title: Trephination of the equine rostral maxillary sinus: efficacy and safety of two trephine sites.
abstract: OBJECTIVE
  To examine 2 rostral maxillary sinus (RMS) trephine sites for safety and efficacy using skulls of horses of varying age.
  
  
  METHODS
  Descriptive study.
  
  
  METHODS
  Cadaveric equine skulls (n=40).
  
  
  METHODS
  Two RMS trephination sites (rostral, caudal) were made in each skull. Radiographic projections using markers at each site were used to determine if sites were within the RMS and directly overlying a cheek tooth. Sinusotomy in 14 skulls was used to determine correlation between radiographic and anatomic location of trephine sites, and of the rostrolateral aspect of the maxillary septum. Age-related risk of trephine site being directly over a cheek tooth was determined using logistic regression.
  
  
  RESULTS
  Trephine site was within the RMS in 98% of skulls using the rostral portal and 68% using the caudal portal. The rostral site was over a cheek tooth in 18% of skulls compared with 10% using the caudal site. There was a significant negative relationship between the trephine site overlying a tooth and horse age for rostral (P=.02) and caudal (P=.03) sites. The radiographic appearance of the maxillary septum correlated to the rostrolateral portion of the septum in 12 of 14 skulls that had sinusotomy.
  
  
  CONCLUSIONS
  The rostral RMS trephine portal is more reliable than the caudal site for entering the RMS. Horses <or=5 years are at high risk for the trephine site overlying a cheek tooth and we advise that RMS trephination in this age group be performed with radiographic guidance.
authors.affiliation: Easter Bush Veterinary Centre, Division of Veterinary Clinical Science, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin, Midlothian, Scotland, EH25 9RG, UK. safia.barakzai@ed.ac.uk
authors.forename: Safia Z
authors.initials: SZ
authors.lastname: Barakzai
authors.forename: Justine
authors.initials: J
authors.lastname: Kane-Smyth
authors.forename: Joanna
authors.initials: J
authors.lastname: Lowles
authors.forename: Neil
authors.initials: N
authors.lastname: Townsend
mesh_terms: D000367:Age Factors; D000818:Animals; D002102:Cadaver; D005626:Frontal Sinus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D006736:Horses; D008443:Maxillary Sinus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery*; D010256:Paranasal Sinuses / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D012307:Risk Factors; D012449:Safety; D014207:Trephining / Q000009:adverse effects / Q000379:methods / Q000662:veterinary*