The Nitrous Oxide Project: assessment of advocacy and national directives to deliver mitigation of anaesthetic nitrous oxide

The environmental emissions attributed to anaesthetic nitrous oxide across the NHS are comparable to the carbon dioxide released by 135,000 flights from Frankfurt to New York. Much of these emissions are attributable to cumbersome and inadequately managed piped systems, resulting in excessive loss and waste. Since 2020, multiple hospital sites have been engaging with the Nitrous Oxide Project, a quality improvement method supporting a 'lean systems' approach to the provision of nitrous oxide. This review considers the frameworks supporting medical gas management in UK healthcare systems, and the impact of professional advocacy and medical gas stewardship to drive anaesthetic nitrous oxide mitigation in the NHS. Nitrous oxide mitigation efforts by grassroots and professional advocacy networks are enhanced through national centralised emission monitoring, distribution of data, technical information and provision of quality analysis. Given the climate harms of nitrous oxide, concerted efforts should be made to rationalise its use, and resources should be committed to supporting this at local, regional and national levels.

Using Bayesian Dynamic Borrowing to Maximize the Use of Existing Data: A Case-Study

Bayesian Dynamic Borrowing (BDB) designs are being increasingly used in clinical drug development. These methods offer a mathematically rigorous and robust approach to increase efficiency and strengthen evidence by integrating existing trial data into a new clinical trial. The regulatory acceptability of BDB is evolving and varies between and within regulatory agencies. This paper describes how BDB can be used to design a new randomised clinical trial including external data to supplement the planned sample size and discusses key considerations related to data re-use and BDB in drug development programs. A case-study illustrating the planning and evaluation of a BDB approach to support registration of a new medicine with the Center for Drug Evaluation in China will be presented. Key steps and considerations for the use of BDB will be discussed and evaluated, including how to decide whether it is appropriate to borrow external data, which external data can be re-used, the weight to put on the external data and how to decide if the new study has successfully demonstrated treatment benefit.

Temperature changes of CoolSticks during simulated use

INTRODUCTION

Cold sensation is often used to check neuraxial anaesthesia and analgesia. One opportunity to reduce the carbon footprint of anaesthesia is to replace vapo-coolant sprays such as ethyl chloride with a reusable device called the CoolStick, which is cooled in a refrigerator between uses. We designed a study to investigate how long the CoolStick remains at its working temperature, which we defined as <15 °C.

METHOD

Experiments were undertaken using a thermocouple and digital temperature sensor attached to the CoolStick. We conducted two experiments to assess temperature changes following removal from the refrigerator for 10 min; the first investigated passive re-warming in the ambient theatre environment and the second investigated re-warming in simulated use. In our third experiment, we investigated the time taken to cool the device in the refrigerator, following use. Each experiment was repeated three times.

RESULTS

In the passive re-warming experiment, the mean CoolStick temperature was 7.3 °C at the start, and 14.3 °C after 10 min. In the simulated use experiment, the mean CoolStick temperature was 7.3 °C at the start, and 18.9 °C at 10 min. In the cooling experiment, the mean CoolStick temperature was 15 °C at the start and 7.6 °C at 40 min.

CONCLUSION

Our study indicates that it is feasible to use the CoolStick for providing cold sensation in clinical practice. Further study would be required to directly compare the effectiveness of the device to existing methods such as coolant sprays or ice in the clinical setting.

Implementing nitrous oxide cracking technology in the labour ward to reduce occupational exposure and environmental emissions: a quality improvement study. Anaesthesia 2022;77:1228-1236. [PMID: 36108342 DOI: 10.1111/anae.15838]

Nitrous oxide, a potent greenhouse gas, is a common labour analgesic. One method which may reduce its carbon footprint is to 'crack' the exhaled gas into nitrogen and oxygen using catalytic destruction. In this quality improvement project, based on environmental monitoring and staff feedback, we assessed the impact of nitrous oxide cracking technology in the maternity setting. Mean ambient nitrous oxide levels were recorded during the final 30 minutes of uncomplicated labour in 36 cases and plotted on a run chart. Interventions were implemented in four stages, comprising: stage 1, baseline (12 cases); stage 2, cracking with nitrous oxide delivered and scavenged via a mouthpiece (eight cases); stage 3, cracking with nitrous oxide via a facemask with an air-filled cushion (eight cases); stage 4, cracking with nitrous oxide via a low-profile facemask, and enhanced coaching on the use of the technology (eight cases). The median ambient nitrous oxide levels were 71% lower than baseline in stage 2 and 81% lower in stage 4. Staff feedback was generally positive, though some found the technology to be cumbersome; successful implementation relies on effective staff engagement. Our results indicate that cracking technology can reduce ambient nitrous oxide levels in the obstetric setting, with potential for reductions in environmental impacts and occupational exposure.

Diagnostic accuracy of screening MR imaging using unenhanced axial CISS and coronal T2WI for detection of small internal auditory canal lesions

BACKGROUND AND PURPOSE

While enhanced T1WI is considered the "gold standard" for detection of internal auditory canal pathology, unenhanced fluid-sensitive sequences have shown high sensitivity for lesion identification. Our purpose was to evaluate the diagnostic accuracy of an unenhanced MR imaging protocol using axial CISS and coronal T2WI for detection of small (10 mm or less) internal auditory canal lesions.

MATERIALS AND METHODS

Twenty-three patients with small internal auditory canal lesions and 13 patients without lesions who had undergone MR imaging using the screening protocol and confirmatory gadolinium-enhanced thin section T1WI were identified. Two blinded neuroradiologists retrospectively evaluated all examinations using 1) only axial CISS, 2) only coronal T2WI, and 3) axial and coronal sequences together. Accuracy, specificity, sensitivity, and interobserver agreement were assessed.

RESULTS

Median maximum lesion dimension was 4 mm (range, 2-10 mm). Accuracy, specificity, and sensitivity for axial CISS alone were 0.94, 0.96, and 0.91 for observer 1 and 0.94, 0.92, and 1.00 for observer 2. The data for the coronal T2WI sequence only were 0.94, 0.96, and 0.91 for observer 1, and 0.99, 1.00, and 0.96 for observer 2. Using axial and coronal sequences, the data were 0.97, 0.96, and 1.00 for observer 1, and 0.99, 0.98, and 1.00 for observer 2. κ coefficients were 0.84 for the axial sequence only, 0.90 for coronal only, and 0.91 for axial and coronal both.

CONCLUSIONS

Screening noncontrast MR imaging using a combination of axial CISS and coronal T2WI sequences can detect small internal auditory canal lesions with 100% sensitivity and excellent interobserver agreement.

Predictors of serum polychlorinated biphenyl concentrations in Anniston residents

The Anniston Community Health Survey was a community-based cross-sectional study of Anniston, Alabama, residents who live in close proximity to a former PCB production facility to identify factors associated with serum PCB levels. The survey comprises 765 Anniston residents who completed a questionnaire interview and provided a blood sample for analysis in 2005-2007. Several reports based on data from the Anniston survey have been previously published, including associations between PCB exposure and diabetes and blood pressure. In this study we examine demographic, behavioral, dietary, and occupational characteristics of Anniston survey participants as predictors of serum PCB concentrations. Of the 765 participants, 54% were White and 45% were African-American; the sample was predominantly female (70%), with a mean age of 55 years. Serum PCB concentrations varied widely between participants (range for sum of 35 PCBs: 0.11-170.4 ng/g wet weight). Linear regression models with stepwise selection were employed to examine factors associated with serum PCBs. Statistically significant positive associations were observed between serum PCB concentrations and age, race, residential variables, current smoking, and local fish consumption, as was a negative association with education level. Age and race were the most influential predictors of serum PCB levels. A small age by sex interaction was noted, indicating that the increase in PCB levels with age was steeper for women than for men. Significant interaction terms indicated that the associations between PCB levels and having ever eaten locally raised livestock and local clay were much stronger among African-Americans than among White participants. In summary, demographic variables and past consumption of locally produced foods were found to be the most important predictors of PCB concentrations in residents living in the vicinity of a former PCB manufacturing facility.

Serum concentrations of polychlorinated biphenyls (PCBs) in participants of the Anniston Community Health Survey

Serum concentrations of 35 ortho-substituted polychlorinated biphenyl congeners (PCBs) were measured in 765 adults from Anniston, Alabama, where PCBs were manufactured between 1929 and 1971. As part of the Anniston Community Health Survey (ACHS), demographic data, questionnaire information, and blood samples were collected from participants in 2005-2007. Forty-six percent of study participants were African-American, 70% were female, and the median age was 56 years. The median concentration of the sum of 35 PCB congeners (ΣPCBs) was 528 ng/g lipid, with a 90th percentile of 2,600 ng/g lipid, minimum of 17.0 ng/g lipid, and maximum of 27,337 ng/g lipid. The least square geometric mean ΣPCBs was more than 2.5 times higher for African-American participants than for White participants (866 ng/g lipid vs. 331 ng/g lipid); this difference did not change materially after adjustment for age, sex, body mass index (BMI) and current smoking. In spite of large differences in absolute PCB levels, relative contributions of individual congeners to ΣPCBs were quite similar between race groups. Nevertheless, while percent contributions to ΣPCBs for most of the most abundant penta- to heptachlorobiphenyls were higher among African-Americans, the percentages were higher in Whites for the lower-chlorinated PCBs 28 and 74 and for octa- to decachlorinated PCBs. No major differences were observed in geometric mean ΣPCBs between women and men when adjusted for age, race, BMI and current smoking (516 ng/g lipid vs. 526 ng/g lipid). Principal component analysis revealed groups of co-varying congeners that appear to be determined by chlorine substitution patterns. These congener groupings were similar between ACHS participants and the National Health and Nutrition Examination Survey (NHANES) 2003-04 sample of the general United States population, despite ACHS participants having serum concentrations of ΣPCBs two to three times higher than those in comparable age and race groups from NHANES.

Intralabyrinthine schwannomas: imaging diagnosis and classification

BACKGROUND AND PURPOSE

ILS is a rare lesion that has a different management from the more common "acoustic" schwannoma. To date, only 137 cases have been reported. We present a classification scheme based on labyrinthine anatomy to describe and localize these lesions. Treatment and prognosis hinge on the appropriate localization of these tumors; thus, a concise terminology that can be used by both the otolaryngologist and radiology communities is desirable.

MATERIALS AND METHODS

After approval of the institutional review board, a retrospective study of all patients with the diagnosis of ILS imaged between 1996 and 2010 was performed. Clinical and imaging data were collected. Patients were imaged with thin-section high-resolution T2 and contrast-enhanced MR imaging.

RESULTS

There were 45 patients with a diagnosis of ILS. Forty-three had complete histories. There were 18 male and 25 female patients with an age range of 21-78 years with a mean age of 53 years. The most common presenting symptom was progressive sensorineural hearing loss. Lesions were characterized on the basis of their location. Intracochlear was most common (14/45) followed by transmodiolar (13/45), intravestibular (7/45), vestibulocochlear (5/45), transmacular (4/45), and transotic (2/45). Sixteen patients underwent surgical resection. The remaining patients were followed clinically and by serial MR imaging.

CONCLUSIONS

ILS is an uncommon but under-reported tumor. We characterized the MR imaging appearance of these tumors by using high-resolution techniques. In addition, an anatomically based classification system is presented that will help the radiologist accurately describe ILS within the inner ear and help the surgeon determine which tumors are potential surgical candidates.

Imaging and clinical characteristics of temporal bone meningioma

BACKGROUND AND PURPOSE

Imaging characteristics of temporal bone meningioma have not been previously reported in the literature. CT and MR imaging findings in 13 cases of temporal bone meningioma are reviewed to define specific imaging features.

METHODS

A retrospective review of our institutional case archive revealed 13 cases of histologically confirmed temporal bone meningioma. CT and MR imaging studies were reviewed to characterize mass location, vector of spread, bone changes, enhancement characteristics, and intracranial patterns of involvement. Clinical presenting signs and symptoms were correlated with imaging findings.

RESULTS

Thirteen temporal bone meningiomas were reviewed in 8 women and 5 men, aged 18-65 years. Meningiomas were stratified into 3 groups on the basis of location and tumor vector of spread. There were 6 tegmen tympani, 5 jugular foramen (JF), and 2 internal auditory canal (IAC) meningiomas. Tegmen tympani and JF meningiomas were characterized by spread to the middle ear cavity. IAC meningiomas, by contrast, spread to the cochlea and vestibule. Hearing loss was the most common clinical presenting feature in all cases of temporal bone meningioma (10/13). The presence of tumor adjacent to the ossicles strongly correlated with conductive hearing loss (7/9).

CONCLUSION

Meningioma involving the temporal bone is rare. Three subgroups of meningioma exist in this location: tegmen tympani, JF, and IAC meningioma. Tegmen tympani and JF meningiomas spread to the middle ear cavity. IAC meningiomas spread to intralabyrinthine structures. Conductive hearing loss is commonly seen in these patients and can be surgically correctable.

The many faces of facial nerve schwannoma

BACKGROUND AND PURPOSE

The imaging appearance of facial nerve schwannomas (FNSs) has been described as an enhancing tubular mass (using T1-enhanced MR) within an enlarged facial nerve canal (using CT). The purpose of this study is to identify how often the FNS imaging findings conform to this description and determine whether there are underlying anatomic explanations for the discrepant imaging appearances identified.

MATERIALS AND METHODS

The clinical, pathologic, and radiologic records of 24 FNS in 23 patients were retrospectively reviewed. Each FNS was evaluated for location along the facial nerve. The lesions were cataloged by facial nerve segment with the imaging characteristics of each segment described.

RESULTS

The average age at time of first imaging was 39 years (age range, 10-70 years). Eighteen (71%) of the 24 FNSs were pathologically confirmed, while the others were determined intraoperatively or diagnostically by the presence of both enlargement of the facial nerve canal and enhancement on contrast-enhanced T1 MR examination. The most common location was in the geniculate fossa (83%), followed by the labyrinthine and tympanic segments of the facial nerve (both 54%). The most common clinical presentation was facial neuropathy (42%).

CONCLUSION

The classic description of FNS on enhanced T1 MR is that of a well-circumscribed fusiform enhancing mass along the course of the intratemporal facial nerve with bone algorithm CT showing sharply defined bony canal enlargement. Modern imaging techniques, however, demonstrate the importance of the surrounding anatomic landscape, leading to various imaging appearances. Lesions traversing the labyrinthine segment can demonstrate a dumbbell appearance. When FNSs track along the greater superficial petrosal nerve, they may present as a round mass projecting up into the middle cranial fossa. FNS of the tympanic segment of the facial nerve preferentially pedunculate into the middle ear cavity, clinically presenting as a middle ear mass. When the mastoid segment of the facial nerve is involved, irregular and "invasive" tumor margins seen on MR can be explained on CT as tumor breaking into surrounding mastoid air cells.

Agreement between three commercially available instruments for measuring short-term heart rate variability

Numerous instruments are commercially available to measure heart rate variability, yet little is known regarding the agreement between such instruments. The objective of this study is to assess agreement between measures of heart rate variability in three commercially available instruments. Thirty subjects (20 males) of median age 27.5 (range 19-59 years) underwent simultaneous ECG recordings, under three different resting conditions: supine, standing and supine with controlled breathing, using three commercially available analysers. Intraclass correlation coefficients tended to show excellent agreement (lower 95% C.I., R > 0.75) between all instruments under all conditions. However, further analysis of selected measurements using the limits of agreement method revealed large variation in values generated by all instruments. There was also an evidence of systematic bias between one instrument and the remaining two. The latter finding was due to discrepant ECG recording protocols that were unrelated to consistent operator timing. This study demonstrates that measures of HRV generated by the three instruments did not agree well in all cases. Discrepancies were due to the recording protocols of the systems. This may lead to incomparable results between instruments. It is therefore recommended that: (a) if different instruments are used in the same study or (b) multi-centre study designs are planned or (c) heart rate variability results are discussed with reference to studies using other instruments, levels of agreement need to be reported to ensure comparability.

Worldwide overview of critical care nursing organizations and their activities

While critical care has been a specialty within nursing for almost 50 years, with many countries having professional organizations representing these nurses, it is only recently that the formation of an international society has been considered. A three-phased study was planned: the aim of the first phase was to identify critical care organizations worldwide; the aim of the second was to describe the characteristics of these organizations, including their issues and activities; and the aim of the third was to plan for an international society, if international support was evident. In the first phase, contacts in 44 countries were identified using a number of strategies. In the second phase, 24 (55%) countries responded to a survey about their organizations. Common issues for critical care nurses were identified, including concerns over staffing levels, working conditions, educational programme standards and wages. Critical care nursing organizations were generally favourable towards the notion of establishing a World Federation of their respective societies. Some of the important issues that will need to be addressed in the lead up to the formation of such a federation are now being considered.

Petrous apex cephaloceles

BACKGROUND AND PURPOSE

Petrous apex cephaloceles (PACs) are uncommon lesions that are usually incidental but may be symptomatic. We reviewed MR and CT studies in 10 patients with PACs to identify characteristic imaging features that facilitate their diagnosis.

METHODS

MR and CT studies from 10 patients with PACs were reviewed retrospectively. In each case the PAC was characterized by lesion center, signal intensity or attenuation, adjacent petrous apex pneumatization, and its relationship to Meckel's cave. Intraoperative findings were reviewed in the three cases in which surgery was performed.

RESULTS

All 10 patients had lobulated expansile cystic petrous apex lesions centered along the posterolateral margin of Meckel's cave. All cysts were contiguous with Meckel's cave. Three patients had bilateral PACs. Four patients had symptoms that could potentially be explained by the PAC, while findings in the other six were incidental observations. Three patients underwent surgery, during which two lesions were diagnosed as meningoceles while the third was diagnosed as an arachnoid cyst protruding through a dural defect.

CONCLUSION

PACs represent a protrusion of meninges and CSF from the posterolateral portion of Meckel's cave into the petrous apex, which is their characteristic imaging appearance. PACs are usually incidental but may be symptomatic. Surgical intervention should be approached cautiously and undertaken only when symptoms are clearly linked to the presence of this lesion.

Dumbbell schwannomas of the internal auditory canal

BACKGROUND AND PURPOSE

Benign tumors of the internal auditory canal (IAC) may leave the confines of the IAC fundus and extend into inner ear structures, forming a dumbbell-shaped lesion. It is important to differentiate dumbbell lesions, which include facial and vestibulocochlear schwannomas, from simple intracanalicular schwannomas, as surgical techniques and prognostic implications are affected. In this article, the imaging and clinical features of these dumbbell schwannomas are described.

METHODS

A dumbbell lesion of the IAC is defined as a mass with two bulbous segments, one in the IAC fundus and the other in the membranous labyrinth of the inner ear or the geniculate ganglion of the facial nerve canal, spanned by an isthmus. Twenty-four patients with dumbbell lesions of the IAC had their clinical and imaging data retrospectively reviewed. Images were evaluated for contour of the mass and extension into the membranous labyrinth or geniculate ganglion.

RESULTS

Ten of 24 lesions were facial nerve dumbbell lesions. Characteristic features included an enhancing "tail" along the labyrinthine segment of the facial nerve and enlargement of the facial nerve canal. Dumbbell schwannomas of the vestibulocochlear nerve (14/24) included transmodiolar (8/14), which extended into the cochlea, transmacular (2/14), which extended into the vestibule, and combined transmodiolar/transmacular (4/14) types.

CONCLUSION

Simple intracanalicular schwannomas can be differentiated from transmodiolar, transmacular, and facial nerve schwannomas with postcontrast and high-resolution fast spin-echo T2-weighted MR imaging. Temporal bone CT is reserved for presurgical planning in the dumbbell facial nerve schwannoma group.

Intratemporal facial nerve neuroma: anatomical location and radiological features

OBJECTIVES

To present the imaging findings and anatomical locations of a series of 88 facial nerve neuromas from two centers over a 30-year period. We describe the salient radiological features of neuromas in each anatomical location and outline the ways in which modern imaging techniques have altered our perception of this entity.

STUDY DESIGN

A retrospective review of tumors presenting to two tertiary care referral institutions since 1970.

METHODS

The charts and available imaging of patients with the diagnosis of facial neuroma were reviewed. These patients presented to the House Ear Clinic between 1970 and 1994 and to the University of Utah Medical Center (Salt Lake City, UT) between 1986 and August 2000. We examined anatomical location to determine patterns of tumor presentation and compared the findings before and after the era of magnetic resonance imaging (MRI).

RESULTS

All segments of the facial nerve were represented. Overall, multiple-segment tumors were almost twice as common (63.6%) as single-segment tumors (36.4%). Before the advent of MRI, all segments of the nerve from the cerebellopontine angle to the tympanic portion were almost equally represented (29.5%-36.3%). After MRI, the geniculate ganglion (68.2%) and labyrinthine portion (52.3%) were by far the most commonly affected areas. Before MRI, there were, on average, 1.89 segments involved per tumor. After MRI, this average number increased to 2.57 segments per tumor. Radiologically, the high-resolution computed tomography and MRI features cannot be generalized. Rather, the imaging features depend on which segments are involved. This is because of the variation in the surrounding anatomical landscape of the facial nerve in its course through the temporal bone.

CONCLUSION

The more sensitive imaging provided by newer radiological techniques has altered our perception of facial neuroma. It has provided us with an increased ability to diagnose and fully evaluate this neoplasm preoperatively, allowing improved patient counseling and surgical planning.

Role of topical steroids in reducing dysfunction after nerve injury

OBJECTIVE

To determine the efficacy of topical dexamethasone in reducing nerve dysfunction after axonotmesis injury.

STUDY DESIGN

A three-armed, blinded study including sham, control, and test groups was designed using the rat sciatic nerve crush injury model.

METHODS

Twenty-two rats were randomly assigned to a control group or a topical steroid group. A standardized sciatic nerve crush injury was performed under sterile conditions on each animal. A separate group of five rats underwent a sham operation to isolate the crush injury as the source of postoperative dysfunction in the control and steroid groups. All animals underwent walking track analysis with calculation of the sciatic functional index (SFI) before surgery and through the postoperative recovery period. Dexamethasone saturated Gelfoam was placed at the site of injury in the topical steroid group. The functional performance of each group was compared throughout the recovery period.

RESULTS

No morbidity associated with topical application of steroids at the injury site was noted. The topical steroid group had improved recovery at postoperative days 14, 18, and 22. This difference was statistically significant at day 14. At the termination of the study, there was a clear trend toward superior recovery for the steroid group compared with controls (90% vs. 73%), but this difference did not reach statistical significance.

CONCLUSIONS

Clinical use of topical steroids to reduce postoperative nerve dysfunction warrants further study.

Preoperative cochlear implant imaging: is magnetic resonance imaging enough?

OBJECTIVE

To investigate the accuracy of magnetic resonance imaging (MRI) as a preoperative imaging technique for cochlear implant candidates.

STUDY DESIGN

Retrospective, blinded.

SETTING

Tertiary medical center.

PATIENTS

31 cochlear implant candidates with various causes of hearing loss.

INTERVENTION

Cochlear implant patients received preoperative high-resolution temporal bone computed tomography (CT), and high-resolution T2-weighted fast spin echo MRI (FSE-MRI). The images were read independently of each other and in a blinded manner by two neuroradiologists. The imaging results were also correlated with intraoperative findings.

MAIN OUTCOME MEASURES

Lack of agreement between the findings for either imaging technique; also, lack of agreement between imaging findings and intraoperative findings.

RESULTS

FSE-MRI is equal to CT imaging in the detection of abnormalities of cochlear patency. It is better than CT imaging in detecting cochlear dysplasia and large vestibular aqueducts, and in determining the presence of the cochlear nerve.

CONCLUSION

FSE-MRI is accurate in predicting inner ear anomalies and obstruction of the cochlear lumen. It also adds information not gathered from CT imaging, such as the presence and size of the cochlear nerve.

Causes of unilateral sensorineural hearing loss screened by high-resolution fast spin echo magnetic resonance imaging: review of 1,070 consecutive cases

OBJECTIVE

Evaluation of the ability of screening high-resolution, nonenhanced, fast spin echo (FSE) T2-weighted magnetic resonance imaging (MRI) of the internal auditory canal (IAC) and cerebellopontine angle (CPA) to detect nonacoustic schwannoma causes of unilateral sensorineural hearing loss (SNHL). FSE-MRI is equally sensitive in detecting acoustic (vestibular) schwannoma as gadolinium-enhanced MRI, but sensitivity to other causes of hearing loss is unknown.

STUDY DESIGN

Retrospective review of screening FSE-MRI studies.

SETTING

Academic otology/neurotology and neuroradiology practices.

PATIENTS

There were 1,070 patients with unilateral SNHL who underwent radiologic screening for retrocochlear pathology.

RESULTS

Normal findings were found in 944 cases. Typical (acoustic) vestibular schwannoma were found in 56 patients. Seventy additional lesions were identified: 27 CPA lesions, 29 inner ear lesions, and 12 intraaxial lesions including 9 infarctions, 1 multiple sclerosis case, 1 mesial temporal lobe sclerosis, and 1 colloid cyst.

CONCLUSIONS

High-resolution T2 FSE-MRI of the IAC and CPA is a highly sensitive screening tool for unilateral SNHL, which can detect a variety of lesions in addition to vestibular schwannomas. To our knowledge in 2 years of follow-up in these patients screened for IAC/CPA lesions, no other lesions causing SNHL have been found. High-resolution FSE screening technique, used in conjunction with appropriate clinical prescreening and referral, can provide an equally sensitive method of evaluating unilateral SNHL compared to gadolinium-enhanced T1 MRI while reducing costs and providing distinct advantages in evaluating nonacoustic schwannoma causes of SNHL.

MR evaluation of vestibulocochlear anomalies associated with large endolymphatic duct and sac

BACKGROUND AND PURPOSE

Large endolymphatic duct and sac (LEDS) is one of the most common anomalies seen in patients with congenital sensorineural hearing loss (SNHL), and is known to occur with other inner ear findings. Our purpose was to use high-resolution T2-weighted fast spin-echo (FSE) MR imaging to describe the features and prevalence of specific anomalies that occur in association with LEDS.

METHODS

We retrospectively reviewed MR images of the inner ear obtained in 63 patients with LEDS and in 60 control subjects. We evaluated each image for features of cochlear and vestibular dysplasia, including deficiency of the cochlear modiolus, gross cochlear dysmorphism, asymmetry of the cochlear scalar chambers, enlargement of the membranous vestibule, gross vestibular dysmorphism, and abnormality of the semicircular canals (SCC).

RESULTS

Cochlear anomalies were present in 76% of ears with LEDS. Modiolar deficiency, gross dysmorphism, and scalar asymmetry were seen in 94%, 71%, and 65% of abnormal cochleas, respectively. Vestibular abnormalities were present in 40% of ears with LEDS. Simple enlargement, gross dysmorphism, and distortion of the lateral SCC were seen in 84%, 16%, and 32% of abnormal vestibules, respectively.

CONCLUSION

Coexistent cochlear anomalies, vestibular anomalies, or both are present in most ears with LEDS, and appear as a spectrum of lesions, ranging from subtle dymorphism to overt dysplasia. The presence of coexistent anomalies in LEDS affects treatment decisions and prognosis. Newer techniques of high-resolution FSE MR imaging provide a means of exquisite characterization of LEDS, as well as more sensitive detection of associated vestibulocochlear anomalies.

Sensorineural hearing loss after occlusion of the enlarged vestibular aqueduct

OBJECTIVE

This study aimed to report the hearing results of endolymphatic sac occlusion in patients with enlarged vestibular aqueduct syndrome.

STUDY DESIGN

The study design was a multiinstitutional retrospective case series.

SETTING

The study was conducted at tertiary otologic referral centers.

PATIENTS

The study included 10 previously unreported patients with progressive sensorineural hearing loss and vestibular aqueducts greater than 1.5 mm in diameter on computerized tomography.

INTERVENTION

Occlusion of the enlarged vestibular aqueduct was performed by means of a transmastoid surgical approach. Either intraluminal endolymphatic sac obliteration (five patients) or extraluminal extradural endolymphatic sac obliteration (five patients) was accomplished with temporalis fascia.

MAIN OUTCOME MEASURES

The postoperative pure tone average (PTA) and speech discrimination scores were compared with the preoperative levels using conventional audiometry.

RESULTS

Nine of 10 patients experienced some degree of sensorineural hearing loss. The median change in PTA was a loss of 21 decibels (dB), and 50% of the patients experienced a sensorineural hearing loss greater than 25 dB. Postoperative change in PTA ranged from +10 dB to -59 dB. The median change in speech discrimination score was a loss of 27.5%. Only one patient had an improvement in both speech discrimination score and pure tone averages after surgery. Patients who underwent extraluminal occlusion had a median PTA loss of 12 dB, and patients who underwent open sac occlusion had a median PTA loss of 34 dB. These were not statistically different.

CONCLUSION

In this series of 10 patients, 5 had a greater than 25 dB decrease in hearing after occlusion of the enlarged vestibular aqueduct. Surgical occlusion of the enlarged vestibular aqueduct showed no significant benefit in hearing preservation. The otologic surgeon is alerted to the potential for severe sensiorineural hearing loss after occlusion of the enlarged vestibular aqueduct.

Ultra high resolution nonenhanced fast spin echo magnetic resonance imaging: cost-effective screening for acoustic neuroma in patients with sudden sensorineural hearing loss

The financial burden for the evaluation of patients for acoustic neuroma in an otolaryngology practice is substantial. Patients with sudden sensorineural hearing loss represent a portion of that population seen with unilateral, asymmetric auditory symptoms who require investigation for acoustic neuroma. For these patients, gadolinium-enhanced magnetic resonance imaging is the diagnostic gold standard. Auditory brain stem response testing has been used in the past as a screening test for acoustic neuroma, but its apparent sensitivity has fallen as the ability to image smaller acoustic neuromas has improved. Fast spin echo magnetic resonance imaging techniques without gadolinium have been shown to be as effective in the detection of acoustic neuroma as contrast-enhanced magnetic resonance imaging. Limited nonenhanced fast spin echo magnetic resonance imaging now provides an inexpensive alternative for high-resolution imaging of the internal auditory canal and cerebellopontine angle. Fast spin echo magnetic resonance imaging can now be done at a cost approximating auditory brain stem response testing while providing the anatomic information of contrast-enhanced magnetic resonance imaging. Cost analysis was done in the cases of 58 patients with sudden sensorineural hearing loss by comparing the costs for routine workup and screening of acoustic neuroma with the cost of fast spin echo magnetic resonance imaging with the use of screening protocols based on literature review. The potential cost savings of evaluating patients with sudden sensorineural hearing loss with fast spin echo magnetic resonance imaging for acoustic neuroma was substantial, with a 54% reduction in screening costs. In an era of medical economic scrutiny, fast spin echo magnetic resonance imaging has become the most cost-effective method to screen suspected cases of acoustic tumors at our institution by improving existing technology while reducing the cost of providing that technology and eliminating charges for impedance audiometry, auditory brain stem response testing, and contrast-enhanced magnetic resonance imaging.

Combined transarterial and transvenous embolisation of jugulotympanic paragangliomas

SUMMARY

Paragangliomas of the jugular region present a greater challenge to the surgeon than paragangliomas in other locations. Because of the vascular nature of the tumour, bleeding can be substantial not only from arterial inflow to the tumour, but also from venous bleeding, if not embolised prior to surgery. Six patients were treated with combined transarterial and transvenous embolisation followed by surgical resection. In each instance, the diagnosis of jugulotympanic paraganglioma was suspected based on MR features. Substantial reduction in loss of blood appears to result from the combined transarterial and transvenous embolisation approach.

Bone cement reconstruction of the ossicular chain: a preliminary report

OBJECTIVE

To determine the feasibility and efficacy of using a bone cement, Oto-Cem, to reconstruct the ossicular chain.

STUDY DESIGN

Prospective clinical trial on nine consecutively chosen adult patients with ossicular chain defects.

PATIENTS AND SETTING

Nine patients with ossicular chain defects involving the long process of the incus were treated at the Carolina Ear and Hearing Clinic. The ossicular chain was reconstructed using bone cement by itself or in conjunction with a stapes prosthesis.

MAIN OUTCOME MEASURES

Preoperative audiograms were compared with audiograms 3, 6, and 12 months after reconstruction.

RESULTS

There was a mean pure-tone average (PTA) improvement of 15 dB in patients undergoing incus to stapes suprastructure reconstruction with the bone cement. The incus to mobile footplate reconstruction (using a stapes prosthesis attached to the newly reconstructed incus) resulted in a 34-dB PTA postoperative improvement. Two of the three patients with incus to oval window repairs experienced a 10-dB improvement in PTA. One of the three patients experienced a loss in speech discrimination and a 2-dB loss in PTA.

CONCLUSIONS

Despite the limited number of patients, this preliminary study demonstrates the effectiveness of Oto-Cem in reconstructing a foreshortened incus. There was a substantial hearing improvement in all but one patient in the incus to stapes or the incus to footplate categories.

'Leave me alone' lesions of the petrous apex

PURPOSE

When troublesome MR imaging findings are noted in the petrous apex, the radiologist must determine if the area in question needs surgical therapy. Two nonsurgical entities, asymmetric fatty marrow and fluid-filled petrous air cells (trapped fluid), can be noted on conventional brain MR images and confused with pathologic lesions. Our observation that radiologists do not always confidently define the nonsurgical petrous apex lesions precipitated this investigation.

METHODS

Twenty-three patients with either asymmetric fatty marrow (six) or unilateral effusion in a pneumatized petrous apex (17) on MR images were studied. Eighteen patients underwent high-resolution temporal bone CT. For all patients, the medical charts were reviewed retrospectively and/or the surgical and clinical follow-up findings were reviewed with the referring physician.

RESULTS

In the patients with asymmetric fatty marrow, MR signal intensity followed fat on all sequences. The questioned apex in the patients with trapped fluid showed mixed MR signal characteristics (low to high T1 signal, high T2 signal). CT scans confirmed nonexpansile air-cell opacification.

CONCLUSION

Asymmetric fatty marrow in the petrous apex and petrous air-cell effusions have characteristic MR and CT features that facilitate their correct diagnosis. Effusions with intermediate or high T1 signal are most frequently confused with cholesterol granulomas. In those patients, long-term CT follow-up may be helpful to confirm their stability.