Walking naturally after spinal cord injury using a brain-spine interface

A spinal cord injury interrupts the communication between the brain and the region of the spinal cord that produces walking, leading to paralysis^1,2. Here, we restored this communication with a digital bridge between the brain and spinal cord that enabled an individual with chronic tetraplegia to stand and walk naturally in community settings. This brain-spine interface (BSI) consists of fully implanted recording and stimulation systems that establish a direct link between cortical signals³ and the analogue modulation of epidural electrical stimulation targeting the spinal cord regions involved in the production of walking^4-6. A highly reliable BSI is calibrated within a few minutes. This reliability has remained stable over one year, including during independent use at home. The participant reports that the BSI enables natural control over the movements of his legs to stand, walk, climb stairs and even traverse complex terrains. Moreover, neurorehabilitation supported by the BSI improved neurological recovery. The participant regained the ability to walk with crutches overground even when the BSI was switched off. This digital bridge establishes a framework to restore natural control of movement after paralysis.

An adaptive closed-loop ECoG decoder for long-term and stable bimanual control of an exoskeleton by a tetraplegic

OBJECTIVE

The article aims at addressing 2 challenges to step motor BCI out of laboratories: asynchronous control of complex bimanual effectors with large numbers of degrees of freedom, using chronic and safe recorders, and the decoding performance stability over time without frequent decoder recalibration.

APPROACH

Closed-loop adaptive/incremental decoder training is one strategy to create a model stable over time. Adaptive decoders update their parameters with new incoming data, optimizing the model parameters in real time. It allows cross-session training with multiple recording conditions during closed loop BCI experiments. In the article, an adaptive tensor-based Recursive Exponentially Weighted Markov-Switching multi-Linear Model (REW-MSLM) decoder is proposed. REW-MSLM uses a Mixture of Expert (ME) architecture, mixing or switching independent decoders (experts) according to the probability estimated by a "gating" model. A Hidden Markov model approach is employed as gating model to improve the decoding robustness and to provide strong idle state support. The ME architecture fits the multi-limb paradigm associating an expert to a particular limb or action.

MAIN RESULTS

Asynchronous control of an exoskeleton by a tetraplegic patient using a chronically implanted epidural electrocorticography (EpiCoG) recorder is reported. The stable over a period of 6 months (without decoder recalibration) 8-dimensional alternative bimanual control of the exoskeleton and its virtual avatar is demonstrated.

SIGNIFICANCE

Based on the long-term (>36 months) chronic bilateral epidural ECoG recordings in a tetraplegic (ClinicalTrials.gov, NCT02550522), we addressed the poorly explored field of asynchronous bimanual BCI. The new decoder was designed to meet to several challenges: the high-dimensional control of a complex effector in experiments closer to real-world behaviour (point-to-point pursuit versus conventional center-out tasks), with the ability of the BCI system to act as a stand-alone device switching between idle and control states, and a stable performance over a long period of time without decoder recalibration.

The Riemannian Spatial Pattern method: mapping and clustering movement imagery using Riemannian geometry

OBJECTIVE

Over the last decade, Riemannian geometry has shown promising results for motor imagery classification. However, extracting the underlying spatial features is not as straightforward as for applying Common Spatial Pattern (CSP) filtering prior to classification. In this article, we propose a simple way to extract the spatial patterns obtained from Riemannian classification: the Riemannian Spatial Pattern (RSP) method, which is based on the backward channel selection procedure.

APPROACH

The RSP method was compared to the CSP approach on ECoG data obtained from a quadriplegic patient while performing imagined movements of arm articulations and fingers.

MAIN RESULTS

Similar results were found between the RSP and CSP methods for mapping each motor imagery task with activations following the classical somatotopic organization. Clustering obtained by pairwise comparisons of imagined motor movements however, revealed higher differentiation for the RSP method compared to the CSP approach. Importantly, the RSP approach could provide a precise comparison of the imagined finger flexions which added supplementary information to the mapping results.

SIGNIFICANCE

Our new RSP method illustrates the interest of the Riemannian framework in the spatial domain and as such offers new avenues for the neuroimaging community. This study is part of an ongoing clinical trial registered with ClinicalTrials.gov, NCT02550522.

Early Hepatic Artery Thrombosis After Pediatric Living Donor Liver Transplantation

AIM

Hepatic artery thrombosis is one of the major complications affecting patient and graft survival after liver transplantation. In this study, we analyzed the factors affecting the development of early hepatic artery thrombosis (eHAT) and its outcomes in pediatric liver transplantation.

METHODS

A total of 175 pediatric patients underwent living donor liver transplantation between January 2013 and November 2018. Factors affecting eHAT and its outcomes were examined.

RESULTS

Nine patients (5.1%) developed eHAT. In multivariate analysis, intraoperative hepatic artery revision and Roux-en-Y hepaticojejunostomy biliary reconstruction type were statistically significant (all, P < .05). Thrombectomy and reanastomosis was performed in 5 patients. Two of them were successful. In total, 3 retransplantations were performed and all of those patients are still alive.

CONCLUSION

The factors affecting eHAT are still a matter of debate. Intraoperative hepatic artery anastomosis revision and Roux-en-Y hepaticojejunostomy reconstruction were independent risk factors for development of eHAT. In the present study, the confidence interval of the variables is high, therefore exact determination of the risk factors may not be possible. Early detection and thrombectomy and reanastomosis may be the first treatment of choice to rescue the patient and graft. When it fails, retransplantation must be an alternative. The results of the present study state that at least once a day the vascular anastomosis must be examined by Doppler ultrasonography in the post-transplant first week. It must be repeated when liver enzymes increase. The patients under high risk for eHAT may be followed up closer.

Endoscopic treatment of biliary complications after living donor liver transplantation in a high volume transplant center in Turkey; a single-center experience

BACKGROUND AND AIM

Biliary complications are an important cause of mortality and morbidity after living donor liver transplantation (LDLT). We present our endoscopic treatment results after LDLT as a single center with high volume.

METHODS

Patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) after LDLT between 2005 and 2015 were included. Clinical data included patient demographics, ERCP indications (stricture or leak), and treatment outcomes, including need for percutaneous and surgical interventions.

RESULTS

ERCP was performed in 446 (39.2%) patients with duct-to-duct anastomosis of 1136 LDLT patients. The most common biliary complication was stricture ± stone (70.6%, 315/446). Stricture and leak occurred in 60 (13.4%) patients. Only biliary leak was found in 40 (8.9%) patients. Our endoscopic treatment success rate in patients with biliary stricture after LDLT was 65.1%. Overall endoscopic success rates in our patients were 55.0% in patients with both leak and stricture, and only leak. In all, our percutaneous transhepatic biliary interventions (PTBI) and ERCP success rate was 90.6% in patients with biliary complications after LDLT.

CONCLUSIONS

Endoscopic treatments are highly effective for biliary complications after LDLT. Effective use of percutaneous interventions in collaboration with endoscopic treatments significantly reduces the need for surgical treatment.

Can Patients Who Develop Cerebral Death in Fulminant Liver Failure Despite Liver Transplantation Be Previously Forseen?

BACKGROUND

The outcome of medical treatment is worse in fulminant liver failure (FLF) developing on acute or chronic ground. Recently, liver transplantations with the use of living and cadaveric donors have been performed in these diseases and good results obtained. In this study, we aimed to present the factors affecting the recovery of cerebral functions after liver transplantation in hepatic encephalopathy (HE) developing in FLF, to identify irreversible patient groups and to prevent unnecessary liver transplantation.

METHODS

In Inonu University's Liver Transplant Institute, 69 patients who made an emergency notice to the National Coordination Center for liver transplantation owing to FLF from January 2012 to December 2015 were included in the study. Patients were divided into 2 groups. Group 1 consisted of 52 patients who underwent liver transplantation and recovered normal brain function, and group 2 had 17 patients who underwent liver transplantation and did not recover normal brain function and had cerebral death. All patients were evaluated before surgery for clinical encephalopathy stage, light reflex, and convulsions. Groups were compared and assessed according to age (>40, 10-40 and <10 years), body mass index, etiologic factor, preoperative laboratory values, transplantation type, mortality, and encephalopathy level. Multivariate analysis was done for specific parameters.

RESULTS

Prothrombin time (PT), international normalized ratio (INR), and total bilirubin values were significantly different between the groups. There was no significant difference between the groups regarding ammonia and lactate levels. There was a statistically significant difference between the groups regarding sodium and potassium levels from serum electrolytes. However, the averages of both groups were within normal limits. pH and total bilirubin levels were meaningful for multivariate analysis.

CONCLUSIONS

HE reversibility, mortality, and morbidity are important in patients with HE who undergo liver transplantation. Therefore, West Haven clinical staging and serum INR, PT, and total bilirubin level may be helpful in predicting the reversibility of FLF patients with HE before liver transplantation. It was determined that West Haven encephalopathy grading is important in determining the reversibility of HE after transplantation in FLF; especially the probability of reversibility of stage 4 HE decreases significantly. High PT and INR levels, hyperbilirubinemia, and serum sodium and potassium concentrations were risk factors for the reversibility of HE in this study.

Postoperative Pulmonary Complications After Liver Transplantation: Assessment of Risk Factors for Mortality

BACKGROUND

The aim of this study was to identify the risk factors related to mortality in liver transplant (LT) patients with post-transplantation pulmonary complications.

METHOD

Patients who underwent liver transplantation in our clinic between January 2010 and January 2012 were retrospectively reviewed for post-transplantation pulmonary complications. Demographic, clinical, radiologic, and postoperative chart data of 153 patients with pulmonary complications were analyzed using an independent samples Student t test, Pearson's χ(2) test, Fisher's exact test, and Yate's corrected χ(2) test. Mortality was analyzed using a multiple logistic regression model. The best-fit breakpoint resulting in a cut-off value for the variables of interest was determined using ROC curves and the Youden index.

RESULTS

The 153 patients with pulmonary complication were divided into 2 groups: mortality (n = 53) and survival (n = 100). Univariate analyses showed significant differences between these 2 groups with respect to MELD score (P = .035), duration of mechanical ventilation (P > .001), pneumonia (P = .01), and endotracheal culture results (P = .001). In the multivariate analysis, hemoglobin (P = .03, odds ratio [OR]: 1.239), MELD score (P = .027, OR: 1.064), duration of mechanical ventilation (P = .003, OR: 1.091), and age (P = .042, OR: 1.001) were significant risk factors for mortality. The best-fit breakpoint analysis yielded cut-off values for hemoglobin (>11.2, sensitivity: 50.9%, specificity: 70%), MELD score (>16, sensitivity: 73.6%, specificity: 42%) and duration of mechanical ventilation (>3, sensitivity: 62.3%, specificity: 76%).

CONCLUSION

Advanced age, high hemoglobin level, high MELD score, and long-term mechanical ventilation are significant risk factors for mortality in liver transplant patients with postoperative pulmonary complications.

An ongoing measles outbreak in the Federation of Bosnia and Herzegovina, 2014 to 2015

Between January 2014 and the beginning of February 2015, the Federal Institute of Public Health in the Federation of Bosnia and Herzegovina has reported 3,804 measles cases. Notable transmission has been observed in three Central Bosnia Canton municipalities: Bugojno, Fojnica and Travnik. Most cases were unvaccinated 2,680 (70%) or of unknown vaccination status 755 (20%). Health authorities have been checking vaccination records and performing necessary prevention measures. The epidemic is still ongoing.

Transverse sinus thrombosis in a living donor: a case report

BACKGROUND

Liver transplantation is among the treatment options for end-stage liver disease. Limited organ donation in our country has resulted in an increased performance of living donor liver transplantations. This case report describes a left transverse cerebral venous sinus thrombosis diagnosed in a living donor hepatectomy patient.

PATIENT

A 45-year-old man underwent right lobe hepatectomy of a 330-g graft for living donor liver transplantation to his 55-year-old hepatitis B virus-positive brother. On the first postoperative day, without any surgical problems he presented with loss of consciousness. Previous medical history was unremarkable. Neurology consultation revealed lethargy and an acute confusional state. Cerebral magnetic resonance imaging venography showed signal alterations in the left transverse sinus wherein thrombosis was diagnosed. Heparin infusion initiated for antithrombotic treatment was adjusted to provide a 1.5 to 2-fold increased baseline activated partial thromboplastin time. On the second day of treatment has clinical status improved and he was discharged on the, fifth day on oral anticoagulant (warfarin) therapy for outpatient follow-up.

RESULTS

Cerebral venous sinus thrombosis is a rare disease with variable clinical onsets. Surgical procedures are among risk factors. An early diagnosis is essential to achieve low mortality and morbidity rates.

Circulating leptin and body composition in chronic obstructive pulmonary disease

Nutritional depletion and weight loss are two features of chronic obstructive pulmonary disease (COPD), and the association between low body mass index (BMI) and poor prognosis in patients with COPD is a common clinical observation. Mechanisms of weight loss are still unclear in COPD. Excessive energy expenditure partly due to increased work of breathing was shown, but other mechanisms have been searched for. Leptin is a hormone secreted by adipocytes that plays an important role in energy homeostasis and regulates body weight through control of appetite and energy expenditure. The aim of this study was to evaluate the association of circulating leptin levels and measures of body composition in COPD patients. Thirty male COPD outpatients (mean age 66.3 +/- 8.4) and 20 controls (mean age 65.9 +/- 10.8) were included in the study. After standard spirometry and body composition measurements, serum leptin concentration was measured by ELISA assay. COPD patients were grouped according to BMI. Mean BMI was 19.01 +/- 2.26 kg/m2 in group 1 (COPD patients with low BMI), 26.85 +/- 4.51 in group 2 COPD (COPD patients with normal/high BMI) and 27.64 +/- 2.75 kg/m2 in healthy controls (group 3). Mean serum leptin concentration was 1.41 +/- 1.86 ng/ml in group 1, 2.60 +/- 1.38 ng/ml in group 2 and 2.82 +/- 1.46 ng/ml in group 3 (p = 0.002). Leptin correlated to not only BMI but also body weight, waist circumference, triceps and biceps skinfold thickness and body fat percent (p < 0.05 for all). Results of this study suggest that the cause of weight loss is not increased circulating leptin in COPD. Instead, leptin remains regulated in COPD and further decreased in patients with low BMI, probably as a compensatory mechanism to preserve body fat content, which should be evaluated in further studies.

A descriptive framework for information processing: an integrative approach

Survival depends on veridical perception of the environment and appropriate response to it. How do high level organisms perceive and compare, in short, evaluate stimuli and how do they select and execute responses? How does information processing proceed? How does the mind work?

Development of a memory trace for a complex sound in the human brain

The development of a memory trace for a complex, unfamiliar sound in the human brain was studied by repeatedly presenting reading subjects with this sound ('standard') which was occasionally replaced by a slightly different sound ('deviant'). Deviants did not elicit the mismatch negativity, an index of automatic change detection in auditory cortex, in the beginning but did later during the session. This result reflects a gradual 'sharpening' of sensory information encoded in the memory trace: the representation of the standard stimulus eventually became precise enough to enable the cortical change-detector mechanism to detect a slight different stimulus.

Specificity of auditory evoked potentials from rat hypothalamus: differential recording by lateral and ventromedial electrodes

Evoked potentials recorded from ventromedial nucleus (VMH) and lateral area (LHA) of the hypothalamus were studied in freely moving rats with respect to specificity of the components to recorded areas and to peripheral stimuli utilized. This study attempts to circumvent some methodological problems and contamination in data with respect to origin of recorded components by comparing monopolar and differential recordings made in VMH and LHA, areas accepted as being involved in food-intake behavior. Of the stable components, the complex with 15-20 ms latency was evaluated as of extra-hypothalamic origin. Meanwhile, those with 25-ms (positive) and 40-ms (negative) average peak latencies were considered as specific to recorded areas. Hypothalamic responses appeared not to be specific to stimulus modality, indicating convergence of different sensory modalities on studied areas. Hunger and satiety appeared to influence the amplitude of the specified components similarly, the study not providing evidence for the reciprocal relation stated in the dual center hypothesis between VMH and LHA.