Diagnostic Imaging of Diseases Affecting the Guttural Pouch

SIMPLE SUMMARY: The guttural pouch of the horse is a diverticulum of the auditory tube and has a complex anatomical structure. Disease of the guttural pouch can lead to neurological signs and hemorrhage due to its close relation to major vessels and some cranial nerves. Endoscopy allows direct visualization of the pouch and is considered to be the gold standard for its evaluation. Nevertheless, diagnostic imaging can bring useful additional information and this review article describes the value of each technique and the main imaging findings to be expected in the diagnosis of guttural pouch disease. ABSTRACT: The most common diseases of the guttural pouch are empyema, tympany, mycosis and temporohyoid osteoarthropathy. The challenge in diagnosis of guttural pouch diseases lies in the complex anatomy of the guttural pouch and adjacent associated structures. Diagnostic imaging is a good complement to endoscopy for the diagnosis of some guttural pouch diseases, especially to make a full assessment of the lesions involving the pouch and surrounding structures. This review article describes the value of each diagnostic imaging technique in the diagnosis of guttural pouch disease and the corresponding imaging findings. Radiography is generally used as the first line to complement endoscopic findings, and can give useful additional information although it is limited by superimposition. Ultrasonographic examination of the guttural pouch is of limited value due to the presence of gas in the guttural pouch but can eventually be used to detect fluid within the pouch or can help to evaluate the soft tissues located lateral and ventral to the guttural pouch. Cross-sectional imaging, especially CT, is increasingly available and appears to be the best technique to fully assess the surrounding soft tissues and to precisely identify lesions of the temporohyoid apparatus, temporal bone and skull base that are associated with guttural pouch disease.