Submental Intubation: an Underutilized Technique for Airway Management in Patients With Panfacial Trauma.

PURPOSE: To evaluate submental intubation compared with secure airways of patients who have sustained significant maxillofacial trauma. PATIENTS AND METHODS: Patient series of 3 patients who underwent submental intubation prior to open reduction internal fixation of fractures associated with the mid and lower face. All of these patients were initially orally intubated, and then converted to submental intubation prior to the reparative procedure. Detailed description of the procedure is discussed in each patient. RESULTS: All the patients received appropriate reduction of facial fractures following submental intubation with no intraoperative complications. Two of the 3 patients were extubated immediately postoperatively and 1 was extubated on the second postoperative day. None of the patients had any complications associated with submental intubation. CONCLUSIONS: Submental intubation is a safe and expedient technique to divert the airway in patients who require operative repair of panfacial injuries. This procedure is preferable over tracheostomy in selected patients of maxillofacial trauma without indication for prolonged ventilation support.

The marginal mandibular nerve in relation to the inferior border of the mandible.

PURPOSE: Injury to the marginal mandibular nerve (MMN) can occur in numerous surgeries involving incisions near the inferior border of the mandible. Injury to this nerve can cause considerable cosmetic and functional deformities. A thorough knowledge and understanding of the anatomic pathway of the MMN is important to avoid permanent nerve damage. The purpose of this study was to determine the position of the marginal mandibular nerve in relation to several key mandibular anatomic landmarks and to identify variations of the nerve as it approaches the inferior border of the mandible. MATERIALS AND METHODS: Human cadavers were dissected superficially from the parotid gland to the mental protuberance to expose the MMN. At complete exposure of the nerve, 5 anatomic landmarks on the inferior border of the mandible were identified and labeled. The distance between the MMN and these landmarks was recorded, and the average measurements were used to approximate the most common pathway of the MMN. RESULTS: It was found that the MMN runs, on average, 0.75 mm below the gonion, 0.08 mm superior to the posterior border of the antegonial notch, 0.06 mm superior to the arc of the antegonial notch, 1.29 mm superior to the anterior border of the antegonial notch, 3.6 mm superior to the point at which the facial artery reaches the inferior border of the mandible, and 10.9 mm superior to the vertical line that extends from the commissure of lip to the inferior border of the mandible. CONCLUSION: These data suggest 3 general pathways of the MMN in relation to the inferior border of the mandible.

A mathematical model of medial consonant identification by cochlear implant users.

The multidimensional phoneme identification model is applied to consonant confusion matrices obtained from 28 postlingually deafened cochlear implant users. This model predicts consonant matrices based on these subjects' ability to discriminate a set of postulated spectral, temporal, and amplitude speech cues as presented to them by their device. The model produced confusion matrices that matched many aspects of individual subjects' consonant matrices, including information transfer for the voicing, manner, and place features, despite individual differences in age at implantation, implant experience, device and stimulation strategy used, as well as overall consonant identification level. The model was able to match the general pattern of errors between consonants, but not the full complexity of all consonant errors made by each individual. The present study represents an important first step in developing a model that can be used to test specific hypotheses about the mechanisms cochlear implant users employ to understand speech.

A mathematical model of vowel identification by users of cochlear implants.

A simple mathematical model is presented that predicts vowel identification by cochlear implant users based on these listeners' resolving power for the mean locations of first, second, and/or third formant energies along the implanted electrode array. This psychophysically based model provides hypotheses about the mechanism cochlear implant users employ to encode and process the input auditory signal to extract information relevant for identifying steady-state vowels. Using one free parameter, the model predicts most of the patterns of vowel confusions made by users of different cochlear implant devices and stimulation strategies, and who show widely different levels of speech perception (from near chance to near perfect). Furthermore, the model can predict results from the literature, such as Skinner, et al. [(1995). Ann. Otol. Rhinol. Laryngol. 104, 307-311] frequency mapping study, and the general trend in the vowel results of Zeng and Galvin's [(1999). Ear Hear. 20, 60-74] studies of output electrical dynamic range reduction. The implementation of the model presented here is specific to vowel identification by cochlear implant users, but the framework of the model is more general. Computational models such as the one presented here can be useful for advancing knowledge about speech perception in hearing impaired populations, and for providing a guide for clinical research and clinical practice.

The effect of temporal gap identification on speech perception by users of cochlear implants.

PURPOSE: This study examined the ability of listeners using cochlear implants (CIs) and listeners with normal hearing (NH) to identify silent gaps of different duration and the relation of this ability to speech understanding in CI users. METHOD: Sixteen NH adults and 11 postlingually deafened adults with CIs identified synthetic vowel-like stimuli that were either continuous or contained an intervening silent gap ranging from 15 ms to 90 ms. Cumulative d', an index of discriminability, was calculated for each participant. Consonant and consonant-nucleus-consonant (CNC) word identification tasks were administered to the CI group. RESULTS: Overall, the ability to identify stimuli with gaps of different duration was better for the NH group than for the CI group. Seven CI users had cumulative d' scores that were no higher than those of any NH listener, and their CNC word scores ranged from 0% to 30%. The other 4 CI users had cumulative d' scores within the range of the NH group, and their CNC word scores ranged from 46% to 68%. For the CI group, cumulative d' scores were significantly correlated with their speech testing scores. CONCLUSIONS: The ability to identify silent gap duration may help explain individual differences in speech perception by CI users.

Heparanase, TrkC and p75NTR: their functional involvement in human medulloblastoma cell invasion.

Medulloblastoma is the most common malignant childhood brain tumor. Although some previous reports have shown up to a 70% 5-year survival for some of these patients, it is at the cost of significant long-term treatment-related morbidity. The cellular mechanisms leading to metastatic disease in medulloblastoma are mainly unknown. For the first time, we demonstrate the differential expression of heparanase in medulloblastomas and how these differences at the mRNA and protein levels affect the activity and invasive properties of three newly developed cell lines. Furthermore, heparanase expression was confirmed in 7 (88%) of 8 medulloblastoma clinical samples by immunohistochemical staining. Heparanase was found to be localized in the cytoplasm and nucleus. Quantitative polymerase chain reaction revealed a negative correlation between heparanase and TrkC (which is associated with a favorable clinical outcome). The activation of TrkC or TrkC/p75NTR by NT-3 affected heparanase activity and cell-invasive properties of medulloblastoma cells in vitro. Taken together, our data extend the body of evidence that invasion and expression/functionality of heparanase, in a context linked to TrkC and p75NTR, may play critical roles in the disease progression of medulloblastoma.

Talker and lexical effects on audiovisual word recognition by adults with cochlear implants.

The present study examined how postlingually deafened adults with cochlear implants combine visual information from lipreading with auditory cues in an open-set word recognition task. Adults with normal hearing served as a comparison group. Word recognition performance was assessed using lexically controlled word lists presented under auditory-only, visual-only, and combined audiovisual presentation formats. Effects of talker variability were studied by manipulating the number of talkers producing the stimulus tokens. Lexical competition was investigated using sets of lexically easy and lexically hard test words. To assess the degree of audiovisual integration, a measure of visual enhancement, R(a), was used to assess the gain in performance provided in the audiovisual presentation format relative to the maximum possible performance obtainable in the auditory-only format. Results showed that word recognition performance was highest for audiovisual presentation followed by auditory-only and then visual-only stimulus presentation. Performance was better for single-talker lists than for multiple-talker lists, particularly under the audiovisual presentation format. Word recognition performance was better for the lexically easy than for the lexically hard words regardless of presentation format. Visual enhancement scores were higher for single-talker conditions compared to multiple-talker conditions and tended to be somewhat better for lexically easy words than for lexically hard words. The pattern of results suggests that information from the auditory and visual modalities is used to access common, multimodal lexical representations in memory. The findings are discussed in terms of the complementary nature of auditory and visual sources of information that specify the same underlying gestures and articulatory events in speech.