Transcranial magnetic stimulation enhances the specificity of multiple sclerosis diagnostic criteria: a critical narrative review

Background

Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease that involves attacks of inflammatory demyelination and axonal damage, with variable but continuous disability accumulation. Transcranial magnetic stimulation (TMS) is a noninvasive method to characterize conduction loss and axonal damage in the corticospinal tract. TMS as a technique provides indices of corticospinal tract function that may serve as putative MS biomarkers. To date, no reviews have directly addressed the diagnostic performance of TMS in MS. The authors aimed to conduct a critical narrative review on the diagnostic performance of TMS in MS.

Methods

The authors searched the Embase, PubMed, Scopus, and Web of Science databases for studies that reported the sensitivity and/or specificity of any reported TMS technique compared to established clinical MS diagnostic criteria. Studies were summarized and critically appraised for their quality and validity.

Results

Seventeen of 1,073 records were included for data extraction and critical appraisal. Markers of demyelination and axonal damage-most notably, central motor conduction time (CMCT)-were specific, but not sensitive, for MS. Thirteen (76%), two (12%), and two (12%) studies exhibited high, unclear, and low risk of bias, respectively. No study demonstrated validity for TMS techniques as diagnostic biomarkers in MS.

Conclusions

CMCT has the potential to: (1) enhance the specificity of clinical MS diagnostic criteria by "ruling in" true-positives, or (2) revise a diagnosis from relapsing to progressive forms of MS. However, there is presently insufficient high-quality evidence to recommend any TMS technique in the diagnostic algorithm for MS.

Age and asymmetry of corticospinal excitability, but not cardiorespiratory fitness, predict cognitive impairments in multiple sclerosis

Background

Cognitive impairment is a disabling and underestimated consequence of multiple sclerosis (MS), with multiple determinants that are poorly understood.

Objectives

We explored predictors of MS-related processing speed impairment (PSI) and age-related mild cognitive impairment (MCI) and hypothesized that cardiorespiratory fitness and corticospinal excitability would predict these impairments.

Methods

We screened 73 adults with MS (53 females; median [range]: Age 48 [21-70] years, EDSS 2.0 [0.0-6.5]) for PSI and MCI using the Symbol Digit Modalities Test and Montréal Cognitive Assessment, respectively. We identified six persons with PSI (No PSI, n = 67) and 13 with MCI (No MCI, n = 60). We obtained clinical data from medical records and self-reports; used transcranial magnetic stimulation to test corticospinal excitability; and assessed cardiorespiratory fitness using a graded maximal exercise test. We used receiver operator characteristic (ROC) curves to discern predictors of PSI and MCI.

Results

Interhemispheric asymmetry of corticospinal excitability was specific for PSI, while age was both sensitive and specific for MCI. MS-related PSI was also associated with statin prescriptions, while age-related MCI was related to progressive MS and GABA agonist prescriptions. Cardiorespiratory fitness was associated with neither PSI nor MCI.

Discussion

Corticospinal excitability is a potential marker of neurodegeneration in MS-related PSI, independent of age-related effects on global cognitive function. Age is a key predictor of mild global cognitive impairment. Cardiorespiratory fitness did not predict cognitive impairments in this clinic-based sample of persons with MS.

Multiple sclerosis-related heat sensitivity linked to absence of DMT prescription and subjective hand impairment but not autonomic or corticospinal dysfunction

OBJECTIVES

Heat sensitivity (HS) describes a temporary worsening of multiple sclerosis (MS) symptoms with increased body temperature. The pathophysiology may relate to central nervous system conduction deficits and autonomic dysfunction. We conducted deep clinical phenotyping of a cohort of persons with MS to identify predictors of HS.

METHODS

We recruited 59 MS participants with HS or No HS. Participants self-reported symptom severity (Hospital Anxiety and Depression Scale, Multiple Sclerosis Impact Scale, and fatigue visual analog scale) and underwent maximal exercise and transcranial magnetic stimulation testing to characterize autonomic and corticospinal function. We examined associations with HS using binomial logistic regression.

RESULTS

People with HS (36/59) had significantly greater disability, depression, fatigue, and physical and psychological functional effects of MS. They also had significantly lower corticospinal excitability but not conduction. After controlling for disease-modifying therapy (DMT), disability, and disease type, self-reported difficulty using hands in everyday tasks was significantly associated with a large increase in the odds of HS. Autonomic and corticospinal dysfunction were not associated with HS. Lack of DMT use alone was also associated with a large increase in the odds of HS.

DISCUSSION

Following a comprehensive assessment of plausible contributors to HS, HS was most strongly associated with lack of a DMT prescription and self-reported hand dysfunction. Surprisingly, objective measurement of autonomic and corticospinal integrity did not contribute to HS.

Lower corticospinal excitability and greater fatigue among people with multiple sclerosis experiencing pain

Introduction

Persons with multiple sclerosis (MS) frequently report pain that negatively affects their quality of life. Evidence linking pain and corticospinal excitability in MS is sparse. We aimed to (1) examine differences in corticospinal excitability in MS participants with and without pain and (2) explore predictors of pain.

Methods

Sixty-four participants rated their pain severity on a visual analog scale (VAS). Transcranial magnetic stimulation (TMS) and validated clinical instruments characterized corticospinal excitability and subjective disease features like mood and fatigue. We retrieved information on participants' prescriptions and disability status from their clinical records.

Results

Fifty-five percent of participants reported pain that affected their daily functioning. Persons with pain had significantly greater fatigue and lower area under the excitatory motor evoked potential (MEP) recruitment curve (eREC AUC), a measure of total corticospinal excitability. After controlling for age, disability status, and pain medications, increased fatigue and decreased eREC AUC together explained 40% of the variance in pain.

Discussion

Pain in MS is multifactorial and relates to both greater fatigue and lesser corticospinal excitability. Future work should better characterize relationships between these outcomes to develop targeted pain interventions such as neuromodulation.

Summary

We examined pain in MS. Individuals with pain had higher fatigue and lower corticospinal excitability than those without pain. These outcomes significantly predicted self-reported pain.

Sex-specific disruption in corticospinal excitability and hemispheric (a)symmetry in multiple sclerosis

Multiple Sclerosis (MS) is a neurodegenerative disease in which pathophysiology and symptom progression presents differently between the sexes. In a cohort of people with MS (n = 110), we used transcranial magnetic stimulation (TMS) to investigate sex differences in corticospinal excitability (CSE) and sex-specific relationships between CSE and cognitive function. Although demographics and disease characteristics did not differ between sexes, males were more likely to have cognitive impairment as measured by the Montreal Cognitive Assessment (MoCA); 53.3% compared to females at 26.3%. Greater CSE asymmetry was noted in females compared to males. Females demonstrated higher active motor thresholds and longer silent periods in the hemisphere corresponding to the weaker hand which was more typical of hand dominance patterns in healthy individuals. Males, but not females, exhibited asymmetry of nerve conduction latency (delayed MEP latency in the hemisphere corresponding to the weaker hand). In males, there was also a relationship between delayed onset of ipsilateral silent period (measured in the hemisphere corresponding to the weaker hand) and MoCA, suggestive of cross-callosal disruption. Our findings support that a sex-specific disruption in CSE exists in MS, pointing to interhemispheric disruption as a potential biomarker of cognitive impairment and target for neuromodulating therapies.

Probing the Brain-Body Connection Using Transcranial Magnetic Stimulation (TMS): Validating a Promising Tool to Provide Biomarkers of Neuroplasticity and Central Nervous System Function

Transcranial magnetic stimulation (TMS) is a non-invasive method used to investigate neurophysiological integrity of the human neuromotor system. We describe in detail, the methodology of a single pulse TMS protocol that was performed in a large cohort of people (n = 110) with multiple sclerosis (MS). The aim was to establish and validate a core-set of TMS variables that predicted typical MS clinical outcomes: walking speed, hand dexterity, fatigue, and cognitive processing speed. We provide a brief and simple methodological pipeline to examine excitatory and inhibitory corticospinal mechanisms in MS that map to clinical status. Delayed and longer ipsilateral silent period (a measure of transcallosal inhibition; the influence of one brain hemisphere's activity over the other), longer cortical silent period (suggestive of greater corticospinal inhibition via GABA) and higher resting motor threshold (lower corticospinal excitability) most strongly related to clinical outcomes, especially when measured in the hemisphere corresponding to the weaker hand. Greater interhemispheric asymmetry (imbalance between hemispheres) correlated with poorer performance in the greatest number of clinical outcomes. We also show, not surprisingly, that TMS variables related more strongly to motor outcomes than non-motor outcomes. As it was validated in a large sample of patients with varying severities of central nervous system dysfunction, the protocol described herein can be used by investigators and clinicians alike to investigate the role of TMS as a biomarker in MS and other central nervous system disorders.

Transcranial Magnetic Stimulation as a Potential Biomarker in Multiple Sclerosis: A Systematic Review with Recommendations for Future Research

Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system. Disease progression is variable and unpredictable, warranting the development of biomarkers of disease status. Transcranial magnetic stimulation (TMS) is a noninvasive method used to study the human motor system, which has shown potential in MS research. However, few reviews have summarized the use of TMS combined with clinical measures of MS and no work has comprehensively assessed study quality. This review explored the viability of TMS as a biomarker in studies of MS examining disease severity, cognitive impairment, motor impairment, or fatigue. Methodological quality and risk of bias were evaluated in studies meeting selection criteria. After screening 1603 records, 30 were included for review. All studies showed high risk of bias, attributed largely to issues surrounding sample size justification, experimenter blinding, and failure to account for key potential confounding variables. Central motor conduction time and motor-evoked potentials were the most commonly used TMS techniques and showed relationships with disease severity, motor impairment, and fatigue. Short-latency afferent inhibition was the only outcome related to cognitive impairment. Although there is insufficient evidence for TMS in clinical assessments of MS, this review serves as a template to inform future research.

Yoga Practitioners Uniquely Activate the Superior Parietal Lobule and Supramarginal Gyrus During Emotion Regulation

Chronic stress contributes to both mental and physical illness. A high prevalence and cost of stress-related illnesses North America warrants investigation into alternative or complementary therapies which may help reduce adverse reactions to stressful stimuli. Emotion regulation is the process of monitoring and adjusting emotional responses to environmental stimuli and stressors. Individuals who participate in physical activity are less likely to have adverse responses to potentially stressful situations, potentially due to adaptions in emotion regulation. Yoga is a form of physical activity involving stretching exercises and meditation, that may lessen individuals’ levels of stress and anxiety and improve emotion regulation. High-frequency heart rate variability (HF-HRV) is considered a measure of parasympathetic nervous system (PNS) activity during the emotion regulation. Measuring HRV and brain activity using functional magnetic resonance imaging (fMRI) offers a useful, noninvasive approach to evaluating “neurovisceral” components of emotion regulation. We aimed to determine whether yoga practitioners (YP) exhibit different patterns of brain activation compared to recreational athletes (RA) without current yoga experience, while viewing emotionally arousing visual stimuli. Our secondary aim was to examine potential differences across groups in HRV throughout the presentation of these stimuli. Analysis of fMRI data during exposure to emotion-evoking (EE) stimuli revealed that the YP group activated two unique brain areas, namely the superior parietal lobule and the supramarginal gyrus. These areas have been associated with attentional awareness and reduced egocentric bias, processes that have been implicated in emotion regulation by others. The RA group activated the inferior middle frontal cortex, an area associated with cognitive reappraisal during emotion regulation. The YP group also demonstrated a trend towards a higher ratio of low- to high-frequency HRV compared to the RA group. The present findings support the presence of experience-dependent neurovisceral mechanisms associated with emotion regulation. Individuals who practice yoga regulate their neurovisceral responses to potentially stressful external stimuli in a different manner than recreational athletes who do not engage in yoga practice. The present study had a small sample size (RA: n = 12; YP: n = 19), which should be taken into account when interpreting the results.

Barefoot running does not affect simple reaction time: an exploratory study

Background

Converging evidence comparing barefoot (BF) and shod (SH) running highlights differences in foot-strike patterns and somatosensory feedback, among others. Anecdotal evidence from SH runners attempting BF running suggests a greater attentional demand may be experienced during BF running. However, little work to date has examined whether there is an attentional cost of BF versus SH running.

Objective

This exploratory study aimed to examine whether an acute bout of BF running would impact simple reaction time (SRT) compared to SH running, in a sample of runners naïve to BF running.

Methods

Eight male distance runners completed SRT testing during 10 min of BF or SH treadmill running at 70% maximal aerobic speed (17.9 ± 1.4 km h⁻¹). To test SRT, participants were required to press a hand-held button in response to the flash of a light bulb placed in the center of their visual field. SRT was tested at 1-minute intervals during running. BF and SH conditions were completed in a pseudo-randomized and counterbalanced crossover fashion. SRT was defined as the time elapsed between the light bulb flash and the button press. SRT errors were also recorded and were defined as the number of trials in which a button press was not recorded in response to the light bulb flash.

Results

Overall, SRT later in the exercise bouts showed a statistically significant increase compared to earlier (p < 0.05). Statistically significant increases in SRT were present at 7 min versus 5 min (0.29 ± 0.02 s vs. 0.27 ± 0.02 s, p < 0.05) and at 9 min versus 2 min (0.29 ± 0.03 s vs. 0.27 ± 0.03 s, p < 0.05). However, BF running did not influence this increase in SRT (p > 0.05) or the number of SRT errors (17.6 ± 6.6 trials vs. 17.0 ± 13.0 trials, p > 0.05).

Discussion

In a sample of distance runners naïve to BF running, there was no statistically significant difference in SRT or SRT errors during acute bouts of BF and SH running. We interpret these results to mean that BF running does not have a greater attentional cost compared to SH running during a SRT task throughout treadmill running. Literature suggests that stride-to-stride gait modulation during running may occur predominately via mechanisms that preclude conscious perception, thus potentially attenuating effects of increased somatosensory feedback experienced during BF running. Future research should explore the present experimental paradigm in a larger sample using over-ground running trials, as well as employing different tests of attention.

Time-Dependent Effects of Cardiovascular Exercise on Memory

We present new evidence supporting the hypothesis that the effects of cardiovascular exercise on memory can be regulated in a time-dependent manner. When the exercise stimulus is coupled temporally with specific phases of the memory formation process, a single bout of cardiovascular exercise may be sufficient to improve memory.

The Effect of an Acute Bout of Moderate-Intensity Aerobic Exercise on Motor Learning of a Continuous Tracking Task

INTRODUCTION

There is evidence for beneficial effects of acute and long-term exercise interventions on several forms of memory, including procedural motor learning. In the present study we examined how performing a single bout of continuous moderate intensity aerobic exercise would impact motor skill acquisition and retention in young healthy adults, compared to a period of rest. We hypothesized that exercise would improve motor skill acquisition and retention, compared to motor practice alone.

MATERIALS AND METHODS

Sixteen healthy adults completed sessions of aerobic exercise or seated rest that were immediately followed by practice of a novel motor task (practice). Exercise consisted of 30 minutes of continuous cycling at 60% peak O2 uptake. Twenty-four hours after practice, we assessed motor learning with a no-exercise retention test (retention). We also quantified changes in offline motor memory consolidation, which occurred between practice and retention (offline). Tracking error was separated into indices of temporal precision and spatial accuracy.

RESULTS

There were no differences between conditions in the timing of movements during practice (p = 0.066), at retention (p = 0.761), or offline (p = 0.966). However, the exercise condition enabled participants to maintain spatial accuracy during practice (p = 0.477); whereas, following rest performance diminished (p = 0.050). There were no significant differences between conditions at retention (p = 0.532) or offline (p = 0.246).

DISCUSSION

An acute bout of moderate-intensity aerobic exercise facilitated the maintenance of motor performance during skill acquisition, but did not influence motor learning. Given past work showing that pairing high intensity exercise with skilled motor practice benefits learning, it seems plausible that intensity is a key modulator of the effects of acute aerobic exercise on changes in complex motor behavior. Further work is necessary to establish a dose-response relationship between aerobic exercise and motor learning.

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.

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.

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Compared tensor and tensor-free tractography methods in stroke participants

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Tensor-free method detected white matter tracts in more individuals with stroke

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Superior identification of white matter abnormalities with tensor-free method

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Relationship between white matter and motor outcome revealed with tensor-free method

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Tensor-free method is a sensitive tractography method for studying chronic stroke.

A single bout of high-intensity aerobic exercise facilitates response to paired associative stimulation and promotes sequence-specific implicit motor learning

The objectives of the present study were to evaluate the impact of a single bout of high-intensity aerobic exercise on 1) long-term potentiation (LTP)-like neuroplasticity via response to paired associative stimulation (PAS) and 2) the temporal and spatial components of sequence-specific implicit motor learning. Additionally, relationships between exercise-induced increases in systemic brain-derived neurotrophic factor (BDNF) and response to PAS and motor learning were evaluated. Sixteen young healthy participants completed six experimental sessions, including the following: 1) rest followed by PAS; 2) aerobic exercise followed by PAS; 3) rest followed by practice of a continuous tracking (CT) task and 4) a no-exercise 24-h retention test; and 5) aerobic exercise followed by CT task practice and 6) a no-exercise 24-h retention test. The CT task included an embedded repeated sequence allowing for evaluation of sequence-specific implicit learning. Slope of motor-evoked potential recruitment curves generated with transcranial magnetic stimulation showed larger increases when PAS was preceded by aerobic exercise (59.8% increase) compared with rest (14.2% increase, P = 0.02). Time lag of CT task performance on the repeated sequence improved under the aerobic exercise condition from early (-100.8 ms) to late practice (-75.2 ms, P < 0.001) and was maintained at retention (-79.2 ms, P = 0.004) but did not change under the rest condition (P > 0.16). Systemic BDNF increased on average by 3.4-fold following aerobic exercise (P = 0.003), but the changes did not relate to neurophysiological or behavioral measures (P > 0.42). These results indicate that a single bout of high-intensity aerobic exercise can prime LTP-like neuroplasticity and promote sequence-specific implicit motor learning.

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.

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.

Total intravenous anesthesia with a propofol-ketamine combination during coronary artery surgery

OBJECTIVE

To evaluate the cardiovascular effects of a propofol-ketamine combination in patients undergoing coronary artery surgery.

DESIGN

Prospective, randomized study.

SETTING

Tertiary care teaching hospital, single center.

PARTICIPANTS

Seventy-eight adult patients.

INTERVENTIONS

Patients were randomly allocated to receive propofol-ketamine for induction and maintenance of anesthesia (n = 36) or fentanyl-enflurane (controls, n = 42).

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and other variables were recorded during and after surgery and for 24 hours in the intensive care unit. Before cardiopulmonary bypass (CPB), there was similar incidence of treatment for hypotension (42% of patients in both groups), tachycardia (propofol-ketamine, 6%; controls, 5%), and myocardial ischemia (propofol-ketamine, 3%; controls, 12%). In the propofol-ketamine group, there was a decreased requirement for inotropic agents after CPB (22% of patients) compared with controls (49% of patients; p = 0.02). There was a reduced incidence of myocardial infarctions (creatine kinase myocardial band >133 U/L) in the propofol-ketamine group compared with the control group (0% v 14%; p = 0.02; Fisher's exact test). Patients in the propofol-ketamine group were more likely to have their tracheas extubated within 8 hours of arrival in the intensive care unit compared with controls (33% v 7%; p = 0.01; Cochran-Mantel-Haenzel test).

CONCLUSIONS

The propofol-ketamine combination was associated with a similar incidence of pre-CPB hypotension and ischemia, a decreased need for inotropes after CPB, an earlier time to tracheal extubation, and a reduced incidence of myocardial infarctions compared with controls.

Tranexamic acid reduces postbypass blood use: a double-blinded, prospective, randomized study of 210 patients

BACKGROUND

Pharmacologic intervention to minimize postbypass bleeding and blood product transfusions has received increasing attention for both medical and economic reasons.

METHODS

Two hundred ten patients were entered into a double-blinded, prospective, randomized study to receive either 10 g of fibrinolytic inhibitor tranexamic acid before incision (n = 104) or 250 mL of placebo saline solution (n = 106). All subjects requiring cardiopulmonary bypass were deemed suitable, including those having first-time coronary bypass grafting, valve replacement, and reoperation.

RESULTS

There were no statistically significant differences between the groups with respect to demographic or operative characteristics. The tranexamic acid group had a 48% reduction in 24-hour blood drainage (p < 0.001) and received 69% fewer total units of packed red blood cells, 83% fewer total units of plasma, and 75% fewer platelet transfusion units than controls. Only 13 of 104 tranexamic acid patients received blood products versus 33 of 106 controls (p < 0.001). The incidences of thrombotic complications, perioperative myocardial infarction, renal failure, and neurologic complications were not significantly different between the two groups. The tranexamic acid group had 0% mortality versus 1.9% for controls (not significant).

CONCLUSIONS

Tranexamic acid is safe and effective in reducing blood loss and blood use in a wide variety of cardiac surgical patients.

Atrial septal lipomatous hypertrophy and ischemic heart disease: an unusual presentation

Lipomatous hypertrophy of the interatrial septum consists of the abnormal accumulation of fatty tissue. We report a patient with unsuspected massive lipomatous hypertrophy of the interatrial septum scheduled to undergo coronary artery surgery. This patient had experienced atrial arrhythmias and obstructive symptoms preoperatively that were ascribed to her coronary artery disease (CAD). The perioperative anesthetic and surgical management of patients with lipomatous hypertrophy of the interatrial septum and CAD is discussed.

Amiodarone versus bretylium for suppression of reperfusion arrhythmias in dogs

Reperfusion arrhythmias are an important complication of interventions to limit infarct size. Recently, amiodarone has been shown to be rapidly effective in suppressing sustained, incessant ventricular tachycardia and ventricular fibrillation in this setting. This study evaluated the time course of arrhythmia suppression and comparative efficacy of amiodarone versus bretylium in a canine model of reperfusion arrhythmias. Of 23 dogs subjected to a Harris two-stage coronary artery ligation followed by release, 18 demonstrated clinically significant ventricular arrhythmias and received either intravenous amiodarone, 5 mg/kg (9 dogs), or intravenous bretylium, 5 mg/kg (9 dogs). Direct-current shocks for sustained ventricular tachycardia or ventricular fibrillation were administered as necessary. Amiodarone rapidly suppressed sustained ventricular tachycardia and ventricular fibrillation in this model with no dog in the amiodarone-treated group requiring cardioversion after completion of the 15-minute infusion versus 4 of 9 dogs in the bretylium-treated group (p less than 0.05). Amiodarone was more effective than bretylium in suppressing episodes of sustained ventricular tachycardia/ventricular fibrillation, episodes of nonsustained ventricular tachycardia, and premature ventricular complexes. The blood pressure and heart rate decreased more after amiodarone administration than after bretylium administration. We conclude that, in the canine reperfusion arrhythmia model, amiodarone is rapidly effective in suppressing ventricular arrhythmias and is more effective than bretylium.

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.

Long-term survival after chemoradiotherapy for locally advanced squamous cell carcinoma of the esophagus

Seven patients with locally far-advanced, inoperable, squamous cell cancer of the esophagus were given two cycles of concurrent radiation and chemotherapy. Each cycle consisted of 5-fluorouracil 1,000 mg/m2/day given as a continuous intravenous infusion over 96 hours, cisplatin 75 mg/m2 given as an intravenous bolus on day 1, and methotrexate 40 mg/m2 given as an intravenous bolus on days 8 and 15. Three thousand rads of radiation were given in 15 fractions between days 1 and 19. Six patients are evaluable for response. Symptomatic relief was obtained by all six and was complete in 4. Five patients achieved a complete response, and two remain alive and disease free. Five of the six evaluable patients survived for at least 12 months. Aggressive chemoradiotherapy may result in significant survival prolongation and symptomatic palliation in this poor-prognosis subset of patients with esophageal cancer.

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.

Impact of a surgical postgraduate course on undergraduate surgical performance

Postgraduate medical education generally has one of two basic goals: to improve general cognitive knowledge or to impart technical and management skills in a narrower area of medicine. Physicians invest enormous amounts of time and money in acquiring continued medical education, but there are little data on the objective benefits derived from such efforts. Because it is so difficult to make valid assessments of additions to cognitive knowledge gained by practicing surgeons, we studied the responses of a more homogeneous group, third- and fourth-year medical students, to an intensive four-day surgical course. These students were serving a surgical clerkship and were required to attend the course. Junior medical students who attended the course received higher scores on written examinations than their peers who did not participate in the course, but this did not reach statistical significance (P = .02). On objective tests, there was no difference between the scores of the fourth-year medical students. This report emphasizes the inherent difficulty in using objective criteria to measure courses.

Thoracic aortic rupture in patients with multisystem injuries

This report attempts to delineate management priorities in patients with thoracic aortic tears and severe multisystem trauma. Nineteen patients with a mean age of 40 years were treated after motor vehicle accidents. An average of five major systems were injured and the majority of patients sustained head injury, severe intra-abdominal injuries, and major fractures, in addition to aortic tears. Hypotension was present in 17 patients. Chest roentgenograms showed a widened mediastinum that subsequently led to angiography in 18 of the 19 patients. Of the 11 patients who required both an exploratory laparotomy for control of intra-abdominal hemorrhaging as well as a thoracotomy for the transected aorta, only four survived. Ten of 19 patients died of combined aortic and severe multisystem injuries. Death was caused by exsanguination in five patients, contusion in two, and by sepsis, head injury, and acute tamponade, respectively, in the remaining three patients. This review documents the need for aggressive aortography in patients with suspected thoracic aortic injuries. Procedural priorities have been outlined for treatment of patients with severe combined injuries to the abdomen and chest.

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.

Coronary artery bypass grafts: increased flow in the early postoperative period

The long-term outcome of coronary artery bypass operations is contingent upon the patency of aortocoronary bypass grafts. Flow measurements taken at operation may not truly reflect the capacity of the graft to carry glow because the heart may not have fully recovered from the consequences of ischemic arrest, despite the protective effects of hypothermic cardioplegia. During a three-year period, we observed increases of up to 200% in the flow rate of 8 of 11 saphenous vein grafts in 7 patients who underwent reoperation for bleeding or cardiac tamponade in the early postoperative period. At initial operation, flow rates ranged from 25 ml/min to 130 ml/min (mean value, 66.8 +/- 10.3 ml/min [standard error of the mean]). At reexploration, flow measurements ranged from 0 ml/min (graft clotted) to 260 ml/min (mean value, 110 +/- 22.8 ml/min). This difference was statistically significant (p less than 0.02). This study documents that flow rate measurements in saphenous vein aorotocoronary bypass grafts can increase in the early postoperative period although the exact mechanism by which this occurs is not known.

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.