An endoscopic Ear Trainer for the low-resource setting.

BACKGROUND: Endoscopic ear surgery is a technique that is growing in popularity. It has potential advantages in the low-resource setting for teaching and training, for the relative ease of transporting and storing the surgical equipment and for telemedicine roles. There may also be advantages to the patient, with reduced post-operative pain, facilitating the ability to complete procedures as out-patients. METHODS: Our Ear Trainer has previously been validated for headlight and microscope otology skills, including foreign body removal and ventilation tube insertion, in both the high- and low-resource setting. This study aimed to assess the Ear Trainer for similar training and assessment of endoscopic ear surgery skills in the low-resource setting. The study was conducted in Uganda on ENT trainees. RESULTS: Despite a lack of prior experience with endoscopes, with limited practice time most participants showed improvements in: efficiency of instrument movement, steadiness of the camera view obtained, overall global rating of the task and performance time (faster task performance). CONCLUSION: These results indicate that the Ear Trainer is a useful tool in the training and assessment of endoscopic ear surgery skills.

Education in ear and hearing care in remote or resource-constrained environments.

BACKGROUND: At the heart of surgical care needs to be the education and training of staff, particularly in the low-income and/or resource-poor setting. This is the primary means by which self-sufficiency and sustainability will ultimately be achieved. As such, training and education should be integrated into any surgical programme that is undertaken. Numerous resources are available to help provide such a goal, and an open approach to novel, inexpensive training methods is likely to be helpful in this type of setting.The need for appropriately trained audiologists in low-income countries is well recognised and clearly goes beyond providing support for ear surgery. However, where ear surgery is being undertaken, it is vital to have audiology services established in order to correctly assess patients requiring surgery, and to be able to assess and manage outcomes of surgery. The training requirements of the two specialties are therefore intimately linked. OBJECTIVE: This article highlights various methods, resources and considerations, for both otolaryngology and audiology training, which should prove a useful resource to those undertaking and organising such education, and to those staff members receiving it.

Evaluation of a low-fidelity ear surgery simulator in a low-resource setting.

OBJECTIVE: The provision of healthcare education in developing countries is a complex problem that simulation has the potential to help. This study aimed to evaluate the effectiveness of a low-cost ear surgery simulator, the Ear Trainer. METHODS: The Ear Trainer was assessed in two low-resource environments in Cambodia and Uganda. Participants were video-recorded performing four specific middle-ear procedures, and blindly scored using a validated measurement tool. Face validity, construct validity and objective learning were assessed. RESULTS: The Ear Trainer provides a realistic representation of the ear. Construct validity assessment confirmed that experts performed better than novices. Participants displayed improvement in all tasks except foreign body removal, likely because of a ceiling effect. CONCLUSION: This study validates the Ear Trainer as a useful training tool for otological microsurgical skills in developing world settings.

Threat effects on human oculo-motor function.

Neuro-anatomical evidence supports the potential for threat-related factors, such as fear, anxiety and vigilance, to influence brainstem motor nuclei controlling eye movements, as well as the vestibular nuclei. However, little is known about how threat influences human ocular responses, such as eye saccades (ES), smooth pursuit eye tracking (SP), and optokinetic nystagmus (OKN), and whether these responses can be facilitated above normal baseline levels with a natural source of threat. This study was designed to examine the effects of height-induced postural threat on the gain of ES, SP and OKN responses in humans. Twenty participants stood at two different surface heights while performing ES (ranging from 8° to 45° from center), SP (15, 20, 30°/s) and OKN (15, 30, 60°/s) responses in the horizontal plane. Height did not significantly increase the slope of the relationship between ES peak velocity and initial amplitude, or the gain of ES amplitude. In contrast height significantly increased SP and OKN gain. Significant correlations were found between changes in physiological arousal and OKN gain. Observations of changes with height in OKN and SP support neuro-anatomical evidence of threat-related mechanisms influencing both oculo-motor nuclei and vestibular reflex pathways. Although further study is warranted, the findings suggest that potential influences of fear, anxiety and arousal/alertness should be accounted for, or controlled, during clinical vestibular and oculo-motor testing.

Development and validation of a low-cost microsurgery Ear Trainer for low-resource settings.

OBJECTIVE: Chronic suppurative otitis media is a neglected condition affecting up to 330 million people worldwide, with the burden of the disease in impoverished countries. The need for non-governmental organisations to hardwire training into their programmes has been highlighted. An ear surgery simulator appropriate for training in resource-poor settings was developed, and its effectiveness in facilitating the acquisition of headlight and microsurgical skills necessary to safely perform procedures via the ear canal was investigated. METHODS: Face validity was assessed via questionnaires. Six tasks were developed: a headlight foreign body removal task, and microscope tasks of foreign body removal, ventilation tube insertion, tympanomeatal flap raising, myringoplasty and middle-ear manipulation. Participants with varying ENT experience were video-recorded performing each task and scored by a blinded expert observer to assess construct validity. RESULTS: Face validity results confirmed that our Ear Trainer was a realistic representation of the ear. Construct validity results showed a statistically significant trend, with experts performing the best and those with limited experience performing better than novices. CONCLUSION: This study validates our Ear Trainer as a useful training tool for assessing headlight and microsurgical skills required to perform otological procedures.

Vestibulo-spinal and vestibulo-ocular reflexes are modulated when standing with increased postural threat.

We investigated how vestibulo-spinal reflexes (VSRs) and vestibulo-ocular reflexes (VORs) measured through vestibular evoked myogenic potentials (VEMPs) and video head impulse test (vHIT) outcomes, respectively, are modulated during standing under conditions of increased postural threat. Twenty-five healthy young adults stood quietly at low (0.8 m from the ground) and high (3.2 m) surface height conditions in two experiments. For the first experiment (n = 25) VEMPs were recorded with surface EMG from inferior oblique (IO), sternocleidomastoid (SCM), trapezius (TRP), and soleus (SOL) muscles in response to 256 air-conducted short tone bursts (125 dB SPL, 500 Hz, 4 ms) delivered via headphones. A subset of subjects (n = 19) also received horizontal and vertical head thrusts (∼150°/s) at each height in a separate session, comparing eye and head velocities by using a vHIT system for calculating the functional VOR gains. VEMP amplitudes (IO, TRP, SOL) and horizontal and vertical vHIT gains all increased with high surface height conditions (P < 0.05). Changes in IO and SCM VEMP amplitudes as well as horizontal vHIT gains were correlated with changes in electrodermal activity (ρ = 0.44-0.59, P < 0.05). VEMP amplitude for the IO also positively correlated with fear (ρ = 0.43, P = 0.03). Threat-induced anxiety, fear, and arousal have significant effects on VSR and VOR gains that can be observed in both physiological and functional outcome measures. These findings provide support for a potential central modulation of the vestibular nucleus complex through excitatory inputs from neural centers involved in processing fear, anxiety, arousal, and vigilance.

The ongoing dilemma of residual cholesteatoma detection: are current magnetic resonance imaging techniques good enough?

INTRODUCTION: There is a clear clinical need to reliably detect residual cholesteatoma after canal wall up mastoid surgery. Ideally, this would be achieved through non-invasive radiological means rather than second-look surgery, thus preventing morbidity in those patients in whom no residual disease is found. CASE REPORT: We describe a case in which non-echo-planar, diffusion-weighted magnetic resonance imaging sequences were used pre-operatively, and compared with subsequent surgical findings. This case highlights both the potential of this increasingly popular magnetic resonance technique and also its current limitations. DISCUSSION: Various magnetic resonance sequencing types have been employed to try to reliably detect residual cholesteatoma, each with varying success. Non-echo-planar, fast-spin echo, diffusion-weighted sequences currently appear to be the most reliable at detecting even the smallest pearl of cholesteatoma, down to 2 mm in diameter. In our unit, a propeller, diffusion-weighted image sequence is employed on a GE Signa scanner. However, both this case study and other reports show that the accuracy of the technique is not 100 per cent. This begs the question of how much one can rely on the findings of such techniques when deciding whether second-look surgery is indicated. Scan-negative patients will require continued follow up as, at the time of imaging, residual disease may not have reached a detectable size.

Leigh syndrome with cytochrome-c oxidase deficiency and a single T insertion nt 5537 in the mitochondrial tRNATrp gene.

We report a nine-year-old boy with the features of Leigh syndrome (LS) and a severe cytochrome-c oxidase (COX) deficiency with a single thymidine insertion at nucleotide position 5537 (T 5537i) in the tRNA Trp gene of mitochondrial DNA. During infancy the boy was irritable and hypotonus was noticed. Early motor development was delayed, although mental development seemed normal until eight months of age. Early neurological signs were nystagmus, hypertonus and optic atrophy. Severe seizures and mental retardation developed subsequently. Major findings on neuroradiological investigation were from the brainstem, thalami and white matter compatible with LS. Spectrophotometric analysis of skeletal muscle mitochondria showed a profound COX deficiency and a marked complex I deficiency. Enzyme-histochemical analysis showed reduced COX activity in the majority of the muscle fibres. There were no ragged red fibres. The T 5537i mutation was found in a high proportion (> 95 %) in blood, liver and muscle tissue of the patient and in blood of the patient's mother (81 %). This mutation has previously been described in one family in which one child had a very high proportion of the T 5537i mutation and clinical features of LS. We conclude that, although mtDNA mutations are considered to be rare in LS with COX deficiency, the T 5537i mutation should be screened for in cases of LS with COX deficiency when SURF1 gene mutations have been excluded, especially when complex I activity is also decreased.

The effects of posteroventral pallidotomy on balance function in patients with Parkinson's disease.

Parkinson's disease is a chronic, progressive neurodegenerative disorder resulting from dopaminergic cell loss in the pars compacta of the substantia nigra. Conventional treatment of Parkinson's disease consists of pharmacological replacement of dopamine. A treatment alternative, posteroventral pallidotomy (PVP), has been used for medically intractable stages of the disease. The purpose of this study was to evaluate the effects of PVP on balance function, as measured by dynamic posturography, in patients with medically intractable Parkinson's disease. Five subjects were studied within 2 days prior to and within 6 months following PVP. Pretreatment abnormalities were found in vestibular, visual, and somatosensory processing in balance function. Posteroventral pallidotomy resulted in improvement in vestibular compensation of posture in some patients, which may be at least partially due to an improvement in latencies to respond to changes in stance. Dynamic posturography is an effective tool in the evaluation of balance and posture in patients with advanced Parkinson's disease.

Formaldehyde fasciaform tympanoplasty: a reliable technique for closing large tympanic membrane perforations.

Formaldehyde fasciaform grafting tympanoplasty is a reliable method, in experienced hands, to close large tympanic membrane perforations. The technique involves using autogenous temporalis fascia shaped by formaldehyde cross-linking on a special fasciaform mold (Hear America, Palo Alto, CA). This study was undertaken with the objective of assessing if an otologist with less experience in using this technique could obtain comparable results. The results of the initial 23 patients treated in this manner by one surgeon between August 1996 and January 1998 are reviewed. Success was measured by the rate of closure of the tympanic membrane perforation and by functional closure of the air-bone gap. Favourable results were obtained, with complete closure of 86% of the perforations and closure of the air-bone gap to 20 dB or less in 90% of subjects when the ossicular chain was intact. The formaldehyde fasciaform tympanoplasty technique produces consistent, reliable, and reproducible results for large tympanic membrane perforations.

Auditory disorder in central nervous system miliary tuberculosis: case report.

We evaluated a 28-year-old female with a unilateral hearing loss of unusual pathogenesis, that of central nervous system miliary tuberculosis. Audiologic and otologic findings were consistent with left retrocochlear disorder, characterized by a profound hearing sensitivity loss, absent acoustic reflexes, normal otoacoustic emissions, and the presence of only wave I of the auditory brainstem response. Imaging studies revealed the presence of multiple punctate lesions, one of which was extra-axial and located at the left cerebellopontine angle. The pattern of audiometric test results, particularly the combination of normal otoacoustic emissions and profound hearing sensitivity loss, contributed importantly to the investigative sequence leading to the final diagnosis.

A double-blind placebo-controlled trial of baclofen in the treatment of tinnitus.

OBJECTIVE: To determine the effectiveness of baclofen in ameliorating tinnitus in adult patients. STUDY DESIGN: Randomized double-blind placebo-controlled trial. SETTING: California Ear Institute at Stanford, California, a tertiary otology/neurotology referral center. PATIENTS: Restricted to adults receiving otologic evaluation at the California Ear Institute at Stanford. Some patients had a primary complaint of tinnitus, whereas others with tinnitus were recruited during treatment for another condition. The study population was felt to be representative of the general population with tinnitus. INTERVENTIONS: Three weeks of baclofen (10 mg orally twice daily for 1 week, 20 mg orally twice daily for the second week, and 30 mg orally twice daily for the third week) or placebo designed to mimic baclofen capsules in route, schedule, appearance, and taste were given to patients. MAIN OUTCOME MEASURES: Tinnitus handicap inventory, pitch and loudness matching, and maskability of tinnitus. RESULTS: Subjective and objective evaluation failed to demonstrate any clinical or statistical advantage of baclofen over placebo. Reports of subjective improvement occurred in only 9.7% of the baclofen versus 3.4% of the placebo groups, a nonsignificant difference. Withdrawal from the baclofen arm of the study occurred in 26% due to side effects, which could be attributed to the medication. CONCLUSIONS: Baclofen is no more effective than placebo in ameliorating tinnitus in adult patients.

Multiple oncocytic laryngeal cysts presenting as acute airway obstruction.

Solitary oncocytic cyst of the larynx is a recognized clinical and pathologic entity. Multiple oncocytic cysts have only rarely been described. A 67-year-old female presented with rapidly progressive airway obstruction requiring emergency tracheotomy. The obstruction was caused by multiple cystic lesions throughout the supraglottic region. Microscopic examination of laryngeal biopsies showed cysts within the lamina propria, lined by oncocytic epithelium. The differential diagnosis and pathogenesis of oncocytic cysts is discussed with a review of other laryngeal cystic lesions.

Connections of the superior olive in the chicken.

The avian superior olive (OS) is known to be a station in the auditory pathway, although its anatomic connections remain uncertain. The afferent and efferent connections of OS neurons in the chicken were identified with wheat germ agglutinin conjugated to horse radish peroxidase (WGA-HRP) injected into the OS nucleus. Projections to the OS originate bilaterally in the cochlear nuclei (nucleus angularis) and the nucleus laminaris. Anterogradely labelled axon terminals were found in the ipsilateral nucleus magnocellularis, the contralateral intermediate nucleus of the lateral lemniscus, and the shell portion of the central nucleus of the inferior colliculus. Retrograde transport of [3H]-glycine from the OS was also charted. Glycine-transporting cells were found ipsilaterally in the nucleus angularis and the nucleus laminaris. Neuronal soma in a newly identified nucleus of the trapezoid body (NTB) were found to actively concentrate glycine, although the neurons probably do not synapse within the OS. Anatomically, the avian OS would appear to be part of the interaural intensity difference pathway; however, our data and published information are insufficient to establish a homology to the human lateral superior olive.

Charcot-Marie-Tooth disease in northern Sweden: pedigree analysis and the presence of the duplication in chromosome 17p11.2.

Sixty-seven patients in 29 families with the diagnosis of Charcot-Marie-Tooth disease or hereditary motor and sensory neuropathy in northern Sweden were examined by pedigree and DNA analysis for the CMT1a duplication within chromosome 17p11.2. There were 39 patients in nine families with Charcot-Marie-Tooth type 1 and autosomal dominant inheritance and in all these cases the duplication was seen. In six patients in three families with Charcot-Marie-Tooth type 1 the pedigrees strongly suggested autosomal recessive inheritance. In two patients DNA analysis was not informative but in the others no duplication was shown. There were also 11 "sporadic" patients and one pair of sibs classified as Charcot-Marie-Tooth type 1, but there was no duplication shown although in four patients DNA analysis was not informative. In nine patients with Charcot-Marie-Tooth type 2 from five families and in 13 unaffected relatives of Charcot-Marie-Tooth patients the CMT1a duplication was not found.

Phrenic nerve reinnervation of the cat's larynx: a new technique with proven success.

Reinnervation of the posterior cricoarytenoid muscle (PCA) should provide vocal cord abduction on inspiration, and passive adduction to enable phonation. Previous investigators have shown that reinnervation is possible, but results have not been clinically encouraging. When reinnervation was successful, the question remained whether it was provided by the transplanted nerve or by the ingrowth of adjacent nerves. In this study the phrenic nerve was transplanted directly into the PCA in a series of 12 cats. Fibrin glue was used to overcome nerve trauma and to prevent retraction of the nerve from the PCA. Laryngoscopy, electromyography, and retrograde labeling of the phrenic motoneurons provided evidence of functional reinnervation in 9 cats. Partial or complete failure in the remaining 3 was due to retraction of the nerve from the muscle. These results appear to justify trials of the procedure in humans.