Effect of head position on radiographic assessment of laryngeal tie-forward procedure in horses.
OBJECTIVE
To assess the effect of head position on relative position of the larynx and hyoid apparatus in horses with palatal dysfunction, and to define a standard position for radiographic assessment of laryngeal tie-forward.


METHODS
Prospective clinical study.


METHODS
Adult horses (n=9) with palatal dysfunction.


METHODS
Left lateral radiographs of the larynx were obtained pre and postoperatively for 3 different head positions (flexed=90 degrees ; neutral=100 degrees ; extended=115 degrees ). Distance between thyrohyoid bone and thyroid cartilage was measured. Data were analyzed to investigate differences between head positions, and to compare differences between pre- and postoperative measurements.


RESULTS
Head position had a significant effect on relative position of the larynx and hyoid apparatus preoperatively. There was no significant difference in postoperative measurements of the 3 head positions. A significant difference between pre- and postoperative measurements was found with the head in the neutral or extended position whereas there were no significant differences between pre- and postoperative measurements using the flexed position.


CONCLUSIONS
Head position affects the relationship between the hyoid apparatus and larynx preoperatively, with greatest distance occurring when the head is extended. In a flexed position, it is not possible to ascertain whether laryngeal position has changed postoperatively.


CONCLUSIONS
A standardized head position is necessary when assessing the laryngeal tie-forward procedure radiographically. An extended head position is most useful for this assessment.
McCluskie
Laura K
LK
Department of Clinical Veterinary Science, University of Bristol, Bristol, UK. Laura.McCluskie@bris.ac.uk
Franklin
Samantha H
SH
Lane
J Geoffrey
JG
Tremaine
W Henry
WH
Allen
Katherine J
KJ
D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D006736:Horses; D007830:Larynx / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D010160:Palate, Soft / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000601:surgery; D010805:Physical Conditioning, Animal / Q000502:physiology; D011182:Postoperative Care / Q000662:veterinary; D011187:Posture / Q000502:physiology; D011300:Preoperative Care / Q000662:veterinary; D011446:Prospective Studies; D011859:Radiography; D015619:Respiratory System Abnormalities / Q000000981:diagnostic imaging / Q000601:surgery / Q000662:veterinary*