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Biomedical subjects

Jeffrey T Vrabec

Publications and source records attributed to Jeffrey T Vrabec.

17 recordsLinked to original sources
PubMed2007

The radiographic prevalence of geniculate ganglion dehiscence in normal and congenitally thin temporal bones.

OBJECTIVE: To determine the prevalence of a dehiscent geniculate ganglion on routine temporal bone computed tomography (CT). STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Two hundred seventy-eight consecutive temporal bone CT examinations for a total of 556 sides were reviewed. One hundred ninety-one sides were excluded. Reasons for exclusion included reconstructed coronal views, no coronal views, or a pathologic process, which involved the geniculate ganglion. Six examinations were from patients with clinical superior canal dehiscence confirmed by surgical repair or positive vestibular evoked myogenic potentials. Twenty-four scans were from patients with radiographic superior canal dehiscence confirmed by two independent readings. MAIN OUTCOME MEASURES: The incidence of geniculate ganglion dehiscence in patients with and without radiographic or clinical superior canal dehiscence. Dehiscent geniculate ganglion was defined as at least two consecutive cuts on a coronal CT showing no bone overlying the geniculate ganglion. RESULTS: The overall incidence of a dehiscent geniculate ganglion was 14.5% in the 365 sides reviewed. The incidence of a dehiscent geniculate ganglion is increased in patients with radiographic and clinical superior canal dehiscence as compared with normal patients and was significantly different by chi analysis (38.1 versus 11.4%). CONCLUSION: The presence of radiographic geniculate ganglion dehiscence is common. This finding has particular importance when the middle cranial fossa or subtemporal approach is used, as the facial nerve is more at risk especially when used to address superior canal dehiscence.

Adolescent↗
PubMed2006

Adult spontaneous CSF otorrhea: correlation with radiographic empty sella.

OBJECTIVE: To determine the prevalence of radiographic empty sella in patients with spontaneous cerebrospinal fluid (CSF) otorrhea. STUDY DESIGN AND SETTING: Retrospective case series of adult patients with CSF otorhinorrhea at an academic tertiary medical center. Patients with history of skull base surgery, trauma, tumor, or chronic ear disease were excluded. Available imaging studies were reviewed with attention to the sella turcica. RESULTS: Eight patients were diagnosed with spontaneous CSF otorrhea. Five of seven patients with adequate imaging studies (71%) had a radiographic empty sella. Seven of eight patients were clinically obese, with a body mass index BMI>30 kg/m2. CONCLUSIONS: Empty sella is a common radiologic finding in patients with spontaneous CSF otorrhea. This supports the theory that increased intracranial pressure contributes to development of spontaneous CSF otorrhea. SIGNIFICANCE: Radiographic empty sella predicts elevated intracranial pressure, which may require further evaluation and treatment in patients with spontaneous CSF otorrhea. EBM RATING: C-4.

Adult↗
PubMed2006

Otomycosis: clinical features and treatment implications.

OBJECTIVES: To determine the clinical presentation, predisposing factors, complications, and treatment outcomes of otomycosis. STUDY DESIGN AND SETTING: Retrospective review of 132 patients with a clinical diagnosis of otomycosis treated from 1998 to 2004 in an academic otology practice. RESULTS: Otalgia and otorrhea were the most common presenting complaints (48%). Prior otologic procedures increase the risk of developing otomycosis. Residual disease was observed in 13% and recurrence in 15% of the subjects. The presence of a mastoid cavity was associated with higher recurrent and residual disease rates. Topical ketoconazole, cresylate otic drops, and aluminum acetate otic drops were all relatively effective with >80% resolution rate on initial application, although topical ketoconazole had a higher resolution rate and lower rate of disease recurrence. CONCLUSIONS AND SIGNIFICANCE: Otomycosis can usually be diagnosed by clinical examination and often occurs in the setting of persistent otorrhea. Complications are not uncommon but usually resolve with application of appropriate topical antifungal agents. Eradication of disease is more difficult in the presence of a mastoid cavity.

Acetates↗
PubMed2006

Invasive cerebrospinal fluid cysts and cephaloceles of the petrous apex.

OBJECTIVE: To describe the presentation, diagnostic evaluation, and surgical management of petrous apex cerebrospinal fluid (CSF) cysts and cephaloceles. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Six patients with symptomatic CSF cysts or cephaloceles. INTERVENTION(S): All patients underwent operative intervention. MAIN OUTCOME MEASURE(S): Presentation, imaging characteristics, operative findings, surgical approach, resolution of symptoms, and complications. RESULTS: Six patients presented with various neurotologic symptoms including vertigo, otalgia, diplopia, meningitis, hearing loss, and retroorbital headaches. Four lesions were centered within the anterior petrous apex and were classified as a cephalocele originating from Meckel's cave. The remaining two lesions were arachnoid cysts that involved the posterior petrous apex. Cysts and cephaloceles both demonstrated bone erosion on computed tomography and were hyperintense on T2-weighted magnetic resonance imaging and isointense or hypointense on T1-weighted magnetic resonance imaging. A variety of surgical approaches was used to treat these lesions. Preoperative symptoms were improved in five of six cases. One patient developed a postoperative CSF leak that resolved with conservative measures. CONCLUSION: Petrous apex CSF cysts and cephaloceles may present with a variety of neurotologic symptoms. Imaging often helps narrow the differential diagnosis, but these lesions can still be confused with other erosive skull base lesions such as cholesterol granulomas, epidermoids, or tumors. Optimal treatment of symptomatic posterior petrous apex CSF cysts is marsupialization via a posterior fossa approach (i.e., retrosigmoid or retrolabyrinthine). A middle fossa approach with obliteration of the anterior petrous apex may be used to treat symptomatic CSF cephaloceles arising from Meckel's cave.

Adult↗
PubMed2004

Quantitative analysis of herpes simplex virus in cranial nerve ganglia.

A susceptible individual exposed to herpes simplex virus (HSV) will develop latent infection in multiple cranial nerve ganglia. There are a few quantitative studies of the viral load within the trigeminal ganglion, but none that investigate other cranial nerve ganglia. In this study, human trigeminal, geniculate, vestibular (Scarpa's) and cochlear (spiral) ganglia were obtained from willed body donors. Real time quantitative polymerase chain reaction (PCR) analysis of the HSV DNA polymerase gene was performed on ipsilateral ganglion sets from the same individual. Viral load, expressed as HSV genomes per 105 cells, was significantly greater in the vestibular ganglion (mean +/- SD, 176705 +/- 255916) than in the geniculate (9948 +/- 22066), cochlear (3527 +/- 9360), or trigeminal (2017 +/- 5578) ganglia. There was not a significant correlation among ganglia from the same individual. The results support the hypothesis that neuronal subpopulations have variable susceptibility to HSV infection.

Base Sequence↗
PubMed2004

Stapes surgery in the United States.

OBJECTIVE: A contemporary analysis of trends in the surgical management of otosclerosis in the United States is presented. DATA SOURCES: U.S. population demographics were obtained from the U.S. Census Bureau. Surgical case data was obtained from publications of the National Center for Health Statistics. Physician population statistics are published by the American Medical Association. DATA EXTRACTION: Available estimates for otologic operations are interpreted according to clinical setting used for data acquisition and surgical practice patterns. Linear regression of included data defines trends in operations performed. Population statistics are used to define changes in the incidence of surgical cases. CONCLUSIONS: The number of stapedectomy cases has declined over the past 30 years. During this same interval, the U.S. population (including the white population) and the number of surgeons has increased. This indicates that the incidence of surgical otosclerosis is declining. Although the true etiology of the decline is uncertain, widespread immunization for measles is a plausible hypothesis.

Adolescent↗
PubMed2003

Central projections of the saccular and utricular nerves in macaques.

The central projections of the utricular and saccular nerve in macaques were examined using transganglionic labeling of vestibular afferent neurons. In these experiments, biotinylated dextran amine was injected directly into the saccular or utricular neuroepithelium of fascicularis (Macaca fascicularis) or rhesus (Macaca mulatta) monkeys. Two to 5 weeks later, the animals were killed and the peripheral vestibular sensory organs, brainstem, and cerebellum were collected for analysis. The principal brainstem areas of saccular nerve termination were lateral, particularly the spinal vestibular nucleus, the lateral portion of the superior vestibular nucleus, ventral nucleus y, the external cuneate nucleus, and cell group l. The principal cerebellar projection was to the uvula with a less dense projection to the nodulus. Principle brainstem areas of termination of the utricular nerve were the lateral/dorsal medial vestibular nucleus, ventral and lateral portions of the superior vestibular nucleus, and rostral portion of the spinal vestibular nucleus. In the cerebellum, a strong projection was observed to the nodulus and weak projections were present in the flocculus, ventral paraflocculus, bilateral fastigial nuclei, and uvula. Although there is extensive overlap of saccular and utricular projections, saccular inputs to the lateral portions of the vestibular nuclear complex suggest that saccular afferents contribute to the vestibulospinal system. In contrast, the utricular nerve projects more rostrally into areas of known concentration of vestibulo-ocular related cells. Although sparse, the projections of the utricle to the flocculus/ventral paraflocculus suggest a potential convergence with floccular projection inputs from the vestibular brainstem that have been implicated in vestibulo-ocular motor learning.

Afferent Pathways↗
PubMed2003

Coronal computed tomography prevalence of superior semicircular canal dehiscence.

OBJECTIVES: The relatively new clinical entity superior canal dehiscence syndrome (SCDS) is diagnosed by clinical symptoms and signs. Coronal computed tomography (CT) has been used to confirm the diagnosis. A consecutive series of temporal bone CT scans was reviewed to define the prevalence of a dehiscent-appearing superior semicircular canal. STUDY DESIGN AND SETTING: Temporal bone CT scans performed over a 2-year period at a university-based tertiary referral center were reviewed independently by 3 individuals. Scans were excluded if coronal images were not obtained or reconstructed from axial images. Prevalence figures for dehiscent-appearing superior semicircular canal were determined by consensus. Medical records of selected individuals with a dehiscent-appearing canal were reviewed for study indications and otologic symptoms. RESULTS: A dehiscent-appearing superior semicircular canal was seen in 9% of studies. Correlation among examiners was greater than 94%. Medical records indicated symptoms suggestive of or compatible with the diagnosis of SCDS in rare cases. CONCLUSION: The prevalence of a dehiscent-appearing superior semicircular canal on coronal CT of the temporal bones performed with 1.0-mm collimation is substantially greater than that predicted by temporal bone histologic study. Clinical symptoms compatible with the diagnosis were seldom recorded, suggesting low specificity. The high sensitivity and low specificity of CT scan create a risk for overdiagnosis of SCDS if the coronal CT scans are not correlated with clinical symptoms.

Adolescent↗
PubMed2003

Delayed-onset facial paralysis after vestibular neurectomy.

OBJECTIVES/HYPOTHESIS: Delayed-onset facial paralysis (beginning more than 3 d after the procedure) has been described as a complication of many different types of otological procedures. The incidence of this problem in vestibular neurectomy and the relationship to surgical approach are detailed in the study. STUDY DESIGN: Retrospective case review. METHODS: In the setting of a tertiary referral center, vestibular neurectomy was performed in 70 individuals with disabling vertigo unresponsive to medical therapy who elected vestibular neurectomy. The main outcome measure was incidence of delayed onset facial paralysis. RESULTS: Delayed-onset facial paralysis was significantly more common after the middle fossa (18%) and translabyrinthine (11%) approaches compared with the retrosigmoid approach (0%). CONCLUSIONS: Surgical approach influences the incidence of delayed-onset facial paralysis. Measures to prevent this complication such as prophylactic antiviral medication or labyrinthine segment decompression may be considered in middle fossa and translabyrinthine operations.

Adult↗
PubMed2003

Herpes simplex virus and Meniere's disease.

OBJECTIVE/HYPOTHESIS: This study was designed to investigate the hypothesis that Meniere's disease is associated with herpes simplex virus (HSV) reactivation in the vestibular ganglion. STUDY DESIGN: Case control study. METHODS: Vestibular ganglia were obtained from archival surgical pathology specimens from patients undergoing vestibular neurectomy for vertigo caused by Meniere's disease. All patients met criteria for classification as definite Meniere's disease according to American Academy of Otolaryngology/Head and Neck Surgery (AAO-HNS) criteria. Control specimens were obtained from willed body donors. Sections from each ganglion were studied for prevalence of viral DNA using a nested polymerase chain reaction designed to amplify the HSV DNA polymerase gene. Quantitative analysis determined the number of viral copies per standard unit of ganglionic DNA. RESULTS: HSV DNA was more prevalent in paraffin embedded ganglia from patients with Meniere's disease (100%) than in fresh-frozen control ganglia (81%) (P =.02). Fixation and paraffin embedding substantially reduced recovery of HSV virus in selected control specimens. Quantitative analysis found no correlation between viral copy number in control ganglia processed frozen versus formalin fixed and paraffin embedded. CONCLUSIONS: HSV is more commonly isolated from vestibular ganglia of patients with Meniere's disease than the general population. The routine histologic preparation of formalin fixation and paraffin embedding significantly altered the quantity of virus detected though not in a predictable manner. The study provides supportive evidence for a viral etiology in Meniere's disease.

Adult↗
PubMed2003

Aeration following intact canal wall mastoidectomy.

This study examines the prevalence and extent of re-aeration of the mastoid cavity following intact canal wall (ICW) mastoidectomy. Temporal bone computed tomography scans from patients with prior unilateral ICW mastoidectomy were identified. Three-dimensional volume reconstruction of the temporal bone was performed to measure aeration bilaterally. Thirty-five scans were analyzed; 16 (46%) showed good aeration in the operated ear and 19 showed poor aeration. The aeration (volume) in the surgical ears and the contralateral ears was significantly less than that in subjects without a history of ear disease. Those with poor aeration were more likely to require additional surgery. For temporal bone pairs with greater volume in the operated ear, the average difference was 1.3 cm3. Surgical creation of a mastoid cavity does not produce a large increase in aeration as compared with the contralateral ear. Following surgery, mastoid opacification may presage recurrent disease. Routine use of mastoidectomy in an attempt to improve aeration is not advocated.

Adolescent↗
PubMed2002

Evaluation of the internal auditory canal with virtual endoscopy.

OBJECTIVE: Three-dimensional imaging can improve the understanding and comprehension of complex anatomy. Recent advances in software development allow the construction of a virtual endoscopic view of anatomic structures. This report applies virtual endoscopic capabilities to imaging of the internal auditory canal. STUDY DESIGN, SETTING, AND PATIENTS: We conducted a retrospective case review at a tertiary referral center of patients with abnormal internal auditory canal anatomy on computed tomography. INTERVENTIONS: Computed tomography images were obtained using conventional clinical algorithms involving multiple, 1-mm-thick slices through the temporal bone. Three-dimensional reconstructions were made using General Electric Advantage Windows Navigator software. The virtual endoscopic image-processing algorithm used selected image intensity threshold levels to visualize internal auditory canal anatomy from an endoscopic perspective. RESULTS: Eleven cases of abnormalities of the internal auditory canal were retrospectively identified. Clinical applications using the virtual endoscopic images are presented. The virtual endoscopic images supported prior clinical decision making in 6 of the 11 cases evaluated. CONCLUSION: This technique shows promise for the diagnosis, surgical planning, and teaching of temporal bone anatomy. Usefulness is dependent on acquisition parameters and clinical indications for examination.

Algorithms↗
PubMed2002

3D CT imaging method for measuring temporal bone aeration.

OBJECTIVE: 3D volume reconstruction of CT images can be used to measure temporal bone aeration. This study evaluates the technique with respect to reproducibility and acquisition parameters. MATERIAL AND METHODS: Helical CT images acquired from patients with radiographically normal temporal bones using standard clinical protocols were retrospectively analyzed. 3D image reconstruction was performed to measure the volume of air within the temporal bone. The appropriate threshold values for air were determined from reconstruction of a phantom with a known air volume imaged using the same clinical protocols. The appropriate air threshold values were applied to the clinical material. RESULTS: Air volume was measured according to an acquisition algorithm. The average volume in the temporal bone CT group was 5.56 ml, compared to 5.19 ml in the head CT group (p = 0.59). The correlation coefficient between examiners was > 0.92. There was a wide range of aeration volumes among individual ears (0.76-18.84 ml); however, paired temporal bones differed by an average of just 1.11 ml. CONCLUSIONS: The method of volume measurement from 3D reconstruction reported here is widely available, easy to perform and produces consistent results among examiners. Application of the technique to archival CT data is possible using corrections for air segmentation thresholds according to acquisition parameters.

Adult↗
PubMed2002

Inverting papilloma of the temporal bone.

OBJECTIVES: Inverting papilloma of the temporal bone is exceedingly rare. The objective is to familiarize the clinician with the clinical presentation and prognosis of this entity. STUDY DESIGN: Retrospective case study and literature review. METHODS: Published reports of inverting papillomas originating in the temporal bone were reviewed in conjunction with two cases presenting at the University of Texas Medical Branch (Galveston, TX). RESULTS: Inverting papillomas of the temporal bone are frequently associated with persistent middle ear effusion and ipsilateral sinonasal tumors and display a higher incidence of malignancy. CONCLUSIONS: Successful management of these tumors requires an aggressive surgical resection. Adjuvant radiation therapy is recommended in patients with malignant changes.

Aged↗
PubMed2002

Hydroxyapatite prosthesis extrusion.

OBJECTIVE: To examine the mechanism of prosthesis extrusion and evaluate preoperative and postoperative variables associated with extrusion of hydroxyapatite prostheses for ossicular reconstruction. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral, university medical center. PATIENTS: Patients undergoing ossiculoplasty with a hydroxyapatite prosthesis and having at least six months follow-up. MAIN OUTCOME MEASURE: Prosthesis extrusion, defined as loss of the tympanic membrane resulting in exposure of the prosthesis. Extrusion is further classified into early (< 2 months) and late (> 6 months). RESULTS: Early extrusion or tympanoplasty graft failure occurred in 15/195 cases (8%). Late extrusion was seen in 17/125 cases (14%). Cases exhibiting late extrusion had a significantly greater incidence of postoperative atelectasis (p < 0.0001), recurrent otitis media (p < 0.0001), and myringitis (p = 0.003) than those with retention of the prosthesis. Regression analysis found an abnormal contralateral ear increased the risk of postoperative recurrent otitis media, while staged surgery reduced the risk, odds ratios of 3.56 (95% confidence interval 2.20-9.37) and 6.84 (95% CI 4.24-17.76) respectively. There were no preoperative variables that predicted postoperative atelectasis or myringitis. CONCLUSIONS: Recurrent otitis media, myringitis, and atelectasis developing after ossiculoplasty are associated with a greater risk of prosthesis extrusion. Predicting postoperative complications from preoperative and intraoperative findings proved difficult. Measures to prevent atelectasis, such as covering the prosthesis with cartilage, are recommended at the time of ossiculoplasty.

Cartilage↗
PubMed2002

Facial nerve grading systems (1985-2002): beyond the House-Brackmann scale.

OBJECTIVE To assess methods of evaluating the function of the facial nerve that have been introduced over the past 15 years, particularly in comparison with the House-Brackmann scale. DATA SOURCES A Medline search was undertaken of the English-language medical literature between 1983 and 2000 to identify proposed methods of evaluating facial nerve function. STUDY SELECTION Although all grading systems were considered, attention was focused on the systems that provided improvements in either precision or ease of use. CONCLUSIONS Because of the limitations and subjectivity of the House-Brackmann scale, several new scales of various degrees of objectivity and ease of use have been introduced. The Nottingham system offers a more objective but easy-to-use facial nerve grading system that has been demonstrated to be valid and that would be easy for the average practitioner to adopt. The authors propose a more systematic evaluation of this system to determine whether its widespread application is appropriate.

Cerebellar Neoplasms↗