Faculty Bibliography

OBJECTIVE: To create an experimental model of Streptococcus pneumoniae type 3 meningogenic labyrinthitis (a leading cause of deafness) similar to that in human disease. DESIGN: Cohort analytic study of guinea pigs that were inoculated intrathecally with varying dilutions of S pneumoniae type 3; the progress of the disease was compared with that in saline solution-inoculated control animals. SUBJECTS: Healthy adult Hartley guinea pigs without clinical evidence of middle ear disease that were conveniently sampled. INTERVENTIONS: Intrathecal inoculation of 10(4) to 10(6) colony-forming units of S pneumoniae type 3 into 13 guinea pigs; signs and symptoms of meningitis/labyrinthitis were observed for 15 days and compared with those in two saline solution-inoculated control animals. MAIN OUTCOME MEASURES: Morbidity--labyrinthitis, meningitis; end point--death. RESULTS: The 10(4) to 10(6) colony-forming units of S pneumoniae type 3 caused inflammation that extended from the meninges to the inner ear via the cochlear aqueduct within 3 days after inoculation; a dose of 10(7) killed animals within 12 hours after inoculation. Three of five animals that were inoculated with a 10(6) dose died 3 days after inoculation; two of three animals that were inoculated with a 10(5) dose lived to 15 days after inoculation. One of two animals that were inoculated with a 10(4) dose did not become infected. Inflammation extended to the middle ear by round-window destruction. Reactive bone formation simulated labyrinthine osteosclerosis. Observers assessed histologic slides "blindly." CONCLUSION: Guinea pigs can survive 15 days after intrathecal inoculation of a 10(5) dose, with morphologic features similar to those in human disease. This is an effective model for this study of meningogenic labyrinthitis.

Phosphacan is a chondroitin sulfate proteoglycan produced by glial cells in the central nervous system, and represents the extracellular domain of a receptor-type protein tyrosine phosphatase (RPTP zeta/beta). We previously demonstrated that soluble phosphacan inhibited the aggregation of microbeads coated with N-CAM or Ng-CAM, and have now found that soluble 125I-phosphacan bound reversibly to these neural cell adhesion molecules, but not to a number of other cell surface and extracellular matrix proteins. The binding was saturable, and Scatchard plots indicated a single high affinity binding site with a Kd of approximately 0.1 nM. Binding was reduced by approximately 15% after chondroitinase treatment, and free chondroitin sulfate was only moderately inhibitory, indicating that the phosphacan core glycoprotein accounts for most of the binding activity. Immunocytochemical studies of embryonic rat spinal phosphacan, Ng-CAM, and N-CAM have overlapping distributions. When dissociated neurons were incubated on dishes coated with combinations of phosphacan and Ng-CAM, neuronal adhesion and neurite growth were inhibited. 125I-phosphacan bound to neurons, and the binding was inhibited by antibodies against Ng-CAM and N-CAM, suggesting that these CAMs are major receptors for phosphacan on neurons. C6 glioma cells, which express phosphacan, adhered to dishes coated with Ng-CAM, and low concentrations of phosphacan inhibited adhesion to Ng-CAM but not to laminin and fibronectin. Our studies suggest that by binding to neural cell adhesion molecules, and possibly also by competing for ligands of the transmembrane phosphatase, phosphacan may play a major role in modulating neuronal and glial adhesion, neurite growth, and signal transduction during the development of the central nervous system

METHODS. Vertebral artery injury is a rarely described complication of anterior cervical decompression. The authors performed a retrospective review of their operative database for the purposes of defining the optimal management of this complication and its avoidance. RESULTS. Four of 1,215 (0.3%) patients undergoing anterior cervical operation sustained arterial injuries. In three cases, primary repair of the artery was successful; in one case, the artery was exposed and ligated. There were no postoperative ischemic complications. Artery laceration occurred during decompression (n = 2), screw tapping (n = 1), and during soft tissue retraction (n = 1). CONCLUSIONS. Injury to the vertebral artery during anterior approaches can be avoided by preoperative identification of anomalous arteries and by intraoperative attention to the midline. When the artery is injured, primary repair may be the optimal management strategy

Cochlear implants have been shown to improve the speech perception and production skills in children. Data are available on congenitally and prelingually deafened children who were implanted at an older age, but data on children implanted below the age of 3 years are scarce. The present study examines the benefits obtained with early implantation of the young deaf child. Fourteen congenitally or prelingually profoundly hearing-impaired children were implanted before the age of 3 years, with the Nucleus multichannel cochlear prosthesis, and followed for 2-5 years. Results indicate an overall improvement in the perception of all aspects of the speech signal in the auditory-only condition with the cochlear implant. All the children use oral language as their primary mode of communication and attend regular schools. Based on the results of this investigation, the authors conclude that implantation of the young deaf child is beneficial to the development of auditory perceptual skills

The decision to perform tonsillectomy and adenoidectomy for treatment of pediatric obstructive sleep apnea syndrome is often made on a clinical basis without formal polysomnography. To examine the accuracy of the clinical diagnosis of pediatric obstructive sleep apnea syndrome, we prospectively evaluated 30 children with obstructive symptoms by a standardized history, physical examination, and review of a tape recording of breathing during sleep. On the basis of this clinical evaluation, patients were divided into three predictive groups: (1) definite obstructive sleep apnea syndrome, (2) possible obstructive sleep apnea syndrome, and (3) unlikely to have obstructive sleep apnea syndrome. Nocturnal polysomnography was used to determine the presence or absence of true sleep apnea. Ten of 18 (55.6%) patients predicted clinically to have definite obstructive sleep apnea syndrome had positive nocturnal polysomnographies. Two of six (33.3%) patients predicted to have possible obstructive sleep apnea syndrome had positive nocturnal polysomnographies. One of six (16.7%) patients predicted to be unlikely to have obstructive sleep apnea syndrome had a positive nocturnal polysomnography. Six nocturnal polysomnographies negative by conventional criteria were suspicious for apnea, but considering these positive for obstructive sleep apnea syndrome did not improve the specificity of the clinical prediction. Our results show that clinical assessment of obstructive sleep apnea syndrome in children is sensitive (92.3%) but not specific (29.4%) for making the diagnosis of obstructive sleep apnea syndrome as compared with nocturnal polysomnography and may contribute to the decision to obtain nocturnal polysomnography in specific circumstances

The principle of distraction osteogenesis, well-established in the enchondral bones of the axial skeleton, has recently been applied to the membranous bones (mandible, cranium) of the craniofacial skeleton in the experimental animal and in the human. In the craniofacial skeleton, however, the technique has been used only to lengthen bone in a direction along its major axis, i.e., unidimensional distraction. A canine model is presented to demonstrate the feasibility of distracting membranous bone away from its dominant axis, i.e., multidimensional distraction. Four mongrel dogs, 5 months of age, were the subjects of this study. Two osteotomies were made in the zygomatic arch, and the bone-lengthening device was fixed to the zygoma. After 7 days of external fixation, the osteotomized segment was lengthened 1 mm/day away from the long axis of the bone for 15 days. External fixation was then maintained for a minimum of 4 weeks, after which the dogs were sacrificed. Craniofacial CT with three-dimensional reconstruction documented multidimensional bone lengthening, and histologic analysis of the specimen confirmed the presence of new cortical bone in the expanded areas. Refinement in technique and miniaturization and internalization of the bone-lengthening device may allow for more precise changes in the amount and direction of lengthening, thus making distraction osteogenesis more widely applicable for use in the human craniofacial skeleton