Mitigating noise-induced hearing loss after blast injury

Introduction

Whilst hearing injuries are not life threatening they may have a profound impact on the victim’s ability to understand and interact with the world around them. Noise-induced hearing loss is a common occupational injury and hearing impairment as a consequence of noise and blast exposure remains the most common injury in both war and peace for military personnel. Health and Safety legislation has made an impact and in the future innovative approaches to mitigate against acoustic injury sustained in the work place will be fundamental. For the Armed Forces, noise exposure during conflict is unpredictable. Furthermore, recent events in the UK and elsewhere have highlighted the potential civilian impact of blast injuries on hearing in the acute setting. No well-established protocol for the management of acute, blast-induced hearing injury currently exists.

Methods

Narrative review is supported by electronic literature searches of PubMed, Embase and the Cochrane Library. Synthesis of published literature and production of flow charts for the acute setting are part of the Emergency Preparedness, Resilience and Response programme.

Results

Whilst there is a lack of high-quality randomised controlled trials, there are a number of studies that may inform our choice of acute management. Animal studies of acute acoustic trauma have shown the potential protective effects of corticosteroids. Human data may be extrapolated from sudden onset sensorineural hearing loss where again there is evidence for the use of corticosteroids. Less certainty exists around the use of other treatments including antioxidants. Intratympanic administration of corticosteroids may be superior to oral administration, particularly in the salvage setting. No evidence exists specifically pertaining to the paediatric population.

Conclusion

Prompt identification of any hearing deficit followed by administration of glucocorticoids either orally or via intratympanic preparations is the mainstay of management. Further research is needed to identify the optimum acute management.

Initial experience of a rapid-insertion bone-anchored hearing system: series of 20 consecutive implants

Objective: The loading of bone-anchored hearing system sound processors usually occurs two to three months after surgical implant. This study examined a new bone-anchored hearing system coupling mechanism that permits loading at two weeks post-implantation without compromising osseointegration. Methods: Twenty implants were implanted into 15 patients. The interval between operation and time of processor loading was recorded, along with the cause of any delay and any late complications. Results: Two patients were fitted with implants at seven and nine weeks. The delay was a result of administrative errors; the patients reported no skin problems. Of the remaining 17 implants, 8 processors were fitted at 2 weeks, 1 at 3 weeks, 4 at 4 weeks, 3 at 7 weeks and 1 at 8 weeks. For those nine implants fitted later than two weeks, the delay was because of incomplete skin healing. Conclusion: The Oticon Medical Xpress system allowed processor loading at two weeks post-operatively, providing skin healing was adequate. Early loading occurred in approximately half of the patients. All patients were fitted within the two to three months traditionally allowed. Prolonged skin healing time was the main reason for the delayed fitting of sound processors.

Robotics can lead to a reproducibly high-quality operative result for ear, nose, and throat patients

The success rates and morbidity of operations on the ear, nose, and throat (ENT) have improved markedly in the last 20-25 years. This has been largely due to improved vision, by microscopes and endoscopes, and has led to a greatly reduced hospital stay. During this time there has been minimal improvement in surgical tools. This paper discusses the need for robotic tools, detailing the clinical constraints that proposed solutions need to adhere to, and presenting a recently trialled micro drilling robot for creating a cochleostomy in the cochlear implant procedure.

The effect of operating time on surgeons' muscular fatigue

INTRODUCTION

A study was completed to determine if operating has an effect on a surgeon's muscular fatigue.

SUBJECTS AND METHODS

Six head and neck surgery consultants, two ENT registrars, 20 normal controls from two tertiary referral centres in the West Midlands participated in the study. Electromyography (EMG) measurements were taken throughout a day of operating and fatigue indices were compared to controls performing desk work.

RESULTS

The percentage changes in mean frequency of muscular contractions were examined; there was no significant difference in fatigue levels between consultants and registrars. Operating led to an increase in fatigue in all subjects, compared to no increase in controls performing desk work. It was also found that the brachioradialis muscle is used more than the mid-deltoid muscle and, hence, fatigues at a faster rate.

CONCLUSIONS

Surgeons should be aware that their muscular fatigue levels will increase as an operation progresses; therefore, if possible, more complex parts of the operation should be performed as early as possible, or, in the case of a very long operation, a change in surgeon may be necessary.

An autonomous surgical robot for drilling a cochleostomy: preliminary porcine trial

OBJECTIVE

To produce an autonomous drilling robot capable of performing a bony cochleostomy whilst minimising the damage to the underlying cochlear endosteum.

DESIGN

In this laboratory based study, a robotic drill was designed to measure the changes in force and torque experienced by the tool point during the drilling process. This information is used to predict the point of breakthrough and stop the drill prior to damaging the underlying endosteal membrane.

SETTING

Aston University.

PARTICIPANTS

Five porcine cochleas.

MAIN OUTCOMES MEASURES

An assessment was made of whether a successful bony cochleostomy was performed, the integrity of endosteal membrane was then assessed.

RESULTS

The autonomous surgical robotic drill successfully performed a bony cochleostomy and stopped without damaging the endosteal membrane in all five cases.

CONCLUSIONS

The autonomous surgical robotic drill can perform a cochleostomy whilst minimising the trauma to the endosteal membrane. The system allows information about the state of the drilling process to be derived using force and torque data from the tool point. This information can be used to effectively predict drill breakthrough and implement a control strategy to minimise drill penetration beyond the far surface.

Empty sella syndrome associated with a hyperfunctioning microadenoma invading the clivus

The empty sella syndrome is usually associated with normal pituitary function. If dysfunction is present, this is commonly hypofunction. Hyperfunctioning microadenomas have been described in the presence of the empty sella syndrome. We present the first reported cases of a microadenoma invading the clivus associated with an empty sella.

ENT challenges at the small scale

BACKGROUND

In this paper we consider two relatively frequently performed operations in the field of ear, nose and throat (ENT) surgery and consider how they could be improved by using robotic applications. We consider currently available robots and propose theoretical robotic solutions.

METHODS

The application of robotic systems for both cochlear implantation and endoscopic sinus surgery was considered. Currently available robotic systems were reviewed and those with potential use in ENT surgery were identified. For aspects of operations where there is no available technology, hypotheses are presented on how robots could help.

RESULTS

Three robotic systems were identified with potential usage in ENT: the Pathfinder neurosurgical robot, the Acrobot knee replacement system and the autonomous smart drill for drilling a cochleostomy.

CONCLUSIONS

The challenge for the future of ENT is being able to perform tasks beyond the level of human perception and abilities. The examples presented here demonstrate that microtechnologies could be used to reduce complications, decrease operating time and improve clinical results.

Total serum IgE and IgE antibodies specific to house dust mite found in two aged-matched cohorts of children with and without otitis media with effusion

OBJECTIVES

To determine whether otitis media with effusion (OME) is associated with elevated serum immunoglobulin E (IgE) and IgE specific for house dust mite.

DESIGN

Forty-seven children who had evidence of bilateral OME, both otoscopically and on tympanometry, on two separate occasions, 3 months apart were admitted for ventilation tubes. Forty-eight children admitted for minor eye surgery who had otoscopically normal ears and no history of middle ear problems were used as controls. Bloods samples were taken under anaesthesia. Total IgE and IgE radioallergosorbent test (RAST) to house dust mite was measured by the Pharmacia Unicap 100 system. The results from the two groups were compared.

SETTING

Birmingham Children's Hospital.

PARTICIPANTS

Children between the ages of 3 and 10. Children with Down's syndrome, cleft lip and palate, ciliary abnormalities, known immunodeficiencies and cardiac abnormalities were excluded.

MAIN OUTCOME MEASURES

Total IgE and RAST to house dust mite. A RAST of >0.35 was taken to be positive.

RESULTS

There was no statistical difference between the control and study groups for the total IgE. Six children from both study and control groups had a raised house dust mite RAST. There was no difference in the levels between either group.

CONCLUSIONS

Our findings indicate that there is no direct relationship between OME and biochemical evidence of allergy, specifically to house dust mite.

Pre-menstrual syndrome--are gonadotropins the cause of the condition?

It is proposed that premenstrual syndrome results from the action of elevated gonadotropin levels in various tissues of body other than their natural target organs. These levels are derived from an increased sensitivity to estrogen after pregnancy, childbirth, etc., particularly with respect to the positive feedback on gonadotropin release from the pituitary. Estrogen in conjunction with gonadotropin-releasing hormone (GnRH) releases excessive amounts of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) at ovulation and in the premenstrual phase (post-menopausal patients have greatly elevated gonadotropins and can also demonstrate cyclic symptoms). Gonadotropin action via adenylate cyclase in the adrenal cortex elevates cortisol, while antagonism of parathyroid hormone action on bone gives rise to hypocalcemia. The physiological and psychological symptoms may thereby be explained.

Hypoxic cell sensitization to radiation damage by a new radiosensitizer: cis-dichloro-bis(1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole-N3)platinum(II) (flap)

A new, stable platinum coordination complex (FLAP) containing the 5-nitroimidazole, metronidazole, has been prepared and characterized. The square-planar platinum(II) complex has two metronidazole molecules and two chlorine atoms in the cis configuration. The properties of FLAP differ significantly from metronidazole alone or other platinum complexes tested in the same system. It has a low toxicity towards Chinese hamster ovary cells and is a very effective radiosensitizer toward hypoxic cells in vitro: a one-h pretreatment with a non-toxic dose of 50 microM gave an enhancement ratio of 2.4. No potentiation of aerated cells to X-irradiation damage was observed after a similar schedule of pretreatment at the higher dose of 100 microM FLAP.

Correlation of hydrophobicity with protein binding for clorobiocin analogs

A new method of equilibrium dialysis was used to measure the binding of analogs of clorobiocin (18631 R.P.) to human serum albumin. Binding constants and numbers of binding sites on human serum albumin were calculated from the binding data and were used to calculate the percentage of compounds free in equilibrium with 4% albumin. Partition coefficients between n-octanol and phosphate buffer (0.05 M, pH 7.4) also were measured. A positive linear correlation (r = 0.918, s = 0.240, and n = 10) was obtained between log (bound/free compound) and log partition coefficient.

Blood plasma binding of acebutolol and diacetolol in man

1 Acebutolol or diacetolol were added to fresh human plasma in varying concentrations and their extent of binding at 25 degrees C measureed by an equilibrium dialysis technique. 2 The extent of binding for both compounds was shown to be very low, being 11-19% for acebutolol and 6-9% for diacetolol. 3 Partition coefficients were measured in an n- octanol/phosphate buffer (0.05M, pH 7.4) solvent system. For a cebutolol, P = 0.62 and for diacetol, P = 0.08. 4 The very low plasma binding is in accord with the hydrophilic partition coefficients of these compounds.

A comparison of the pharmacological and biochemical properties of substrate-selective monoamine oxidase inhibitors

1. M&B 9302, E-250, NSD 2023, and Lilly 51641, substrate-selective inhibitors of monoamine oxidase (MAO), and two non-selective inhibitors of MAO (tranylcypromine and phenelzine) have been compared in the rat for activity in (i) inhibiting rat brain monoamine oxidase in vitro and in vivo using tyramine, 5-hydroxytryptamine (5-HT) and benzylamine as substrates; (ii) increasing brain levels of noradrenaline (NA) and 5-HT and (iii) antagonizing tetrabenazine-induced sedation.2. Concentrations of M&B 9302 and Lilly 51641 required to produce 50% inhibition of 5-HT oxidation by brain mitochondrial MAO were 1.4 x 10(-8)M and 2.5 x 10(-7)M respectively. Higher concentrations were required to inhibit tyramine oxidation whilst benzylamine oxidation was inhibited only at concentrations above 10(-5)M.3. E-250 showed the reverse substrate-selectivity in inhibiting the oxidation of benzylamine at concentrations below that required to inhibit the oxidation of 5-HT. NSD 2023 showed little substrate selectivity in vitro.4. Qualitatively similar results were obtained in vivo, except that NSD 2023 showed more marked substrate-selectivity.5. All the inhibitors except E-250 produced a dose-related rise in brain 5-HT levels. Only phenelzine and Lilly 51641 showed a linear relationship between NA levels and dose.6. All the drugs antagonized, in dose-related fashion, the effects of tetrabenazine in reducing locomotor activity. E-250 and NSD 2023 failed to restore locomotor activity to control levels whilst in high doses the other inhibitors, when given before tetrabenazine, produced a considerable increase in locomotor activity.7. Antagonism of tetrabenazine sedation appears to be correlated with (a) inhibition of the enzyme species that oxidize 5-HT and NA but not with inhibition of the enzyme species that oxidize benzylamine; (b) the rise in brain 5-HT levels rather than NA levels.