Pain-Related Suppression of Beta Oscillations Facilitates Voluntary Movement.

Increased beta oscillations over sensorimotor cortex are antikinetic. Motor- and pain-related processes separately suppress beta oscillations over sensorimotor cortex leading to the prediction that ongoing pain should facilitate movement. In the current study, we used a paradigm in which voluntary movements were executed during an ongoing pain-eliciting stimulus to test the hypothesis that a pain-related suppression of beta oscillations would facilitate the initiation of a subsequent voluntary movement. Using kinematic measures, electromyography, and high-density electroencephalography, we demonstrate that ongoing pain leads to shorter reaction times without affecting the kinematics or accuracy of movement. Reaction time was positively correlated with beta power prior to movement in contralateral premotor areas. Our findings corroborate the view that beta-band oscillations are antikinetic and provide new evidence that pain primes the motor system for action. Our observations provide the first evidence that a pain-related suppression of beta oscillations over contralateral premotor areas leads to shorter reaction times for voluntary movement.

Beta-band activity and connectivity in sensorimotor and parietal cortex are important for accurate motor performance.

Accurate motor performance may depend on the scaling of distinct oscillatory activity within the motor cortex and effective neural communication between the motor cortex and other brain areas. Oscillatory activity within the beta-band (13-30Hz) has been suggested to provide distinct functional roles for attention and sensorimotor control, yet it remains unclear how beta-band and other oscillatory activity within and between cortical regions is coordinated to enhance motor performance. We explore this open issue by simultaneously measuring high-density cortical activity and elbow flexor and extensor neuromuscular activity during ballistic movements, and manipulating error using high and low visual gain across three target distances. Compared with low visual gain, high visual gain decreased movement errors at each distance. Group analyses in 3D source-space revealed increased theta-, alpha-, and beta-band desynchronization of the contralateral motor cortex and medial parietal cortex in high visual gain conditions and this corresponded to reduced movement error. Dynamic causal modeling was used to compute connectivity between motor cortex and parietal cortex. Analyses revealed that gain affected the directionally-specific connectivity across broadband frequencies from parietal to sensorimotor cortex but not from sensorimotor cortex to parietal cortex. These new findings provide support for the interpretation that broad-band oscillations in theta, alpha, and beta frequency bands within sensorimotor and parietal cortex coordinate to facilitate accurate upper limb movement. SUMMARY STATEMENT: Our findings establish a link between sensorimotor oscillations in the context of online motor performance in common source space across subjects. Specifically, the extent and distinct role of medial parietal cortex to sensorimotor beta connectivity and local domain broadband activity combine in a time and frequency manner to assist ballistic movements. These findings can serve as a model to examine whether similar source space EEG dynamics exhibit different time-frequency changes in individuals with neurological disorders that cause movement errors.

Automated classification of pain perception using high-density electroencephalography data.

The translation of brief, millisecond-long pain-eliciting stimuli to the subjective perception of pain is associated with changes in theta, alpha, beta, and gamma oscillations over sensorimotor cortex. However, when a pain-eliciting stimulus continues for minutes, regions beyond the sensorimotor cortex, such as the prefrontal cortex, are also engaged. Abnormalities in prefrontal cortex have been associated with chronic pain states, but conventional, millisecond-long EEG paradigms do not engage prefrontal regions. In the current study, we collected high-density EEG data during an experimental paradigm in which subjects experienced a 4-s, low- or high-intensity pain-eliciting stimulus. EEG data were analyzed using independent component analyses, EEG source localization analyses, and measure projection analyses. We report three novel findings. First, an increase in pain perception was associated with an increase in gamma and theta power in a cortical region that included medial prefrontal cortex. Second, a decrease in lower beta power was associated with an increase in pain perception in a cortical region that included the contralateral sensorimotor cortex. Third, we used machine learning for automated classification of EEG data into low- and high-pain classes. Theta and gamma power in the medial prefrontal region and lower beta power in the contralateral sensorimotor region served as features for classification. We found a leave-one-out cross-validation accuracy of 89.58%. The development of biological markers for pain states continues to gain traction in the literature, and our findings provide new information that advances this body of work.NEW & NOTEWORTHY The development of a biological marker for pain continues to gain traction in literature. Our findings show that high- and low-pain perception in human subjects can be classified with 89% accuracy using high-density EEG data from prefrontal cortex and contralateral sensorimotor cortex. Our approach represents a novel neurophysiological paradigm that advances the literature on biological markers for pain.

Microstructural properties of premotor pathways predict visuomotor performance in chronic stroke.

Microstructural properties of the corticospinal tract (CST) descending from the motor cortex predict strength and motor skill in the chronic phase after stroke. Much less is known about the relation between brain microstructure and visuomotor processing after stroke. In this study, individual's poststroke and age-matched controls performed a unimanual force task separately with each hand at three levels of visual gain. We collected diffusion MRI data and used probabilistic tractography algorithms to identify the primary and premotor CSTs. Fractional anisotropy (FA) within each tract was used to predict changes in force variability across different levels of visual gain. Our observations revealed that individuals poststroke reduced force variability with an increase in visual gain, performed the force task with greater variability as compared with controls across all gain levels, and had lower FA in the primary motor and premotor CSTs. Our results also demonstrated that the CST descending from the premotor cortex, rather than the primary motor cortex, best predicted force variability. Together, these findings demonstrate that the microstructural properties of the premotor CST predict visual gain-related changes in force variability in individuals poststroke. Hum Brain Mapp 37:2039-2054, 2016. © 2016 Wiley Periodicals, Inc.

Neuroimaging Evidence of Motor Control and Pain Processing in the Human Midcingulate Cortex.

Human neuroimaging and virus-tracing studies in monkey predict that motor control and pain processes should overlap in anterior midcingulate cortex (aMCC), but there is currently no direct evidence that this is the case. We used a novel functional magnetic resonance imaging paradigm to examine brain activity while subjects performed a motor control task, experienced a pain-eliciting stimulus on their hand, and performed the motor control task while also experiencing the pain-eliciting stimulus. Our experiment produced 3 novel results. First, group-level analyses showed that when separate trials of motor control and pain processing were performed, overlapping functional activity was found in the same regions of aMCC, supplementary motor area (SMA), anterior insula, and putamen. Secondly, increased activity was found in the aMCC and SMA when motor control and pain processing occurred simultaneously. Thirdly, individual-level analyses showed that 93% of subjects engaged the same region of aMCC during separate trials of motor control and pain processing irrespective of differences in the sulcal/gyral morphology of the cingulate cortex across individuals. These observations provide direct evidence in humans that the same region of aMCC is engaged for motor control and pain processing.

Resection of Mycotic Iliac Artery Aneurysm with Extra-Anatomic Bypass: An Alternative to Aneurysmorrhaphy in Difficult Situations.

Mycotic aneurysms of the iliac and other large arteries are rare and are associated with increased morbidity and mortality. Treatment of mycotic aneurysms usually requires modification of the surgical technique done for cases of degenerative or atherosclerotic aneurysms. Degenerative and atherosclerotic fusiform aneurysms are usually managed with aneurysmorrhaphy using a prosthetic graft, which however is not ideal for mycotic aneurysms. Avoidance of prosthetic material at the site of mycotic aneurysm is a better option with higher chances of resolution of infection and favorable patient outcome.

Ewing's sarcoma of kidney extending into IVC and RA: resection using modified cannulation strategy for CPB.

Ewing's sarcoma of the kidney is a rare tumor. Although renal carcinomas are known to involve the inferior cava, extension of the tumor up to the right atrium is not common. In the majority of cases when the tumor extends into the infrahepatic part of the inferior vena cava, it can be removed from the abdominal approach. Few patients require the use of cardiopulmonary bypass for removal of the tumor in the inferior vena cava and right atrium. The management of patients requiring resection of kidney tumors and right atrial mass is more complicated and requires a team approach consisting of oncosurgeons, cardiac surgeons, and cardiac anesthetists. The resection of the kidney tumor with a mass in the right atrium is usually done concomitantly. The cardiopulmonary bypass cannulation strategy needs to be modified in such cases.

Mechanical consequences of cell-wall turnover in the elongation of a Gram-positive bacterium.

A common feature of walled organisms is their exposure to osmotic forces that challenge the mechanical integrity of cells while driving elongation. Most bacteria rely on their cell wall to bear osmotic stress and determine cell shape. Wall thickness can vary greatly among species, with Gram-positive bacteria having a thicker wall than Gram-negative bacteria. How wall dimensions and mechanical properties are regulated and how they affect growth have not yet been elucidated. To investigate the regulation of wall thickness in the rod-shaped Gram-positive bacterium Bacillus subtilis, we analyzed exponentially growing cells in different media. Using transmission electron and epifluorescence microscopy, we found that wall thickness and strain were maintained even between media that yielded a threefold change in growth rate. To probe mechanisms of elongation, we developed a biophysical model of the Gram-positive wall that balances the mechanical effects of synthesis of new material and removal of old material through hydrolysis. Our results suggest that cells can vary their growth rate without changing wall thickness or strain by maintaining a constant ratio of synthesis and hydrolysis rates. Our model also indicates that steady growth requires wall turnover on the same timescale as elongation, which can be driven primarily by hydrolysis rather than insertion. This perspective of turnover-driven elongation provides mechanistic insight into previous experiments involving mutants whose growth rate was accelerated by the addition of lysozyme or autolysin. Our approach provides a general framework for deconstructing shape maintenance in cells with thick walls by integrating wall mechanics with the kinetics and regulation of synthesis and turnover.

Thoracic Spinal Anesthesia for Laparoscopic Cholecystectomy: An Observational Feasibility Study.

BACKGROUND: The expanding horizons of the application of Segmental Thoracic Spinal anesthesia in day-to-day anesthesia practice prompted us to perform this study in a large subset of healthy patients with the aim of determining the feasibility, safety, advantages, and complications of this mode of anesthesia. MATERIAL AND METHODS: The prospective observational study was conducted from April 2020 to March 2022, 2.146 patients with symptoms of cholelithiasis and planned for laparoscopic cholecystectomy were included in this study, and 44 patients from this study were excluded due to pre-defined exclusion criteria. The patients belonging to ASA lIl, lV, severe cardiovascular or renal disability, on beta blockers, coagulation anomaly, spinal deformities, or previous spine surgeries were not included in the study. The patients exhibiting allergy to local anesthetics, requiring more than two attempts for the procedure, patchy or inadequate effects after spinal anesthesia, or change in the plan of surgery intraoperatively were also excluded from the study. All other patients were given subarachnoid block at T10-T11 intervertebral space with 26G Quincke needle and Inj. Bupivacaine Heavy (0.5%) 2.4 mL with 5µg of Dexmedetomidine. Intraoperative parameters, number of attempts, the incidence of paresthesia during the procedure intraoperative and postoperative complications, and patient satisfaction were evaluated and recorded. RESULTS: Spinal anesthesia was successful in 2,074 patients and was achieved in a single attempt of procedure in 92% of patients. The incidence of paresthesia during needle insertion was 5.8%. Hypotension was observed in 18% of patients, bradycardia (13%), and nausea (10%) in a few patients, with shoulder tip pain in only 6% of patients. The majority of patients (94%) were "very satisfied" with the procedure. There were no episodes of any adverse event during the postoperative period. CONCLUSION:  Thoracic spinal anesthesia is a regional anesthesia technique practically feasible for healthy patients undergoing laparoscopic cholecystectomy with a manageable incidence of intraoperative complications and no evidence of any neurological complications. It has the advantage of providing manageable hemodynamics, minimal postoperative complication, and an acceptable degree of patient satisfaction.

Mitral valve replacement in patients of rheumatic heart disease associated with immune thrombocytopenia.

Immune thrombocytopenia in association with rheumatic heart disease is not commonly seen. Surgical management of rheumatic heart disease becomes more challenging in the presence of immune thrombocytopenia. The risk of complications increases manifold and judicious medical management before, during, and after surgery is imperative. We discuss two such cases, the complications we faced and the problems we anticipated before, and their prevention. Both patients were managed without using immunoglobulins or doing splenectomy. The literature on valve replacement in patients of immune thrombocytopenia and the implications of immune thrombocytopenia in the management of patients with rheumatic heart disease is also reviewed.

Excision of a giant lung bulla in a child: Repair of bronchial leaks using redundant bullous wall/membrane.

Large lung bullae are rare in children. We report a rare case of a large bulla in the right lung causing compression of the underlying lung with a shift of the mediastinum to the contralateral side. Excision of the bulla was done and a novel technique was used in the repair of bronchial air leakage sites with part of the bullous wall/membrane. The patient recovered well with re-expansion of the underlying collapsed lung.

Vein of Giacomini can lead to the recurrence of varicosities after endovenous laser ablation of varicose veins.

Endovenous laser ablation is a commonly performed intervention in the treatment of varicose veins. The technique is generally safe and has low complication rates. A case of recurrent varicose veins that had undergone endovenous laser ablation multiple times is reported. The cause of recurrence, in this case, was the vein of Giacomini, the presence of which was probably missed at the time of initial intervention. This case highlights the importance of the vein of Giacomini in causing recurrent varicosities after laser ablation.

Large mediastinal/thoracic benign teratoma presenting with haemoptysis: Report of a case and review of the literature.

The mediastinal teratomas can grow to a large size before becoming symptomatic. The symptoms are usually due to the compression of adjacent structures. A computed tomographic scan of the chest is the investigation of choice for making a provisional diagnosis and planning for further management. Removal of large mediastinal/thoracic teratoma can be associated with various intraoperative and postoperative complications, which can be life-threatening sometimes. We operated on a patient with a large mediastinal mass extending into the right thoracic cavity up to the costo-phrenic angle. The postoperative period was eventful and required judicious intensive care. The patient eventually recovered with conservative treatment. A literature search was done on PubMed using the keywords benign mediastinal teratoma. Case series/original articles published in the last two decades, that is, after the year 2000, were evaluated. As per the review of the literature, the prevalence of benign mediastinal teratoma may be higher in eastern countries. Thoracoscopic surgery is the preferred modality except for cases with adhesions or infiltration into surrounding structures.

Early and midterm patency of arteriovenous fistula for hemodialysis access using different techniques and their advantages and disadvantages.

This descriptive retrospective study was done to observe the different techniques of arteriovenous fistula creation for advantages and disadvantages, complications, and early and midterm patency. Fifty-three arteriovenous fistulas were created from September 2018 to August 2020 using four different techniques. Radio-cephalic arteriovenous fistula was usually the first option. Other techniques like brachio-cephalic arteriovenous fistula, radio-basilic arteriovenous fistula, and brachio-basilic arteriovenous fistula were used when the radio-cephalic fistula had thrombosed or could not be constructed due to small-sized cephalic vein in the forearm. The majority of patients (41 (77.35%)) underwent radio-cephalic fistula creation. Early patency was 38 (92.7%) in the radio-cephalic technique whereas it was 12 (100%) in the radio-basilic, brachio-cephalic, and brachio-basilic techniques combined. The midterm patency was 32 (78%) in the radio-cephalic technique, 5 (83%) in the brachio-cephalic technique, 3 (75%) in the radio-basilic technique, and 1 (50%) in the brachio-basilic technique. Radio-basilic and brachio-cephalic are alternative techniques for fistula creation after radio-cephalic depending upon the size of the basilic vein in the forearm or cephalic vein in the cubital fossa or arm. The radio-basilic technique may have advantages over the brachio-cephalic technique which need to be further evaluated. Proximal fistulas like brachio-basilic and brachio-cephalic are more commonly associated with limb edema.

Allergic bronchopulmonary aspergillosis in association with rheumatic heart disease: report of three cases.

Allergic bronchopulmonary aspergillosis is usually seen in patients with asthma or cystic fibrosis. Its association with rheumatic heart disease has not been adequately reported in literature. We report our experience of three cases who were diagnosed cases of rheumatic heart disease. Their symptomatology and clinical findings required further evaluation and investigations, which were suggestive of allergic bronchopulmonary aspergillosis. The patients were treated with steroids and/or antifungals before proceeding with the valve replacement.

Giant isolated iliac artery aneurysm with ipsilateral hydronephrosis treated with aneurysm resection and extra-anatomic bypass.

Isolated iliac artery aneurysms are rare and very rarely it may lead to hydronephrosis. The majority of uncomplicated iliac artery aneurysms can be managed with endovascular interventions but large complicated iliac artery aneurysms with compression on adjacent structures may require open surgery. We share our experience of a case of a large isolated iliac artery aneurysm with compression of the ureter probably leading to ureteric calculi and hydronephrosis on the ipsilateral side. The patient was managed with aneurysm resection and extra-anatomic bypass.

Successful patient outcome following surgery of carotid body tumor and temporary hypoglossal nerve dysfunction.

Carotid body tumors, also known as paragangliomas or chemodectomas, are rare tumors. They are mostly benign slow-growing tumors arising from neural crest cells, but can give rise to complications because of their location and close relation to carotid vessels and cranial nerves. A 40-year male patient diagnosed with a carotid body tumor is discussed along with a review of cranial nerve complications associated with the management of carotid body tumors. This case highlights the complete recovery after a temporary hypoglossal nerve deficit following surgery. Another important aspect is that syncopal attacks might occur in carotid body tumors and early surgery is required to prevent complications.

Mechanics of Vorticella contraction.

Vorticella convallaria is one of a class of fast-moving organisms that can traverse its body size in less than a millisecond by rapidly coiling a slender stalk anchoring it to a nearby surface. The stalk houses a fiber called the spasmoneme, which winds helically within the stalk and rapidly contracts in response to calcium signaling. We have developed a coupled mechanical-chemical model of the coiling process, accounting for the coiling of the elastic stalk and the binding of calcium to the protein spasmin. Simulations of the model describe the contraction and recovery processes quantitatively. The stalk-spasmoneme system is shown to satisfy geometric constraints, which explains why the cell body sometimes rotates during contraction. The shape of the collapsing and recovering stalk bounds its effective bending stiffness. Simulations suggest that recovery from the contracted state is driven by the stalk at a rate controlled by dissociation of calcium from spasmin.

A symplectic integration method for elastic filaments.

A new method is proposed for integrating the equations of motion of an elastic filament. In the standard finite-difference and finite-element formulations the continuum equations of motion are discretized in space and time, but it is then difficult to ensure that the Hamiltonian structure of the exact equations is preserved. Here we discretize the Hamiltonian itself, expressed as a line integral over the contour of the filament. This discrete representation of the continuum filament can then be integrated by one of the explicit symplectic integrators frequently used in molecular dynamics. The model systematically approximates the continuum partial differential equations, but has the same level of computational complexity as molecular dynamics and is constraint-free. Numerical tests show that the algorithm is much more stable than a finite-difference formulation and can be used for high aspect ratio filaments, such as actin.

Proximal penholding method - A variant to enhance safety of ultrasoundguided central venous cannulation: A prospective pilot study.

Aims: A significant incidence of Posterior Vessel Wall Puncture (PVWP) was reported during ultrasound guidance (USG) for internal jugular vein (IJV) catheterization. We studied a new technique of USGIJV cannulation to minimize or avoid PVWP, thereby decreasing overall complication rate, irrespective of the operators' experience level. Materials and Methods: After ethical approval, a prospective study was conducted on adult patients of either gender between 18-65 years of age, belonging to the American Society of Anesthesiologists Physical Status I-III, undergoing general anesthesia and requiring USG-guided IJV cannulation. After induction of general anesthesia and intubation, USG-guided IJV cannulation was done using technique of "proximal pen-holding method" in patients placed in supine position with neck rotated in 15° rotation to the opposite side. The primary outcome was defined as success rate of USG-guided IJV cannulation and incidence of PVWP. The secondary outcome was the incidences of complications such as arterial puncture, adjacent tissue damage, and performer's ease of the procedure (0-10 scale; 0 denoting no ease and extreme difficulty and 10 denoting extreme ease and no difficulty). Results: In 135 patients, right IJV puncture, guidewire, and central line insertion were achieved in single attempt without any PVWP by nine operators which included two anesthesia consultants and seven senior registrars. No complications were reported and ease of procedure were rated as median (interquartile range) of 10 (10). Conclusions: The "proximal pen-holding method" for real-time USG-IJV cannulation helped in avoiding PVWP with lesser complication rate and greater performer's ease.