Mean Wave Amplitude Research Articles

Applicability of using dynamic MRI to evaluate alleged cranial rhythmic impulse (CRI)

ObjectivesTo evaluate the feasibility of using dynamic MRI to measure the features of cranial rhythmic impulse (CRI).Design and settingFifteen healthy participants (9 females and 6 males, aged 25 to 77) underwent dynamic MRI in a sagittal T2 HASTE view at a rate of 0.60 Hz for 30 s. The MRI videos were analyzed using video tracking software. Three points were marked: the glabella, the midpoint of the sella turcica, and a symmetrical point of the glabella on the occiput. The distances between these points were measured across 46 frames. Amplitudes and rates of asymmetrical CRI waves were calculated using Excel formulas.ResultsThe mean wave frequencies were 5.65 Hz for the anteroposterior distance, 6.2 Hz from sella turcica to occiput, and 6.76 Hz from sella turcica to glabella. The mean wave amplitudes were 0.39 mm, 0.6 mm, and 0.49 mm for the respective distances. Both intraclass correlation coefficients (ICC) and reliability coefficient (R) indicated excellent reliability (R, ICC > 0.90). The technical error of measurement (TEM) exceeded 1 mm for the anteroposterior and sella-to-occiput distances, while it was 0.32 mm for the sella-to-glabella distance.ConclusionsDynamic MRI demonstrates potential in measuring the features of CRI, particularly in assessing CRI wave rate. While the ICC values indicate high reliability, the TEM values suggest that using MRI to measure CRI wave amplitude may only be dependable for the distance from the sella to the glabella.

A method for calculating the grand average of a set of auditory brain-stem responses.

To calculate a grand average waveform for a set of auditory brain-stem responses (ABRs), no generally accepted method exists. Here, we evaluate a new method using temporal adjustment of the underlying ABRs. Compared to a method without temporal adjustment, the new method results in higher amplitudes of the individual waves in the grand average. The grand average produced by the method better represents the group mean wave-amplitudes because it reduces smearing of the individual waves caused by inter-subject latency variability.

Intracranial pulse pressure amplitude as an indicator of intracranial compliance: observations in symptomatic children with Chiari malformation type I.

Reduced intracranial compliance (ICC) may be an important factor in the pathophysiology of Chiari malformation type I (CM-I). However, direct measurement of ICC is controversial because of its invasiveness, particularly in children. Instead, ICC may be estimated from continuous measurements of intracranial pressure (ICP), where the metric mean wave amplitude (MWA) has been found to be more useful as a surrogate marker of ICC than mean ICP. This observational study investigated the distribution of MWA and mean ICP in symptomatic children with CM-I, as well as their association with clinical and radiological findings. From a consecutive series of children treated for CM-I at a single institution between 2006 and 2023, the authors analyzed ICP scores in those who underwent an overnight preoperative ICP recording in which MWA was calculated. Clinical and radiological data were retrieved from the patient records. Thirty-seven children (mean age 12.4 ± 3.6 years) with symptomatic CM-I were identified. From the overnight ICP measurements, the average MWA was 5.2 ± 1.3 mm Hg: 56% of children had an abnormal MWA (> 5 mm Hg) and 33% had a borderline MWA (4-5 mm Hg). In contrast, the average mean ICP was 9.7 ± 4.1 mm Hg: 8% of children had an abnormal mean ICP (> 15 mm Hg) and 41% had a borderline mean ICP (10-15 mm Hg). Thus, more children were found to have an abnormal MWA than an abnormal mean ICP (p < 0.001). MWA was significantly higher in the subgroup of children with medullary compression in the foramen magnum, as seen on MRI, than in those without (5.6 ± 1.0 mm Hg vs 4.7 ± 1.4 mm Hg, p = 0.03), whereas a similar difference was not observed for mean ICP (9.9 ± 4.6 mm Hg vs 9.7 ± 3.7 mm Hg, p = 0.889). In this cohort of symptomatic children with CM-I, MWA was more frequently abnormal than mean ICP, with a clinically significant discrepancy in half of the patients. Moreover, MWA was significantly higher in patients with medullary compression. Based on these findings, the authors' interpretation is that in children with CM-I, the ICC may be reduced, as indicated by increased MWA, even though the mean ICP is within normal thresholds.

OGBN P36 Surgical Consideration in Patients with Ineffective Oesophagus: Implications for Low Risk of Dysphagia and Suitability for Antireflux Operation

Abstract Background Ineffective oesophageal motility (IOM) is a minor motility disorder that is commonly found in patients. The IOM diagnosis is based on heterogenous combination of failed peristalsis, weak peristalsis activity and peristaltic defects that are observed during the stimulation to 5mL standard water swallows. IOM is implicated to post-surgical dysphagia and therefore influences the surgical decision making. This paper will address this topic. Methods A retrospective review was conducted on patients who underwent oesophageal high-resolution manometry (HRM) between March and May 2023. The diagnosis of IOM was based on the international Chicago Classification guideline (version 4.0). Patients' oesophageal motility profiles were assessed for peristaltic reservation (PR) and oesophageal contractile mean wave amplitude (MWA). PR &amp;gt;100% in IOM patients indicates low risk of dysphagia after laparoscopic Nissen fundoplication (LNF). Similarly, normal MWA indicate a low risk of dysphagia in considering patients for Magnetic Sphincter Augmentation (MSA). Results 120/270 patients (44.4%) were diagnosed with IOM (female:male=86:34, median age 52 years old). Mean PR in IOM patients was 217.8% [95%CI:181.2%-254.4%] with 60.8% demonstrating PR &amp;gt;100%. Average MWA found in IOM patients was 40.8mmHg (95%CI:38.5mmHg-43.1mmHg) with 38.3% demonstrating normal MWA. 13.3% (16/120) of patients did not invoke peristalsis on MWS, but 6 of the 16 patients showed normal MWA. 24.2% (29/120) patients demonstrated PR &amp;gt;100% and normal MWA. 14.2% (17/120) of patients showed adequate PR and weak MWA and pose risk of postsurgical dysphagia. 75% (90/120) of patients with IOM were suitable for at least one antireflux operation. Conclusions Approximately half of the oesophageal physiology patients have IOM and three-quarters of these patients are suitable for at least one form surgical intervention with low risk postsurgical dysphagia. Only 14.2% of patients with IOM pose a risk of post-surgical dysphagia. The overall findings suggests that surgical intervention may be a viable option for patients with IOM that could potentially improve their quality of life and prevent reflux oesophagitis/pre-cancerous Barrett’s oesophagus. This study was limited by not investigating the relationship between IOM pathophysiology and the reflux oesophagitis severity grade.

Low versus High Intracranial Compliance in Adult Patients with Chiari Malformation Type 1–Comparison of Long-Term Outcome After Tailored Treatment

In patients with Chiari malformation type 1 (CMI) presenting with low intracranial compliance (ICC), foramen magnum decompression (FMD) often fails and the complication rate may be higher. We therefore routinely perform a preoperative assessment of ICC from intracranial pressure measurement. Patients with low ICC are treated with ventriculoperitoneal shunt (VPS) before FMD. In this study, we assess the outcome of patients with low ICC, compared with patients with high ICC treated with FMD alone. We reviewed the clinical and radiologic data of all consecutive patients with CMI treated between April 2008 and June 2021. ICC was assessed by overnight measurement of the pulsatile intracranial pressure: mean wave amplitude (MWA) above a previously defined threshold for abnormality was considered a surrogate marker for low ICC. The outcome was scored by Chicago Chiari Outcome Scale. Of 73 patients, 23 with low ICC (average MWA 6.8 ± 1.2 mm Hg) received VPS before FMD, whereas 50 with high ICC (average MWA 4.4 ± 1.0 mm Hg) received only FMD. After a mean follow-up of 78.7 ± 41.4 months, 96% of all patients subjectively improved. The mean Chicago Chiari Outcome Scale score was 13.1 ± 2.2. Enlargement of cerebrospinal fluid space in the foramen magnum was achieved in 95% and regression of syringomyelia in 74% of cases. We found no significant difference in outcome between the patients with low and high ICC. By identifying patients with CMI associated with low ICC and tailoring their treatment by VPS before FMD, we achieved favorable clinical and radiologic outcomes comparable to those with high ICC.

Effect of doctor-patient news-induced moral judgments on pain empathy for doctors and patients in China.

Pain empathy's preferential nature tends to trigger prejudice and intergroup conflicts. Given the current degree of proliferation of doctor-patient conflict news in China, this study aims to determine whether readers of doctor-patient news-initiated moral judgments prefer pain empathy for doctors or patients. This study utilized localized doctor-patient news with high or low moral performance (based on morality ratings of patients' behaviors) as moral-judgment-eliciting materials, and painful pictures as pain empathy-eliciting materials. The event-related potential (ERP) technique was utilized to assess moral judgment's effect on the cognitive empathy component and to investigate electroencephalogram signals' accuracy in classifying four brain response patterns when facing doctor or patient is experiencing or not experiencing pain. Under low moral text material, participants exhibited smaller mean wave amplitude of positive 300 (P3) and late positive potential (LPP) to painful pictures than non-painful pictures when facing patients; under high moral text material, participants exhibited larger mean wave amplitude of P3 and LPP to painful pictures than non-painful pictures when facing doctors. Electroencephalogram (EEG) signals' classification accuracy was significant in 0-1,000 ms in both high and low moral judgments, but the classification accuracy was higher in low moral judgments in some cognitive empathy stages (0.51, 0.53-0.55, 0.66-0.79, and 0.88-1 s). Under low moral judgment, individuals pay less attention to the patient's (perpetrator's) pain; under high moral judgment, individuals empathize with the doctor (the person praised), showing that news-induced moral judgment can sway readers' empathy for different social groups. In cognitive empathy, individuals' brain representations are more discriminatory under low than high moral judgments when confronted with pain by doctors and patients, which provides insight into objectively recognizing group bias.

Statistical Study of the Relationship Between Pi1/2‐Band Wave Powers and Firehose Instability Criterion During Fast Flows in the Magnetotail Plasma Sheet

AbstractFast flows play a significant role in the transport of magnetic flux, mass, and energy in the terrestrial plasma sheet. Abundant wave activities occur during fast flows, however, what determines their wave powers is not fully understood. Here, we statistically investigate the relation of Pi1‐band (10–40 s) and Pi2‐band (40–150 s) mean wave amplitudes (MWAs) to the threshold of firehose instabilities during fast flows based on observations of the Magnetospheric Multiscale mission. To reduce the effect of dipolarization processes on the MWAs, we only analyze the fast flows with an average BZ &lt; 3 nT, where BZ is the Z component of the magnetic field in the geocentric solar magnetospheric coordinate system. The compressional and transverse components of the magnetic field fluctuations during fast flows are mostly comparable for each frequency range. The probability of reaching firehose unstable condition tends to be larger for the faster fast flow. The Pi1/2‐band MWAs tend to be larger as the probability of the firehose unstable condition near the neutral sheet is larger for the fast flows with a certain average velocity near the neutral sheet, although they have a weak relationship. Our results suggest that the firehose instability is a possible factor to affect the Pi1/2‐band MWAs during the fast flow in the magnetotail current sheet.

A New Perspective on the Pathophysiology of Idiopathic Intracranial Hypertension: Role of the Glia-Neuro-Vascular Interface.

Idiopathic intracranial hypertension (IIH) is a neurological disease characterized by symptoms and signs of increased intracranial pressure (ICP) of unknown cause. Most attention has been given to the role of cerebrospinal fluid (CSF) disturbance and intracranial venous hypertension caused by sinus vein stenosis. We previously proposed that key pathophysiological processes take place within the brain at the glia-neuro-vascular interface. However, the relative importance of the proposed mechanisms in IIH disease remains unknown. Modern treatment regimens aim to reduce intracranial CSF and venous pressures, but a substantial proportion of patients experience lasting complaints. In 2010, the first author established a database for the prospective collection of information from individuals being assessed for IIH. The database incorporates clinical, imaging, physiological, and biological data, and information about treatment/outcome. This study retrieved information from the database, asking the following research questions: In IIH subjects responding to shunt surgery, what is the occurrence of signs of CSF disturbance, sinus vein stenosis, intracranial hypertension, and microscopic evidence of structural abnormalities at the glia-neuro-vascular interface? Secondarily, do semi-quantitative measures of abnormal ultrastructure at the glia-neurovascular differ between subjects with definite IIH and non-IIH (reference) subjects? The study included 13 patients with IIH who fulfilled the diagnostic criteria and who improved following shunt surgery, i.e., patients with definite IIH. Comparisons were done regarding magnetic resonance imaging (MRI) findings, pulsatile and static ICP scores, and immune-histochemistry microscopy. Among these 13 IIH subjects, 6/13 (46%) of patients presented with magnetic resonance imaging (MRI) signs of CSF disturbance (empty sella and/or distended perioptic subarachnoid spaces), 0/13 (0%) of patients with IIH had MRI signs of sinus vein stenosis, 13/13 (100%) of patients with IIH presented with abnormal preoperative pulsatile ICP [overnight mean ICP wave amplitude (MWA) above thresholds], 3/13 (23%) patients showed abnormal static ICP (overnight mean ICP above threshold), and 12/13 (92%) of patients with IIH showed abnormal structural changes at the glia-neuro-vascular interface. Comparisons of semi-quantitative structural variables between IIH and aged- and gender-matched reference (REF) subjects showed IIH abnormalities in glial cells, neurons, and capillaries. The present data suggest a key role of disease processes affecting the glia-neuro-vascular interface.

The role of pulsatile and static intracranial pressure measurements in the management of children with craniosynostosis-an institutional experience from 49 patients.

Although measurement of intracranial pressure (ICP) has occasionally been utilized in children with craniosynostosis (CSS), data on parameters of pulsatile ICP in CSS are still lacking, and the role of pulsatile ICP measurements in the management of CSS is not well established. From our department's database, we retrieved the data from children in whom the measurement of static and pulsatile ICP was a part of the diagnostic work-up in different clinical situations related to CSS. Both clinical and ICP data were retrospectively reviewed and analyzed. We identified 49 children with CSS, median age 4.4years (range 0.2-18.9), in whom a total of 67 diagnostic ICP measurements were undertaken between 2002 and 2014. The CSS was syndromal in 23 cases. The rationale for ICP measurement was a question of indication for cranial vault expansion surgery (CVES) in 12 patients (Group 1), of its timing in 10 patients (Group 2), of suspected abnormally elevated ICP or hydrocephalus in 11 patients (Group 3), of indication for repeated CVES in 13 patients (Group 4), or shunt dysfunction in three patients (Group 5). The average mean ICP for the whole cohort was 15.1 ± 5.5mmHg and mean wave amplitude (MWA) 5.3 ± 2.2mmHg. There was no significant difference in ICP parameters when compared between Groups 1-5. Fundoscopy revealed papilledema in five out of 32 children (15.6%). There were significantly higher parameters of pulsatile ICP (MWA) in patients with papilledema, but no statistically significant difference in parameters of static ICP. In this cohort of pediatric patients with CSS presenting with various diagnostic challenges, we found the diagnostic measurement of static and pulsatile ICP useful in selecting the optimal treatment modality and timing of surgery. Papilledema was associated with elevated pulsatile ICP, a parameter that in previous studies has been shown to correlate with impaired intracranial compliance.

Free rings of bouncing droplets: stability and dynamics

Abstract

CORRELATION BETWEEN SEVERITY OF EROSIVE REFLUX ESOPHAGITIS AND ITS MANOMETRIC FINDINGS IN A TERTIARY HOSPITAL AT EAST COAST, PENINSULAR MALAYSIA.

The burden of Gastroesophageal Reflux Disease, GERD in Asia-Pacific region is increasing. Objectives: To evaluate the manometric finding in erosive reflux esophagitis and its correlation with severity among patients who were seen at Surgical Department, Hospital Tengku Ampuan Afzan (HTAA), Kuantan. Methodology: This was a cross sectional study which involved 60 patients seen from September 2012 until January 2014. Patients were required to fill up the Reflux Disease Specific Questionaire and subsequently underwent manometric evaluation. Descriptive statistics and Pearson’s correlation were applied using SPSS version 18.0. Results: There was no correlation between the severity of Erosive Reflux Disease with the Lower Esophageal Sphincter Pressure or esophageal motility. There was positive correlation (r = + 0.54) between severity of Erosive Reflux Disease and velocity variables of esophageal motility but it was not statistically significant. Discussion: Few experts opined that Erosive Reflux Disease is associated with esophageal dysmotility but there was no specific pattern of esophageal mean wave amplitude in our study sample. The limitation of this study was the sample’s selection and size. Thus, we need further study with better methodology and sample size. Conclusion: In conclusion, there was no significant correlation between the severity of Erosive Reflux Esophagitis on the Lower Esophageal Sphincter pressure and the esophageal motility

Magnetic Sphincter Augmentation and Postoperative Dysphagia: Characterization, Clinical Risk Factors, and Management

IntroductionMagnetic sphincter augmentation (MSA) results in less severe side effects compared with Nissen fundoplication, but dysphagia remains the most common side effect reported by patients after MSA. This study aimed to characterize and review the management of postoperative dysphagia and identify the preoperative factors that predict persistent dysphagia after MSA. Material and MethodsThis is a retrospective review of prospectively collected data of patients who underwent MSA between 2013 and 2018. Preoperative objective evaluation included upper endoscopy, esophagram, high-resolution impedance manometry (HRIM), and esophageal pH testing. Postoperative persistent dysphagia was defined as a postoperative score of > 3 for the dysphagia-specific item within the GERD-HRQL at a minimum of 3 months following MSA. A timeline of dysphagia and dilation rates was constructed and correlated with the evolution of our patient management practices and modifications in surgical technique. ResultsA total of 380 patients underwent MSA, at a mean (SD) follow up of 11.5 (8.7) months, 59 (15.5%) patients were experiencing persistent dysphagia. Thirty-one percent of patients required at least one dilation for dysphagia or chest pain and the overall response rate to this procedure was 67%, 7 (1.8%) patients required device removal specifically for dysphagia. Independent predictors of persistent dysphagia based on logistic regression model included (1) absence of a large hernia (OR 2.86 (95% CI 1.08–7.57, p = 0.035)); (2) the presence of preoperative dysphagia (OR 2.19 (95% CI 1.05–4.58, p = 0.037)); and (3) having less than 80% peristaltic contractions on HRIM (OR 2.50 (95% CI 1.09–5.73, p = 0.031)). Graded cutoffs of distal contractile integral (DCI), mean wave amplitude, DeMeester score, sex, and body mass index were evaluated within the model and did not predict postoperative dysphagia. Frequent eating after surgery, avoidance of early dilation, and increase in the size of the LINX device selected decreased the need for dilation. ConclusionIn a large cohort of patients who underwent MSA, we report 15.5% rate of persistent postoperative dysphagia. The overall response rate to dilation therapy is 67%, and the efficacy of dilation with each subsequent procedure reduces. Patients with normal hiatal anatomy, significant preoperative dysphagia, and less than 80% peristaltic contractions of the smooth muscle portion of the esophagus should be counseled that they have an increased risk for persistent postoperative dysphagia.

Intracranial volume versus static and pulsatile intracranial pressure values in children with craniosynostosis.

Reduced intracranial volume (ICV) and raised intracranial pressure (ICP) are assumed to be principal pathophysiological mechanisms in childhood craniosynostosis. This study examined the association between ICV and ICP and whether ICV can be used to estimate the ICP. The authors analyzed ICV and ICP measurements from children with craniosynostosis without concurrent hydrocephalus and from age-matched individuals without craniosynostosis who underwent diagnostic ICP measurement. The study included 19 children with craniosynostosis (mean age 2.2 ± 1.9 years) and 12 reference individuals without craniosynostosis (mean age 2.5 ± 1.6 years). There was no difference in ICV between the patient and reference cohorts. Both mean ICP (17.1 ± 5.6 mm Hg) and mean wave amplitude (5.9 ± 2.6 mm Hg) were higher in the patient cohort. The results disclosed no significant association between ICV and ICP values in the patient or reference cohorts, and no association was seen between change in ICV and ICP values after cranial vault expansion surgery (CVES) in 5 children in whom ICV and ICP were measured before and after CVES. In this cohort of children with craniosynostosis, there was no significant association between ICV and ICP values prior to CVES and no significant association between change in ICV and ICP values after CVES in a subset of patients. Therefore, ICV could not reliably estimate the ICP values. The authors suggest that intracranial hypertension in childhood craniosynostosis may not be caused by reduced ICV alone but rather by a distorted relationship between ICV and the volume of intracranial content (brain tissue, CSF, and blood).

Evolution of gastroesophageal reflux after laparoscopic vertical gastrectomy. A radiographic, manometric and pH-metric study.

the relationship between laparoscopic vertical gastrectomy (LVG) and gastroesophageal reflux (GER) is still controversial. Therefore, its study is of great interest in order to obtain definitive conclusions. The goal of the study was to establish whether LVG modifies pH-metric GER in obese patients and to analyze the associated factors. the first 26 patients who underwent LVG in our institution were enrolled in the study. A barium swallow, 24-hour ambulatory pH-metry and four-channel intraluminal esophageal manometry (IEM) were all performed before and one year after surgery. among the pH-metric data, there was a significant increase in the DeMeester index after the procedure (p = 0.028), while other parameters remained unchanged. Furthermore, 50% of patients with preoperative pH-metric GER had normal values at one year after surgery. IEM showed a decrease in lower esophageal sphincter (LES) pressure and in the mean wave amplitude at the distal third of the esophagus (p = 0.007 and p = 0.025, respectively). The rate of newly-developed hiatal hernias in the radiographic study was 36.4%. LVG mildly increases GER, which is likely related to the development of hiatal hernias and a decrease in LES pressure and esophageal sweep. However, LVG should not be contraindicated for patients with preoperative pH-metric GER, as this may clear after the procedure.

Utility of the Tympanic Membrane Pressure Waveform for Non-invasive Estimation of The Intracranial Pressure Waveform

Time domain analysis of the intracranial pressure (ICP) waveform provides important information about the intracranial pressure-volume reserve capacity. The aim here was to explore whether the tympanic membrane pressure (TMP) waveform can be used to non-invasively estimate the ICP waveform. Simultaneous invasive ICP and non-invasive TMP signals were measured in a total of 28 individuals who underwent invasive ICP measurements as a part of their clinical work up (surveillance after subarachnoid hemorrhage in 9 individuals and diagnostic for CSF circulation disorders in 19 individuals). For each individual, a transfer function estimate between the invasive ICP and non-invasive TMP signals was established in order to explore the potential of the method. To validate the results, ICP waveform parameters including the mean wave amplitude (MWA) were computed in the time domain for both the ICP estimates and the invasively measured ICP. The patient-specific non-invasive ICP signals predicted MWA rather satisfactorily in 4/28 individuals (14%). In these four patients the differences between original and estimated MWA were <1.0 mmHg in more than 50% of observations, and <0.5 mmHg in more than 20% of observations. The study further disclosed that the cochlear aqueduct worked as a physical lowpass filter.

Routine esophageal manometry is not useful in patients with normal videoesophagram.

Videoesophagram (VEG) and esophageal manometry (EM) are components of the preoperative evaluation for foregut surgery. EM is able to identify motility disorders and diminished contractility that may alter surgical planning. However, there are no clearly defined criteria to guide this. Reliable manometry is not always easily obtained, and therefore its necessity in routine preoperative evaluation is unclear. We hypothesized that if a patient has normal videoesophagram, manometry does not reveal clinically significant esophageal dysfunction. We reviewed patients who underwent protocolized videoesophagram and manometry at our institution. Measures of esophageal motility including the mean distal contractile integral (DCI), mean wave amplitude (MWA), and percent of peristaltic swallows (PPS) were analyzed. The Chicago Classification was used for diagnostic criteria of motility disorders. Normal VEG was defined as stasis of liquid barium on less than three of five swallows. There were 418 patients included. 231 patients (55%) had a normal VEG, and 187 patients (45%) had an abnormal VEG. In the normal VEG group, only 2/231 (0.9%) patients had both abnormal DCI and PPS, 1/231 (0.4%) patients had both abnormal DCI and MWA and no patients had both abnormal MWA and PPS. There were no patients with achalasia or absent contractility and 1 patient with ineffective esophageal motility (IEM) in the normal VEG group. This was significantly different from the abnormal VEG group which included 4 patients with achalasia, 1 with absent contractility and 22 with IEM (p < 0.0001). The negative predictive value of VEG was 99.6% and the sensitivity was 96.4%. A normal videoesophagram reliably excluded the presence of clinically significant esophageal dysmotility that would alter surgical planning. Routine manometry is not warranted in patients with normal videoesophagram, and should be reserved for patients with abnormal VEG.

The role of preoperative high resolution manometry in predicting dysphagia after laparoscopic Nissen fundoplication.

Laparoscopic fundoplication is an accepted surgical management of refractory gastro-esophageal reflux disease (GERD). The use of high resolution esophageal manometry (HRM) in preoperative evaluation is often applied to determine the degree of fundoplication to optimize reflux control while minimizing adverse sequela of postoperative dysphagia. Assess the role of preoperative HRM in predicting surgical outcomes, specifically risk assessment of postoperative dysphagia and quality of life, among patients receiving laparoscopic Nissen fundoplication for GERD with immediate postoperative (< 4 weeks clinic), short-term (3-month clinic), and long-term (34 ± 10.4 months of telephone) follow-up. Retrospective analysis of 146 patients over the age of 18 who received laparoscopic Nissen fundoplication at University of Vermont Medical Center from July 1, 2011 through December 31, 2014 was completed, of which 52 patients with preoperative HRM met inclusion criteria. Exclusion criteria included history of: (a) named esophageal motility disorder or aperistalsis; (b) esophageal cancer; (c) paraesophageal hernia noted intraoperatively. Elevated basal integrated relaxation pressure (IRP), which is the mean of 4 s of maximal lower esophageal sphincter (LES) relaxation within 10s of swallowing, was significantly correlated with worsened severity of post-fundoplication dysphagia (r = 0.572, p < 0.0001 with sensitivity and NPV of 100%) and poorer quality of life (r = 0.348, p = 0.018) at up to 3-years follow-up. The presence of preoperative dysphagia was independently related to post-fundoplication dysphagia at short-term (r = 0.403, p = 0.018) and long-term follow-up (r = 0.415, p = 0.005). Also, both elevated mean wave amplitude (r=-0.397, p = 0.006) and distal contractile integral (DCI) (r = - 0.294, p = 0.047) were significantly, inversely correlated to post-Nissen dysphagia. No significant association was demonstrated between other preoperative HRM parameters and surgical outcomes. Inadequacy of lower esophageal sphincter (LES) relaxation with swallowing as delineated by elevated IRP is significantly predictive of worse long-term postoperative outcomes including dysphagia and quality of life scores. Further assessment of tailoring anti-reflux surgical approach with partial vs. total fundoplication to functionally resistant LES is required.

Combined scattering loss of radiation belt relativistic electrons by simultaneous three‐band EMIC waves: A case study

AbstractMultiband electromagnetic ion cyclotron (EMIC) waves can drive efficient scattering loss of radiation belt relativistic electrons. However, it is statistically uncommon to capture the three bands of EMIC waves concurrently. Utilizing data from the Electric and Magnetic Field Instrument Suite and Integrated Science magnetometer onboard Van Allen Probe A, we report the simultaneous presence of three (H+, He+, and O+) emission bands in an EMIC wave event, which provides an opportunity to look into the combined scattering effect of all EMIC emissions and the relative roles of each band in diffusing radiation belt relativistic electrons under realistic circumstances. Our quantitative results, obtained by quasi‐linear diffusion rate computations and 1‐D pure pitch angle diffusion simulations, demonstrate that the combined resonant scattering by the simultaneous three‐band EMIC waves is overall dominated by He+ band wave diffusion, mainly due to its dominance over the wave power (the mean wave amplitudes are approximately 0.4 nT, 1.6 nT, and 0.15 nT for H+, He+, and O+ bands, respectively). Near the loss cone, while 2–3 MeV electrons undergo pitch angle scattering at a rate of the order of 10−6–10−5 s−1, 5–10 MeV electrons can be diffused more efficiently at a rate of the order of 10−3–10−2 s−1, which approaches the strong diffusion level and results in a moderately or heavily filled loss cone for the atmospheric loss. The corresponding electron loss timescales (i.e., lifetimes) vary from several days at the energies of ~2 MeV to less than 1 h at ~10 MeV. This case study indicates the leading contribution of He+ band waves to radiation belt relativistic electron losses during the coexistence of three EMIC wave bands and suggests that the roles of different EMIC wave bands in the relativistic electron dynamics should be carefully incorporated in future modeling efforts.

The correlation between pulsatile intracranial pressure and indices of intracranial pressure-volume reserve capacity: results from ventricular infusion testing.

OBJECTIVE The objective of this study was to examine how pulsatile and static intracranial pressure (ICP) scores correlate with indices of intracranial pressure-volume reserve capacity, i.e., intracranial elastance (ICE) and intracranial compliance (ICC), as determined during ventricular infusion testing. METHODS All patients undergoing ventricular infusion testing and overnight ICP monitoring during the 6-year period from 2007 to 2012 were included in the study. Clinical data were retrieved from a quality registry, and the ventricular infusion pressure data and ICP scores were retrieved from a pressure database. The ICE and ICC (= 1/ICE) were computed during the infusion phase of the infusion test. RESULTS During the period from 2007 to 2012, 82 patients with possible treatment-dependent hydrocephalus underwent ventricular infusion testing within the department of neurosurgery. The infusion tests revealed a highly significant positive correlation between ICE and the pulsatile ICP scores mean wave amplitude (MWA) and rise-time coefficient (RTC), and the static ICP score mean ICP. The ICE was negatively associated with linear measures of ventricular size. The overnight ICP recordings revealed significantly increased MWA (> 4 mm Hg) and RTC (> 20 mm Hg/sec) values in patients with impaired ICC (< 0.5 ml/mm Hg). CONCLUSIONS In this study cohort, there was a significant positive correlation between pulsatile ICP and ICE measured during ventricular infusion testing. In patients with impaired ICC during infusion testing (ICC < 0.5 ml/mm Hg), overnight ICP recordings showed increased pulsatile ICP (MWA > 4 mm Hg, RTC > 20 mm Hg/sec), but not increased mean ICP (< 10-15 mm Hg). The present data support the assumption that pulsatile ICP (MWA and RTC) may serve as substitute markers of pressure-volume reserve capacity, i.e., ICE and ICC.

Perioperative monitoring of pulsatile and static intracranial pressure in patients with Chiari malformation type 1 undergoing foramen magnum decompression.

Patients with Chiari malformation type 1 (CMI) often present with elevated pulsatile and static intracranial pressure (ICP). The preferred treatment of CMI, foramen magnum decompression (FMD), is assumed to normalise ICP and craniospinal pressure dissociation. In order to further explore the mechanisms behind FMD, the present study investigated whether or not pulsatile and static ICP normalises immediately after FMD. The study included CMI patients undergoing FMD with perioperative ICP monitoring as a part of clinical management. The pulsatile and static ICP scores were retrieved from the department's ICP database, and the clinical and radiological data from the patient records. Eleven patients were included in the study. During the first 3 days following FMD, mixed model analysis revealed no significant time-dependent differences of preoperatively elevated either pulsatile (mean wave amplitude, MWA; p = 0.85) and/or static (mean ICP, p = 0.90) ICP. Percentage of mean ICP >15 mmHg increased during days 2 and 3 after FMD. Two patients from the present series had to receive ventriculoperitoneal shunt after FMD in the early postoperative period. The present observations suggest that anatomical restoration of cerebrospinal fluid pathways by FMD does not lead to immediate normalisation of preoperatively altered pulsatile and static ICP in patients with CMI. This finding may explain persistent symptoms during the early period after FMD.