Current treatment options for a bilateral vocal cord palsy (tracheostomy, posterior cordotomy, arytenoidectomy) are suboptimal, with a focus primarily on a static means of airway restoration at the expense of voice production and potentially swallow safety. This paper reports on a cadaveric proof-of-concept electromagnetic system that has the potential to restore both vocal cord abduction and adduction in a dynamic manner with the aim of restoring all laryngeal functions. Using an ex vivo porcine larynx, the authors constructed a system consisting firstly of a neodymium disk magnet implanted lateral to the arytenoid and fixed in place with a suture. A cylindrical solenoid electromagnet was then sited in a window cut in the thyroid cartilage. This system was subsequently coupled to a battery and three-way switch. When the electromagnet was activated to provide a pull function, the vocal cord moved laterally by 1.9mm, resulting in a 31.4% increase in cross-sectional area of the airway. With magnetic push, the cord returned to a neutral position. It is speculated that coupling this system to a respiratory effort sensor (in a similar fashion to a hypoglossal nerve stimulator used for sleep apnoea) might enable vocal cord abduction to be triggered automatically on inspiration. There will clearly be several practical limitations to such a function-critical system in vivo. These include the need for a completely failsafe power source, the potential for interference from other electromagnetic sources and the likely incompatibility with MRI imaging techniques. Nevertheless, this article does highlight the need for continued research to optimise treatments for bilateral vocal cord palsies, and would seem to confirm that a system that can restore both vocal cord abduction and adduction represents an ideal, and achievable, solution.
The electromagnetic larynx
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