Duncan R. Ingrams

Autofluorescence characteristics of oral mucosa

The fluorescence characteristics of tissues depend upon their biochemical composition and histomorphological architecture, both of which undergo a change during malignant transformation. These changes are detectable as an alteration in the fluorescence spectral profile of the tissues.

Sinus Surgery: Does Mitomycin C Reduce Stenosis?

This experimental study investigates the effect of mitomycin C (MMC) on sinus mucosal healing. MMC has an antiproliferative action on fibroblasts. It is used in glaucoma surgery to prevent restenosis of fistulas. Antrostomies were drilled in rabbit maxillary sinuses. One side was used as a control and the other treated with MMC at a concentration of 0.04, 0.4, or 1 mg/mL. Two animals from each group were sacrificed at 1, 2, 4, and 12 weeks. The antrostomies in the control and 0.04‐mg/mL groups had closed by 1 week; in the 0.4‐mg/mL group by 4 weeks, and in the 1.0‐mg/mL group by 12 weeks. Ciliary function was initially impaired but normalized within 1 week. Both light and scanning electron microscopy showed no permanent damage to the cilia. These results suggest that MMC can be used to delay closure of antrostomies in sinus surgery.

Slow-release 5-fluorouracil and triamcinolone reduces subglottic stenosis in a rabbit model.

A previous pilot study suggested that a sustained-release conjugate that provided a slow release of 5-fluorouracil and triamcinolone acetonide injected into the tracheal and paratracheal tissues of rabbits at the time of subglottic surgery reduced the formation of subglottic stenosis. Our study was undertaken to confirm the effect. Ten milligrams of the compound suspended in hyaluronic acid was injected at the time of injury via a laryngofissure approach. The results showed that the control group had a mean stenosis of 52%, whereas the treated group had a mean stenosis of 32%. There was a significant difference between the treated and untreated groups (p = 003). It is hoped that this co-drug ultimately can be used in humans to reduce stenosis formation after laryngotracheal surgery and in other forms of otorhinolaryngological surgery.

Diagnostic fluorescence spectroscopy of oral mucosa

Autofluorescence characteristics of normal, dysplastic, and malignant squamous tissues from the oral cavity were measured with a spectrofluorometer in the excitation range of 250 - 500 nm and emission range of 350 - 750 nm. Fluorescence excitation-emission matrices (EEM) were obtained from samples collected from patients in the clinic and in the operating room. The same samples were submitted for histopathological examination following spectroscopic measurements. The contour plots obtained from the EEMs of the samples showed consistent differences between normal and abnormal tissues. All the abnormal samples showed enhanced red region (> 600 nm) fluorescence with a prominent peak at 635 nm, when excited by 410 nm light. A ratio contour plot (abnormal/normal) enhanced spectral differences in the red region. A fiber-optic based spectrofluorometer for EEM measurements is being developed for further investigations.

Does slow-release 5-fluorouracil and triamcinolone reduce subglottic stenosis?†††

The surgical management of subglottic stenosis may be complicated by reformation of strictures. A slow-release combination of 5-fluorouracil, which has an antiproliferative effect on fibroblasts, and the corticosteroid triamcinolone acetonide has been used experimentally to control scar production in ophthalmic operations. This study was performed to determine if this material also can be used to reduce formation of subglottic stenosis. Subglottic stenosis was induced in rabbits by means of injury to the subglottic mucosa and submucosa. A suspension of the compound at a concentration of 2.5 mg/ml or 12.5 mg/ml was injected into the adjacent soft tissues. A control group of rabbits received the same volume of the suspension fluid but no compound. Two rabbits from each group were killed 1,2, and 12 weeks postoperatively. No stenosis was seen at 1 or 2 weeks, but at 12 weeks the rate of formation of subglottic stenosis was decreased to a mean of 15.20% in the experimental groups compared with 47.37% in the control group. There were no indications of local or systemic toxicity. The promising results from this preliminary study suggest that use of this compound may reduce restenosis among patients treated surgically for subglottic stenosis. Further studies are being conducted.

How reliably can computed tomography predict thyroid invasion prior to laryngectomy?: Predicting Thyroid Invasion at Laryngectomy

There is little evidence to support the removal of thyroid tissue during total laryngectomy. Although oncological control of the tumor is the priority, thyroidectomy can lead to hypothyroidism and hypoparathyroidism. This study aimed to test the usefulness of preoperative computed tomography in predicting histological invasion of the thyroid.

Prevention of subglottic stenosis: The use of a slow release preparation of 5-fluorouracil and triamcinolone acetonide in rabbits

Unilateral vocal fold paralysis is a problem that can have a significant impact on physiologic function. A lateralized vocal fold may lead to glottic incompetence with breathiness and air wasting. This prevents formation of a protective glottic seal and disrupts the cough mechanism. Vocalization is also impaired, as the paralyzed fold results in a weak or hoarse voice with diminished loudness and endurance. Vocal fold positioning after paralysis has been difficult to typify. There is variability of vocal fold position between subjects and also unpredictable changes in vocal fold position over time. Generally, vocal fold position is variable because of the diversity of etiologic factors causing paralysis and the tendency of the recurrent laryngeal nerve to undergo spontaneous partial reinnervation that is often synkinetic. However, the observed changes have only been described in two dimensions, and observations have conflicted as to whether a paralyzed fold resides in a higher or lower position than the normal vocal fold. Differences in vocal fold height undetected by routine office laryngoscopy could preclude optimal apposition and vibration of the vocal folds, with resultant glottic compromise. Type I thyroplasty is a method that uses a Silastic implant placed in a window in the thyroid ala between the inner and outer perichondrium for external medialization of the paralyzed true vocal fold by lateral compression (Isshiki NI, Morita H, Okamura H, et al.: Thyroplasty as a new phonosurgical technique. Acta Otolaryngol 1974;78:451-7). Subjects who have undergone type I thyroplasty were recruited and videoendoscopic, acoustic, and aerodynamic measures were obtained and compared with those recorded preoperatively. In addition, each subject underwent magnetic resonance imaging to obtain the three-dimensional orientation of the larynx. The results of this study will help determine why some patients do not achieve a marked improvement in vocal parameters despite the appearance of effective medialization on endoscopic examination. Measures of acoustic analysis will determine whether suboptimal acoustic results correlate with three-dimensional misalignment seen on magnetic resonance imaging. Specific knowledge on this problem may warrant modification of current surgical regimens to provide both a better voice and improved glottic competence. Poster 22

Strategies for the management of recurrent head and neck squamous cell carcinoma

This review summarizes recent literature on the management options for recurrent squamous cell carcinoma in the head and neck. It remains true that survival from recurrent squamous cell carcinoma in the head and neck is poor; therefore, the best management is avoidance. In the presence of a recurrence, there is a range of different modalities of management (curative and palliative) that can be employed. The use of a combination of surgical clearance, tissue transfer, and brachytherapy has been used to good effect. Electroporation used in conjunction with cytotoxic agents, and interstitial laser therapy are interesting new developments.

Preliminary investigation of applications in the larynx of the 810-nm high-energy pulsed diode laser

Laryngeal lesions such as papillomata can be removed with CO2 laser but the scar that forms after repeated treatments can cause reduction in the function of the larynx. This scarring may be made worse by infection caused by interruption in the epithelial surface. It is hoped that if the vasculature of these lesions can be thrombosed without damage to the epithelium, the lesion will atrophy without the risk of infection and scar formation. A series of in vitro experiments were carried out to determine if the 810 nm high energy pulsed diode laser could be used to coagulate blood. Experiments with a laser fluence of 22 J/cm2 on flowing and stationary animal and human blood in 750 micrometers diameter capillary tubes showed that single pulses caused a maximum detectable rise in temperature of 16 degree(s)C and no coagulation. Multiple pulses in slow flowing blood did generate a sustained temperature rise of 40 degree(s)C which may be enough to cause coagulation. Further in vitro and in vivo studies are underway to determine the clinical usefulness of this energy source.