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C Shelton

Publications and source records attributed to C Shelton.

At least 19 recordsLinked to original sources
PubMed2006

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.

Adolescent↗
PubMed2004

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.

Adult↗
PubMed2001

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.

Critical Care↗
PubMed2001

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.

Adolescent↗
PubMed2001

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.

Adolescent↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Administration, Topical↗
PubMed2000

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.

Cochlear Implantation↗
PubMed1999

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.

Adolescent↗
PubMed1999

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.

Cochlea↗
PubMed1998

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.

Acoustic Impedance Tests↗
PubMed1998

Susac syndrome.

Explore the source record for details and available documents.

Adult↗
PubMed1998

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.

Auditory Threshold↗
PubMed1998

'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.

Adipose Tissue↗
PubMed1997

Stapedectomy vs stapedotomy. Do you really need a laser?

OBJECTIVE: To compare the effectiveness of different techniques of stapes surgery in improving the hearing of individuals with otosclerosis. METHODS AND DESIGN: Large and small fenestra techniques, as well as the instrument used to make the fenestra (drill or laser), were compared with regard to effectiveness and rate of side effects. The charts of 875 patients who underwent primary stapedectomies performed by members of the House Ear Clinic, Los Angeles, Calif, were reviewed. Patients who underwent stapedectomy for reasons other than otosclerosis and those with inadequate post-operative bone conduction threshold data were excluded. A group of 550 patients met the criteria. This group was broken into categories depending on the technique of stapedectomy and the instrument used to create the fenestra. The techniques were then compared using air-bone gap closure at different frequencies, pure tone average, and the rate of significant side effects. RESULTS: The study indicated that small fenestra stapedotomy and large fenestra techniques have similar rates of closure of the air-bone gap. Small fenestra stapedotomy has a slightly lower rate of postoperative sensorineural hearing loss, especially at higher frequencies. With regard to the small fenestra technique, there was no significant difference in either postoperative air-bone gap closure or postoperative sensorineural hearing loss, regardless of whether the fenestra was created by laser or microdrill. CONCLUSIONS: While we did find a statistically significant difference between the large and small fenestra techniques in postoperative sensorineural hearing loss at higher frequency, the difference is small and is probably not clinically significant. Therefore, we find that similar good results can be obtained by the experienced surgeon using either the large or small fenestra technique. Similarly, we found the laser and microdrill to be equally safe and effective in the creation of the fenestra.

Case-Control Studies↗