Management of the aging nose.

As a growing segment of our population, mature patients seeking rhinoplasty for both functional and aesthetic reasons will increasingly be encountered by the facial plastic surgeon. The aging process is characterized by a gradual derotation and deprojection of the nasal tip. This article provides an overview of versatile and proven techniques that may be applied to the majority of aging nose rhinoplasty cases and that have been found to yield predictable and lasting results.

Auditory response properties of neurons in the tectal longitudinal column of the rat.

The newly-discovered tectal longitudinal column (TLC) spans the paramedian region of the mammalian tectum. It has connections with several nuclei of the auditory system. In this report, we provide the first detailed description of the responses of TLC neurons to auditory stimuli, including monaural and binaural tones and amplitude modulated tones. For comparison, responses in the inferior colliculus (IC) were also recorded. Neurons in the TLC were sensitive to similar ranges of frequency as IC neurons, could have comparably low thresholds, and showed primarily excitatory responses to stimulation of the contralateral ear with either phasic or sustained response patterns. Differences of TLC compared to IC neurons included broader frequency tuning, higher average threshold, longer response latencies, little synchronization or rate tuning to amplitude modulation frequency and a smaller degree of inhibition evoked by stimulation of the ipsilateral ear. These features of TLC neurons suggest a role for the TLC in descending auditory pathways.

Aesthetic and functional management of eyelid and orbital reconstruction.

Major head and neck resections may result in ocular defects that are functionally and/or aesthetically incapacitating. Restoration of the eyelid and orbit must address lateral canthal laxity, midface ptosis, eyelid retraction and ptosis, globe malposition, and dysfunctional lacrimal drainage. Here we discuss lateral canthal reconstruction, midface-lifting, eyelid spacer grafts, gold weight placement, surgical approaches to the orbit, free flap options for orbital reconstruction, and endoscopic lacrimal surgery. Successful outcomes in eyelid and orbital reconstruction depend upon proper knowledge, planning, and multidisciplinary management.

Nasal implants.

In this article, options for nasal implantation during rhinoplasty are discussed. The range of implant options currently available to the nasal surgeon is considered in detail. Various types of autografts, homografts, and alloplasts commonly used in the nose are introduced and described. Indications for each nasal implant type are considered, as are the advantages and limitations of each option.

Connections of functional areas in the mustached bat's auditory cortex with the auditory thalamus.

The auditory thalamus is the major target of the inferior colliculus and connects in turn with the auditory cortex. In the mustached bat, biosonar information is represented according to frequency in the central nucleus of the inferior colliculus (ICc) but according to response type in the cortex. In addition, the cortex has multiple areas with neurons of similar response type compared to the single tonotopic representation in the ICc. To investigate whether these transformations occur at the level of the thalamus, we injected anatomical tracers into physiologically defined locations in the mustached bat's auditory cortex. Injections in areas used for target ranging labeled contiguous regions of the auditory thalamus rather than separate patches corresponding to regions that respond to the different harmonic frequencies used for ranging. Injections in the two largest ranging areas produced labeling in separate locations. These results indicate that the thalamus is organized according to response type rather than frequency and that multiple mappings of response types exist. Injections in areas used for target detection labeled thalamic regions that were largely separate from those that interconnect with ranging areas. However, injections in an area used for determining target velocity overlapped with the areas connected to ranging areas and areas involved in target detection. Thus, separation by functional type and multiplication of areas with similar response type occurs by the thalamic level, but connections with the cortex segregate the functional types more completely than occurs in the thalamus.

Detection of interaural correlation by neurons in the superior olivary complex, inferior colliculus and auditory cortex of the unanesthetized rabbit.

A critical binaural cue important for sound localization and detection of signals in noise is the interaural time difference (ITD), or difference in the time of arrival of sounds at each ear. The ITD can be determined by cross-correlating the sounds at the two ears and finding the ITD where the correlation is maximal. The amount of interaural correlation is affected by properties of spaces and can therefore be used to assess spatial attributes. To examine the neural basis for sensitivity to the overall level of the interaural correlation, we identified subcollicular neurons and neurons in the inferior colliculus (IC) and auditory cortex of unanesthetized rabbits that were sensitive to ITDs and examined their responses as the interaural correlation was varied. Neurons at each brain level could show linear or non-linear responses to changes in interaural correlation. The direction of the non-linearities in most neurons was to increase the slope of the response change for correlations near 1.0. The proportion of neurons with non-linear responses was similar in subcollicular and IC neurons but increased in the auditory cortex. Non-linear response functions to interaural correlation were not related to the type of response as determined by the tuning to ITDs across frequencies. The responses to interaural correlation were also not related to the frequency tuning of the neuron, unlike the responses to ITD, which broadens for neurons tuned to lower frequencies. The neural discriminibility of the ITD using frozen noise in the best neurons was similar to the behavioral acuity in humans at a reference correlation of 1.0. However, for other reference ITDs the neural discriminibility was more linear and generally better than the human discriminibility of the interaural correlation, suggesting that stimulus rather than neural variability is the basis for the decline in human performance at lower levels of interaural correlation.

Electrical stimulation for intraoperative evaluation of thoracic pedicle screw placement.

STUDY DESIGN: Thoracic pedicle screws were stimulated electrically while recording electromyography (EMG) activity in associated muscle groups intraoperatively. Screw position was then evaluated after surgery using computed tomography (CT). The CT results were compared with evoked EMG threshold values. OBJECTIVE: To report our experience with pedicle screw stimulation in thoracic vertebrae in 22 patients who underwent thoracic level spinal instrumentation from May 1999 to March 2001. SUMMARY OF BACKGROUND DATA: Pedicle screw stimulation for intraoperative assessment of screw placement has been reported in lumbosacral spinal procedures. Evoked EMG thresholds >10 or 11 mA are associated with increased probability of vertebral cortex violation and postoperative complications. Thresholds >15 mA provide a 98% confidence of accurate screw positioning on postoperative CT scans. METHODS: Evoked EMG activity was recorded from ulnar carpal flexors, intercostals, or abdominal muscle groups, depending on the level of screw placement. Postoperative CT scans were read by a staff orthopedic spine surgeon, a senior resident in orthopedics, and a musculoskeletal radiologist. RESULTS: Results of 87 screws are reported. Five screws (5.7%) showed penetration on postoperative CT scans. Six screws (6.9%) had stimulation thresholds < or =11 mA, of which three showed cortical breakthrough. Of the 81 screws with thresholds >11 mA, 79 (97.5%) were within the vertebra. No postoperative neurologic complications were noted in any of the 22 patients. CONCLUSION: These results are consistent with previous studies of lumbosacral pedicle screws. In this series, stimulation thresholds >11 mA have a 97.5% negative predictive value, suggesting that cortical violation is highly unlikely. Although judgment of screw placement should not depend solely on stimulation thresholds, pedicle screw stimulation may provide rapid and useful intraoperative information on screw placement during procedures involving the use of thoracic pedicle screws.

Revision ossicular reconstruction with the titanium Kurz prosthesis.

OBJECTIVE/HYPOTHESIS: One European multicenter study has reported favorable outcomes after ossicular reconstruction with the titanium Kurz prosthesis. At the time of this study, however, no study has analyzed its outcomes when used for reconstruction after prior failure with another implant (revision reconstruction). The study reports our experience with the titanium Kurz prosthesis for revision ossicular reconstruction. STUDY DESIGN: A retrospective review was made of all revision ossicular reconstructions at our institution from October 1998 to September 2001. METHODS: Seventeen cases were reviewed. Patients were divided into two groups: patients who underwent revision ossicular reconstruction with the Kurz prosthesis and patients who underwent revision ossicular reconstruction with another prosthesis (the "other" group). Audiograms were reviewed and air-bone gaps were calculated for each patient. RESULTS: The average postoperative air-bone gap after Kurz revision was 15.6 dB, a statistically significant improvement over the average postoperative air-bone gap from the "other" revision group (P =.022). CONCLUSION: The titanium Kurz prosthesis has been an effective implant at our institution for revision ossicular reconstruction. Future research should focus on a prospective, randomized trial comparing the Kurz prosthesis with other prostheses currently in use.