Daniel Dahlberg

Bio: Daniel Dahlberg is an academic researcher from Oslo University Hospital. The author has contributed to research in topics: Brain abscess & Cyst. The author has an hindex of 8, co-authored 14 publications receiving 235 citations.

Diagnosis of ventricular drainage-related bacterial meningitis by broad-range real-time polymerase chain reaction.

Abstract: OBJECTIVE: To compare a broad-range real-time polymerase chain reaction (PCR) diagnostic strategy with culture to evaluate additional effects on the etiological diagnosis and the quantification of the bacterial load during the course of ventricular drainage-related bacterial meningitis (VR-BM). METHODS: We applied a PCR that targeted conserved regions of the 16S ribosomal ribonucleic acid gene to cerebrospinal fluid (CSF) samples from patients with external ventricular drainage or a ventriculoperitoneal shunt during the course of VR-BM. We compared the PCR results with CSF cultures. A total of 350 routine CSF samples were consecutively collected from 86 patients. The CSF deoxyribonucleic acid was automatically purified and subjected to PCR. Amplicons from the PCR samples that were positive for VR-BM were subsequently deoxyribonucleic acid sequenced for final identification. Clinical data were extracted from patient files. RESULTS: Sixteen patients had at least one VR-BM-positive sample as diagnosed from culture or PCR. Nineteen episodes were diagnosed with signs of VR-BM (n = 16 patients) or were determined to be contaminated (n = 3 patients). Four episodes of VR-BM were diagnosed via PCR alone and were predominantly caused by gram-negative pathogens, five episodes were diagnosed via culture alone, and seven episodes were diagnosed via both culture and PCR. Five patients had mixed infections. Overall, 71 samples were positive for VR-BM as indicated by either one or both of the methods. Eighteen CSF samples were VR-BM positive as indicated by culture alone, and 21 CSF samples were positive as indicated via PCR alone. CONCLUSIONS: Culture supplemented with broad-range, real-time PCR may increase the number of etiologically diagnosed VR-BM episodes, particularly when these are caused by gram-negative bacteria.

Intracranial Non-traumatic Aneurysms in Children and Adolescents

Abstract: An intracranial aneurysm in a child or adolescent is a rare, but potentially devastating condition. As little as approximately 1200 cases are reported between 1939 and 2011, with many of the reports presenting diverting results. There is consensus, though, in that pediatric aneurysms represent a pathophysiological entity different from their adult counterparts. In children, there is a male predominance. About two-thirds of pediatric intracranial aneurysms become symptomatic with hemorrhage and the rate of re-hemorrhage is higher than in adults. The rate of hemorrhage from an intracranial aneurysm peaks in girls around menarche. The most common aneurysm site in children is the internal carotid artery, in particular at its terminal ending. Aneurysms in the posterior circulation are more common in children than adults. Children more often develop giant aneurysms, and may become symptomatic from the mass effect of the aneurysm (tumorlike symptoms). The more complex nature of pediatric aneurysms poses a larger challenge to treatment alongside with higher demands to the durability of treatment. Outcome and mortality are similar in children and adults, but long-term outcome in the pediatric population is influenced by the high rate of aneurysm recurrences and de novo formation of intracranial aneurysms. This urges the need for life-long follow-up and screening protocols.

Minimally Invasive Microsurgical Resection of Primary, Intradural Spinal Tumors is Feasible and Safe: A Consecutive Series of 83 Patients.

Abstract: Background To date, the traditional approach to intraspinal tumors has been open laminectomy or laminoplasty followed by microsurgical tumor resection. Recently, however, minimally invasive approaches have been attempted by some. Objective To investigate the feasibility and safety of minimally invasive surgery (MIS) for primary intradural spinal tumors. Methods Medical charts of 83 consecutive patients treated with MIS for intradural spinal tumors were reviewed. Patients were followed up during the study year, 2015, by either routine history/physical examination or by telephone consultation, with a focus on tumor status and surgery-related complications. Results Mean age at surgery was 53.7 yr and 52% were female. There were 49 schwannomas, 18 meningeomas, 10 ependymomas, 2 hemangioblastomas, 1 neurofibroma, 1 paraganglioma, 1 epidermoid cyst, and 1 hemangiopericytoma. The surgical mortality was 0%. In 87% of cases, gross total resection was achieved. The complication rate was 11%, including 2 cerebrospinal fluid leakages, 1 asymptomatic pseudomeningocele, 2 superficial surgical site infections, 1 sinus vein thrombosis, and 4 cases of neurological deterioration. There were no postoperative hematomas, and no cases of deep vein thrombosis or pulmonary embolism. Ninety-three percent of patients were ambulatory and able to work at the time of follow-up. Conclusion This study both demonstrates that it is feasible and safe to remove select, primary intradural spinal tumors using MIS, and augments the previous literature in favor of MIS for these tumors.

Minimally invasive microsurgical resection of primary, intradural spinal tumours using a tubular retraction system.

Abstract: Study design. This is a retrospective review of prospectively collected data. Background. Primary, intradural spinal tumours have traditionally been microsurgically resected following macrosurgical laminectomy or laminoplasty. We hypothesize that approach-related morbidity can be reducedwith less-invasive approaches; we have therefore implemented a minimally invasive approach, with the assistance of a tubular retraction system, for microsurgical resection of primary intradural spinal tumours. Methods. From January 2007 to December 2009, 54 patients underwent surgery for a spinal intradural tumour. Of these, nine patients who underwent minimally invasive posterior unilateral transmuscular surgery using a tubular retraction system were included in this study. Resection grade and surgery-related complications were retrospectively reviewed. Results. All tumours were totally resected (verified by postoperative magnetic resonance imaging). There were no post-operative complications. Eight of the nine patients w...

Toxic levels of ammonia in human brain abscess.

Abstract: OBJECT Brain abscesses could lead to cerebral symptoms through tissue destruction, edema, changes in brain architecture, and increased intracranial pressure. However, the possibility that the pus itself could contribute to symptoms has received little attention. Brain abscesses are areas of tissue destruction, proteolysis, and formation of free amino acids, which are energy substrates for bacteria and possible sources of ammonia. Ammonia is neurotoxic, may cause brain edema, and could contribute to the symptoms of brain abscesses. METHODS The authors analyzed the extracellular phase of pus from 14 patients with brain abscesses with respect to ammonia and amino acids. For comparison, CSF from 10 patients undergoing external ventricular drainage was included. The ammonia-forming ability of Streptococcus intermedius and Staphylococcus aureus, two common microbial isolates in brain abscesses, was studied in vitro. RESULTS In brain abscesses ammonia was 15.5 mmol/L (median value; range 1.7–69.2 mmol/L). In CSF...

Tract Profiles of White Matter Properties: Automating Fiber-Tract Quantification

Abstract: Tractography based on diffusion weighted imaging (DWI) data is a method for identifying the major white matter fascicles (tracts) in the living human brain. The health of these tracts is an important factor underlying many cognitive and neurological disorders. In vivo, tissue properties may vary systematically along each tract for several reasons: different populations of axons enter and exit the tract, and disease can strike at local positions within the tract. Hence quantifying and understanding diffusion measures along each fiber tract (Tract Profile) may reveal new insights into white matter development, function, and disease that are not obvious from mean measures of that tract. We demonstrate several novel findings related to Tract Profiles in the brains of typically developing children and children at risk for white matter injury secondary to preterm birth. First, fractional anisotropy (FA) values vary substantially within a tract but the Tract FA Profile is consistent across subjects. Thus, Tract Profiles contain far more information than mean diffusion measures. Second, developmental changes in FA occur at specific positions within the Tract Profile, rather than along the entire tract. Third, Tract Profiles can be used to compare white matter properties of individual patients to standardized Tract Profiles of a healthy population to elucidate unique features of that patient's clinical condition. Fourth, Tract Profiles can be used to evaluate the association between white matter properties and behavioral outcomes. Specifically, in the preterm group reading ability is positively correlated with FA measured at specific locations on the left arcuate and left superior longitudinal fasciculus and the magnitude of the correlation varies significantly along the Tract Profiles. We introduce open source software for automated fiber-tract quantification (AFQ) that measures Tract Profiles of MRI parameters for 18 white matter tracts. With further validation, AFQ Tract Profiles have potential for informing clinical management and decision-making.

2017 Infectious Diseases Society of America's Clinical Practice Guidelines for Healthcare-Associated Ventriculitis and Meningitis.

Abstract: The Infectious Diseases Society of America (IDSA) Standards and Practice Guidelines Committee collaborated with partner organizations to convene a panel of 10 experts on healthcare-associated ventriculitis and meningitis. The panel represented pediatric and adult specialists in the field of infectious diseases and represented other organizations whose members care for patients with healthcare-associated ventriculitis and meningitis (American Academy of Neurology, American Association of Neurological Surgeons, and Neurocritical Care Society). The panel reviewed articles based on literature reviews, review articles and book chapters, evaluated the evidence and drafted recommendations. Questions were reviewed and approved by panel members. Subcategories were included for some questions based on specific populations of patients who may develop healthcare-associated ventriculitis and meningitis after the following procedures or situations: cerebrospinal fluid shunts, cerebrospinal fluid drains, implantation of intrathecal infusion pumps, implantation of deep brain stimulation hardware, and general neurosurgery and head trauma. Recommendations were followed by the strength of the recommendation and the quality of the evidence supporting the recommendation. Many recommendations, however, were based on expert opinion because rigorous clinical data are not available. These guidelines represent a practical and useful approach to assist practicing clinicians in the management of these challenging infections.

Integration of a Spectral Domain Optical Coherence Tomography System into a Surgical Microscope for Intraoperative Imaging

Abstract: Over the years, multiple milestones have revolutionized vitreoretinal surgery. The x–y surgical microscope control, wide-angle viewing, and fiberoptic illumination are all examples of instrumentation that have been integrated to radically improve pars plana vitreoretinal surgery.1–6 A major advance in vitreoretinal surgery may be the integration of retinal imaging into the operating room. Optical coherence tomography (OCT) has dramatically increased the efficacy of treatment of ophthalmic disease through improvement in diagnosis, understanding of pathophysiology, and monitoring of progression over time. Its ability to provide a high-resolution, cross-sectional, three-dimensional view of the relationships of vitreoretinal anatomy during surgery makes intraoperative OCT a logical complement to the vitreoretinal surgeon. Early attempts at intraoperative OCT have already improved our understanding of the feasibility of intraoperative management and the role it might play in surgical decision-making. Epiretinal membrane (ERM) relationships, macular hole configurations, optic pit characteristics, retinal detachment features, and features of retinopathy of prematurity (ROP) have all been described by means of intraoperative OCT (Lee LB, et al. IOVS 2010;51:ARVO E-Abstract 6076).7–10 One major limitation of intraoperative OCT is the availability of a device that integrates OCT capability into the operating microscope. Until now, published studies have used an OCT system separate from the operating microscope for imaging during surgery or for examination of patients under anesthesia.7–10 When the current systems are used for intraoperative scanning, surgery must be halted while the scans are performed. Thus, one can image retinal architecture and vitreoretinal relationships after manipulations, but cannot obtain real-time OCT imaging of actual tissue manipulation. The ideal device would provide a real-time platform for true intraoperative feedback to the surgeon. This approach would require device integration with the microscope, to allow for OCT scanning during surgery and should provide the surgeon with OCT visualization without interfering with the view of the real-time operative field. In addition, surgical instrumentation should be visible on OCT imaging while not obstructing the view of the underlying tissues. In this study, we developed and tested a prototype microscope-mounted spectral domain (SD)OCT device to evaluate its potential for use in retinal microsurgery on the posterior pole. We also characterized the OCT appearance of the current armamentarium of instruments to better understand what is required for a fully integrated operative system, including the operative microscope, SDOCT, and OCT-compatible instrumentation.