The sinonasal communication in the horse: examinations using computerized three-dimensional reformatted renderings of computed-tomography datasets

Brinkschulte et al. BMC Veterinary Research 2014, 10:72 http://www.biomedcentral.com/1746-6148/10/72 RESEARCH ARTICLE Open Access The sinonasal communication in the horse: examinations using computerized three-dimensional reformatted renderings of computed-tomography datasets Markus Brinkschulte1*, Astrid Bienert-Zeit1, Matthias Lüpke2, Maren Hellige1, Bernhard Ohnesorge1† and Carsten Staszyk3† Abstract Background: Sinusitis is a common disease in the horse. In human medicine it is described, that obstruction of the sinonasal communication plays a major role in the development of sinusitis. To get spatial sense of the equine specific communication ways between the nasal cavity and the paranasal sinuses, heads of 19 horses, aged 2 to 26 years, were analyzed using three-dimensional (3D) reformatted renderings of CT-datasets. Three-dimensional models were generated following manual and semi-automated segmentation. Before segmentation, the two-dimensional (2D) CT-images were verified against corresponding frozen sections of cadaveric heads. Results: Three-dimensional analysis of the paranasal sinuses showed the bilateral existence of seven sinus compartments: rostral maxillary sinus, ventral conchal sinus, caudal maxillary sinus, dorsal conchal sinus, frontal sinus, sphenopalatine sinus and middle conchal sinus. The maxillary septum divides these seven compartments into two sinus systems: a rostral paranasal sinus system composed of the rostral maxillary sinus and the ventral conchal sinus and a caudal paranasal sinus system which comprises all other sinuses. The generated 3D models revealed a typically configuration of the sinonasal communication ways. The sinonasal communication started within the middle nasal meatus at the nasomaxillary aperture (Apertura nasomaxillaris), which opens in a common sinonasal channel (Canalis sinunasalis communis). This common sinonasal channel ramifies into a rostral sinonasal channel (Canalis sinunasalis rostralis) and a caudo-lateral sinonasal channel (Canalis sinunasalis caudalis). The rostral sinonasal channel ventilated the rostral paranasal sinus system, the caudo-lateral sinonasal channel opened into the caudal paranasal sinus system. The rostral sinonasal channel was connected to the rostral paranasal sinuses in various ways. Whereas, the caudal channel showed less anatomical variations and was in all cases connected to the caudal maxillary sinus. Volumetric measurements of the sinonasal channels showed no statistically significant differences (P < 0.05) between the right and left side of the head. Conclusions: Under physiologic conditions both paranasal sinus systems are connected to the nasal cavity by equine specific sinonasal channels. To resolve sinus disease it is aimed to maintain or even reconstruct the normal anatomy of the sinonasal communication by surgical intervention. Therefore, the presented 3D analyses may provide a useful basis. Keywords: Horse, Computed tomography, Nasomaxillary aperture, Apertura nasomaxillaris, Upper airway, Sinonasal channel system, Paranasal sinuses * Correspondence: † Equal contributors 1 Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, Hannover D-30559, Germany Full list of author information is available at the end of the article © 2014 Brinkschulte et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. Brinkschulte et al. BMC Veterinary Research 2014, 10:72 http://www.biomedcentral.com/1746-6148/10/72 Background Diseases of the equine paranasal sinuses are of special interest in equine medicine, since sinusitis is a common and widespread disease [1]. The detailed anatomy of the equine paranasal sinuses and the nasal cavity is and has been extremely challenging. However, detailed knowledge of these structures is essential for successful diagnostic and surgical intervention [2-4]. In human medicine, drainage is the most important factor for establishing physiologic conditions of the paranasal sinuses [5]. Furthermore, obstructions of the sinonasal pathways are suspected to be a primary factor in developing sinusitis in man [2]. The development of the equine paranasal sinuses starts during organogenesis. At this time the mucosa of the middle nasal meatus protrudes into the diploe of the maxillary bone; through which a two-parted anlage of the maxillary sinuses (separating into the rostral and caudal maxillary sinus) is developed [6]. This embryological concept explains the anatomical finding that all equine paranasal sinuses are connected to the middle nasal meatus via a nasomaxillary aperture (Apertura nasomaxillaris) [7,8]. The nasomaxillary aperture is described as a common entrance into the rostral and caudal maxillary sinus [6,8-12]. The rostral maxillary sinus (Sinus maxillaris rostralis, SMR) is connected to the ventral conchal sinus (Sinus conchae ventralis, SCV) establishing the rostral paranasal sinus system. The caudal maxillary sinus (Sinus maxillaris caudalis, SMC) is the central compartment of the caudal paranasal sinus system and opens into the dorsal conchal sinus (Sinus conchae dorsalis, SCD), the middle conchal sinus (Sinus conchae mediae, SCM), the frontal sinus (Sinus frontalis, SF) and the sphenopalatine sinus (Sinus sphenopalatinus, SSP). Because of continuous communication between the frontal sinus and dorsal conchal sinus a compound term for both compartments is conchofrontal sinus (Sinus conchofrontalis). But for superior visualisations in the current study both compartments are separated from each other and visualized with two different colours. Remarkably, the rostral and caudal paranasal sinus systems are completely separated by the maxillary septum [13]. Thus, the airways between the nasomaxillary aperture and the two sinus systems should be divided into at least two separated branches, one ventilating the rostral paranasal sinus system and another ventilating the caudal paranasal sinus system. However, the courses and dimensions of the connecting airways between the nasomaxillary aperture and the maxillary sinuses are not fully understood so far. Such detailed knowledge and a spatial understanding of the communication ways between the nasal cavity and paranasal sinuses is essential for establishing new transnasal diagnostic and surgical procedures that maintain or reconstruct normal anatomy of diseased sinonasal pathways. Page 2 of 10 Therefore the aim of this study was to examine the spatial configuration and the volumetric expansion of the sinonasal communication in non-diseased horses. Further, anatomical terms are suggested to establish a precise and self-explanatory nomenclature for the complex anatomy of the equine sinonasal pathways. Methods Nineteen eq (...truncated)