Short term priming effect of brain-actuated muscle stimulation using bimanual movements in stroke.

OBJECTIVE: Brain-computer interface triggered-functional electrical stimulation (BCI-FES) is an emerging neurorehabilitation therapy post stroke, mostly for the affected hand. We explored the feasibility of a bimanual BCI-FES and its short-term priming effects, i.e. stimuli-induced behaviour change. We compared EEG parameters between unimanual and bimanual movements and differentiated the effect of age from the effect of stroke. METHODS: Ten participants with subacute stroke, ten age-matched older healthy adults, and ten younger healthy adults underwent unimanual and bimanual BCI-FES sessions. Delta alpha ratio (DAR) and brain symmetry index (BSI) were derived from the pre- and post- resting-state EEG. Event-related desynchronization (ERD) and laterality index were derived from movement- EEG. RESULTS: Participants were able to control bimanual BCI-FES. ERD was predominantly contralateral for unimanual movements and bilateral for bimanual movements. DAR and BSI only changed in healthy controls. Baseline values indicated that DAR was affected by stroke while BSI was affected by both age and stroke. CONCLUSIONS: Bimanual BCI control offers a larger repertoire of movements, while causing the same short-term changes as unimanual BCI-FES. Prolonged practice may be required to achieve a measurable effect on DAR and BSI for stroke. SIGNIFICANCE: Bimanual BCI-FES is feasible in people affected by stroke.

MRCP as a biomarker of motor action with varying degree of central and peripheral contribution as defined by ultrasound imaging.

Motor imagination is an alternative rehabilitation strategy for people who cannot execute real movements. However, it is still a matter of debate to which degree it involves activation of deeper muscle structures, which cannot be detected by surface electromyography (SEMG). Sixteen able-bodied participants performed cue based isometric ankle plantar flexion (active movement) followed by active relaxation under four conditions: executed movements with two levels of muscle contraction (fully executed and attempted movements, EM and AM) and motor imagination with and without detectable muscle twitches (IT and I). The most prominent peaks and distinctive phases of movement-related cortical potential (MRCP) were compared between conditions. Ultrasound imaging (USI) and SEMG were used to detect movements. IT showed spatially distinctive significant differences compared to both I and AM during active movement preparation and reafferentation phase; further widespread differences were found between IT and AM during active movement execution and posteriorly during preparation for active relaxation. EM and AM showed the largest differences frontally during active movement planning and posteriorly during execution of active relaxation. Movement preparation positivity P1 showed a significant difference in amplitude between IT and AM but not between IT and I. USI can detect subliminal movements (twitches) better than SEMG. MRCP is a biomarker sensitive to different levels of muscle contraction and relaxation. IT is a motor condition distinguishable from both I and AM. EEG biomarkers of movements could be used to identify pathological conditions, that manifest themselves during either active contraction or active relaxation.NEW & NOTEWORTHY Ultrasound imaging can detect subtle muscle movements (twitches) that are not detectable with electromyography. Almost a quarter of trials of imagined movements in able-bodied people are accompanied by twitches. Analysis of movement-related cortical potential showed that motor imagination with twitches is a condition distinguishable from motor imagination without twitches and from motor attempts.

Home used, patient self-managed, brain-computer interface for the management of central neuropathic pain post spinal cord injury: usability study.

BACKGROUND: Central Neuropathic Pain (CNP) is a frequent chronic condition in people with spinal cord injury (SCI). Previously, we showed that using laboratory brain-computer interface (BCI) technology for neurofeedback (NFB) training, it was possible to reduce CNP in people with SCI. In this study, we show results of patient self-managed treatment in their homes with a BCI-NFB using a consumer EEG device. METHODS: Users: People with chronic SCI (17 M, 3 F, 50.6 ± 14.1 years old), and CNP ≥4 on a Visual Numerical Scale. LOCATION: Laboratory training (up to 4 sessions) followed by home self-managed NFB. User Activity: Upregulating the EEG alpha band power by 10% above a threshold and at the same time downregulating the theta and upper beta (20-30 Hz) band power by 10% at electrode location C4. Technology: A consumer grade multichannel EEG headset (Epoch, Emotiv, USA), a tablet computer and custom made NFB software. EVALUATION: EEG analysis, before and after NFB assessment, interviews and questionnaires. RESULTS: Effectiveness: Out of 20 initially assessed participants, 15 took part in the study. Participants used the system for 6.9 ± 5.5 (median 4) weeks. Twelve participants regulated their brainwaves in a frequency specific manner and were most successful upregulating the alpha band power. However they typically upregulated power around their individual alpha peak (7.6 ± 0.8 Hz) that was lower than in people without CNP. The reduction in pain experienced was statistically significant in 12 and clinically significant (greater than 30%) in 8 participants. Efficiency: The donning was between 5 and 15 min, and approximately 10-20% of EEG data recorded in the home environment was noise. Participants were mildly stressed when self-administering NFB at home (2.4 on a scale 1-10). User satisfaction: Nine participants who completed the final assessment reported a high level of satisfaction (QUESQ, 4.5 ± 0.8), naming effectiveness, ease of use and comfort as main priorities. The main factors influencing frequency of NFB training were: health related issues, free time and pain intensity. CONCLUSION: Portable NFB is a feasible solution for home-based self-managed treatment of CNP. Compared to pharmacological treatments, NFB has less side effects and provides users with active control over pain. TRIAL REGISTRATION: GN15NE124 , Registered 9th June 2016.

The effect of voluntary modulation of the sensory-motor rhythm during different mental tasks on H reflex.

OBJECTIVES: The aim of this study was to explore the possibility of the short-term modulation of the soleus H reflex through self-induced modulation of the sensory-motor rhythm (SMR) as measured by electroencephalography (EEG) at Cz. METHODS: Sixteen healthy participants took part in one session of neuromodulation. Motor imagery and mental math were strategies for decreasing SMR, while neurofeedback was used to increase SMR. H reflex of the soleus muscle was elicited by stimulating tibial nerve when SMR reached a pre-defined threshold and was averaged over 5 trials. RESULTS: Neurofeedback and mental math both resulted in the statistically significant increase of H reflex (p=1.04·10(-6) and p=5.47·10(-5) respectively) while motor imagery produced the inconsistent direction of H reflex modulation (p=0.57). The average relative increase of H reflex amplitude was for neurofeedback 19.0±5.4%, mental math 11.1±3.6% and motor imagery 2.6±1.0%. A significant negative correlation existed between SMR amplitude and H reflex for all tasks at Cz and C4. CONCLUSIONS: It is possible to achieve a short-term modulation of H reflex through short-term modulation of SMR. Various mental tasks dominantly facilitate H reflex irrespective of direction of SMR modulation. SIGNIFICANCE: Improving understanding of the influence of sensory-motor cortex on the monosynaptic reflex through the self-induced modulation of cortical activity.

The influence of central neuropathic pain in paraplegic patients on performance of a motor imagery based Brain Computer Interface.

OBJECTIVE: The aim of this study was to test how the presence of central neuropathic pain (CNP) influences the performance of a motor imagery based Brain Computer Interface (BCI). METHODS: In this electroencephalography (EEG) based study, we tested BCI classification accuracy and analysed event related desynchronisation (ERD) in 3 groups of volunteers during imagined movements of their arms and legs. The groups comprised of nine able-bodied people, ten paraplegic patients with CNP (lower abdomen and legs) and nine paraplegic patients without CNP. We tested two types of classifiers: a 3 channel bipolar montage and classifiers based on common spatial patterns (CSPs), with varying number of channels and CSPs. RESULTS: Paraplegic patients with CNP achieved higher classification accuracy and had stronger ERD than paraplegic patients with no pain for all classifier configurations. Highest 2-class classification accuracy was achieved for CSP classifier covering wider cortical area: 82±7% for patients with CNP, 82±4% for able-bodied and 78±5% for patients with no pain. CONCLUSION: Presence of CNP improves BCI classification accuracy due to stronger and more distinct ERD. SIGNIFICANCE: Results of the study show that CNP is an important confounding factor influencing the performance of motor imagery based BCI based on ERD.

Tracheal diameter at birth in severe congenital diaphragmatic hernia treated by fetal endoscopic tracheal occlusion.

OBJECTIVE: To investigate tracheal dimensional differences seen at birth following fetal endoscopic tracheal occlusion (FETO) in cases of severe congenital diaphragmatic hernia (CDH) and to report on their clinical follow-up. PATIENTS AND METHODS: In chest X-rays, taken within 48 h after birth, we measured the tracheal diameter at the level of the tracheal entry into the chest, 1 cm above the level of the carina and at middistance between these sites in 37 fetuses with severe CDH treated by FETO. These measurements were compared with those in 74 preterm and term neonates with no congenital lung abnormalities. RESULTS: In the CDH group, compared to the controls, the tracheal diameter corrected for gestational age was significantly larger at all three levels of the trachea. Regression analysis showed that significant predictors of the tracheal diameter at the level of tracheal entry into the chest were the observed to expected (o/e) lung area to head circumference ratio (LHR) and the duration of tracheal occlusion. In the CDH group, postnatal follow-up until the age of 22 months (1-70) showed that 5 of 24 neonates had an effort-induced barking cough. CONCLUSION: A large number of infants with severe CDH surviving after FETO have a degree of tracheomegaly that is associated with the severity of CDH as assessed by pre-FETO LHR. This tracheomegaly does not constitute an obvious clinical problem.

Kinematic modelling of a robotic gait device for early rehabilitation of walking.

Rehabilitation of walking is an essential element in the treatment of incomplete spinal cord injured (SCI) patients. During the early post injury period, patients find it challenging to practice upright walking. Simulating stepping movements in a supine posture may be easier and promote earlier rehabilitation. A robotic orthotic device for early intervention in spinal cord injury that does not require the patient to be in an upright posture has been modelled. The model comprises a two-bar mechanical system that is configured and powered to provide limb kinematics that approximate normal overground walking. The modelling work has been based on gait analysis performed on healthy subjects walking at 50 per cent, 75 per cent, and 100 per cent of normal cadence. Simulated angles of hip, knee, and ankle joints show a comparable range of motion (ROM) to the experimental walking data measured in healthy subjects. The model provides operating parameters for a prospective recumbent gait orthosis that could be used in early walking rehabilitation of incomplete SCI patients.

Quantification and visualisation of differences between two motor tasks based on energy density maps for brain-computer interface applications.

OBJECTIVE: To determine the most discriminative features for a brain-computer interface (BCI) system based on statistically significant differences between two energy density maps calculated from EEG signals during two different motor tasks. METHODS: EEG was recorded in ten healthy volunteers while performing different cue based, 3s sustained, real and imaginary right hand movements. Energy density maps were calculated over fixed 240 ms and 2 Hz time-frequency windows (called resels) for each movement and statistically significant resels were determined. After that, normalised energy values of the statistically significant resels were compared between two real as well as between two imaginary movements using a parametric test. RESULTS: The largest differences between energy density maps between two motor tasks were noticed on electrode location Cp3 in the higher alpha and the beta bands (i.e., 12-30 Hz), for both real and imaginary movements. The method reduced a total number of discriminative features between two motor tasks to fewer than 2% for the imaginary and fewer than 3% for the real movements on the electrode location Cp3. CONCLUSIONS: The method can be used for visualisation and feature extraction for BCI and other applications where event related desynchronisation/synchronisation (ERD/ERS) maps should be compared. SIGNIFICANCE: If a reliable on-line classification of imaginary movements of the same limb would be achieved it could be combined with classification of movements of different parts of the body. That would increase a number of separable classes of a BCI system, thereby providing a larger number of command signals to control the external devises such as computers and robotic devices.

Influence of variable nerve fibre geometry on the excitation and blocking threshold. A simulation study.

The aim of the study was to investigate how variable fibre geometry influences the excitation and blocking threshold of an undulating peripheral nerve fibre. The sensitivity of the excitation and blocking thresholds of the nerve fibres to various geometric and stimulation parameters was examined. The nerve fibres had a spiral shape (defined by the undulation wavelength, undulation amplitude and phase), and the internodal length varied. Diameter-selective stimulation of nerve fibres was obtained using anodal block. Simulation was performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a model of a peripheral undulating human nerve fibre to simulate the fibre response to stimulation. The excitation threshold of the undulating fibres was up to 100% higher than the excitation threshold of the straight fibres. When a nerve was stimulated with long pulses, which are typically applied for anodal block (> 400 micros), the blocking threshold of the undulating fibres was up to four times higher than the blocking threshold of the straight fibres. Dependencies of the excitation threshold on geometric and stimulation parameters were the same as for a straight fibre. Dependencies of the blocking threshold on geometric and stimulation parameters were different compared with a straight fibre. Owing to the fibre undulation and variable internodal length, the blocking threshold and the minimum pulse duration to obtain anodal block were generally different in the proximal and distal directions. Owing to variable fibre geometry, the excitation threshold varied by up to +/- 40% of the mean value, and the blocking threshold varied by up to +/- 60 % of the mean value. Owing to undulation, the blocking threshold of large fibres could be higher than the blocking threshold of small-diameter fibres, even if they had the same geometry. The results indicate that, during skeletal muscle stretching and contracting or during variation in joint angle, the excitation and blocking thresholds of the nerve fibres change owing to variations in fibre geometry. A straight fibre model could be too simple for modelling the response of peripheral nerve fibres to electrical stimulation.

Different pulse shapes for selective large fibre block in sacral nerve roots using a technique of anodal block: an experimental study.

The aim of this study was experimentally to investigate whether it is possible to reduce the charge per phase that is applied during selective large fibre block. Sacral roots in pigs were stimulated. Sacral roots contain large somatic nerve fibres and small parasympathetic nerve fibres. Large nerve fibres that innervate the external urethral and external anal sphincters were selectively blocked using a technique of anodal block. In that way, selective activation of the detrusor muscle and the rectum innervated by parasympathetic fibres could be obtained. The square stimulation pulse was replaced with three different pulse shapes that had the same duration as the square pulse and consisted of a depolarising prepulse and a blocking part of the pulse. Compared with the square pulse, the charge per phase needed for anodal block could be reduced with all three pulse shapes. Maximum reduction of the charge per pulse was 17+/-6%. A lower charge might make anodal block safer in long-term applications.

The optimization of turnaround time for blood samples in an emergency clinical laboratory.

The University Medical Centre Ljublijana is a 3200-bed general hospital. A laboratory information system, developed to improve the reliability and usefulness of test results, was installed in the emergency laboratory in November 1994. At that time, all test requests received by the laboratory were treated as equally urgent, but in December 1994, a reorganisation took place, which involved the introduction of a priority system. We conducted a study in the period from November 1994 to September 1995. The turnaround time for blood analyses was evaluated by the method of case study. The influence of information technology and organisational changes on individual components of the turnaround time was assessed. This study has shown a positive effect of the recently introduced information technology and organisational changes on the turnaround time. The median turnaround time improved for all phases of the laboratory process. The greatest improvement occurred in validity check time.

Lithium-associated cognitive and functional deficits reduced by a switch to divalproex sodium: a case series.

BACKGROUND: Lithium remains a first-line treatment for the acute and maintenance treatment of bipolar disorder. Although much has been written about the management of the more common adverse effects of lithium, such as polyuria and tremor, more subtle lithium side effects such as cognitive deficits, loss of creativity, and functional impairments remain understudied. This report summarizes our experience in switching bipolar patients from lithium to divalproex sodium to alleviate such cognitive and functional impairments. METHOD: Open, case series design. RESULTS: We report seven cases where substitution of lithium, either fully or partially, with divalproex sodium was extremely helpful in reducing the cognitive, motivational, or creative deficits attributed to lithium in our bipolar patients. CONCLUSION: In this preliminary report, divalproex sodium was a superior alternative to lithium in bipolar patients experiencing cognitive deficits, loss of creativity, and functional impairments.

Neuroleptic dosage regimens in psychotic inpatients: a retrospective comparison.

The authors examined the inpatient records of consecutively discharged psychotic patients treated with neuroleptics in 1976 and a similar group of patients treated in 1985, when drug regimens at our institution changed considerably. Although demographic parameters were quite similar in the 2 years, the group of patients treated in 1985 received significantly less neuroleptic medication during the course of treatment. Nonetheless, clinical outcome in 1985 was as good as that in 1976. The implications of this result, that low dosages may be as efficacious as high dosages while exposing patients to less neuroleptic medication, are discussed.

Acute cardiovascular response to monoamine oxidase inhibitors: a prospective assessment.

Despite the widespread use of monoamine oxidase inhibitors (MAOIs) and the well-known adverse event of hypertensive crisis, few studies have addressed the acute cardiovascular response to an MAOI dose. We prospectively measured pulse and blood pressure changes just before and at 1, 2, 3, and 4 hours after MAOI administration in 18 patients. Significant but asymptomatic increases from baseline in mean systolic and diastolic blood pressure occurred within 2 hours after MAOI administration, with return to near baseline by 4 hours. The mechanism of this reaction is unknown.