Biomedical subjects

J D Dahm

Publications and source records attributed to J D Dahm.

5 recordsLinked to original sources

PubMed1999

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.

Anastomosis, Surgical↗

PubMed1998

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.

Animals↗

PubMed1998

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.

Adult↗

PubMed1998

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.

Animals↗

PubMed1997

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.

Animals↗