CSF rhinorrhoea after endonasal intervention to the anterior skull base (CRANIAL): proposal for a prospective multicentre observational cohort study.

BACKGROUND: The endonasal transsphenoidal approach (TSA) has emerged as the preferred approach in order to treat pituitary adenoma and related sellar pathologies. The recently adopted expanded endonasal approach (EEA) has improved access to the ventral skull base whilst retaining the principles of minimally invasive surgery. Despite the advantages these approaches offer, cerebrospinal fluid (CSF) rhinorrhoea remains a common complication. There is currently a lack of comparative evidence to guide the best choice of skull base reconstruction, resulting in considerable heterogeneity of current practice. This study aims to determine: (1) the scope of the methods of skull base repair; and (2) the corresponding rates of postoperative CSF rhinorrhoea in contemporary neurosurgical practice in the UK and Ireland. METHODS: We will adopt a multicentre, prospective, observational cohort design. All neurosurgical units in the UK and Ireland performing the relevant surgeries (TSA and EEA) will be eligible to participate. Eligible cases will be prospectively recruited over 6 months with 6 months of postoperative follow-up. Data points collected will include: demographics, tumour characteristics, operative data), and postoperative outcomes. Primary outcomes include skull base repair technique and CSF rhinorrhoea (biochemically confirmed and/or requiring intervention) rates. Pooled data will be analysed using descriptive statistics. All skull base repair methods used and CSF leak rates for TSA and EEA will be compared against rates listed in the literature. ETHICS AND DISSEMINATION: Formal institutional ethical board review was not required owing to the nature of the study - this was confirmed with the Health Research Authority, UK. CONCLUSIONS: The need for this multicentre, prospective, observational study is highlighted by the relative paucity of literature and the resultant lack of consensus on the topic. It is hoped that the results will give insight into contemporary practice in the UK and Ireland and will inform future studies.

Chronic active Epstein-Barr virus: a multidisciplinary approach.

A 17-year-old Caucasian male presented to ENT with angular stomatitis, oral ulceration and cervical lymphadenopathy. Over the subsequent 18 months he developed recurrent upper respiratory tract infections, pyrexia of unknown origin, oral ulceration and maxillary sinus osteomyelitis. Extensive investigation ensued from various specialties. Positive investigations included a mild but persistently elevated serum Epstein-Barr virus PCR; however, no unifying diagnosis was elicited. It is noteworthy that a significant factor contributing to a delay in his diagnosis was poor compliance with invasive investigations. Ultimately, deteriorating liver function prompted liver biopsy which confirmed a diagnosis of chronic active Epstein-Barr virus infection (CAEBV). This enabled referral for curative treatment in the form of a stem cell transplant. CAEBV is extremely rare in Western countries. Due to fatal complications early diagnosis is critical for successful treatment. Our case highlights the need for regular clinical re-evaluation and a comprehensive multispecialty approach in such cases.

An overview of numerical modelling of nasal airflow.

Computer modelling of fluid flows is a mature technology used widely in engineering. The process, known as computational fluid dynamics (CFD), allows accurate prediction of fluid flow and associated phenomena based on the mathematical laws governing fluid behaviour. A fluid may be defined as any substance that can flow and thus both liquids and gases behave as fluids. The mathematical predictions of CFD can therefore be applied to nasal airflow. In current clinical practice, it is only possible to perform a few limited measurements of nasal airflow, and the clinical relevance of these measurements is questionable. Computer models are not limited by the anatomical inaccessibility of the nasal cavities, and a detailed objective characterisation of airflow can therefore be provided in all areas of an individual nose. In addition, the ability to remodel computer simulations offers a potential predictive tool for planning nasal surgery. This article provides an overview of the basic concepts of computational fluid dynamics, and a summary of the current capabilities of this technology in the characterisation of nasal airflow. The objective is to give otorhinolaryngologists a basic understanding of the computer modelling of nasal airflow, and the background information with which to evaluate CFD-based rhinology literature.

Discrete interband mutual focusing in nonlinear photonic lattices.

We study nonlinear coupling of mutually incoherent beams associated with different Floquet-Bloch waves in a one-dimensional optically-induced photonic lattice. We demonstrate experimentally how such interactions lead to asymmetric mutual focusing and, for waves with opposite diffraction properties, to simultaneous focusing and defocusing as well as discreteness-induced beam localization and reshaping effects.

Corticosteroids and peritonsillar abscess formation in infectious mononucleosis.

Peritonsillar abscess formation is an uncommon complication of infectious mononucleosis (IM). Early case reports implicated corticosteroids in the development of such abscesses, however, subsequent studies suggested that these drugs do not promote the formation of abscesses at several sites outside the central nervous system. It has recently been demonstrated that zwitterionic polysaccharides, in bacterial capsules, form complexes with CD4(+) T lymphocytes leading to abscess formation. A patient is presented who developed peritonsillar abscess a few days after initiation of corticosteroid therapy for IM; the medical literature was reviewed in respect of this subject. It appears that the occurrence of these abscesses in IM is not strongly linked to corticosteroid treatment. The authors, therefore, recommend that steroids should not be withheld from patients with severe IM on the basis that they may precipitate the development of peritonsillar abscess.

Numerical model of a nasal septal perforation.

This paper describes numerical simulation of airflow in a nose with a nasal septal perforation. Diseased airflow is compared to airflow in a healthy nasal model. The healthy model has been generated from CT scans from the Antrim Area Hospital ENT clinic and is close to being anatomically accurate. The nasal septal perforation has been superimposed on the healthy geometry using image manipulation software. The flow is modeled as laminar, steady state, with the flow rates corresponding to quiet breathing at rest approximately 165 ml/sec. Healthy flow patterns show that the majority of the flow travels close to nasal septum, in the region close to the middle turbinate. In the diseased case, high shear stresses concentrated at the posterior region of the perforation explain bleeding associated with nasal perforations.

Gastroesophageal reflux and chronic rhinosinusitis.

PURPOSE OF REVIEW: Chronic rhinosinusitis (CRS) and gastroesophageal reflux disease (GERD) are two common conditions which have been reported to occur together more frequently than expected. It has, therefore, been proposed that GERD may have an aetiologic role in CRS. This study reviews the results of research into the possible reflux and reflex mechanisms that may link CRS and GERD. RECENT FINDINGS: Robust assessment of gastric reflux into the nasopharynx using circumferential pH probes which are less subject to artefact have demonstrated that direct reflux into the nasopharynx is a rare event. Pepsinogen has only been found in the nasal cavity in one study which had unexpected results, raising doubts about the validity of the methodology. A reflex increase in nasal congestion and mucus secretion has been demonstrated experimentally, but in a small number of patients, which precluded statistical significance. The relationship between reflux and mucus secretion is supported, though, by randomized controlled trials showing decreased postnasal drip with proton-pump inhibitor therapy. SUMMARY: Recent evidence suggests that GERD does not play a causative role in CRS. However, there is evidence of an oesophageal-nasal reflex, particularly in regard to mucus secretion and symptoms of postnasal drip. The presence of GERD would, therefore, be expected to worsen nasal symptom scores.

A model of airflow in the nasal cavities: Implications for nasal air conditioning and epistaxis.

BACKGROUND: A friction force is generated when moving air contacts the nasal walls, referred to as wall shear stress. This interaction facilitates heat and mass transfer between the mucosa and air, i.e., air-conditioning. The objective of this research was to study the distribution of wall shear stress within the nasal cavity to identify areas that contribute significantly to air-conditioning within the nasal cavity. METHODS: Three-dimensional computational models of the nasal airways of five healthy subjects (three male and two female subjects) were constructed from nasal CT scans. Numerical simulations of nasal airflow were conducted using the commercial computational fluid dynamics code Fluent 6 (Ansys, Inc., Canonsburg, PA). Wall shear stress was derived from the numerical simulation. Air-conditioning was simulated to confirm the relationship with wall shear stress. RESULTS: Nasal airflow simulations predicted high wall shear stress along the anterior aspect of the inferior turbinate, the anteroinferior aspect of the middle turbinate, and within Little's area. CONCLUSION: The airflow simulations indicate that the inferior and middle turbinates and Little's area on the anterior nasal septum contribute significantly to nasal air-conditioning. The concentration of wall shear stress within Little's area indicates a desiccating and potentially traumatic effect of inhaled air that may explain the predilection for spontaneous epistaxis at this site.

The epidemiology of peritonsillar abscess disease in Northern Ireland.

OBJECTIVES: 1. To describe the epidemiology of peritonsillar abscess disease in Northern Ireland. 2. To describe the impact of the nature of microbiological sampling on culture results. METHOD: Retrospective review of cases of peritonsillar abscess identified by diagnostic coding in three centres in Northern Ireland between August 2001 and July 2002. RESULTS: One hundred and twenty eight cases of confirmed peritonsillar abscess were treated as inpatients accounting for 1 in 10,000/year of the population in the hospitals' catchment area. The mean age was 26.4 (range 9-78) years. Sixty-nine patients were male; the mean length of hospital stay was 3 days. Culture yield was greatest from needle aspirates; throat swabs and blood cultures were typically unhelpful. Beta haemolytic streptococci were the most common isolates. Resistance among Group A haemolytic streptococci to macrolide antibiotics was present in 26% of isolates. Heterophile antibody testing was routine and revealed that Epstein-Barr virus infectious mononucleosis had a prevalence of 1.8% in this group of patients. CONCLUSION: In this population, although there were many similarities with the clinical features reported by other investigators, there were also several differences. Notably, we found a comparatively low proportion of anaerobic infections. Although cultures results did not influence individual patient treatment, reviewing data derived from populations is valuable for guiding empirical antibiotic therapy. SUMMARY: The epidemiology of peritonsillar abscess disease is not well described. Other investigators describing the bacteriology give differing results, presumably reflecting different countries and techniques. The need for routine microbiological testing has been questioned in several reports, but the benefit of routine culture and sensitivity data for planning empirical antibiotic treatment has not been explored. We present a retrospective review of 128 cases of confirmed peritonsillar abscess in Northern Ireland from August 2001 to July 2002. The annual population incidence in this region is 1 in 10,000/year. In this group concurrent Epstein-Barr virus infection was found to have a prevalence of 1.8%. The yield of positive cultures from routine microbiological sampling was low in comparison to that reported in detailed prospective studies, from various countries. Needle aspiration was the best technique for obtaining pus for culture; throat swabs and blood cultures were unhelpful. Culture results did not affect individual patient treatment, but may have a potentially useful role for selecting empirical therapy.

Controlled generation and steering of spatial gap solitons.

We demonstrate the first fully controlled generation of immobile and slow spatial gap solitons in nonlinear periodic systems with band-gap spectra, and observe the key features of gap solitons that distinguish them from discrete solitons, including a dynamical transformation of gap solitons due to nonlinear interband coupling. We also describe theoretically and confirm experimentally the effect of the anomalous steering of gap solitons in optically induced photonic lattices.