Network dynamics predict improvement in working memory performance following donepezil administration in healthy young adults.

Attentional selection in the context of goal-directed behavior involves top-down modulation to enhance the contrast between relevant and irrelevant stimuli via enhancement and suppression of sensory cortical activity. Acetylcholine (ACh) is believed to be involved mechanistically in such attention processes. The objective of the current study was to examine the effects of donepezil, a cholinesterase inhibitor that increases synaptic levels of ACh, on the relationship between performance and network dynamics during a visual working memory (WM) task involving relevant and irrelevant stimuli. Electroencephalogram (EEG) activity was recorded in 14 healthy young adults while they performed a selective face/scene working memory task. Each participant received either placebo or donepezil (5mg, orally) on two different visits in a double-blinded study. To investigate the effects of donepezil on brain network dynamics we utilized a novel EEG-based Brain Network Activation (BNA) analysis method that isolates location-time-frequency interrelations among event-related potential (ERP) peaks and extracts condition-specific networks. The activation level of the network modulated by donepezil, reflected in terms of the degree of its dynamical organization, was positively correlated with WM performance. Further analyses revealed that the frontal-posterior theta-alpha sub-network comprised the critical regions whose activation level correlated with beneficial effects on cognitive performance. These results indicate that condition-specific EEG network analysis could potentially serve to predict beneficial effects of therapeutic treatment in working memory.

Surgical management of metastatic spinal tumors.

BACKGROUND: The spine is the most common site of skeletal metastases. The evolution of surgical methods, medical treatment, and radiation therapy has led to improved survival, functional status, and quality of life for patients with cancer. The role of surgery in the treatment of patients with spinal metastases has evolved over time. METHODS: A review of publications describing the role of open surgery and vertebroplasty was performed and the results are summarized. RESULTS: The treatment goals of spinal metastases include the preservation and restoration of neurologic function and spinal stability. Modern imaging modalities provide accurate methods of tumor diagnosis. A variety of approaches and stabilization techniques are available and should be tailored to the location of the tumor and systemic comorbidities. CONCLUSIONS: As part of multidisciplinary treatment that includes radiation therapy and chemotherapy, surgery provides an effective method of restoration and preservation of neurologic function and spinal stability for patients with metastatic spinal tumors.

A novel electroencephalography-based tool for objective assessment of network dynamics activated by nociceptive stimuli.

BACKGROUND: Pain perception is typically assessed using subjective measures; an objective measure of the response to pain would be valuable. In this study, Brain Network Activation (BNA), a novel multivariate pattern analysis and scoring algorithm, was applied to event-related potentials (ERPs) elicited by cortical responses to brief heat stimuli. Objectives of this study were to evaluate the utility of BNA as a quantitative and qualitative measure of cortical response to pain. METHODS: Contact Heat Evoked Potentials (CHEPs) data were collected from 17 healthy, right-handed volunteers (10 M, 7F) using 5 different temperatures (35, 41, 46, 49 and 52 °C). A set of spatio-temporal activity patterns common to all the subjects in the group (Reference Brain Network Model; RBNM) was generated using the BNA algorithm, based on evoked responses at 52 °C. RESULTS: Frame by frame 'unfolding' of the brain network across time showed qualitative differences between responses to painful and non-painful stimuli. Brain network activation scores were shown to be a better indicator of the individual's sensitivity to pain when compared to subjective pain ratings. Additionally, BNA scores correlated significantly with temperature, demonstrated good test-retest reliability, as well as a high degree of sensitivity, specificity and accuracy in correctly categorizing subjects who reported stimuli as painful. CONCLUSIONS: These results may provide evidence that the multivariate analysis performed with BNA may be useful as a quantitative, temporally sensitive tool for assessment of pain perception.

Transient failure of opening of the lower oesophageal sphincter on upright oesophagrams: radiographic and clinical findings.

The purpose of our study was to determine the frequency, radiographic features, and clinical importance of transient failure of opening of the lower oesophageal sphincter (LOS) on upright double-contrast views of the oesophagus. A computerized search of radiology records identified 16 patients who had transient failure of opening of the LOS on upright views from biphasic oesophagrams or upper gastrointestinal tract examinations using high-density barium but normal opening of the LOS on prone views using low-density barium. The radiographic findings were reviewed and correlated with the clinical and manometric findings. In all cases, barium studies revealed tapered, beaklike narrowing of the distal oesophagus on upright double-contrast views, with a normal-appearing distal oesophagus, normal opening of the LOS, and intact peristalsis on prone single-contrast views. Only seven patients (44%) had dysphagia. Five of these patients had clinical follow-up, and the dysphagia improved or resolved without specific treatment for LOS dysfunction in four. The remaining patient had persistent dysphagia, but this individual had polymyositis as the likely cause for his dysphagia. Manometry revealed incomplete relaxation of the LOS in two patients and normal relaxation in one. Our experience suggests that failure of opening of the LOS may be observed as a transient finding of little clinical importance on upright double-contrast views of the oesophagus using high-density barium, with normal opening of the LOS on prone single-contrast views using low-density barium. It is important to be aware of this finding, so that it is not mistaken for achalasia or other abnormalities of the distal oesophagus.

Glutaraldehyde-induced esophageal injury. Histologic study of laboratory rats.

RATIONALE AND OBJECTIVES: A patient was encountered with a long esophageal stricture that may have been caused by glutaraldehyde-contaminated endoscopic equipment. An in vivo study of laboratory rats was performed to determine the effect of glutaraldehyde exposure on the esophagus. METHODS: Ten laboratory rats were divided into five groups that received daily gavage of the esophagus with either 3.2% glutaraldehyde solution (treated rats) or 1 mL of normal saline (control rats) for varying durations. After the rats were killed, histologic sections from the esophagus were reviewed in a blind fashion. The degree of inflammatory infiltrate at the gastroesophageal junction was quantified as mild, moderate, or marked. RESULTS: Histologic examination revealed greater neutrophilic infiltration in the submucosa of the gastroesophageal junction in three of four glutaraldehyde-treated rats compared with controls. Treated rats also had evidence of segmental esophageal vasculitis not seen in any of the controls. Both controls and treated rats had areas of myositis and myonecrosis within the esophagus. CONCLUSION: Exposure to glutaraldehyde has a toxic effect on the rat esophagus. Glutaraldehyde-induced esophageal injury should therefore be considered in patients who develop esophagitis or esophageal strictures after upper endoscopy.

Elevation of soluble intercellular adhesion molecule-1 levels in symptomatic and asymptomatic carotid atherosclerosis.

OBJECTIVE: Recent data suggest that the increased expression of intercellular adhesion molecule-1 (ICAM-1) in atherosclerotic plaque taken from the carotid bifurcation correlates with the development of neurological symptoms. As a result, the authors sought to compare the serum levels of soluble forms of ICAM-1 (sICAM-1) in patients who were asymptomatic with those who were symptomatic for carotid artery stenosis as well as in patients who were matched in terms of sex, age, and risk factors who did not have carotid artery disease. METHODS: Using enzyme-linked immunosorbent assay, serum sICAM-1 levels were prospectively determined in 54 patients scheduled to undergo carotid endarterectomy for either symptomatic or asymptomatic high-grade stenosis (> or =60%) and in 5 additional patient controls. Data are expressed as mean +/- standard error of the mean, with significance defined as P < 0.05 using the Mann-Whitney two-tailed test for two-column comparison or analysis of variance and Fisher protected least significant difference test. RESULTS: Using a univariate model, serum sICAM-1 levels were significantly elevated in patients with carotid artery stenosis as compared with control patients without stenosis (347 +/- 15 ng/ml versus 216 +/- 8.2 ng/ml) (P < 0.01). When the asymptomatic and symptomatic patients with carotid artery stenosis were considered separately, these levels were still elevated relative to those of control patients (asymptomatic [312 +/- 18 ng/ml] and symptomatic [376 +/- 22 ng/ml] patients; P = 0.06 for asymptomatic versus control patients, P < 0.01 for symptomatic versus control patients). Symptomatic patients also had significantly elevated sICAM-1 levels as compared with asymptomatic patients (P < 0.05). Despite the fact that female patients demonstrated higher ICAM-1 levels than male patients (P < 0.05), sex, age, and risk factors such as the presence of hypercholesterolemia, diabetes, hypertension, or a history of smoking did not confound these findings. CONCLUSION: Levels of sICAM-1 are higher in patients with carotid stenosis than in control patients. Symptomatic patients demonstrate significantly elevated levels as compared with asymptomatic patients. These data support the contention that ICAM-1 is a reliable marker of carotid disease progression and suggest that serum levels may be useful in following certain asymptomatic patients.

The baboon (Papio anubis) extracranial carotid artery: an anatomical guide for endovascular experimentation.

BACKGROUND: As novel endovascular strategies are developed for treating neurological disease, there is an increasing need to evaluate these techniques in relevant preclinical models. The use of non-human primates is especially critical given their structural and physiological homology with humans. In order to conduct primate endovascular studies, a comprehensive understanding of the carotid anatomy is necessary. We therefore performed a detailed examination of the vessel lengths, lumen diameters and angles of origin of the baboon extracranial carotid system. METHODS: We characterized the extracranial carotid system often male baboons (Papio anubis, range 15.1-28.4 kg) by early post-mortem dissection. Photographic documentation of vessel lengths, lumen diameters, and angles of origin were measured for each segment of the carotid bilaterally. RESULTS: The common carotid arteries averaged 94.7 +/- 1.7 mm (left) and 87.1 +/- 1.6 mm (right) in length. The average minimal common carotid lumen diameters were 3.0 +/- 0.3 mm (left) and 2.9 +/- 0.2 mm (right). Each animal had a common brachiocephalic artery arising from the aorta which bifurcated into the left common carotid artery and right braciocephalic artery after 21.5 +/- 1.6 mm. The vascular anatomy was found to be consistent among animals despite a wide range of animal weights. CONCLUSIONS: The consistency in the Papio anubis extracranial carotid system may promote the use of this species in the preclinical investigation of neuro-interventional therapies.

Multiple superficial gastric erosions due to Crohn's disease of the stomach. Radiologic and endoscopic diagnosis.

A case of Crohn's disease involving the stomach and duodenum is presented. The patient had a four-and-a-half year history of ankylosing spondylitis. Double contrast radiography of the stomach and duodenum showed multiple superficial gastric erosions and a duodenal ulcer. There were typical changes of Crohn's disease in the terminal ileum. At endoscopy, numerous superficial erosions were seen in the stomach and duodenum and biopsies of the stomach showed granulomatous inflammation, consistent with Crohn's disease. These lesions are similar to those seen in the colon in the early stages of granulomatous colitis and it is likely that this represents the early stage of Crohn's disease in the stomach. With increasing application of double-contrast radiography and endoscopy, these lesions may be found more frequently.

Adynamic ileus after caesarean section mimicking intestinal obstruction: findings on abdominal radiographs.

The purpose of this study was to determine the spectrum of findings and the frequency of apparent distal colonic obstruction on abdominal radiographs in women with obstructive symptoms following Caesarean section. A search of radiology files yielded 21 patients who had abdominal radiographs because of obstructive symptoms during the early post-operative period. The radiographs were reviewed retrospectively to characterize the bowel gas patterns in these patients. Medical records were also reviewed to determine the treatment and patient course. Abdominal radiographs showed findings suggestive of distal colonic obstruction in 15 patients (71%), small bowel obstruction in 2 (10%), adynamic ileus in 3 (14%) and a normal bowel gas pattern in 1 (5%). In all 15 patients with apparent distal colonic obstruction, there was minimal or no gas in the rectosigmoid, with an associated pelvic mass representing the enlarged post-partum uterus, which compressed the rectosigmoid and prevented it from filling with gas. All 21 patients had rapid clinical or radiographic improvement on conservative management, indicating a transient post-operative ileus. Radiologists should be aware of the limitations of abdominal plain radiographs following Caesarean section so that a post-operative ileus is not mistaken for a distal colonic obstruction and conservative measures can be undertaken to decompress the bowel until the ileus resolves.

Radiographically diagnosed antral gastritis: findings in patients with and without Helicobacter pylori infection.

The purpose of this study was to characterize the radiographic findings of antral gastritis and to determine whether there are differences in the appearance of antral gastritis in patients with and without Helicobacter pylori infection. A search of radiology, endoscopy and pathology files revealed 90 patients with antral gastritis on double contrast upper gastrointestinal tract studies who had endoscopy with testing for H. pylori. The barium studies were evaluated to further characterize the findings of antral gastritis without knowledge of the H. pylori status of the patients or of the endoscopy or pathology findings. The radiographic findings of antral gastritis included thickened folds in 67 patients (74%), polypoid antral gastritis (a subset of patients with thickened folds) in 6 (9%), antral erosions in 21 (23%), enlarged areae gastricae in 14 (16%), crenulation of the lesser curvature in 4 (4%), mucosal nodularity in 2 (2%), a hypertrophied antral-pyloric fold in 2 (2%) and antral striae in 1 (1%). 43 patients (48%) with antral gastritis were H. pylori positive and 47 patients (52%) were H. pylori negative. Thickened folds were detected in 39 H. pylori-positive patients (91%) with antral gastritis vs 28 H. pylori-negative patients (60%) (p<0.001); polypoid gastritis in 6 H. pylori-positive patients (14%) vs 0 H. pylori-negative patients (p<0.05); enlarged areae gastricae in 14 H. pylori-positive patients (33%) vs 0 H. pylori-negative patients (p<0.0001); and antral erosions in 2 H. pylori-positive patients (5%) vs 19 H. pylori-negative patients (40%) (p<0.0001). Our experience suggests that antral gastritis caused by H. pylori infection is associated with characteristic features on double contrast studies (including thickened folds, polypoid gastritis and enlarged areae gastricae) and that this condition is rarely associated with antral erosions. Thus, radiologists can often suggest whether the patient's gastritis is caused by H. pylori on the basis of radiographic findings.

Value of digital fluoroscopy for the diagnosis of pneumatosis coli.

Two cases are presented of benign pneumatosis coli diagnosed on digital fluoroscopic barium enema examinations, in which the gas-filled cysts in the colonic wall were only recognized by postprocessing of the images (i.e. increasing the brightness and contrast settings) at the computer workstation. When digital barium enemas are performed, we therefore recommend image postprocessing to evaluate polypoid lesions in order to differentiate pneumatosis coli from true colonic neoplasms.

Fecal impaction: a cause of isolated small bowel dilatation on abdominal radiographs.

OBJECTIVE: The purpose of this study was to assess the frequency of isolated small bowel dilatation on abdominal radiographs in patients with colonic fecal impaction and also to elucidate the cause of this finding. METHODS: A computerized search of radiology files revealed 515 patients with colonic fecal impaction on abdominal radiographs. The radiologic reports described isolated small bowel dilatation not related to other known causes of ileus or obstruction in 18 (3.5%) of the 515 patients. The films were reviewed to determine the distribution of fecal impaction and the degree and extent of small bowel dilatation. In 16 cases, medical records were reviewed to determine the clinical presentation, treatment, and course. Finally, follow-up radiographs were reviewed in four cases to determine the response to treatment of the impaction. RESULTS: All 16 patients with available medical records had abdominal symptoms. The average diameter of the dilated small bowel on abdominal radiographs was 3.7 cm. Fourteen patients (78%) had a diffuse colonic fecal impaction (nine) or a predominantly right-sided fecal impaction (five) that involved the cecum, and the remaining four (22%) had a left-sided colonic fecal impaction. All 12 patients with clinical follow-up had resolution of symptoms and all four with follow-up radiographs had resolution of small bowel dilatation after treatment of the underlying impaction. CONCLUSION: Fecal impaction should be considered in the differential diagnosis of small bowel dilatation on abdominal radiographs, as treatment of the underlying impaction usually produces a dramatic clinical response with resolution of the small bowel dilatation on follow-up radiographs.

Metoclopramide-ceruletide assisted small bowel examination.

We investigated the feasibility of performing a combined upper gastrointestinal and small bowel examination. Metoclopramide was given at the start of the examination and ceruletide was injected to hasten small bowel transit. The quality and duration of fifty examinations (Group I) was compared to that of fifty patients receiving metoclopramide alone (Group II) and fifty patients undergoing unaided examinations (Group III). The mean duration of the entire study was 29.3 minutes for Group I patients, 37.6 minutes for patients in Group II and 69.1 minutes for Group III subjects. The combination of agents produced contracted fold patterns in the jejunum and ileum that rendered individual loops more accessible to individual study under fluoroscopy in approximately 50% of subjects.

Cement salvage of instrumentation-associated vertebral fractures.

BACKGROUND AND PURPOSE: Spinal instrumentation plays a key role in the treatment of spinal instability in patients with metastatic tumors. Poor bone quality, radiation, and diffuse osseous tumor involvement present significant challenges to spinal stabilization with instrumentation and occasionally result in postinstrumentation compression fractures. Vertebral cement augmentation has been effective in the treatment of painful tumor-related compression fractures. Our objective was to describe cement augmentation options in the treatment of vertebral compression fractures associated with spinal instrumentation in patients with metastatic tumors. MATERIALS AND METHODS: Patients who underwent percutaneous vertebral cement augmentation in the treatment of instrumentation-associated vertebral compression fractures between 2005 and 2011 were included in the analysis. Only fractures that occurred within the construct or at an adjacent level were included. The change in Visual Analog Scale and need for further surgery were analyzed. RESULTS: Eleven patients met the inclusion criteria, with 8 tumors located in the thoracic spine and 3 tumors in the lumbar spine. The median time between instrumented surgery and vertebral augmentation was 5 months (1-48 months) and the median follow-up after cement augmentation was 24 months (4-59 months). A total of 22 vertebrae that were either within or immediately adjacent to the surgical instrumentation underwent vertebral augmentation. All patients reported a decrease in their pain scores (mean decrease: 6 Visual Analog Scale points; P < .003). One patient required reoperation after cement augmentation. None of the patients experienced vertebral cement augmentation-related complications. CONCLUSIONS: Vertebral cement augmentation represents a safe and effective treatment option in patients with recurrent or progressive back pain and instrumentation-associated vertebral compression fractures.

Introducing a novel approach of network oriented analysis of ERPs, demonstrated on adult attention deficit hyperactivity disorder.

OBJECTIVE: Introducing a network-oriented analysis method (brain network activation [BNA]) of event related potential (ERP) activities and evaluating its value in the identification and severity-grading of adult ADHD patients. METHODS: Spatio-temporal interrelations and synchronicity of multi-sited ERP activity peaks were extracted in a group of 13 ADHD patients and 13 control subjects for the No-go stimulus in a Go/No-go task. Participants were scored by cross-validation against the most discriminative ensuing group patterns and scores were correlated to neuropsychological evaluation scores. RESULTS: A distinct frontal-central-parietal pattern in the delta frequency range, dominant at the P3 latency, was unraveled in controls, while central activity in the theta and alpha frequency ranges predominated in the ADHD pattern, involving early ERP components (P1-N1-P2-N2). Cross-validation based on this analysis yielded 92% specificity and 84% sensitivity and individual scores correlated well with behavioral assessments. CONCLUSIONS: These results suggest that the ADHD group was more characterized by the process of exerting attention in the early monitoring stages of the No-go signal while the controls were more characterized by the process of inhibiting the response to that signal. SIGNIFICANCE: The BNA method may provide both diagnostic and drug development tools for use in diverse neurological disorders.