Implantation of bone-anchored hearing device using a three-dimensional template in a child.

BACKGROUND: Implantation of bone-anchored hearing devices is performed to improve hearing in patients with chronic suppurative otitis media who cannot wear a conventional hearing aid. The surgical procedure can be safely performed in children aged over five years. CASE REPORT: A 15-year-old patient with bilateral chronic suppurative otitis media and conductive hearing loss underwent the procedure to implant a bone-anchored hearing device but was found to have skull thickness of less than 2.5 mm and the procedure was abandoned. A computed tomography scan of the skull was undertaken and a three-dimensional template was reconstructed to identify appropriate thickness of the skull to implant the abutment during a second procedure. CONCLUSION: Bone-anchored hearing devices can be implanted by prior imaging and using a template to identify the area of appropriate skull thickness to implant the abutment safely.

Removal of external ear canal exostoses by piezo surgery: a novel technique.

BACKGROUND: External auditory canal exostoses are known to occur in patients who engage in cold-water sports. Although the majority of patients with exostosis remain asymptomatic, larger lesions can cause wax impaction, conductive hearing loss and predispose to recurrent otitis externa. OBJECTIVE: A novel technique is described of using a piezo saw to excise exostoses that are symptomatic. The piezo saw is used to perform various procedures, but its use in removing exostoses has not been described in the literature. CONCLUSION: Excision of exostoses of the ear canal using a piezo saw is a safe technique and patients have a speedy recovery. This paper describes a new technique for removing exostoses.

Incorporating genome-wide DNA sequence information into a dynamic whole-cell model of Escherichia coli: application to DNA replication.

The advent of thousands of annotated genomes, detailed metabolic reconstructions and databases within the flourishing field of systems biology necessitates the development of functionally complete computer models of whole cells and cellular systems. Such models would realistically describe fundamental properties of living systems such as growth, division and chromosome replication. This will inevitably bridge bioinformatic technologies with ongoing mathematical modelling efforts and would allow for in silico prediction of important dynamic physiological events. To demonstrate a potential for the anticipated merger of bioinformatic genome-wide data with a whole-cell computer model, the authors present here an updated version of a dynamic model of Escherichia coli, including a module that correctly describes the initiation and control of DNA replication by nucleoprotein DnaA-ATP molecules. Specifically, a rigorous mathematical approach used to explicitly include the genome-wide distribution of DnaA-binding sites on the replicating chromosome into a computer model of a bacterial cell is discussed. A new simple deterministic approximation of the complex stochastic process of DNA replication initiation is also provided. It is shown for the first time that reasonable assumptions about the mechanism of DNA replication initiation can be implemented in a deterministic whole-cell model to make predictions about the timing of chromosome replication. Furthermore, it is proposed that a large increase in the concentration of DnaA-binding boxes will result in a decreased steady-state growth rate in E. coli.

Reusable versus disposable instruments in tonsillectomy: a comparative study of outcomes.

Tonsillectomy, traditionally performed using reusable instruments (RIs), has recently been performed using disposable instruments (DIs), to prevent the theoretical risk of spreading new variant Creutzfeldt-Jakob disease. Following this, there have been concerns of increased risk of complications, especially haemorrhage. We audited our hospital's complication rates of 100 tonsillectomies performed using RI and 100 using DIs. We analysed the overall complication rates and the postoperative haemorrhage rates. and compared them with the broader groups of RIs versus DIs. We also compared patients who did not have diathermy with those who did have diathermy. The overall complication rate was 6% with RIs and 33% with DIs and the haemorrhage rate was 1% and 12%, respectively. With DIs, these rates were significantly higher in the diathermy subgroup. We believe this is the first study to look at the complications due to DIs.

Towards the development of a minimal cell model by generalization of a model of Escherichia coli: use of dimensionless rate parameters.

A model of a minimal cell would be a valuable tool in identifying the organizing principles that relate the static sequence information of the genome to the dynamic functioning of the living cell. Our approach for developing a minimal cell model is to first generalize an existing model of Escherichia coli by expressing reaction rates as ratios to a set of reference parameters. This generalized model is a prototype minimal cell model that will be developed by adding detail to explicitly include each chemical species. We tested the concept of a generalized model by testing the effect of scaling all enzyme-catalyzed reactions in the E. coli model. The scaling has little effect on cellular function for a wide range of kinetic ratios, where the kinetic ratio is defined as the rate of all enzyme-catalyzed reactions in a given model relative to those in the E. coli model.

A new and clinically symptomatic variant of thyroid cartilage anatomy.

We present a previously undescribed variation in the anatomy of the superior cornu of the thyroid cartilage. In the five cases described, the tip of the cornu turned medially and caused an indentation into the pharynx. These indentations were symptomatic and caused pain and globus sensation. Resection of them led to resolution of the symptoms. A survey of the incidence of this variation of the thyroid cartilage in a clinic population is presented.

Schwannoma of the chorda tympani nerve.

We report a case of schwannoma of the chorda tympani. This is a very rare benign tumour and only five other cases have been found in the literature. This is the first case to mimic a cholesteatoma presenting as a pearly tumour in the postero-superior segment of the drum with aural discharge and conductive deafness. Diagnosis is usually by biopsy and treatment is surgical with preservation of facial and auditory function. A summary of the other presentations of this tumour together with a review of the histopathology of the disease is presented.

Endosupralayngeal laser resection of a symptomatic anatomical laryngeal variant: a minimally-invasive technique for a newly-recognised condition.

A variant of thyroid cartilage anatomy has recently been described as a cause of significant pharyngeal and laryngeal symptoms. After clinical recognition, spiral CT imaging confirms the anatomical relationships and a minimally-invasive technique is offered to allow surgical removal of the variant. The authors describe the surgical technique that was developed to avoid the need for an alternative, more conventional, external approach, and the instruments found to be particularly suitable for providing appropriate access to the supralaryngeal region.

Failure of insertion of a laryngeal mask airway caused by a variation in the anatomy of the thyroid cartilage.

We report the failure of insertion of a laryngeal mask airway in a patient with a pre-operative diagnosis of an abnormality of the superior cornua of the thyroid cartilage. We believe that this is the first time that this reason for failure has been reported.

Measurement of albumin in nasal lavage using the technique of chemiluminescent immunoassay.

A method has been developed that uses chemiluminescent acridinium esters rather than radioactive iodine in an immunoassay for albumin. Albumin is a protein derived from plasma sources found in nasal fluids. As such, it can be used as an important marker of plasma exudation in experimental rhinology. The assay was developed as an alternative to radioimmunoassay for a number of reasons: chemiluminescent assays do not require radioactive materials and the complex safety related aspects of their usage; the assays are easy to perform and do not require expensive equipment; and the assay is capable of the sensitivity required to detect very small changes in albumin concentrations in nasal fluids. The assay measures albumin with a sensitivity of 1.2 ng/ml. The working range of the assay is 1.0-23.7 micrograms/ml with an interassay coefficient of variation < or = 15%. This working range encompasses the range of albumin usually found in nasal lavage samples from normal volunteers.

A new approach to improving illumination in the nose during endonasal surgery.

Despite improvements in light sources the problem of illumination during endonasal surgery persists. This is particularly so in the presence of blood which absorbs light and renders the operative field dark as a consequence. This paper describes a series of in vitro experiments that show how improved illumination is possible using readily available, inexpensive, sterilisable and flexible materials. The hypothesis tested was that white coloured materials, when placed into the nasal cavity during endonasal surgery, improve illumination of the operative field by reflecting light onto the area of surgical interest. This hypothesis was tested with the use of a light proof box into which were introduced blood coloured and reflective materials. The light reflected back from a fixed blood coloured surface within the box was measured. The introduction of white materials into the box provided greater illumination than blue or foil surfaces.