theory (GSPT) to provide a performance model of the educational system and as a basis for the key outcome metrics: the volumes of performance capacity envelopes of individual students. Feedback is aimed at achieving both better curriculum design and teaching methods. In addition to conceptual issues, a web-based implementation plan and experimental validation plan is described. The quantitative modeling approach taken, including choice of appropriate levels of abstraction, has provided better understanding of the system used to provide engineering education and a basis for quantitatively linking components of the program to student performance in a causal manner. The educational system performance model is discussed in the context of competency models. It is believed that this approach holds promise for not only documenting a meaningful type of outcome but also for providing insight into the rationale for steps taken in attempts to improve an educational system.