Assessing mechanisms of recovery during robot-aided neurorehabilitation of the upper limb.

OBJECTIVE: The present study aimed to qualify and quantify the different components of motor recovery in a group of stroke patients treated by robot-aided techniques. In addition, the learning model of each motor recovery component was analyzed. METHODS: Two groups of poststroke patients were treated with the use of an elbow-shoulder manipulator, respectively, within (recent) and after (chronic) the first 6 months of their cerebrovascular accident. Both groups were evaluated by means of standard clinical assessment scales and a robot-measured evaluation method. RESULTS: These findings confirm that motor training consisting of voluntary movements assisted by the robot device led to significant improvements in motor performance in terms of the kinematic and dynamic components of the arm movements. This corresponded to improvement of impairment as confirmed by the clinical scale results. CONCLUSIONS: Knowledge of the recovery components and of the associated performance acquisition model may be useful in assessing and training stroke patients and should make it possible to precisely plan and, if necessary, modify the rehabilitation strategies.

Measurement of isometric muscle strength: a reproducibility study of maximal voluntary contraction in normal subjects and amyotrophic lateral sclerosis patients.

Amyotrophic lateral sclerosis (ALS) is a degenerative disease of unknown cause, resulting in the progressive loss of voluntary motor activity. Traditional methods of evaluating patients with ALS (neurologic assessment, manual muscle testing and rating scales) involve subjective elements and lack the sensitivity needed to detect small but meaningful changes in deterioration and therapeutic efficacy. This paper presents a recently developed strength measurement instrument, useful for the long-term monitoring of muscle strength deterioration in ALS. In addition, a reproducibility study to assess the intra- and interobserver reliability of maximal voluntary isometric contraction is reported. The strength measurement instrument consists of a strain gauge force transducer, a bridge amplifier and a mechanical structure to counteract movements. A personal computer acquires the strength signal during each voluntary contraction and automatically computes the maximal value. Reproducibility of measurement was assessed in 18 normal subjects tested twice, on successive days, with the same examiner and under the same conditions. The interexaminer reproducibility of measurement was assessed in a group of 13 normal subjects and 10 ALS patients. Each subject of the two groups was independently examined by three examiners. The two reproducibility studies showed a high intraclass correlation coefficient (0.91-0.97) and low SEM and measurement error (3-10%) in all muscle regions tested. The Bland and Altman plots confirmed these results.

Comparison between spectral analysis and the phenylephrine method for the assessment of baroreflex sensitivity in chronic heart failure.

Baroreflex sensitivity assessed by means of the phenylephrine test plays a prognostic role in patients with previous myocardial infarction, but the need for drug injection limits the use of this technique. Recently, several non-invasive methods based on spectral analysis of systolic arterial pressure and heart period have been proposed, but their agreement with the phenylephrine test has not been investigated in patients with heart failure. The two methods (phenylephrine test and spectral analysis) were compared in a group of 49 patients with chronic congestive heart failure both at rest and during controlled breathing. The linear correlation and the limits of agreement between the phenylephrine test slope and the alpha-index [alpha(c); corrected by the coherence function between the interbeat interval (RR interval) and systolic arterial pressure] were evaluated. Only 16 patients had a measurable alpha-index at rest in both the low-frequency (LF) and high-frequency (HF) bands; the alpha(c)-index allowed measurements in all patients. It correlated moderately with the phenylephrine test slope at rest (r=0. 71 and P<0.001 in LF; r=0.57 and P<0.001 in HF) and during controlled breathing (r=0.51 and P<0.001 in LF; r=0.63 and P<0.001 in HF). Multivariate regression analysis showed that only alpha(c)LF during rest and alpha(c)HF during controlled breathing contributed significantly to baroreflex gain estimation. However, the agreement between methods was weak; the normalized limits of agreement and bias were -162 to 243% (0.46 ms/mmHg) for alpha(c)LF and -185 to 151% (-0.99 ms/mmHg) for alpha(c)HF. Thus the comparison between baroreflex sensitivity measurements obtained by the phenylephrine test and spectral analysis showed a moderate correlation between the two methods; however, despite the linear association, a consistent lack of agreement between the two techniques was found. Because both systematic and random factors contribute to the difference, these two techniques cannot be considered as alternatives for the assessment of heart failure.

How can usability measurement affect the re-engineering process of clinical software procedures?

As a consequence of the dramatic improvements achieved in information technology standards in terms of single hardware and software components, efforts in the evaluation processes have been focused on the assessment of critical human factors, such as work-flow organisation, man-machine interaction and, in general, quality of use, or usability. This trend is particularly valid when applied to medical informatics, since the human component is the basis of the information processing system in health care context. With the aim to establish an action-research project on the evaluation and assessment of clinical software procedures which constitute an integrated hospital information system, the authors adopted this strategy and considered the measurement of perceived usability as one of the main goals of the project itself: the paper reports the results of this experience.

[Processes of speech production: Analysis of the methods and applications in a group of normal subjects (I)]. / Studio dei Processi di Produzione della Parola: Metodi di Analisi ed Applicazione in un Gruppo di Soggetti Normali (Parte I).

The measurement of reaction times in response to suitable stimuli may provide insight into the separate functional blocks corresponding to diverse speech production mechanisms. The quantitative evaluation of speech motor performance provides useful information for the early detection and long-term monitoring of many neurological diseases. The vocal reaction times (VRTs) technique and its application in the assessment of a group of normal subjects is presented. Speech motor performance and the effect of age were investigated by measuring VRTs and speech duration, in a group of thirty normal subjects divided into three age groups (18-44, 45-59, 60-80). VRTs were measured by using an immediate and delayed reaction stimulation paradigm. Analysis of the acoustic and electromyographic signals indicated that reaction times increased with age in both the immediate and delayed tasks; also the acoustic signal durations increased with age. The analysis of variance showed that the difference between the young and elderly groups was statistically significant. This technique may be considered a useful tool to provide qualitative and quantitative measures of the processes involved in speech production.

[Processes of speech production: Application in a group of subjects chronically exposed to organic solvents (II)]. / Studio dei Processi di Produzione della Parola: Applicazione in un Gruppo di Soggetti Esposti Cronicamente a Solventi Organici (Parte II).

The aim of this study was to evaluate the effects of chronic exposition to neurotoxic solvents in a group of laundry operators by means of Vocal Reaction Times (VRTs) measurements. A group of normal subjects, matched for age and educational level, constituted the controls. Vocal Reaction Times were measured by a device that presented to each subject a sequence of words on a computer screen, acquired the acoustic signal and measured VRTs and durations. During the test a random sequence of words was presented to the subjects; the protocol consisted of two immediate reading task and two delayed reading tasks. The test was performed using concrete and meaningless words. Statistical analysis showed that reaction times measured on the acoustic signals were longer for the exposed group than for the controls. The differences between durations were significant for the delayed reading tasks using concrete words and for all tasks using meaningless words. These findings suggest that this technique may be considered a useful tool for the assessment of the preclinical alterations of CNS in the monitoring of individuals chronically exposed to neurotoxic solvents.

[Telematics equipment for poison control surveillance. Its applications in the health management of relevant chemical incidents]. / Strumenti telematici per attività di tossicovigilanza. Applicazioni nella gestione sanitaria degli incidenti chimici rilevanti.

Health management of major chemical incidents requires a close collaboration between rescuers (on the disaster site and in the emergency department) and the poison center. The study tested telematic technologies allowing telepresence and teleconsulting, a real time and continuous connection among health care personnel and toxicologists involved in the management of the emergency. The link between the poison center (PC) and the emergency department in the local hospital is provided by a ISDN operating video conferencing system, while the data transmission from the site of the accident to the PC is achieved with a personal computer and GSM cellular data transmission. Toxicological databases and risk assessment software are integrated in the system, to support information sharing. To test such instruments in operative nearly realistic conditions, the main phase of the study has implemented simulated chemical disasters in different locations in Italy. Instruments for telepresence and teleconsulting have been effectively utilized to evaluate from a remote location the scenario and the severity of the accident, by inspecting either specific details or the whole scene, to enable PC guiding the triage of the victims before and after hospitalization, to utilize and share data, such as intervention protocols or patient records, and to document all the activities. In summary, this experience shows that the telematic link allows the toxicologists of the poison center to rapidly understand the situation, and to correctly learn about the conditions of patients with the help of images. The results of this study indicate the valuable benefits of telematic instruments for the health care in case of major chemical disasters occurring in a remote geographical location or in an area which lacks local toxicological experts, where specialized expertise can be achieved by the use of telematic technologies.

An example of usability measurement in clinical software procedures.

As a consequence of the dramatic improvements achieved in information technology standards in terms of single hardware and software components, efforts in the evaluation processes have been focused on the assessment of critical human factors, such as work-flow organisation, man-machine interaction and, in general, quality of use, or usability. This trend is particularly valid when applied to medical informatics, since the human component is the basis of the information processing system in health care context. With the aim to establish an action-research project on the evaluation and assessment of clinical software procedures which constitute an integrated Hospital Information System, the authors adopted this strategy and considered the measurement of perceived usability as one of the main goals of the project itself: the paper reports the results of this experience.

Multiparametric quantitative evaluation of the speech production system: a study in normal subjects.

This paper describes a systems architecture developed for the study of the speech production system. The architecture utilizes two personal computers: the "Word-Image Presenter" (WIP) that presents a sequence of words to the subject under examination as visual stimulation, and the "Signal Acquisition System" that controls the WIP, acquires the acoustic signal, the oromandibular electromyographic signals, the kinematic lip and jaw signals and measures reaction times and durations. Thirty normal subjects divided into three age groups (18-44, 45-59, 60-80) underwent examination by means of the described system. During the test a random sequence of two words was presented to the subjects; the protocol consisted of an immediate reading task and two delayed reading tasks with variable foreperiods of 0.1 and 1.5 s for one task and 0.5 and 4 s for the other. The analysis of the resultant acoustic and electromyographic signals indicated that reaction times increased with age in both the immediate and delayed tasks. The analysis of variance showed that the difference between the young and elderly groups was statistically significant. The sample size of the groups, however, is too small to consider these results normative data.

The accuracy of power-spectrum analysis of heart-rate variability from annotated RR lists generated by Holter systems.

The accuracy of spectral analysis of heart-rate variability performed on annotated RR interval lists obtained from several commercial Holter systems was appraised. Five tape-recorder-based systems (Del Mar 750, Marquette 8000, Oxford Medilog Excel, Remco Cardioline AD 35 and Reynolds Pathfinder PA3) and four solid-state systems (Hewlett Packard 43420B, Marquette Seer, Oxford 6000FD2, Reynolds E-Ram) were considered. Two ECG signals with fixed real morphology but characterized by a different degree of modulation of the RR interval (reduced and normal variability) were fed into the recorders evaluated. The total power and the power in the very low-, low- and high-frequency bands were then estimated on all Holter-generated RR sequences. Spectral analysis was performed by both the autoregressive and fast-Fourier-transform methods. The estimation error of each parameter was statistically characterized and, for tape-recorder-based systems, inferential analysis was used to test for differences between recorders, tapes and times of recording. The centre and dispersion of the estimation error changed markedly from system to system. Some tape-recording systems showed large inter-recorder differences. The degree of spectral distortion was never uniform among selected bands. Solid-state systems performed better than tape-recording ones but both were limited in the accuracy by the quantization of RR interval measurement. The fast Fourier method yielded spectral estimates more stable than the autoregressive method. Our data clearly show that spectral analysis of very low-variability signals may be seriously affected by Holter recording and preprocessing of ECG signals.

Can body surface mapping improve the diagnostic power of standard electrocardiography in effort myocardial ischemia?

Limitations of the standard 12-lead electrocardiogram in sensitivity, specificity and information content on the effort induced ischemic process might be partly due to an inadequate sampling of cardiac electrical events. An extensive array of electrodes is an effective way to verify this hypothesis. Actually body surface mapping provides: a 10-15% increase in diagnostic yield mainly in patients with mild coronary artery disease and elusive signs of ischemia in standard leads a very approximate indication of the extent of coronary artery disease a substantial contribution to the identification of the site of ischemia. Regarding the last point, preliminary results of an ongoing study are reported. One hundred and three patients with recent myocardial infarction have been studied by exercise test with simultaneous recording of surface map and Thallium 201 scan. So far in the subset with inferior myocardial infarction (76 patients) three different map patterns corresponding to different ischemic regions (anterior, inferior and posterior) have been identified. In anterior myocardial infarction (27 patients) a characteristic map pattern for exercise-induced myocardial ischemia has been observed, apparently able to discriminate between ischemia and the changes of early repolarization induced by the dyskinesia of the infarcted ventricular wall. In conclusion, electrocardiographic mapping makes a practical contribution to the understanding of ischemia-induced cardiac electrical events.

Exercise hemodynamics 1 month, 2 months and 1 year after myocardial infarction: prognostic considerations.

Sequential electrocardiographic and hemodynamic changes were studied at rest and during symptom-limited bicycle exercise in oligo-asymptomatic patients after myocardial infarction (MI). The exercise tests were performed after the acute episode on days 29 +/- 4 (E1) and 62 +/- 6 (E2) in 128 patients; on days 37 +/- 5 (E1) and 380 +/- 4 (E3) in 97 patients; on days 37 +/- 4 (E1), 72 +/- 6 (E2) and 394 +/- 30 (E3) in 44 patients. All patients underwent an intensive physical training during the second month after the MI. All groups showed a significant increase in work capacity and reduction in heart rate and rate-pressure product at similar work load (E2 and E3 vs. E1). These changes were independent from the level of exercise pulmonary wedge pressure (E-PWP). On the average a reduction of PWP was observed in more compromised patients after training, which became more marked at 1 year. At similar work load 1 year after MI the cardiac index reduced in less compromised patients (E1-PWP greater than 30 mm Hg) while it remained unchanged in patients with E1-PWP less than or equal to 30 mm Hg. Continuation or interruption of the physical training did not seem to affect the hemodynamic evolution. The incidence of ST-segment depression did not change from 1 month to 2 months and 1 year after MI, while both incidence and amount of ST-segment elevation significantly decreased and the sum of R-wave voltages in 12 lead ECG increased at 1 year. In conclusion, oligo-asymptomatic patients, trained and treated by drugs, trend to improve in the first year post-infarct.

Effects of training and of verapamil on exercise capacity in patients recovering from myocardial infarction. A double-blind study.

Physical training causes an increase of aerobic capacity in normal and cardiac patients. The influences of training plus placebo and training plus verapamil have been studied in a double-blind randomized trial on 40 patients recovering from actue myocardial infarction. The two groups were comparable as to clinical characteristics, initial work capacity, and amount of stress tolerated during the training sessions. The training produced a significant increase of total work capacity and maximum VO2, in both groups; the difference between the means of the two groups was not significant. The variation of heart rate, rate pressure product at different work loads and cardiac volume after training were significantly lower in the verapamil group. The anginal threshold did not change in the placebo group and showed a trend to increase in patients treated with verapamil. These results suggest that carefully observed rehabilitation markedly improves the physical capacity of the patients after acute myocardial infarction. Such improvement is enhanced by treatment with verapamil.