Impact on Health-Related Quality of Life of Induction Chemotherapy Compared With Concurrent Cisplatin and Radiation Therapy in Patients With Head and Neck Cancer.

AIMS: Organ preservation, an important goal in the treatment of head and neck squamous cell carcinoma (HNSCC), may include induction chemotherapy and cisplatin with radiation therapy (CRT). To our knowledge, no reports have directly compared the impact of induction chemotherapy with that of CRT on health-related quality of life (HRQOL). MATERIALS AND METHODS: In a phase II trial, we assessed the HRQOL of patients treated with induction chemotherapy followed by CRT. Eligible patients had stage III-IV HNSCC. HRQOL questionnaires were administered at baseline, the end of induction (EOI), the end of CRT (EOCRT) and after CRT. Functional Assessment of Cancer Therapy (FACT version 4) assessed HRQOL. We carried out a comparison of changes in HRQOL from baseline to EOI and from EOI to EOCRT. This trial is registered with ClinicalTrials.gov (NCT01566435). RESULTS: Thirty patients were enrolled in the study. Most HRQOL questionnaires were completed (88%). The mean total FACT scores did not differ from baseline to EOI (general: 83.8 versus 79.1, P = 0.08; head and neck: 109.7 versus 105.8, P = 0.33; Total Outcome Index: 69.7 versus 62.3, P = 0.03; respectively, using P ≤ 0.01 to adjust for multiple simultaneous tests of differences). However, total FACT scores significantly worsened from EOI to EOCRT (79.1 versus 62.3, P = 0.01; 105.8 versus 74.2, P < 0.01; 62.3 versus 34.2, P = 0.01; respectively). Within domains, the head and neck cancer subscale score did not differ from baseline to EOI (median 28.5 versus 27.0, P = 0.69), but significantly worsened from EOI to EOCRT (27.0 versus 9.5, P < 0.01). Swallowing, oral pain and voice quality improved from baseline to EOI, but worsened from EOI to EOCRT. Physical and functional scores worsened from baseline to EOI and from EOI to EOCRT. The emotional well-being score improved from baseline to EOI but worsened from EOI to EOCRT. CONCLUSIONS: Overall, HRQOL did not significantly change from baseline to EOI but dramatically worsened from EOI to EOCRT.

Novel THAP1 sequence variants in primary dystonia.

BACKGROUND: THAP1 encodes a transcription factor (THAP1) that harbors an atypical zinc finger domain and regulates cell proliferation. An exon 2 insertion/deletion frameshift mutation in THAP1 is responsible for DYT6 dystonia in Amish-Mennonites. Subsequent screening efforts in familial, mainly early-onset, primary dystonia identified additional THAP1 sequence variants in non-Amish subjects. OBJECTIVE: To examine a large cohort of subjects with mainly adult-onset primary dystonia for sequence variants in THAP1. METHODS: With high-resolution melting, all 3 THAP1 exons were screened for sequence variants in 1,114 subjects with mainly adult-onset primary dystonia, 96 with unclassified dystonia, and 600 controls (400 neurologically normal and 200 with Parkinson disease). In addition, all 3 THAP1 exons were sequenced in 200 subjects with dystonia and 200 neurologically normal controls. RESULTS: Nine unique melting curves were found in 19 subjects from 16 families with primary dystonia and 1 control. Age at dystonia onset ranged from 8 to 69 years (mean 48 years). Sequencing identified 6 novel missense mutations in conserved regions of THAP1 (G9C [cervical, masticatory, arm], D17G [cervical], F132S [laryngeal], I149T [cervical and generalized], A166T [laryngeal], and Q187K [cervical]). One subject with blepharospasm and another with laryngeal dystonia harbored a c.-42C>T variant. A c.57C>T silent variant was found in 1 subject with segmental craniocervical dystonia. An intron 1 variant (c.71+9C>A) was present in 7 subjects with dystonia (7/1,210) but only 1 control (1/600). CONCLUSIONS: A heterogeneous collection of THAP1 sequence variants is associated with varied anatomical distributions and onset ages of both familial and sporadic primary dystonia.

Laryngeal reinnervation with the hypoglossal nerve. I. Physiology, histochemistry, electromyography, and retrograde labeling in a canine model.

This study was performed to determine whether the hypoglossal nerve (cranial nerve XI [XII]) would serve as a useful donor for laryngeal reinnervation by anastomosis to the recurrent laryngeal nerve (RLN). Twenty hemilarynges in 10 dogs were studied prospectively after XII-RLN anastomosis (group A; n = 5), split XII-RLN anastomosis (group B; n = 3), XII-RLN anastomosis with a 2-cm interposition graft (group C; n = 2), no treatment (group D; n = 5), RLN section (group E; n = 2), or ansa cervicalis-RLN anastomosis (group F; n = 3). Spontaneous activity was observed monthly by infraglottic examination through permanent tracheostomies and was recorded by electromyography. Laryngeal adductory pressure and induced phonation were obtained by stimulating the RLN while passing a pressure transducer balloon or humidified air through the glottis. At sacrifice, the laryngeal muscles were stained for adenosine triphosphatase to determine the ratio of type I to type II fibers. Retrograde labeling of the brain stem was performed with horseradish peroxidase. Infraglottic examination at 6 months showed a full range of adductory motion in groups A and B during the swallow reflex, comparable with that in group D. Groups C and F showed good bulk and tone, but little spontaneous motion. Group E remained paralyzed. Stimulation of the transferred nerves caused more activity in groups A and B than in the other groups; groups C and F partially adducted at high levels. The laryngeal adductory pressure responses of groups A and B were similar to those of group D. The XII-reinnervated larynges were capable of producing normal induced phonation. Retrograde labeling of the RLN showed that the reinnervating axons originated only in the hypoglossal nucleus. Electromyography of the reinnervated adductor muscles confirmed spontaneous activity in the dogs (awake). Histochemical analysis confirmed slow-to-fast transformation of both the posterior and lateral cricoarytenoid muscles, indicating that significant reinnervation occurred. We conclude that the hypoglossal nerve functions well as a donor for adductory reinnervation of the larynx.

Inhibition of motor nerve regeneration in a rabbit facial nerve model.

OBJECTIVES/HYPOTHESIS: We hypothesized that intramuscular injection of vincristine into the upper lip selectively prevents reinnervation of the target muscle (quadratus labii superioris) after facial nerve transection. STUDY DESIGN: Prospective controlled experiment. METHODS: Transection injuries with primary neurorrhaphy were performed just proximal to the buccal and zygomatic branches of both facial nerves in 20 rabbits. The left (experimental) quadratus labii superioris muscle was injected with 200 microg vincristine 72 hours after injury; the right (control) side was injected with saline. Functional, electrophysiological and histological studies were performed 6 weeks after surgery. RESULTS: After 6 weeks, the control side had a mean axon count (distal buccal branch) of 1160, conduction velocity of 50.4 m/s, reduction of compound action potential amplitude of 44%, and functional index of 1.67 units. The experimental side had a mean axon count of 265, conduction velocity of 16.5 m/s, reduction of compound action potential amplitude of 88%, and a functional index of 0.176 units. All parameters were significantly reduced by vincristine blockade (P <.05). The zygomatic division (not exposed to vincristine) displayed a trend toward increased axon counts, but this was not statistically significant (P =.131). CONCLUSIONS: These results demonstrate that reinnervation of a selected muscle can be prevented by injection of vincristine. Enhanced reinnervation of adjacent muscle groups may also occur. Thus, nerve blockade by vincristine may be useful for the prevention of synkinesis.

Functional study of four neurotoxins as inhibitors of post-traumatic nerve regeneration.

OBJECTIVES/HYPOTHESIS: Chemical inhibition of nerve regeneration was studied as a potential adjunct in the treatment of injuries to the facial or recurrent laryngeal nerve. We propose that by treating selected muscles with an inhibitor of nerve regeneration shortly after injury, synkinesis may be controlled. STUDY DESIGN: Nerve regeneration after crush injury was studied in the rat posterior tibial and sciatic nerves, well-established models for the study of peripheral nerve injuries. METHODS: Four days after controlled crush injury to the posterior tibial nerve, the gastrocnemius muscle was injected with saline (control, n = 8), phenol (n = 6), doxorubicin (n = 6), or vincristine (n = 11). Injection without crush injury was performed using vincristine (n = 4) or botulinum toxin (n = 4). Four rats underwent crush injury to the sciatic nerve followed 4 days later by botulinum toxin injection to the gastrocnemius muscle. The percent of functional recovery (%FR) of the nerve was assessed using walking track analysis. RESULTS: Vincristine significantly retarded nerve regeneration. Five weeks after injury, %FR returned to normal in controls, as well as in the phenol, doxorubicin, and botulinum toxin groups, while in the vincristine group %FR was less than 60% of baseline (P <.0001). Vincristine injections without crush injury showed no significant reduction in print length factor. Functional recovery in the botulinum/crush group was more rapid than the botulinum without crush group. CONCLUSIONS: Application of vincristine to the gastrocnemius muscle significantly inhibits regeneration of the posterior tibial nerve after crush injury. Botulinum toxin does not prolong functional recovery after nerve injury; rather, crush injury protects against the prolonged chemodenervation seen with botulinum toxin. Doxorubicin and phenol injection did not prolong functional recovery at the doses tested.

Laryngeal adductory pressure as a measure of post-reinnervation synkinesis.

Laryngeal adductory pressure (LAP) is the pressure induced as the vocal folds squeeze on a balloon while the recurrent laryngeal nerve (RLN) is stimulated. The LAP has been shown to vary with the frequency of stimulation, with a characteristic slope. The RLN was divided and reanastomosed 4 different ways in 12 canine hemilaryngeal preparations; the 4 subgroups represented a range of expected post-reinnervation synkinesis recovery patterns. The LAP frequency-response curve was measured before surgery and at monthly intervals for 6 months after surgery. In the "best-case" group (RLN adductor and abductor trunks each divided and reanastomosed), the slope was found to return to normal. The 2 whole RLN division-reanastomosis groups (precise realignment or 180 degrees rotation) both gave results similar to those of the "worst-case" group (RLN adductor and abductor trunks divided and transposed); these 3 subgroups were all significantly different from baseline. The slope of the LAP frequency-response curve may be a useful means of indirectly quantifying laryngeal synkinesis.

Laryngeal reinnervation with the hypoglossal nerve: II. Clinical evaluation and early patient experience.

OBJECTIVES/HYPOTHESIS: To determine whether the hypoglossal nerve (XII) can serve as a suitable donor for human laryngeal reinnervation. STUDY DESIGN: Prospective, nonrandomized. METHODS: Measurements were made on patients undergoing open neck procedures to determine the length of XII available and that required to perform XII-recurrent laryngeal nerve (RLN) anastomosis. The morbidity of combined XII and RLN injuries was studied using temporary lidocaine block of the ipsilateral XII in patients with unilateral vocal fold paralysis (UVFP). A pilot series of patients with UVFP who underwent XII-RLN reinnervation was evaluated for morbidity of the procedure, and for improvement in voice and swallowing. RESULTS: In 89 necks the average available length of XII was 2 cm less than that needed to reach the larynx, indicating the RLN stump must be at least 3 cm to allow tension-free anastomosis. Twenty-five patients with untreated UVFP underwent temporary lidocaine block of XII; 8 had slight changes in their speech, none had increased aspiration. Nine patients underwent XII-RLN reinnervation. Postoperative speech analysis correlated well with the findings of the temporary lidocaine block of XII. One-year follow-up of five patients showed excellent voice quality, resolution of any preoperative aspiration, and minimal morbidity. Slight adductory movement of the reinnervated vocal fold was seen during tongue thrust. Electromyography confirmed substantial polyphasic action potentials in the thyroarytenoid muscle. CONCLUSIONS: The hypoglossal nerve is a very suitable donor for reinnervation of patients with UVFP. There should be enough length for primary XII-RLN anastomosis in most patients. Donor site morbidity is acceptable. Preoperative lidocaine block of XII is a good predictor of actual donor site morbidity and could be used to assess patients undergoing facial-hypoglossal anastomosis as well.

Chemodenervation of the rat hemilarynx with phenol.

In this study, the injection of phenol into the true vocal fold was evaluated on a rat model as a possible treatment for adductor spasmodic dysphonia. A 10% phenol solution was injected into the right true vocal fold. Quantitative measurement of vocal fold adductory force showed reduction to 35% of the preinjection value 3 months after injection (p < .05). Qualitative evaluation by videolaryngoscopy demonstrated maintenance of the normal vocal fold range of motion. Histologic studies showed a transient inflammatory infiltrate and myolysis, while the vocal fold mucosa and the cricoarytenoid joints remained undamaged. Further investigation into the potential use of phenol for treating spasmodic dysphonia is warranted.

Laryngeal chemodenervation: effects of injection site, dose, and volume.

A canine model was used to measure changes in laryngeal adductory pressure (LAP) following injections of vecuronium bromide, a short-acting neuromuscular blocking agent. At a constant volume, LAP was inversely related to the dose (and concentration) of vecuronium injected. At a constant dose (0.05 mg), LAP did not vary significantly over a wide range of injection volumes, from 0.05 to 0.50 mL. At a constant dose and volume, the site of injection was varied among the anterior, middle, and posterior vocal fold, the interarytenoid region, and the anterior contralateral vocal fold. Reduction in LAP was greatest (p<.05) for the posterior vocal fold injection site (78% reduction); less reduction was seen for the middle (54%) and anterior (52%) vocal fold and interarytenoid (43%) injection sites. These results have implications for laryngeal botulinum toxin injections, which are discussed.

Seroprevalence of Neospora caninum infection in dairy and beef cattle in Spain.

In recent years, neosporosis has been identified as a major cause of abortion in dairy and beef cattle. Although the disease has been described worldwide, there is a Jack of information concerning the prevalence of this infection in different cattle production systems. The aim of this study was to investigate the seroprevalence of Neospora caninum infection in a representative area of beef and dairy cattle production in Spain. A cross-sectional study was undertaken in which herds constituted the initial sampling unit and two strata (dairy and beef herds) were considered. Using a 95% level of confidence and setting 5% (beef) and 5.4% (dairy) error limits, 216 beef and 143 dairy herds were randomly selected and sampled. Nine animals (> 1 year old) were randomly sampled in each herd to detect the presence of the infection. A herd was considered infected when at least one animal was seropositive. In total, serum samples from 1121 dairy and 1712 beef animals were collected and tested for specific anti-N. caninum IgG using an ELISA. Specific antibodies were detected in 55.1% (119/216) beef and 83.2% (119/143) dairy herds. Individual prevalences obtained were 17.9% (306/1712) for beef and 35.9% (402/1121) for dairy animals. Presence of N. caninum infection was higher in dairy than in beef herds and the association between infection and the cattle production system (dairy or beef) was statistically significant [(chi2)Y= 29.21, P < 0.001, OR = 4.04 (2.35-6.99)]. Herd size of dairy cattle did not appear to be associated with N. caninum infection. On the contrary, infection was associated with herd size in beef cattle (chi2 = 12.79, P < 0.01). Finally, no association was found between replacement or pasture management and infection in beef herds.

How surgeon age affects posttreatment surveillance strategies for upper aerodigestive tract cancer patients.

PURPOSE: Strategies for the surveillance of patients with upper aerodigestive tract (UADT) epidermoid cancer after potentially curative treatment are not uniform, and the most suitable regimen remains unknown. We investigated the effect of surgeon age on follow-up strategy. MATERIALS AND METHODS: The 824 members of the Society of Head and Neck Surgeons (SHNS) and the 522 members of the American Society for Head and Neck Surgery (ASHNS) who were not members of the SHNS were surveyed using a custom-designed questionnaire to measure how these surgical experts performed follow-up on patients with UADT cancer. Subjects were asked how often they used 14 specific follow-up modalities for patients with resectable UADT cancer during years 1 to 5 after potentially curative primary treatment. Repeated-measures analysis of variance was used to compare practice patterns by surgeon age, as well as by tumor, node, metastasis (TNM) stage and year postsurgery. RESULTS: Responses from 199 SHNS members (24%) and 221 ASHNS members (42%) were considered assessable. Strategies were highly correlated across TNM stages and years postsurgery for most of the 14 modalities. Mean follow-up intensity differed significantly by surgeon age only for bone scan and liver function tests. Although statistically significant, the differences in surveillance strategies among age groups were clinically small. CONCLUSION: Surveillance practice patterns of surgeons caring for patients after treatment for UADT cancer do not vary substantially with practitioner age. Postgraduate education is a plausible mechanism for this homogenization of practitioner behavior.

Practice patterns and clinical guidelines for posttreatment follow-up of head and neck cancers: a comparison of 2 professional societies.

OBJECTIVES: To determine and compare the current follow-up practice patterns of members of 2 professional societies of head and neck surgeons, and to compare these with the societies' published clinical practice guidelines. DESIGN: A survey was mailed to the 640 members of the American Society for Head and Neck Surgery (ASHNS); results were compared with those of a similar survey of the 824 members of the Society of Head and Neck Surgery (SHNS) and with the clinical practice guidelines of the consensus committee of both societies. MAIN OUTCOME MEASURES: Data were collected regarding the frequency of follow-up visits after potentially curative resection of head and neck epidermoid carcinoma and the types of diagnostic studies performed at each visit. RESULTS: A total of 318 ASHNS members responded to 1 of the mailings (49.7%), of which 280 responses (43.8%) were evaluable. Most surgeons relied on directed history, physical examination, and routine chest radiograph at varying intervals for detection of recurrences and second primary tumors. Other tests were used sporadically. For frequency of follow-up testing, the percentage of surgeons who followed the published guidelines varied from 97% in postoperative year 1 to 62% in postoperative year 5. A mean of 24% of surgeons varied from the guidelines in their use of chest radiographs, and 45% varied in their use of liver function tests. The ASHNS members used significantly more office visits than the SHNS members during the first 2 postoperative years. CONCLUSIONS: The strategies used by members of the ASHNS and the SHNS for posttreatment surveillance after potentially curative resection of malignant neoplasms of the head and neck were generally similar but showed some important differences. Most surgeons used directed history and physical examination at regular intervals, and annual chest radiographs. The follow-up practices of most members of these societies, which have recently merged, fall within the recommendations of the Clinical Guidelines Task Force.

Hypoglossal nerve transfer for laryngeal reinnervation: a preliminary study.

The hypoglossal nerve is a logical donor nerve for hemilaryngeal reinnervation because 1) its activity coincides with normal laryngeal adduction during speech and deglutition; 2) it is a large nerve with many axons; and 3) donor site morbidity is low. This method of laryngeal reinnervation has not been previously reported. Previous studies using the ansa cervicalis for reinnervation have failed to show spontaneous activity. Hypoglossal-to-recurrent laryngeal nerve anastomosis was performed on a series of 5 dogs. The vocal folds were viewed monthly, with the animals awake, by infraglottic examination through a permanent tracheostomy. One dog failed due to technical error. The remaining 4 dogs began to exhibit spontaneous vocal fold adduction within 2 to 4 months. Vocal fold motion was synchronous with spontaneous tongue motion. Complete glottic closure was seen during swallowing at 3 to 5 months. Intraglottic pressure measurements following reinnervation were normal. Hypoglossal nerve transfer appears to be capable of providing functional adduction to the paralyzed hemilarynx. The potential advantages and disadvantages of this new technique are discussed.

Prevalence of Tritrichomonas foetus infection in beef bulls in northwestern Spain.

The purpose of this study was to investigate the prevalence of Tritrichomonas foetus infection in beef bulls in north-western Spain. The study area comprised of 350 herds (5909 cows and 102 bulls) managed under extensive or semi-extensive systems where natural mating alone or alternated with artificial insemination are used. The targets of this survey were bulls of 1 year of age or older. Preputial smegma samples were taken from 70 bulls (68.6% of bull population) servicing a total of 184 herds (52.6%) and 4136 cows (69.9%). Data collected at sampling included farm location, herd size, age, breed, private or communal bull and previous infertility problems in the herd. The percentage of infected bulls was 2.9% (2 of 70). Age of infected bulls was 5 and 7 years and both were of the local breed, Asturiana de los Valles. These results confirm the presence of T. foetus infection in Spain and the necessity to include this disease in the differential diagnosis of reproductive failure in rangeland grazing cattle.

Costs of posttreatment surveillance for patients with upper aerodigestive tract cancer.

OBJECTIVES: To determine the range of recommended follow-up strategies for patients with upper aerodigestive tract cancer treated with curative intent and to estimate the cost of follow-up. DESIGN: Economic analyses of the costs associated with 31 follow-up strategies (12 generic and 19 site specific) identified from a MEDLINE search of the literature for 1978 to 1997 and a search of major textbooks. Generic strategies are not specific for site or histology and are exclusive of strategies designed for the rare patient, ie, patients who would not be considered average in terms of clinical characteristics. Charge data obtained from the Part B Medicare Annual Data File and the Hospital Outpatient Bill File were used as a proxy for cost. SETTING: Ambulatory care. MAIN OUTCOME MEASURES: Nationwide Medicare-allowed charges and an actual-charge proxy for 5 years of surveillance after treatment for upper aerodigestive tract cancer. RESULTS: Medicare-allowed charges for 5-year follow-up ranged from a low of $739 to a high of $14,079 for the generic and site-specific strategies combined and from $739 to $4646 for the 12 generic strategies alone. When Medicare-allowed charges were converted to a proxy for actual charges using a conversion ratio of 1.62, the range was $1198 to $22,807 for all strategies combined (a 19-fold difference in charges) and $1198 to $7597 for the generic strategies alone (a 5-fold difference in charges). CONCLUSIONS: Charges vary extensively across surveillance strategies, particularly if site-specific strategies are considered, although the potential benefit of more intensive, higher-cost strategies on survival or quality of life has yet to be demonstrated.

How tumor stage affects surgeons' surveillance strategies after surgery for carcinoma of the upper aerodigestive tract.

BACKGROUND: The factors that influence decision-making among surgeons are not well understood. The authors evaluated how tumor stage in otherwise healthy patients subjected to potentially curative surgery for upper aerodigestive tract (UADT) epidermoid carcinoma affects the self-reported follow-up strategies employed by practicing surgeons. METHODS: Hypothetical patient profiles and a detailed questionnaire based on these profiles were mailed to the 824 members of the Society of Head and Neck Surgeons (SHNS) and the 522 members of the American Society for Head and Neck Surgery who were not members of SHNS. The effect of TNM stage on the surveillance strategies chosen by the respondents was analyzed. RESULTS: Ten of the 14 most commonly employed surveillance modalities were ordered significantly more frequently with increasing TNM stage. This effect persisted through 5 years of follow-up, but the differences across stages were small. Only 30% of respondents modified their strategies according to the patient's TNM stage. CONCLUSIONS: Most surgeons performing surveillance after potentially curative surgery in otherwise healthy patients with UADT carcinoma use the same follow-up strategy irrespective of TNM stage. These data permit rational design of a randomized clinical trial of two alternate follow-up plans.

Primary subglottic cancer.

This retrospective study reviews 39 patients with primary subglottic cancer seen between 1955 and 1988 by the Department of Otolaryngology at Washington University. This number constitutes 1.8% of laryngeal cancer cases diagnosed during this period. Twenty-eight patients (71.8%) had epidermoid cancer, of which 19 (67.9%) had "early" disease (stages I and II), and nine (32.1%) had "advanced" (stages III and IV). Overall 5-year survival was 57.7%. Disease-free survival was 46.2%. Patients treated with radiotherapy alone, surgery alone, or both had disease-free 5-year survivals of 22.2%, 41.7%, and 100%, respectively. Combination therapy showed a significantly higher (P < .01) disease-free survival than radiotherapy alone.

Long-term model of induced canine phonation.

Experimental induced phonation in the dog has been used in short-term studies by several investigators and has proved quite useful in laryngeal research. In this study a long-term canine phonation model is described that uses permanently implanted electrodes on the superior and recurrent laryngeal nerves. A serial induced phonation model has not been previously reported and is needed for laryngeal research in which voice results are a primary end point. Inexpensive, reliable, nontoxic electrodes were designed and fabricated. The laryngeal nerves were found to be quite susceptible to injury, necessitating a series of changes in electrode design. Electrode durability and laryngeal nerve viability improved with each design modification; the final design gave a recurrent laryngeal nerve viability rate of 100% at 6 weeks, 83% at 9 weeks, and 73% at 12 weeks. Induced phonation was successfully produced on a repeated basis by stimulating the recurrent laryngeal nerves while passing air through the larynx, in 22 (95.6%) of 23 animals. Stimulation of the superior laryngeal nerves increased vocal fold length and tension but was not required for phonation. Technical aspects of chronic implantation and stimulation of the laryngeal nerves are discussed. The development and successful long-term implantation of electrodes on the laryngeal nerves and their use in repeated induced phonation have not been reported previously.

Tracheostomy for long-term laryngeal experimentation.

To perform laryngeal research involving long-term survival surgery, a permanent tracheostomy is often necessary. For experiments using a long-term induced canine phonation model, we required a tracheostomy that was placed as low as possible, to maximize the subglottic space superior to the stoma. The ideal experimental tracheostomy would also be safe and easy to perform, require no tracheostomy tube, and be low maintenance, requiring minimal cleaning or suctioning. Tracheostomies were performed in 37 dogs based on previously published methods. If the stoma was placed below the twelfth tracheal ring, the perioperative mortality rate was 57% because of kinking of the trachea and subsequent airway obstruction. When the tracheostomy was performed above this level, the mortality rate was reduced to 3%. A number of significant modifications in technique were made to achieve this improvement and resulted in the last 12 dogs having no complications. Several of the tracheostomies were maintained for more than 18 months. The method derived meets the above criteria for the ideal experimental tracheostomy and also meets our needs for a long-term induced phonation model.

Reversibility of medialization laryngoplasty. An experimental study.

Medialization laryngoplasty has become a routine procedure for cases of unilateral vocal fold paralysis. In certain clinical situations, it may become desirable to reverse the procedure and remove the implant. This process was studied experimentally in eight dogs in a chronic model of induced canine phonation. A silicone polymer implant was inserted to medialize one normal vocal fold for a period of 1 month, after which it was removed. Motion of the cricoarytenoid (CA) joint and induced phonation were studied weekly while the implant was in place, and for another month following implant removal. Significant abnormalities were found even with this relatively short period of implantation. With the implant in place, impairment of CA joint mobility was found in seven of the eight dogs, precluding phonation. A dense fibrous capsule rapidly developed around the implant, making its removal technically difficult. Following implant removal, a gradual return to normal function was found in only three of the eight dogs. One of the animals had evidence of neural injury, while four had intact neural function but impaired mobility or fixation of the CA joint. Medialization laryngoplasty should not be considered a reversible procedure. The clinical implications of these findings are discussed.