White Matter Biomarkers Associated with Motor Change in Individuals with Stroke: A Continuous Theta Burst Stimulation Study.

Continuous theta burst stimulation (cTBS) is a form of noninvasive repetitive brain stimulation that, when delivered over the contralesional hemisphere, can influence the excitability of the ipsilesional hemisphere in individuals with stroke. cTBS applied prior to skilled motor practice interventions may augment motor learning; however, there is a high degree of variability in individual response to this intervention. The main objective of the present study was to assess white matter biomarkers of response to cTBS paired with skilled motor practice in individuals with chronic stroke. We tested the effects of stimulation of the contralesional hemisphere at the site of the primary motor cortex (M1c) or primary somatosensory cortex (S1c) and a third group who received sham stimulation. Within each stimulation group, individuals were categorized into responders or nonresponders based on their capacity for motor skill change. Baseline diffusion tensor imaging (DTI) indexed the underlying white matter microstructure of a previously known motor learning network, named the constrained motor connectome (CMC), as well as the corticospinal tract (CST) of lesioned and nonlesioned hemispheres. Across practice, there were no differential group effects. However, when categorized as responders vs. nonresponders using change in motor behaviour, we demonstrated a significant difference in CMC microstructural properties (as measured by fractional anisotropy (FA)) for individuals in M1c and S1c groups. There were no significant differences between responders and nonresponders in clinical baseline measures or microstructural properties (FA) in the CST. The present study identifies a white matter biomarker, which extends beyond the CST, advancing our understanding of the importance of white matter networks for motor after stroke.

An Acute Bout of Barefoot Running Alters Lower-limb Muscle Activation for Minimalist Shoe Users.

Despite the abundance of barefoot running-related research, there have been no electromyography studies evaluating the effects of this mode of exercise on habitual users of minimalist footwear. The present study investigated differences in muscle activation during acute bouts of barefoot and shod running, in minimalist shoe users. 8 male participants ran on a motorized treadmill for 10 min under both conditions, at 70% maximal aerobic speed. Electromyographic data were sampled from the biceps femoris, gluteus maximus, gastrocnemius medialis, tibialis anterior, and vastus lateralis during both swing and stance. Root-mean-square analysis of electromyographic data was conducted to compare muscle activation between conditions. During stance, barefoot running resulted in greater muscle activity in gastrocnemius medialis and gluteus maximus, and lower muscle activity in tibialis anterior. During swing, barefoot running resulted in increased muscle activity in vastus lateralis and gastrocnemius medialus. These results indicate that, for minimalist shoe users, an acute bout of barefoot running results in significantly different lower-limb muscle activity. Increased activation in the above muscles presents a possible mechanism for injury, which should be considered during exercise prescription.

Ambulatory transcutaneous carbon dioxide monitoring for children with neuromuscular disease.

OBJECTIVE: Early screening and diagnosis of nocturnal hypoventilation can slow progression to diurnal hypercapnia and mortality in children with neuromuscular disease (NMD). However, gold standard, laboratory-based polysomnography (PSG) testing is a limited resource. Therefore, we evaluated the diagnostic accuracy of ambulatory transcutaneous carbon dioxide (tcCO2) monitoring used in the home compared to PSG in children with NMD. METHODS: Prospective, cross-sectional study in children 0-18 years old with a confirmed diagnosis of NMD and a clinically indicated need for PSG. Ambulatory tcCO2 was assessed by a respiratory therapist in participant's homes. Demographics, and PSG (including tcCO2). RESULTS: We enrolled 39 children with NMD; 3 had unusable ambulatory tcCO2 data because of failure of drift correction on the machine (n = 2) or an air bubble (n = 1). The remaining 36 patients aged 11 months to 16 years (median (IQR) 12.5 years (6.0-15.8)) had ambulatory tcCO2 and outpatient level 1 PSG data. Ambulatory tcCO2 monitoring had a sensitivity of 20.0% (95% confidence interval [CI] 0.5-71.6%) and a specificity of 93.5% (95% CI 78.6-99.2%). Almost all children and/or parents (34/36, 94%) preferred ambulatory monitoring over in-hospital PSG. CONCLUSIONS: Ambulatory transcutaneous carbon dioxide monitoring was not sufficiently accurate as a clinical tool for the diagnosis of nocturnal hypoventilation our cohort of children with neuromuscular disease despite being preferred over PSG by both children and parents.

Adsorption behavior of hexafluorophosphate on selected bonded phases.

The adsorption behavior of ammonium hexafluorophosphate was studied on four HPLC columns packed with adsorbents of different ability for dispersive interactions using frontal chromatography with LC/MS detection in negative ESI mode. Hexafluorophosphate (PF(6)(-)) adsorption isotherms were measured from acetonitrile/water and methanol/water mixtures. Increased PF(6)(-) adsorption with increased acetonitrile content was found between 0 and 15% of acetonitrile in the eluent. Further increase of the acetonitrile concentration leads to an exponential decrease of PF(6)(-) adsorption. Methanol, on the other hand, causes a steady decrease of PF(6)(-) adsorption with increased organic concentration in the mobile phase.

Comparing a diffusion tensor and non-tensor approach to white matter fiber tractography in chronic stroke.

Diffusion tensor imaging (DTI)-based tractography has been used to demonstrate functionally relevant differences in white matter pathway status after stroke. However, it is now known that the tensor model is insensitive to the complex fiber architectures found in the vast majority of voxels in the human brain. The inability to resolve intra-voxel fiber orientations may have important implications for the utility of standard DTI-based tract reconstruction methods. Intra-voxel fiber orientations can now be identified using novel, tensor-free approaches. Constrained spherical deconvolution (CSD) is one approach to characterize intra-voxel diffusion behavior. In the current study, we performed DTI- and CSD-based tract reconstruction of the corticospinal tract (CST) and corpus callosum (CC) to test the hypothesis that characterization of complex fiber orientations may improve the robustness of fiber tract reconstruction and increase the sensitivity to identify functionally relevant white matter abnormalities in individuals with chronic stroke. Diffusion weighted magnetic resonance imaging was performed in 27 chronic post-stroke participants and 12 healthy controls. Transcallosal pathways and the CST bilaterally were reconstructed using DTI- and CSD-based tractography. Mean fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were calculated across the tracts of interest. The total number and volume of reconstructed tracts was also determined. Diffusion measures were compared between groups (Stroke, Control) and methods (CSD, DTI). The relationship between post-stroke motor behavior and diffusion measures was evaluated. Overall, CSD methods identified more tracts than the DTI-based approach for both CC and CST pathways. Mean FA, ADC, and RD differed between DTI and CSD for CC-mediated tracts. In these tracts, we discovered a difference in FA for the CC between stroke and healthy control groups using CSD but not DTI. CSD identified ipsilesional CST pathways in 9 stroke participants who did not have tracts identified with DTI. Additionally, CSD differentiated between stroke ipsilesional and healthy control non-dominant CST for several measures (number of tracts, tract volume, FA, ADC, and RD) whereas DTI only detected group differences for number of tracts. In the stroke group, motor behavior correlated with fewer diffusion metrics derived from the DTI as compared to CSD-reconstructed ipsilesional CST and CC. CSD is superior to DTI-based tractography in detecting differences in diffusion characteristics between the nondominant healthy control and ipsilesional CST. CSD measures of microstructure tissue properties related to more motor outcomes than DTI measures did. Our results suggest the potential utility and functional relevance of characterizing complex fiber organization using tensor-free diffusion modeling approaches to investigate white matter pathways in the brain after stroke.

Congenitally cleft atrioventricular valves associated with secundum atrial septal defects.

Three patients with the rare association of secundum ASD and congenital clefts of A-V valves are reported. These three patients illustrate the predictive valve of vectoracardiographic analysis in precisely determining the anatomic location of the valvular pathology. The embryologic origins of the lesion are briefly discussed. A review of the literature supports the use of vector analysis in the evaluation of the patients with this type of heart disease.

Management of necrotizing tracheostomy infections.

Management of three patients with necrotizing tracheostomy infections resulting in tracheal dissolution was reviewed with respect to presentation, cause, and management. Loss of tracheal substance led to difficulty in ventilation because of a large air leak. The stomal area cavitated in two patients, denuding the right common carotid artery in one. Purulent peristomal drainage was present in all three patients. Common factors of possible etiologic significance included necrotizing polymicrobial gram-negative tracheobronchial infections caused by Pseudomonas, Enterobacter, and Klebsiella species. Also of possible importance were suture fixation of the appliance, history of neurologic injury, and closure of the incision. Immediate therapy consisted of oral intubation for ventilatory purposes and a regimen of hourly application of 1% neomycin dressings. Seven to 21 days were necessary to allow formation of sufficient granulation tissue to support replacement of the tracheostomy appliance for continued mechanical ventilation. Once spontaneous ventilation was possible, a Montgomery T-tube was inserted for long-term tracheal stenting prior to reconstruction. The two patients treated by tracheal stenting are long-term survivors. Avoidance of suture fixation of the appliance, aggressive treatment of bronchopulmonary infection, and adequate stomal toilet may help to avoid this devastating complication.

Thoracic CT scanning in critically ill patients. Information obtained frequently alters management.

Conventional radiographic studies of the chest in the intensive care unit often fail to positively identify suspected intrathoracic pathology due to many patient- and equipment-related variables. Our experience has indicated that CT scanning of the chest improves diagnostic accuracy, precisely defines anatomic abnormalities, frequently affects treatment decisions, and has been performed safely in this fragile patient population. Examples of correctable lesions have included pneumothorax, empyema, lung abscess, mediastinal abscess and pleural effusion. Chest CT findings always occurred while the portable plane chest radiographs were nondiagnostic. CT-directed intervention often improved patient outcome.

Utility of pneumonotomy in the treatment of cavitary lung disease.

Three patients were judged to be prohibitive operative risks despite the need for urgent drainage of cavitary pulmonary lesions. Cavernostomy was performed in each case, with a satisfactory long-term outcome in two patients. The third patient recovered from his pulmonary insult, but died much later, secondary to an unrelated illness. One patient had a purulent lung abscess due to aspiration, one had atypical tuberculosis resistant to all antibiotics, and the third patient experienced massive hemoptysis from a tuberculous cavity. Two-stage procedures were utilized in the first two patients, while urgent operation in the third patient was facilitated by adhesions from a previous thoracotomy and pleural infection. Care must be taken to minimize endobronchial and pleural contamination by meticulous attention to detail during the performance of percutaneous tube drainage. There are relatively few indications for percutaneous drainage of cavitary pulmonary lesions in this antibiotic era. However, certain clinical situations should prompt consideration for a pneumonotomy. These include a severely septic or debilitated patient who is unresponsive to medical management, the presence of resistant pathogens in a compromised host, and the presence of severe adhesive pleuritis which may prohibit an expeditious thoracotomy and resection for massive hemoptysis.

Correlation between needle biopsy of lung tumors and histopathologic analysis of resected specimens.

Needle aspiration of a pulmonary mass may accurately delineate malignant from nonmalignant pulmonary lesions; however, needle aspiration may be unable to identify a specific cell type. Therefore, a retrospective review of patients undergoing needle aspiration of pulmonary masses was carried out for the years, 1979 through September 1984. A Lee needle was used, which produces a sample of tissue 1-mm in diameter suitable for histopathologic analysis as well as a cytologic specimen. A total of 87 needle biopsies were carried out, but only 46 patients later underwent resection. Five patients (6 percent) sustained a pneumothorax, and four required a chest tube. Minimal hemoptysis occurred in three patients (3 percent). Eight patients were subsequently found to have benign lesions, and there were 38 malignant tumors. Seven needle biopsies (18 percent; 7/38) were nondiagnostic and subsequently proved to be malignant. Thirty-one needle biopsies were diagnostic of malignant neoplasms (82 percent; 31/38). Twenty specimens showed the same cell type as the needle biopsy (65 percent 20/31). Eleven resected specimens disagreed with the cell type from the needle biopsy (35 percent; 11/31). In these 11 patients a change in management was indicated because of the delineation of a different cell type in only four (11 percent of all 38 patients with cancer). Mixed tumors and small cell carcinoma provide the area of most concern. Our conclusions are that needle biopsy accurately indicated a malignant neoplasm in 82 percent of the patients undergoing later resection and that the specimens from Lee needle biopsy accurately predicted the cell type in 65 percent of the specimens. The inaccurate histologic diagnosis was important clinically in only 11 percent of the patients. Overall, the needle biopsy of pulmonary lesions provided a correct decision on management in 87 percent of the cases in which biopsy provided diagnosis of a malignant neoplasm (31 patients).

Coverage of the open sternotomy wound with Biobrane dressing.

Massive edema accumulated after prolonged cardiopulmonary bypass for coronary grafting such that neither the sternum nor the presternal skin could be closed after insertion of a left ventricular assist device. To protect the mediastinum from infection, we applied Biobrane synthetic temporary wound dressing and placed a moist gauze dressing over it. When the dressing was removed 4 days later, the wound was pink, granulating, free from infection, and suitable for closure. Use of Biobrane biologic dressing should be considered when the mediastinum must remain exposed after median sternotomy.

Mixed small cell and non-small cell lung cancer.

Seventeen (10 percent) of 176 patients with small-cell carcinoma of the lung seen at this hospital since 1976 proved to have mixed small-cell and non-small-cell tumors. The presence of a mixed lung cancer was established prior to chemotherapy or irradiation in nine patients. Eight were initially diagnosed as pure small-cell carcinoma but proved to have a mixed tumor at either surgery or autopsy. Of the 17 patients, eight received chemotherapy, and four had a partial response. Six of the 40 autopsies performed on patients with small-cell lung cancer demonstrated intrathoracic tumor which was histologically mixed. Extrathoracic metastases in these patients were heterogeneous and included pure small-cell, pure non-small-cell, and mixed histologic type. We conclude that mixed small-cell and non-small-cell lung cancers are relatively frequent and carry important prognostic and therapeutic implications. Clinical management of patients with small-cell lung cancer should therefore be flexible and tailored to the potential for histologic diversity. Mixed lung cancer in previously untreated patients suggests a common endodermal origin for small-cell and non-small-cell pulmonary tumors.

The effect of fiberoptic bronchoscopy on cerebral hemodynamics in patients with severe head injury.

STUDY OBJECTIVE: Concerns exist about the effect of flexible fiberoptic bronchoscopy (FFB) on intracranial pressure (ICP). We studied the effect of FFB on cerebral hemodynamics in patients with severe head injury. DESIGN: Prior to FFB, patients were anesthetized and muscle relaxants were given as necessary to eliminate coughing. Comparisons were made of mean arterial pressure (MAP), ICP, and cerebral perfusion pressure (CPP) prior to, during, and after FFB, as well as comparisons of mean cerebral hemodynamic values in an 8-hour period before and after FFB. Observations were made of changes in neurologic status post-FFB. SETTING: Surgical intensive care unit of Level 1 Trauma Center. PATIENT POPULATION: Fifteen patients with severe head injury in whom ICP was monitored and who required FFB for diagnosis of nosocomial pneumonia or treatment of lobar collapse. RESULTS: Pre-FFB ICP averaged 14.3 mm Hg (range, 6 to 26 mm Hg). During FFB, patients experienced a mean increase in ICP of 13.5 mm Hg above basal values (p = 0.0001). At peak ICP, MAP increased from a baseline of 92.3 mm Hg (SD +/- 16.1) to 111.5 mm Hg (+/- 13.9). Mean CPP was 83.7 mm Hg at peak ICP (range, 52 to 121 mm Hg), a 14.0% increase over baseline. The ICP and MAP returned to basal levels following bronchoscopy. No patient had a clinically significant increase in ICP or demonstrated any deterioration in Glasgow Coma Scale score or neurologic examination findings post-FFB. CONCLUSIONS: Although FFB causes an increase in ICP in patients with severe head injury, MAP also rises, and an adequate CPP is maintained. The ICP returns to basal levels after the procedure. When properly performed, FFB does not adversely affect neurologic status in patients with severe head injury.

Thoracic surgical content of an undergraduate surgical curriculum.

The surgical services have long been an excellent training ground for teaching clinical skills common to all physicians. The thoracic surgical service provides an additional opportunity to offer experience in trauma, resuscitation, and the management of many emergency situations common to all medical and surgical illness. With the use of a methodology previously reported by the Association for Surgical Education, a survey was developed and circulated among surgical department chairmen, directors of thoracic surgical training programs, and the medical school classes of 1978 who had completed 5 postgraduate years of training and/or practice. A modified Delphi technique was used to assess the information, and the rank order of mean scores for knowledge and skills was constructed for the various categories within the thoracic surgery curriculum. The Pearson product-moment correlation for the rank order of knowledge and skills demonstrated a high degree of correlation between directors and students (0.904 and 0.917, respectively), directors and chairmen (0.948 and 0.982, respectively), and between students and chairmen (0.900 and 0.952, respectively) for knowledge and skills. The most important knowledge categories were critical care and resuscitation (rank order 2.15), hemodynamic measurements and analysis (2.10), pulmonary embolus (2.06), and assessment of pulmonary function (1.92). The most important skills listed were thoracentesis (1.92), endotracheal intubation (1.86), and central vein cannulation (1.69). Analysis of data such as these permits construction of a surgery curriculum responsive to the goals and objectives of the faculty and implements the viewpoints of many individuals representing multiple backgrounds to formulate the most appropriate content for undergraduate surgical education.

Management of transmediastinal gunshot wounds.

Gunshot wounds that transverse the mediastinum are major management problems for two primary reasons: (1) multiple injuries to vital structures are common and (2) the operative approach to control hemorrhage may not afford the optimum exposure to repair the various injuries encountered. We devised a management plan whereby patients in hemodynamically unstable condition underwent immediate operation and patients in stable condition underwent a rapid work-up to evaluate the organs at risk for injury including angiography, esophagoscopy, esophagography, bronchoscopy, and pericardial exploratory surgery while under local anesthesia. A total of 76 patients were treated. Thirty-three patients in unstable condition underwent immediate thoracotomy for hemorrhage or shock or median sternotomy for cardiac tamponade. Multiple organs were injured (average 2.7) and the mortality rate was high (12 of 33) because of the severity of the injuries. Twenty-seven of 43 patients in stable condition required operation after the systematic evaluation disclosed injuries to the great vessels (11), esophagus (9), trachea and bronchi (6), and heart (6). Three patients died of delayed complications (6.9%). The 16 patients who were in stable conditions and had no demonstrable injury were closely followed without operation with one complication and one death from an associated abdominal injury. A management plan for this difficult subset of patients with penetrating thoracic trauma is detailed.

A 32-year experience in 100 patients with giant paraesophageal hernia: the case for abdominal approach and selective antireflux repair.

BACKGROUND: Giant paraesophageal hiatal hernia (GPEH) presents a risk of catastrophic complications that include massive bleeding, strangulation, and perforation and should be repaired. Controversy persists as to the surgical approach and whether an antireflux repair is required. METHODS: This study reviews the experience with 100 patients with GPEH who underwent surgical repair between 1967 and 1999. Eighty patients underwent an elective operation, and 20 patients underwent an emergency procedure for complications of GPEH. The gastroesophageal junction was above the hiatus ("combined" hernia with sliding component) in 23 patients and in the abdomen in 77 patients, including 3 patients with a true parahiatal hernia. RESULTS: A thoracic approach was used in 18 patients, mostly early in our experience; postoperative gastric volvulus requiring transabdominal repair developed in 2 patients. The remaining 82 patients underwent an abdominal repair, with temporary gastrostomy to prevent gastric displacement in 75 patients; the hernial sac was resected, and the hiatus was reconstructed in all of the patients. Thirty-five patients with reflux on preoperative work up underwent a fundoplication, with gastroplasty in 2 patients because of a short esophagus. No patient has experienced hernia recurrence. Whereas symptomatic relief was excellent in all patients with elective repair, mild reflux was present in 2 patients after emergency operation. There were no deaths among the patients who underwent elective operation; there were 2 hospital deaths among those patients who underwent emergency operation (10%). CONCLUSIONS: GPEH should be repaired soon after recognition. Reflux should be evaluated before the operation, and if present, fundoplication should be part of the repair along with the reduction of the hernia, excision of the sac, gastropexy, and crural closure. These are best achieved with an abdominal approach.

Thoracoplasty: current application to the infected pleural space.

Thoracoplasty, once commonly used in the management of cavitary pulmonary disease, continues to find application in the obliteration of infected pleural spaces. This study reports a series of 13 patients receiving thoracoplasty between 1976 and 1989. Five patients had chronic apical empyema spaces without prior resection of lung tissue. Two of the empyemas were due to tuberculosis, two were due to atypical mycobacteria, and one was due to postpneumonic empyema. All patients had extensive destruction of upper lobe tissue. Eight patients had undergone prior pulmonary resection; 3 had persistent infected spaces in the early postoperative period, 3 had development of empyemas and bronchopleural fistulas late (5 to 19 years) after pulmonary resection, and 2 had postpneumonectomy empyema. All patients had rigid cavity walls preventing space obliteration by rib removal alone and required concomitant resection of the thickened pleura and intercostal muscle tissues. Bronchopleural fistulas were present in 11 patients and were closed with adjacent nonintercostal muscle. All patients survived and had successful obliteration of the infected spaces with acceptable physiological and cosmetic results. We conclude that thoracoplasty remains a useful procedure in the management of the infected pleural space in select patients.

Bronchial obstruction after upper lobectomy: kinked bronchus relieved by stenting.

Post resectional kinking of the lower lobe bronchus caused obstructive symptoms in 2 patients following upper lobectomy. Exaggerated upward displacement of the remaining lower lobe seemed to be causative. Intrabronchial stenting relieved the obstruction in each case with satisfactory intermediate term results.

Use of the rhomboid major muscle flap for esophageal repair.

A 16-year-old boy sustained vehicular blunt trauma with delayed esophageal rupture that resulted in empyema and an esophagopleurocutaneous fistula. Diverting esophagostomy, gastrotomy, and transpyloric jejunostomy were performed, and these procedures permitted satisfactory nutritional support of the patient. Staged direct closure of the esophagus buttressed by a rhomboid muscle flap preserved normal esophageal function. Both clinical application and cadaver dissections have demonstrated that the rhomboid flap has an excellent blood supply and that it can be used to repair lesions on either side in the upper half of the esophagus. Because this flap is extrathoracic, it is not usually distorted by intrathoracic sepsis or previous thoracic incisions. The rhomboid major muscle flap is an excellent alternative to conventional autogenous grafts for esophageal repair.

Replacement of degenerated mitral and aortic bioprostheses without explantation.

BACKGROUND: The most common indication for reoperation in patients with a bioprosthetic valve is primary tissue failure. Explantation of the bioprosthesis is time consuming, and for a mitral valve, may be complicated by cardiac rupture at the atrioventricular junction or the posterior left ventricular wall where a strut is imbedded, injury to the circumflex artery, and late perivalvular leak; for an aortic valve, annular disruption and perivalvular leak may complicate explantation. A new approach to simplify these procedures and avoid these complications, by excising only the bioprosthetic tissue and attaching a bileaflet mechanical valve to the intact stent, was developed in 1991 and was evaluated over a 9-year period in 50 patients who had had one (34), two (10), three (4), or four (2) previous open cardiac operations. METHODS: Since 1991, we have replaced degenerated mitral bioprostheses in 34 patients (25 to 84 years of age; 12 male, 22 female) by preserving the stent and suturing a St. Jude or Carbomedics bileaflet valve to the atrial side of the bioprosthetic cuff; the mitral valve was exposed through a median sternotomy in 21 patients and through a right anterolateral thoracotomy in 13. Using a similar approach, starting in 1995, 16 additional patients (55 to 73 years of age; 11 male, 5 female) with degenerated aortic bioprostheses had the aortic valve replaced by excising the bioprosthetic tissue and amputating the struts, then suturing a Carbomedics valve to the aortic side of the bioprosthetic cuff. This allows the use of a bileaflet valve similar in size to the bioprosthesis with exact matching of the orifices. RESULTS: Bypass time averaged 61 +/- 14 minutes and aortic cross-clamp time 43 +/- 12 minutes. There has been no operative mortality. Three late deaths occurred at 9, 37, and 58 months, and were not valve related. No gradients of hemodynamic significance have been detected on transesophageal echocardiographic follow-up. CONCLUSIONS: Leaving the bioprosthetic cuff intact eliminates the need for extensive dissection, thus shortening and simplifying the procedure and diminishing its attendant mortality and morbidity. This valve-on-valve approach also allows replacement of a degenerated bioprosthesis with a bileaflet valve of comparable size rather than a smaller one jammed into the orifice of the bioprosthetic stent, thus avoiding undue trauma to the bileaflet valve and maintaining excellent hemodynamic function.