Adaptations to Oral and Pharyngeal Swallowing Function Induced by Injury to the Mylohyoid Muscle
- PDF / 1,006,878 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 36 Downloads / 198 Views
ORIGINAL ARTICLE
Adaptations to Oral and Pharyngeal Swallowing Function Induced by Injury to the Mylohyoid Muscle Suzanne N. King1,4 · Brittany Fletcher1 · Bradley Kimbel1 · Nicholas Bonomo2 · Teresa Pitts3,4 Received: 20 March 2019 / Accepted: 18 December 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Muscle injury is a frequent side effect of radiation treatment for head and neck cancer. To understand the pathophysiology of injury-related dysfunction, we investigated the effects of a single muscle injury to the mylohyoid on oropharyngeal swallowing function in the rat. The mylohyoid protects the airway from food/liquid via hyolaryngeal elevation and plays an active role during both oral and pharyngeal swallowing. We hypothesized (1) that fibrosis to the mylohyoid alters swallowing bolus flow and licking patterns and (2) that injury to the mylohyoid changes normal activity of submental, laryngeal, and pharyngeal muscles during swallowing. A chilled cryoprobe was applied to the rat mylohyoid muscle to create a localized injury. One and two weeks after injury, swallowing bolus transit was assessed via videofluoroscopy and licking behavior via an electrical lick sensor. The motor activity of five swallow-related muscles was analyzed immediately after injury using electromyography (EMG). Comparisons were made pre- and post-injury. Fibrosis was confirmed in the mylohyoid at 2 weeks after injury by measuring collagen content. One week after injury, bolus size decreased, swallowing rate reduced, and licking patterns were altered. Immediately post-injury, there was a significant depression in mylohyoid and thyropharyngeus EMG amplitudes during swallowing. Our results demonstrated that injury to the mylohyoid is sufficient to cause changes in deglutition. These disruptions in oral and pharyngeal swallowing were detected prior to long-term fibrotic changes, including delays in tongue movement, alterations in bolus flow, and changes in sensorimotor function. Therefore, injuring a single important swallowing muscle can have dramatic clinical effects. Keywords Muscle injury · Mylohyoid · Fibrosis · Swallow · Lick · Cryoinjury · Deglutition · Deglutition disorders
* Suzanne N. King [email protected] Brittany Fletcher [email protected] Bradley Kimbel [email protected] Nicholas Bonomo [email protected] Teresa Pitts [email protected] 1
Department of Otolaryngology – Head and Neck Surgery and Communicative Disorders, University of Louisville, Louisville, KY, USA
2
School of Medicine, University of Louisville, Louisville, KY, USA
3
Department of Neurological Surgery, University of Louisville, Louisville, KY, USA
4
Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY 40207, USA
Introduction Dysphagia is a major complication of radiation treatment for head and neck cancer. Radiation-associated dysphagia includes reductions in base of tongue retraction, hyolaryngeal displacement, and movement of ph
Data Loading...
