Sphenopalatine Sinus Research Articles

Computed tomographic findings of a nasal neuroendocrine neoplasm with intracranial extension in a horse

SummaryA 20‐year‐old Irish Sport Horse gelding was presented to the Royal Veterinary College Equine Referral Hospital for investigation of left‐sided epistaxis, depression and gait abnormalities of approximately 1 month duration. Physical examination and cranial nerve evaluation were unremarkable. A small amount of haemorrhagic discharge was noted from the left nostril. Gait evaluation was suggestive of proprioceptive deficits. Computed tomography (CT) identified a mass lesion within the left conchofrontal and sphenopalatine sinuses extending through the cribriform plate into the calvarium. Histopathology of the mass revealed a neuroendocrine neoplasm, for which a diagnosis of esthesioneuroblastoma was favoured. This case highlights the usefulness of CT for the identification and extent of an intracranial mass and therefore its prognosis, however, histopathological examination was necessary to confirm the diagnosis.

Vascular air embolisation and expansile sphenopalatine sinus haematoma secondary to a fracture of the rostral skull in a horse

Vascular air embolisation and expansile sphenopalatine sinus haematoma secondary to a fracture of the rostral skull in a horse

Applied anatomy of the skull in the Arabian horse: A computed tomographic, cross-sectional, volumetric and morphometric study.

This study was conducted to present a comprehensive and integrative computed tomography (CT) – anatomical cross sections atlas of skull, volumetric properties of the paranasal sinuses, and morphometric values for surface cranial nerves in the adult Arabian horse. Ten heads of Arabian horse breed were used. The different structures in the nasal, oral and cranial cavities were determined and labelled in the anatomical sections and their corresponding CT scan images. Three paranasal sinuses namely maxillary, conchofrontal and sphenopalatine sinuses were identified in the CT scan images. The caudal maxillary sinus was the largest paranasal sinus with 131.93 ± 7.67 cm3 volume and the sphenopalatine sinus 13.3 ± 1.2 cm3 volume was the smallest one. The infraorbital foramen was located 4.16 ± 0.18 cm and 4.70 ± 0.35 cm far away from the most rostral point of the facial crest and alveolar root, respectively. The mean distance between the mental foramen and most lateral incisive tooth was 3.12 ± 0.29 cm. These results including present CT scan‐cross‐sectional atlas, paranasal sinuses volume and morphometric properties would be applicable in practice for more precise diagnosis of head lesions and blocking the surface terminal branches of the cranial nerves during surgical operations in this valuable horse's breed.

Volumetric measurements of paranasal sinuses and examination of sinonasal communication in healthy Shetland ponies: anatomical and morphometric characteristics using computed tomography

BackgroundDespite clinical importance and frequent occurrence of sinus disease, little is known about the size of paranasal sinuses and their communication in ponies and small horses. To examine the shape and volume of the paranasal sinuses and evaluate the sinonasal communication, three-dimensional (3D) reconstructions of computed tomography (CT) datasets of 12 healthy adult Shetland ponies were performed and analysed. Linear measurements of head length and width were taken. Using semi-automatic segmentation, 3D-models of all sinus compartments were created. Volumetric measurement of the seven sinus compartments were conducted and statistical analysis was performed. Sinus volumes were compared between the left and right sinuses and the relation to age and head size was evaluated.ResultsStructure and shape of the paranasal sinus system in Shetland ponies was similar to that of large horses. All seven sinus compartments on each side of the head were identified (rostral maxillary sinus, ventral conchal sinus, caudal maxillary sinus, dorsal conchal sinus, middle conchal sinus, frontal sinus, sphenopalatine sinus). The existence of a bilateral cranial and a caudal system formed by a maxillary septum was visible in all 12 individuals. The volumetric sizes of the left and right sinuses did not differ significantly (p > 0.05). A positive correlation between the size of the paranasal sinuses and the head length was shown. A relation between sinus volumes and age could not be proved in adult ponies aged > six years. Communication between single sinus compartments was identified. Furthermore, communication with the nasal cavity over the nasomaxillary aperture (Apertura nasomaxillaris) and a common sinonasal channel (Canalis sinunasalis communis) as well as its splitting up into a rostral and a caudolateral channel could be seen. Examination of the sinonasal communication was challenging and only a descriptive evaluation was possible.ConclusionsOur findings concerning the size, shape and volumetric dimensions of Shetland pony CT images could help improve CT interpretation of abnormal clinical cases as well as aiding clinicians to develop and select appropriate instruments for medical inspection and treatments.

Computed Tomographic Assessment of Individual Paranasal Sinus Compartment and Nasal Conchal Bulla Involvement in 300 Cases of Equine Sinonasal Disease.

Background: Computed tomographic (CT) imaging has allowed new anatomical studies and detailed clinical imaging of the complex, overlapping equine sinonasal structures. Despite the widespread use of CT, no study has specifically identified which compartments are most commonly affected with sinus disorders. CT has also shown the presence of intercurrent, ipsilateral nasal disorders, especially infection of the nasal conchal bullae (NCB) in many cases of sinus disease, but the frequency of intercurrent NCB infections has not been reported.Objectives: To identify which sinus compartments are most commonly affected in horses with clinical sinus disorders and to record the prevalence of NCB involvement in such cases.Study Design: Retrospective examination of CT images of horses with confirmed unilateral sinus disease.Methods: The CT images of 300 horses, from three different equine hospitals with clinically confirmed sinus disease [mainly dental (53%) and primary sinusitis (25.7%)] were retrospectively examined to determine which sinus compartments and NCBs were affected.Results: The rostral, more dependent sinus compartments were most commonly involved, i.e., the rostral maxillary sinus in 284/300 (94.7% affected) and the ventral conchal sinus (87% affected). The caudal maxillary sinus (65.3%), dorsal conchal sinus (52.7%), frontal sinus (26%), ethmoidal sinus (32%) and sphenopalatine sinus (28.7%) were less commonly affected. There was infection or destruction of the ipsilateral NCBs in 56% of horses with sinus disorders, including the ventral NCBs in 42.3%, dorsal NCBs in 29% and both NCBs in 18% of cases.Main Limitations: The horses with sinonasal disease that underwent head CT imaging include more problematic cases and horses of high value, rather than the general horse population.Conclusions: The more dependant (i.e., the RMS and VCS) sinus compartments are most commonly involved in sinus disorders, with the RMS involved in nearly every case. The more dorsally located sinuses (i.e., caudal group) are less commonly involved. Many horses with sinus disease also have disorders of their nasal conchal bullae and so the term sinonasal disease seems appropriate for these disorders.

Best way to assess the sphenopalatine sinus

The sphenopalatine (SP) sinuses communicate with the caudal maxillary sinuses and are in close apposition to the ethmoturbinates and cranium. Multiple pathologies of the SP sinus are reported, but pathology in this location can be challenging to diagnose. Radiographs of the region are difficult to interpret due to the superimposition of multiple structures. Recently, computed tomography (CT) has become preferable for detailed diagnosis of sinus disorders. Surgical access to the SP sinuses is limited and therefore accurate diagnosis can influence treatment options and improve outcomes.

Radiographic, computed tomographic and surgical anatomy of the equine sphenopalatine sinus in normal and diseased horses.

Knowledge of imaging anatomy, surgical anatomy and disorders affecting the sphenopalatine sinus are currently lacking. To describe the computed tomographic (CT) and surgical anatomy of the sphenopalatine sinus and diagnosis, treatment and outcome in clinical cases with sphenopalatine sinus disease. Cadaver observational study and retrospective case series. The sphenopalatine sinuses of 10 normal cadaver heads were examined with digital radiography, CT and sinoscopic examination prior to anatomical sectioning. Sphenopalatine sinus anatomy was described and compared between cadaver specimens across the imaging modalities. Medical records (January 2004-2014) of cases diagnosed with sphenopalatine sinus disease were reviewed. The anatomy of the sphenopalatine sinus was variable. The borders of the sphenopalatine sinus were not identifiable on plain radiographs, whereas CT provided useful anatomical information. The palatine portion of the sphenopalatine sinus was consistently accessible sinoscopically and the sphenoidal portion was accessible in 6/10 cadaver heads. Fourteen cases of sphenopalatine sinus disease were identified, presenting with one or more clinical signs of exophthalmos, blindness, unilateral epistaxis or unilateral nasal discharge. Diagnoses included neoplasia (7), progressive ethmoidal haematoma (4), sinus cyst (2) and empyema (1). Computed tomography provided diagnostic information but could not differentiate the nature of soft tissue masses. Standing sinoscopic access to the palatine portion of the sphenopalatine sinus was possible for evaluation, biopsy and resection of abnormal soft tissues. Surgical access to the sphenoidal portion was limited. Eight horses were alive at 1 year after diagnosis, with a worse outcome associated with CT evidence of bone loss and a diagnosis of neoplasia. Sphenopalatine sinus disease should be considered a rare cause of the clinical signs described. Knowledge of the anatomical variation of the sphenopalatine sinus is vital for interpreting CT images. A combination of CT and sinoscopy provides the most comprehensive approach for diagnosis and treatment of sphenopalatine sinus disease.

Ethmoidal Infection with Aspergillus spp. in 3 Horses: Successful Treatment by Transendoscopic Removal of Mycotic Plaques Alone or in Combination with Systemic Itraconazole

Reasons for performing studyEthmoidal infection with Aspergillus spp. is rarely reported in horses. Three horses suffering from unilateral infection with Aspergillus spp. of the ethmoid with varying underlying conditions are described.Study designCase series.MethodsDiagnosis was made by endoscopy of the ethmoid (presence of white mycotic plaques on a layer of thick yellow mucus) and confirmed by fungal culture (A. fumigatus) and/or cytology. Clinical details and outcome were obtained from the medical records and by contacting owners.ResultsHorse 1 and 2 had a progressive ethmoid haematoma (PEH) and had been treated for over 5 months with repeated formalin injections (one horse after initial surgical debulking of the PEH that also invaded the maxillary and sphenopalatine sinuses) before the infection with Aspergillus was diagnosed. The third horse, presented with poor performance and nasal discharge, had congenitally abnormal anatomy of the right dorsal nasal passage and right ethmoids. In the 2 horses with PEH the mycotic plaques were removed transendoscopically successfully. After 6 weeks the infection was no longer present at endoscopy in both horses (follow‐up endoscopy: Horse 1 no relapse >16 months and Horse 2 no relapse >7 months). In the third horse, it was not possible to remove all mycotic plaques, therefore systemic treatment with itraconazole (3 mg/kg bwt q. 12 h for 8 weeks orally) was started. After 8 weeks, the clinical signs had resolved and endoscopy showed that the Aspergillus infection had cleared (follow‐up: no relapse >14 months). No side effects were seen with systemic itraconazole treatment.ConclusionsIn horses with underlying ethmoidal conditions, secondary infection with Aspergillus spp. may occur. Transendoscopic removal of the mycotic plaques alone may be successful and if this approach is not feasible or unsuccessful, systemic treatment with itraconazole can be considered.Ethical animal research: Research ethics committee oversight not currently required by this conference: retrospective study of clinical records. Owners gave informed consent for their horses' inclusion in the study. Source of funding: Utrecht University. Competing interests: None declared.

The role of head computed tomography in equine practice

SummaryThis retrospective study describes the computed tomography (CT) findings in 59 horses presented with diseases of the head over 8 years that underwent CT examination of this region, including dental or sinonasal diseases (Group A) (n = 42), osseous and/or articular diseases (Group B) (n = 11) and soft tissue diseases (Group C) (n = 6). For Group A, radiographic and CT findings comparison was possible. Computed tomography had higher sensitivity (100%) and specificity (96.7%) than radiography in diagnosing dental disease. Compared to CT, radiographic identification of sinus involvement was less sensitive, particularly for ventral conchal and sphenopalatine sinuses and presented an overall sensitivity of 43.5 and 16.7%, respectively. In Group B CT allowed identification of a higher number of bone fragments and fractures in the maxillary, lacrimal, sphenoidal, temporal and zygomatic bones not identified radiographically. Accurate identification of CT changes in the temporomandibular joint and temporohyoid articulation was also possible. Group C included both intra‐ and extra‐cranial disease, retrobulbar masses being the most representative pathology (n = 3). In this group, CT was considered the gold standard for detection of periorbital diseases. We conclude that CT is an imaging technique with high diagnostic value for evaluating the equine head, yielding additional information over multiple radiographic views, which may alter the outcome of the case. Additionally, this paper reports several conditions not previously described using CT.

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

BackgroundSinusitis 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.ResultsThree-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.ConclusionsUnder 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.

Computed tomography and sectional anatomy of the head cavities in donkey (Equus asinus)

The purpose of this study was to describe the computed tomographic (CT) anatomy of normal donkey head cavities to be used as a basis for interpretation of CT images of donkey. Six adult donkeys' heads of undetermined sex were used in this study. The donkey heads were divided into three regions-nasal, orbital, and cranial-to show the morphology of the following cavities: nasal cavity, paranasal sinuses, orbital cavity, oral cavity, pharyngeal cavity, especially the guttural pouch, cranial cavity and temporomandibular joint. The donkey head had six pairs of sinuses: three paranasal (the frontal, maxillary and sphenopalatine sinuses) and three nasal (dorsal, middle and ventral conchal) sinuses. The maxillary sinus was subdivided into rostral and caudal compartments by a thin incomplete bony septum that was identified and labeled according to cheek teeth landmarks. The topographic description and relationship between the nasal, oral, orbital, cranial, temporomandibular joint, pharyngeal cavities and paranasal sinuses were demonstrated. The articular disc, articular surface and joint capsule of the temporomandibular joint were indicated easily in our CT and cross sectional images.

USING SEMI‐AUTOMATED SEGMENTATION OF COMPUTED TOMOGRAPHY DATASETS FOR THREE‐DIMENSIONAL VISUALIZATION AND VOLUME MEASUREMENTS OF EQUINE PARANASAL SINUSES

The system of the paranasal sinuses morphologically represents one of the most complex parts of the equine body. A clear understanding of spatial relationships is needed for correct diagnosis and treatment. The purpose of this study was to describe the anatomy and volume of equine paranasal sinuses using three-dimensional (3D) reformatted renderings of computed tomography (CT) slices. Heads of 18 cadaver horses, aged 2-25 years, were analyzed by the use of separate semi-automated segmentation of the following bilateral paranasal sinus compartments: rostral maxillary sinus (Sinus maxillaris rostralis), ventral conchal sinus (Sinus conchae ventralis), caudal maxillary sinus (Sinus maxillaris caudalis), dorsal conchal sinus (Sinus conchae dorsalis), frontal sinus (Sinus frontalis), sphenopalatine sinus (Sinus sphenopalatinus), and middle conchal sinus (Sinus conchae mediae). Reconstructed structures were displayed separately, grouped, or altogether as transparent or solid elements to visualize individual paranasal sinus morphology. The paranasal sinuses appeared to be divided into two systems by the maxillary septum (Septum sinuum maxillarium). The first or rostral system included the rostral maxillary and ventral conchal sinus. The second or caudal system included the caudal maxillary, dorsal conchal, frontal, sphenopalatine, and middle conchal sinuses. These two systems overlapped and were interlocked due to the oblique orientation of the maxillary septum. Total volumes of the paranasal sinuses ranged from 911.50 to 1502.00 ml (mean ± SD, 1151.00 ± 186.30 ml). 3D renderings of equine paranasal sinuses by use of semi-automated segmentation of CT-datasets improved understanding of this anatomically challenging region.

Results of computed tomography in horses with ethmoid hematoma: 16 cases (1993–2005)

To determine whether CT provides unique information about the treatment or prognosis for horses with ethmoid hematoma (EH). Retrospective case series. 16 horses with EH. Horses with a diagnosis of EH that had undergone a diagnostic CT study were included. Clinical features, treatment, outcome, radiographic and CT images, and histologic specimens were reviewed. CT provided new diagnostic information that affected treatment in 10 of 16 horses. Bilateral disease occurred in 8 of 16 horses and was undetected in 5 horses prior to CT. Paranasal sinus involvement occurred in all horses, but was incompletely defined prior to CT in 7 of 16 horses. The sphenopalatine sinus was affected in 6 of 16 horses as detected on CT; 4 of 6 of these were bilaterally affected. Medical and surgical treatments were performed. Six of 10 horses had a successful outcome, with recurrence in 4 of 10. Five of 6 patients in which treatment addressed all lesion sites identified by CT had a successful outcome. Bilateral disease did not confer a poor prognosis when all affected sites were treated. Sphenopalatine sinus involvement may have been associated with recurrence. CT provided anatomic information that may facilitate effective treatment of horses with EH, particularly in patients with bilateral disease and paranasal sinus involvement. Computed tomography is recommended for patients in which the lesion cannot be viewed endoscopically, when sinus involvement or multifocal disease are suspected, or when the lesion has been unresponsive to treatment.

The postnatal development of the paranasal sinuses in the horse

In horses, paranasal sinuses form an elaborate system of interconnected cavities in the viscero‐and neurocranium. These sinuses are clinically significant, because sinus infections can affect vital structures, such as the optic nerve. To treat sinus infections, bony landmarks are used, such as the nasoincisive notch, for locating and accessing the sinuses via trepanation. In order to better understand the topographic and age‐related changes of the paranasal sinuses in relation to bony landmarks, we evaluated the postnatal development of the sinuses in horses, ages ranging from 3 days to 31 years old, via 3D reconstruction based on CT images. This non‐invasive method of virtual dissection avoids artifacts, such as those incurred due to incomplete filling of corrosion casts, because the paranasal sinuses can be segmented and reconstructed in their entirety. The reconstructed dimensions of the various paranasal sinuses are correlated to the growth of the cranium, as well as to the age of the horse, to determine whether there are size‐or age‐specific topographic relationships. For example, in the 6 years between 3‐year and 9‐year old horses, the volume of the caudal maxillary sinus increases 5 times, whereas the volume of the sphenopalatine sinus increases only 3 times and the volume of the neurocranial cavity increases only about 10 %. This study may also contribute to the understanding of NO production in the sinuses.

COMPUTED TOMOGRAPHIC APPEARANCE OF EQUINE SINONASAL NEOPLASIA

The computed tomography (CT) features of tumors involving the nasal cavity and/or paranasal sinuses of 15 horses were reviewed. The 15 tumors included five neuroendocrine tumors/neuroblastomas, two undifferentiated carcinomas, two myxosarcomas, and one each of nasal adenocarcinoma, hemangiosarcoma, chondroblastic osteosarcoma, anaplastic sarcoma, myxoma, and ossifying fibroma. All tumors except the ossifying fibroma were iso- or hypoattenuating relative to masseter muscle. Thirteen of the fifteen tumors exhibited moderate or marked osteolysis of adjacent cortical bone and 14/15 were characterized by destructive changes of the nasal turbinates, nasal septum, and/or infraorbital canal. Ten horses had moderate or marked involvement of the cribriform plate and six had clear intracranial extension of the mass. CT features were compared to radiographic findings for 10 horses. A mass was observed in 10/10 radiographic studies and mass within the caudal maxillary sinus (7/8) and rostral maxillary sinus (6/7) was identified correctly in most horses. The radiographs were least sensitive for identifying masses within the sphenopalatine sinus (0/5), cranium (0/4), and retrobulbar space (1/7) compared to CT. The radiographs also underestimated potential features of malignancy, such as severity of osteolysis or osseous production. While radiographs are a useful screening tool for identification of sinonasal masses, CT provides greater information regarding mass extent, features of malignancy, and important prognostic indicators.

Nasal and Paranasal Sinuses of the Donkey: Gross anatomy and Computed Tomography

The current work aimed to describe the anatomical findings of the nasal and paranasal sinuses of the donkey by gross anatomical observation of the skull and cadaver head through cross-sections, sagittal sections and computed tomography (CT) imaging. Seven adult donkeys and ten skulls were used in this study. The donkey head had six pairs of sinuses, three paranasal; the frontal, maxillary and sphenopalatine sinuses and three nasal; dorsal, middle and ventral conchal sinuses. The left and right frontal sinuses were completely divided by a thick bony septum. Each frontal sinus is united rostrally with the dorsal conchal sinus forming concho-frontal sinus that communicated directly with the caudal maxillary sinus by fron- tomaxillary opening. The maxillary sinus is divided into rostral and caudal compartments by a thin incomplete bony septum. The caudal maxillary sinus is divided into medial and lateral compartments by the infraorbital canal that run longitudinally through it. The rostral maxillary sinus is communicated with the ventral conchal sinus through the conchomaxillary opening, while the rostral and caudal maxillary sinuses are connected with the middle nasal meatus via the slit-like nasomaxillary opening. Approach to the interior of the frontal, rostral and caudal maxillary was deter- mined. The location, size, and shape of the paranasal sinuses openings (conchomaxillary, nasomaxillary, frontomaxillary and sphenopalatinal openings and opening of middle conchal sinus into caudal maxillary sinus) communicated the sinuses with the nasal cavity were identified in CT. The frontomaxillary opening was the largest opening, while the nasomaxillary opening was the nar- rowest one. CT images with cross-sections provided clear, unobstructed images on the paranasal structures, while paranasal lining was unclear in CT images because of its thin layer.

Posterior segment diseases

Diseases of the vitreous, fundus and optic nerve are described and illustrated according to their ophthalmological appearance. Vitreal alterations are commonly of developmental, degenerative, age related, traumatic or inflammatory origin and of minor clinical relevance. In contrast, those affecting the fundus, may be accompanied by visual deficits or blindness. Fundic lesions of inflammatory (multifocal or peripapillary chorioretinitis, haemorrhage, retinal detachment) and traumatic origin have to be differentiated from congenital (congenital stationary night blindness, colobomatous defects, retinal dysplasia), degenerative (cystic retinal degeneration), metabolic (equine motor neuron disease), neoplastic and age related alterations (senile retinopathy). Inflammation (acute neurochorioretinitis) and ischaemia (ischaemic neuro-chorioretinopathy) involving the optic nerve will lead to blindness. The optic disc can be aplastic/hypoplastic or excavated due to coloboma or glaucoma, affected by ligation of the carotid and palatine arteries. Optic disc masses may arise due to inflammation, severe systemic haemorrhage, neoplasia or trauma. Lesions of the retrobulbar optic nerve can be caused by Borna virus infection, fungal granuloma, toxic insult, halicephalobiasis, trauma, severe blood loss and infection of the sphenopalatine sinus.

Standing surgical removal of a progressive ethmoidal haematoma invading the sphenopalatine sinuses in a horse

SummaryProgressive ethmoidal haematomas (PEH) have been described as encapsulated, gradually expanding masses, which typically develop from the ethmoidal turbinates. Plain skull radiographs have been shown to be useful in determining the extent of the soft tissue mass if it invades the paranasal sinuses; however, where it is available, computed tomography (CT) offers substantial advantages in the evaluation of the full extent of a PEH. This Case Report describes a PEH invading into the sphenopalatine sinus, and the use of CT in accurately identifying the extent of the lesion.

Blindness, optic atrophy and sinusitis in the horse

The case histories described each presented with a visual deficit, varying from permanent total blindness with ophthalmoscopic evidence of optic atrophy to variable and transient visual disturbances, including occasional blindness, but with absence of ophthalmoscopic or any other ocular abnormality. Three horses of widely different age and type, but all with an original history of upper respiratory tract infection. All three cases were examined by a specialist veterinary ophthalmologist. In addition, magnetic resonance imaging (MRI) and, where possible, postmortem and histopathological examinations were performed. The common factor to all three cases proved to be infection of the spheno-palatine sinuses with subsequent distension and compression of adjacent optic nerve(s) and optic chiasm. Specialist veterinary ophthalmological examination proved of extremely limited value. The importance of MRI (and CT) scans for accurate diagnosis, and therefore possible successful treatment, is emphasized. Our cases were compared with similar cases in man, where visual disturbances due to spheno-palatine sinus involvement are recognized, but rare, in similar situation.

Clinical anatomy of the equine sphenopalatine sinus.

Disorders of the equine sphenopalatine sinus, including empyema and neoplasia, have been reported to cause damage to cranial nerves II and V. However, the clinical anatomy of these sinuses is not well described in horses. To examine the anatomy of the sphenopalatine sinuses in a range of equidae and, in particular, to examine the relationship of these sinuses to adjacent major nerves and vessels. The anatomy of the sphenoidal and palatine paranasal sinuses was examined in 16 equidae, primarily using transverse skull sections. Relevant structures were documented and photographed. There was much variation between individual horses in sphenopalatine sinus anatomy. The sphenoidal sinuses were small in young horses and appeared to become larger and more complex with age. Variation was present in the extent that the sphenopalatine sinus extended into the basisphenoid bone. The septum dividing left and right sphenoidal sinuses was frequently not midline, but was intact in all cases. The sphenoidal and palatine sinuses communicated in most horses. In such cases, what could accurately be termed the (combined) sphenopalatine sinuses usually drained directly into the caudal maxillary sinuses. Additionally, in 5 out of 16 cases, some compartments of the sphenoidal sinus also drained into the ethmoidal sinus. The dorsal and lateral walls of the sphenoidal sinus were very thin and directly adjacent to cranial nerves II, III, IV, V and VI and major blood vessels. The equine sphenoidal and palatine sinuses are very variable in their anatomy, but are always in close proximity to multiple cranial nerves and major blood vessels. Many cranial nerves and blood vessels could be damaged with disorders involving the sphenopalatine sinus, potentially causing major and variable neurological syndromes, haemorrhage and extension of sepsis.