PubMed Health⌕ Search

Biomedical subjects

C A Buchman

Publications and source records attributed to C A Buchman.

At least 19 recordsLinked to original sources
PubMed2006

Cochlear implantation in the irradiated temporal bone.

OBJECTIVE: To demonstrate the feasibility and complexities of cochlear implantation in the setting of bilateral temporal bone osteoradionecrosis. STUDY DESIGN: Case report. SETTING: Tertiary care referral centre. CASE DESCRIPTION: A 66-year-old woman with bilateral temporal bone osteoradionecrosis and profound hearing loss, following treatment for tonsillar cancer, underwent cochlear implantation. Prior canal wall down mastoidectomy and subsequent temporal bone resection with free flap reconstruction had been performed on the implanted ear. The contralateral ear received a canal wall down mastoidectomy. A completely dehiscent mastoid segment of the facial nerve and extensive fibrosis were evident in the implanted ear. Only minimal fibrous reaction was found within the cochlea, allowing for full electrode insertion. At three months, speech recognition testing documented a consonant-nucleus-consonant (CNC) word score of 54 per cent. CONCLUSIONS: This report demonstrates the feasibility of cochlear implantation after temporal bone surgery and free flap reconstruction in the setting of diffuse osteoradionecrosis. The patient's excellent open-set speech understanding using the cochlear implant implies that radiation did not severely damage the central auditory pathways. Thus, some patients with radiation-induced hearing loss may be appropriate cochlear implant candidates. Special attention should be paid to surgical planning, as complications related to wound healing, electrode insertion and facial nerve injury may be more likely.

Aged↗
PubMed2001

Safety and efficacy of topical mitomycin C in myringotomy patency.

OBJECTIVE: To develop an alternative method for prolonged middle ear ventilation using topical mitomycin C. STUDY DESIGN AND SETTING: Twenty guinea pigs with normal ears had bilateral myringotomies performed using the argon laser. After myringotomy, either mitomycin C (0.4 mg/mL) or saline pledgets were applied topically. Monitoring consisted of otomicroscopy and distortion-product otoacoustic emissions. RESULTS: Before myringotomy, all tympanic membranes were intact, and distortion-product otoacoustic emissions were measurable. After myringotomy, none (0%) of the saline-treated myringotomies were patent at day 7 as compared with 100% of the mitomycin C-treated myringotomies. At day 42, 10 (52.6%) of 19 mitomycin-treated myringotomies remained patent and 4 (28.6%) of 14 were patent at 131 days. Five (13.1%) ears developed purulent otorrhea; 3 were mitomycin C-treated and 2 were treated with saline solution.- Distortion-product otoacoustic emissions testing did not document any evidence of ototoxicity. CONCLUSION: Topical mitomycin C appears to be safe and effective at prolonging the duration of myringotomy patency in the guinea pig. SIGNIFICANCE: Mitomycin C may be useful as an adjunct for preventing myringotomy closure.

Administration, Topical↗
PubMed2000

Influenza A virus infection of human middle ear cells in vitro.

HYPOTHESIS: Human-derived normal middle ear mucosal cells can be harvested and cultured and will support influenza A virus (INF A) infection. STUDY DESIGN: Protocols for the collection and in vitro culture of middle ear mucosal cells were developed and used to investigate the effects of INF A infection as it relates to the pathogenesis of otitis media. MATERIALS AND METHODS: Middle ear mucosa was harvested during surgeries that opened the normal middle ear. Middle ear mucosal cells were plated and grown in collagen-coated dishes. Cells were characterized before and after INF A exposure using phase-contrast and immunofluorescence microscopy as well as reverse transcriptase-polymerase chain reaction (RT-PCR) for cytokeratin 18 gene expression and INF A. RESULTS: Primary cultures of human middle ear epithelial cells were established. Prolonged growth of middle ear cells yielded a second cell type that failed to stain for cytokeratin on immunofluorescence but continued to produce positive RT-PCR results on cytokeratin 18 analysis. After INF A exposure, cytological changes and immunofluorescence staining showed cellular infection. RT-PCR analysis using INF A-specific primers showed positive results for up to 72 hours after viral exposure. CONCLUSIONS: Primary cultures of human middle ear mucosal cells have been established. Two distinctly different cell culture systems have been developed: 1) middle ear epithelial cells and 2) either dedifferentiated epithelial cells or fibroblasts. Exposure of both cell types to INF A demonstrates that each can support cellular infection and viral replication. These models should be useful for studies of the pathogenesis of virus-mediated otitis media.

Cells, Cultured↗
PubMed2000

Tumor-associated hemorrhage in patients with acoustic neuroma.

OBJECTIVE: To describe the clinical significance of tumor-associated hemorrhage in patients with acoustic neuromas. STUDY DESIGN: Retrospective chart review. SETTING: University-based, tertiary care teaching hospital. PATIENTS: Three patients with acoustic neuromas who experienced symptomatic tumoral bleeding. INTERVENTIONS: Radiographic imaging, surgical removal of tumors, and pathologic analysis. MAIN OUTCOME MEASURES: Patient histories, radiologic characteristics, surgical results, and pathologic findings. RESULTS: Tumoral hemorrhage can occur in patients with acoustic neuromas. These three cases and a review of the world literature suggest that tumor size may be the most important risk factor for tumor-related hemorrhage. CONCLUSION: These findings have implications for those patients with acoustic neuromas who choose not to have surgical removal.

Aged↗
PubMed1999

Alternative to endoscopic sinus surgery in the management of pediatric chronic rhinosinusitis refractory to oral antimicrobial therapy.

We determined the safety, feasibility, and efficacy of a treatment regimen consisting of maxillary sinus aspiration and irrigation with or without adenoidectomy, followed by culture-directed intravenous antibiotics and oral prophylaxis, for children with chronic rhinosinusitis refractory to oral antimicrobial therapy. Twenty-seven children (age 1-12 years, mean 6.7 years) with symptomatic (mean duration 16 months) and computed tomography-proven sinus disease, which persisted despite at least 1 month of oral antibiotics, were treated. Twenty-four patients (89%) had complete resolution of their presenting symptoms after intravenous therapy; in 3 (11%), intravenous therapy failed and endoscopic sinus surgery was required. Follow-up data were available for 26 of the children (96%); 23 of them had initial complete resolution. At last follow-up (mean 282 days, range 26-1095 days), 10 of these 23 patients (44%) remained asymptomatic, and 13 (57%) had had at least one other episode of sinusitis (mean 1.0, range 1-3) treated with oral antibiotics, with resolution. Treatment-related complications included superficial thrombophlebitis (7%), diarrhea (7%), intravenous catheter guide-wire kink requiring venotomy (4%), and serum sickness-like syndrome (4%). These preliminary results suggest that this treatment plan is relatively safe and feasible and that it may be a reasonable alternative to endoscopic sinus surgery in children with chronic rhinosinusitis unresponsive to orally administered antimicrobial therapy.

Anti-Bacterial Agents↗
PubMed1999

Effects of nasal obstruction on Eustachian tube function and middle ear pressure.

To evaluate the relationship between nasal obstruction and otitis media, 10 ferrets were studied before and after either unilateral (E = 5) or bilateral (n = 5) nasal obstruction. Observations included otomicroscopic assessments of middle ear status, tympanometric recordings of middle ear pressure and forced-response, inflation-deflation and continuous monitoring tests of Eustachian tube function. During the 6 8 week post-obstruction follow-up period no animal developed evidence of otitis media. Abnormal positive middle ear pressures lasting for the period of follow-up occurred only in the animals with bilateral nasal obstruction. Eustachian tube function test results showed these pressures to be generated during swallowing. No changes in the passive function of the tube were documented in either group, but changes in active function consistent with alterations in the pressure gradient between the middle ear and the nasopharynx were observed in both groups.

Acoustic Impedance Tests↗
PubMed1999

Illness and otological changes during upper respiratory virus infection.

OBJECTIVES: Upper respiratory virus infection is associated with the expression of symptoms and signs of illness, and with the development of complications in anatomically contiguous structures. In most epidemiological studies, the frequency of the various complications is expressed as a fraction of the total population judged to be ill by report, signs, or symptoms. Because not all infected subjects become ill and because infected non-ill subjects may develop complications, such risk estimates could be inaccurate. The objective of this study was to estimate the magnitude of the presentation bias during controlled, experimental infections. STUDY DESIGN: This was a prospective, experimental study of the relationship between illness and otological complications during experimental upper respiratory virus infection in 316 adult volunteers. METHODS: The data for illness and for abnormal middle ear underpressure in adult (18-54 y) volunteers experimentally infected with one of three viruses (rhinovirus type 39, rhinovirus strain hanks, influenza A virus) were analyzed and expressed as the relative frequencies of infected subjects reporting illness, developing abnormal middle ear pressure, and developing abnormal middle ear pressure in the absence of illness. RESULTS: For all three viruses, illness was documented in approximately 50% of the infected subjects. While the frequency of persons developing abnormal middle ear underpressure was greater in the infected-ill subjects, approximately one third of all infected subjects developing that complication did not report illness. CONCLUSIONS: These results support a large presentation bias in epidemiological surveys of viral upper respiratory infections, and infer that those surveys underestimate the true frequency of complications resulting from such infections.

Adolescent↗
PubMed1999

Beta-2 transferrin assay in the identification of perilymph.

HYPOTHESIS: Western blot assay for beta-2 transferrin protein is a clinically useful method for the detection of human perilymph and should be used for the diagnosis of perilymph fistulas (PLFs). BACKGROUND: Considerable controversy exists regarding the diagnosis of PLF. Recent studies suggest that the detection of beta-2 transferrin protein may be useful in the identification of perilymph. METHODS: To evaluate the usefulness of the beta-2 transferrin assay for identifying human perilymph, paired perilymph samples and negative controls were collected on Gelfoam pledgets from 20 patients who had surgery that opened the inner ear. Blinded immunoelectrophoretic assay (Western blot) for beta-2 transferrin was performed on each specimen. RESULTS: Only one (5%) of the known perilymph samples and none of the control specimens were definitely positive for beta-2 transferrin. Combined with historical data, this assay has 29% sensitivity, 100% specificity, 100% positive predictive value, and 31% negative predictive value. CONCLUSIONS: These findings suggest that the beta-2 transferrin protein assay may not be a reliable method for detecting human perilymph when performed using this technique.

Cochlear Aqueduct↗
PubMed1999

Intraoperative corticosteroids in acoustic tumor surgery.

BACKGROUND: Corticosteroids are frequently used for the prevention and treatment of neural edema. Although perioperative steroid therapy has been used in patients undergoing acoustic neuroma removal, the efficacy of such therapy has not been previously documented. METHODS: A retrospective review of 169 patients who underwent acoustic neuroma surgery with (n = 75) or without (n = 94) a single dose of intraoperative corticosteroids was performed. Tumor size ranged from 0.4 cm to 6 cm (mean, 2.1; SD, 1.0) The translabyrinthine approach was used in 85% of the patients, and the middle cranial fossa approach was used in 13%. Data were analyzed for differences in postoperative facial function and complication rates. RESULTS: After controlling for differences in tumor size, no significant effects of steroid therapy were found for any of the outcome variables. CONCLUSIONS: This retrospective study showed no apparent benefit from intraoperative steroid use in acoustic neuroma surgery. A prospective, randomized, placebo-controlled trial should be performed to confirm these findings.

Anti-Inflammatory Agents↗
PubMed1999

Cochlear implants in the geriatric population: benefits outweigh risks.

Cochlear implantation has become widely accepted as an effective means of hearing rehabilitation in severely and profoundly deaf individuals. In the elderly, cochlear implantation involves a number of unique issues that can affect patient outcomes. These factors include age-related changes in the auditory system, prolonged durations of deafness, diminished communication abilities, and coexisting medical and psychosocial problems. In general, the results of cochlear implantation in the elderly have been comparable with those of younger adults. Perioperative attention to medical and surgical details allows for safe insertion and a minimum of postoperative complications. Patients older than 65 have obtained excellent results by both audiologic and quality-of-life measures.

Aged↗
PubMed1999

Acoustic tumor growth: implications for treatment choices.

BACKGROUND: Knowledge of acoustic neuroma (AN) growth is essential for treatment planning. METHODS: A retrospective analysis of 119 patients with AN (mean age, 65 years; range, 37-84 years) followed with interval magnetic resonance imagings (MRIs) was performed. Change in maximum tumor dimension as a function of follow-up period was analyzed. RESULTS: Overall, maximum tumor dimension increased >2 mm in only 30% of patients. Of those that grew, the mean growth rate was 3.8 mm/year (maximum, 25 mm/year). Age, gender, and laterality did not predict growth. Most tumors that grew (86.1 %) were <20 mm at presentation. However, tumors >20 mm were statistically more likely to grow (71%, p =0.028). CONCLUSIONS: Most ANs followed with periodic MRIs do not grow. Available clinical information usually cannot predict growth. Serial MRIs are advocated for all patients treated with observation.

Adult↗
PubMed1998

Prechallenge antibodies moderate disease expression in adults experimentally exposed to rhinovirus strain hanks.

This double-blind study determined the influence of serum neutralizing antibody titers on the rate of infection and magnitude of disease expression after experimental exposure of adult volunteers to rhinovirus strain Hanks (RV-H). A total of 133 healthy volunteers were tested for antibody status, cloistered for a 6-day period, and challenged with RV-H at the end of the first cloister day. On these days, response to viral challenge is assessed with symptom diaries and physical examinations. The low-titer infected group was significantly different from the intermediate-titer infected and the uninfected groups in terms of postchallenge nasal and throat symptoms, expelled secretion weights, nasal mucociliary clearance rates, and frequency of negative middle ear pressures. A similar trend held for the infected high-titer vs. low-titer group comparisons. These data show that high homotypic serum neutralizing antibody titers are associated with protection from infection and lessened signs and symptoms following experimental RV-H exposure.

Adult↗
PubMed1998

Analysis of adult otitis media: polymerase chain reaction versus culture for bacteria and viruses.

Recent studies using the polymerase chain reaction (PCR) have identified bacterial and viral genomic sequences in culture-negative pediatric middle ear effusions. To evaluate this technique in adults, 19 effusions were analyzed to compare bacterial and viral culture and PCR detection of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and adenovirus. Effusions from 4 subjects positive for human immunodeficiency virus (HIV) were analyzed by PCR for HIV virus. Three of 19 effusions were culture-positive for bacteria, and 0 of 19 for viruses. Fifteen of 19 effusions were PCR-positive for bacterial genomic sequences, and 0 of 19 for adenovirus. Thirteen of 15 PCR-positive specimens demonstrated S pneumoniae, 5 of 15 H influenzae, and 0 of 13 M catarrhalis. All 4 effusions from HIV-positive subjects were PCR-positive for HIV. No effusion was culture-positive and PCR-negative. These results confirm that culture-negative middle ear effusions contain genomic sequences from bacterial pathogens. Finding of HIV RNA and DNA in effusion from HIV-positives suggests replicating virus in this fluid.

Adenoviridae↗
PubMed1996

Prechallenge antibodies: moderators of infection rate, signs, and symptoms in adults experimentally challenged with rhinovirus type 39.

This study determined the influence of serum neutralizing antibody titers on infection rate, symptom manifestations, and provoked signs and pathophysiologies in adults experimentally exposed to rhinovirus type 39 (RV-39). Antibody status was determined for 151 healthy volunteers who were then cloistered in a hotel for 6 days. At the end of the first cloister day, the volunteers were challenged with RV-39 in a median tissue culture infective dose of 100. On each of the 6 days, a nasal examination was performed, symptoms were scored, and objective tests of nasal mucociliary function, nasal airway patency, secretion production, and middle ear pressures were completed. Both subjects and investigators were blinded to the prechallenge serum homotypic antibody titers of the subjects. Four subjects presented with a wild virus and were excluded from the analysis. Of the 147 included subjects, prechallenge serum antibody titers to RV-39 were low (under 2) in 56 subjects, intermediate (2 to 8) in 51 subjects, and high (above 16) in 40 subjects. The high-titer group was significantly different from the low-titer group with respect to viral shedding, symptom load, subjective extent of illness, and secretion production, as well as in the frequency of subjects with abnormal nasal mucociliary clearance and positive middle ear pressures. The study results document that for experimental RV-39 exposure, high levels of homotypic serum neutralizing antibody titers are associated with protection from infection and a lessened degree of disease expression, but not with a reduction of otologic complications.

Adolescent↗
PubMed1996

The learning curve for acoustic tumor surgery.

Although operative experience is considered to be critically important in the surgical management of acoustic tumors, little objective evidence substantiates this claim. The present study was undertaken to determine whether a learning curve exists for acoustic tumor surgery. The first 96 acoustic tumor patients managed surgically by a new neurotologic team were retrospectively reviewed. A significant improvement (P<.0003; F=6.32) in the ability to achieve good (grade II or better) postoperative facial nerve function was identified. Improving trends for complete resection rate and hearing preservation were documented, and the incidence of cerebrospinal fluid (CSF) leaks declined; however, statistical significance was not achieved. For postoperative facial nerve function, approximately 60 cases were necessary before the new team achieved results similar to those of highly experienced surgeons. The frequencies of complete resection, CSF leaks, hearing preservation, stroke, and mortality were comparable to those of experienced neurotologic teams. The findings of this study may have implications for both patient care and physician training.

Clinical Competence↗
PubMed1995

Influenza A virus--induced acute otitis media.

To better understand the significance of viral upper respiratory tract infections in the pathogenesis of acute otitis media (OM), 27 adults underwent intranasal inoculation with influenza A virus. Monitoring consisted of antibody titer determination, tympanometry, and otoscopy. Microbiologic analysis consisted of cultures and polymerase chain reaction (PCR)-based detection for influenza A virus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. All subjects became infected with the challenge virus. By day 4, 16 (59%) developed middle ear pressures of -100 mm H2O or below and 4 (25%) of them developed OM. One subject (4%) developed purulent OM requiring myringotomy for pain relief. Middle ear effusion cultures were negative. PCR analysis of that subject's middle ear effusion and nasal washes were positive for influenza A virus and S. pneumoniae. These findings support a causal role for viral upper respiratory tract infections in the pathogenesis of OM, possibly mediated by middle ear underpressures and viral and bacterial middle ear infection.

Acute Disease↗
PubMed1995

Otologic and systemic manifestations of experimental influenza A virus infection in the ferret.

In an effort to further validate an animal model and to better define the mechanisms relating viral upper respiratory tract infections and acute otitis media, we infected 10 ferrets intranasally with influenza A virus. Infection was monitored by cultures and antibody titers, illness was monitored by signs and temperatures, and otologic complications were monitored by otoscopy, tympanometry, and eustachian tube function testing. All animals became infected. Forced-response test results showed progressive increases in the passive function variables after inoculation. Inflation-deflation test results documented progressive impairment of active tubal function, which was accompanied by the development of middle ear underpressures. No otitis media was seen. The results suggest that influenza A virus infection results in progressive, subtotal occlusion of the eustachian tube lumen, which compromises the ventilatory function of the tube, thereby promoting the development of middle ear underpressures. These findings support the hypothesized pathophysiologic relationship between viral upper respiratory tract infections, eustachian tube dysfunction, middle ear underpressures, and acute otitis media. Given these pathophysiologic changes and previously documented physiologic similarities to the eustachian tube-middle ear system of human beings, we conclude that the ferret represents an appropriate animal model for studying the pathogenic processes related to viral upper respiratory tract infections, eustachian tube dysfunction, and otitis media and for testing of potential prophylactic and therapeutic regimens.

Animals↗