The effects of laser irradiation of cartilage on chondrocyte gene expression and the collagen matrix.

OBJECTIVES: Laser reshaping of cartilage is an emerging technology aimed at replacing conventional techniques for aesthetic and reconstructive surgery. Little is known about the mechanisms of wound healing following the photothermal heating during laser reshaping and, ultimately, how collagen remodels in the irradiated tissue. Healthy hyaline and elastic cartilage as found in the ear, nose, larynx, and trachea does not express collagen type I which is characteristic of fibro-cartilage and scar tissue. The aim of the study was to determine if collagen I and II gene expression occurs within laser irradiated rabbit septal cartilage. METHODS: Nasal septum harvested from freshly euthanized New Zealand White rabbits were irradiated with an Nd:YAG laser. After 2 weeks in culture, the laser spot and surrounding non-irradiated regions were imaged using immunofluorescence staining and evaluated using reverse transcription polymerase chain reaction (RT-PCR) to determine the presence of collagen I and II, and ascertain collagen I and II gene expression, respectively. RESULTS: All laser irradiated specimens showed a cessation in collagen II gene expression within the center of the laser spot. Collagen II was expressed in the surrounding region encircling the laser spot and within the non-irradiated periphery in all specimens. Immunohistochemistry identified only type II collagen. Neither collagen I gene expression nor immunoreactivity were identified in any specimens regardless or irradiation parameters. CONCLUSIONS: Laser irradiation of rabbit septal cartilage using dosimetry parameters similar to those used in laser reshaping does not result in the detection of either collagen I gene expression or immunoreactivity. Only collagen type II was noted after laser exposure in vitro following cell culture, which suggests that the cellular response to laser irradiation is distinct from that observed in conventional wound healing. Laser irradiation of cartilage can leave an intact collagen matrix which likely allows chondrocyte recovery on an intact scaffold.

Thermoforming of tracheal cartilage: viability, shape change, and mechanical behavior.

BACKGROUND AND OBJECTIVES: Trauma, emergent tracheostomy, and prolonged intubation are common causes of severe deformation and narrowing of the trachea. Laser technology may be used to reshape tracheal cartilage using minimally invasive methods. The objectives of this study were to determine: (1) the dependence of tracheal cartilage shape change on temperature and laser dosimetry using heated saline bath immersion and laser irradiation, respectively, (2) the effect of temperature on the mechanical behavior of cartilage, and (3) tissue viability as a function of laser dosimetry. MATERIALS AND METHODS: Ex vivo rabbit trachea cartilage specimens were bent and secured around a cylinder (6 mm), and then immersed in a saline bath (45 and 72 degrees C) for 5-100 seconds. In separate experiments, tracheal specimens were irradiated with a diode laser (lambda = 1.45 microm, 220-400 J/cm(2)). Mechanical analysis was then used to determine the elastic modulus in tension after irradiation. Fluorescent viability assays combined with laser scanning confocal microscopy (LSCM) were employed to image and identify thermal injury regions. RESULTS: Shape change transition zones, between 62 and 66 degrees C in the saline heating bath and above power densities of 350 J/cm(2) (peak temperatures 65+/-10 degrees C) for laser irradiation were identified. Above these zones, the elastic moduli were higher (8.2+/-4 MPa) than at lower temperatures (4.5+/-3 MPa). LSCM identified significant loss of viable chondrocytes within the laser-irradiation zones. CONCLUSION: Our results indicate a change in mechanical properties occurs with laser irradiation and further demonstrates that significant thermal damage is concurrent with clinically relevant shape change in the elastic cartilage tissues of the rabbit trachea using the present laser and dosimetry parameters.

Long-term botulinum toxin dose consistency for treatment of adductor spasmodic dysphonia.

OBJECTIVES: Botulinum toxin (BTX) injection is currently the primary and most common treatment for adductor spasmodic dysphonia (ADSD). A variety of injection strategies and dosage regimens have been described. This study reports on our experience with the dosage schedule and dosing consistency of BTX for the treatment of ADSD. METHODS: We retrospectively reviewed our laryngeal BTX database for the period 1991 to 2005. Our strict inclusion requirements limited our selection to 13 patients who had received a minimum of 6 injections (average, 11.5; range, 6 to 19) of BTX for ADSD. RESULTS: The average total dose of BTX to the larynx for each treatment episode was 3.9 units (range, 1.5 to 7.5). The total dose administered tended to trend downward among patients who began treatment from 1991 to 1998, indicating that the initial dose (usually 2.5 units per side) may have been high. Those patients who began from 1999 onward had a more stable dose, indicating that the initial dose (usually 1.5 units per side) was more suitable. The subjects underwent an average of 2.2 injections (range, 1 to 5) before reaching their optimal BTX dose. The total number of treatments performed in this group of patients was 150, of which 145 were successful (96.7%). CONCLUSIONS: The BTX dose for the optimal treatment of ADSD usually remains consistent over time, as does the treatment interval. An initial dose of 1.5 units per side or less appears to improve dosing stability, indicating that the initial dosing of 2.5 units per side in our study was often greater than required. The optimal BTX dose was usually ascertained by the second or third injection. In our patient population, the long-term dosing consistency of BTX confirmed that neither tachyphylaxis nor increasing sensitivity to BTX occurred during the course of treatment for ADSD.

Long-term analysis of surgical correction of the senile upper lip.

OBJECTIVE: A quantitative comparison of immediate and long-term results of surgical correction of the senile upper lip using lip advancement and lip lift. METHODS: Retrospective review of 30 patients who underwent senile upper lip repair, including lip advancement or lip lift. Digital image analysis was used to standardize each patient's preoperative and postoperative photographs for accurate, objective comparison. RESULTS: Lip lift and lip advancement achieve significant improvement in the appearance of the senile upper lip (P < .001). This improvement is sustained during many years (mean, 5 y; P < .001). Using repeated measures analysis of variance, no significant difference was found in the operative group compared with the control group when examining age-related change. CONCLUSION: Lip advancement and lip lift can restore the senile upper lip to a more youthful and natural appearance with sustained long-term benefits.

Minimally invasive ear reshaping with a 1450-nm diode laser using cryogen spray cooling in New Zealand white rabbits.

BACKGROUND: Otoplasty is the current standard of care for treating prominent ears, a psychologically and sometimes functionally disabling disorder. The technically demanding procedure carries many risks such as poor aesthetic outcome, need for revision surgery, and need for general anesthesia. This study investigates the use of laser irradiation combined with cryogen skin cooling and stenting to reshape cartilage in the ears of New Zealand white rabbits. METHODS: In this prospective, randomized, internally controlled animal study, the right ears of 9 rabbits were mechanically deformed with a jig and then irradiated with a 1450-nm diode laser combined with cryogen skin cooling (14 J/pulse with cryogen spray for 33 milliseconds per cycle and a 6-mm spot size). The left ear served as the control. The ears were splinted for 1, 3, or 4 weeks. The rabbits were then given a lethal dose of intravenous pentobarbital, and the splints were removed and ears examined and photographed. Light and confocal microscopy were performed on the specimens. RESULTS: Shape change was observed in all 9 treated rabbit ears, while none of the control ears (stenting alone) showed significant change. Qualitatively, reshaped ears were stiffer after 4 weeks of splinting than after 1 or 3 weeks. None of the rabbits showed evidence of skin injury nor did they show signs of postprocedural pain. Findings from histologic analysis in the treated areas showed evidence of an expanded chondrocyte population in the region of laser irradiation, along with some perichondrial thickening and some fibrosis of the deep dermis. Confocal microscopy revealed minimal cellular death at 1 week and none thereafter. CONCLUSIONS: Cartilage reshaping using laser energy can be performed safely transcutaneously using cryogen spray cooling in rabbits. This animal model has similarity to human ears with regard to skin and cartilage thickness and is a stepping stone toward developing minimally invasive laser auricle reshaping in humans.

Human nasal cartilage ultrastructure: characteristics and comparison using scanning electron microscopy.

OBJECTIVES/HYPOTHESIS: Human nasal cartilage is hyaline cartilage, although the function and loads placed on it are different depending on the location. We hypothesized that important differences exist between the nasal septal cartilage and lower lateral cartilage (LLC) ultrastructures. Such differences would be important in the field of cartilage engineering. METHODS: Ten specimens (6 septum and 4 LLC) of cartilage from patients undergoing nasal surgery (rhinoplasty or septoplasty) were obtained and examined using scanning electron microscopy. Micrographs were then analyzed and measured using photograph analysis software. RESULTS: The collagen fibers of septal cartilage were found to be arranged in a mesh framework, with larger lacunae and thicker fibers measuring 3.18 microm (standard deviation = 0.75 microm), with a 99.9% confidence interval of 2.74 to 3.54 microm. LLC fibers, on the other hand, were arranged in less-organized sheets, with fibrous extensions, and had fewer, narrower lacunae. The fibers from the LLC averaged 2.29 microm, with a 99.9% confidence interval of 1.17 to 3.42 microm. CONCLUSIONS: Significant ultrastructural differences exist between the cartilage of the nasal septum and LLC. These are almost certainly the result of their embryologic origins and different forces placed on the structures they support. A less-organized pattern with smaller collagen fibers is present in the LLC versus the more-organized, layered, thicker collagen fibers of the septum. These differences may prove to be critical in the future of cartilage engineering.