Learning Objectives 5 Know the common clinical presentations for otitis, sinusitis, and mastoiditis. 5 Identify common and uncommon microbiologic causes of otitis, sinusitis, and mastoiditis. 5 Understand the distinguishing characteristics for acute, recurrent, and chronic clinical courses of each disease. 5 List the important risk factors for developing severe infections of the paranasal sinuses. 5 Outline the approach to diagnosis, including signs and symptoms that warrant laboratory or imaging evaluations. 5 Describe the indications for medical and surgical treatment of otitis, sinusitis, and mastoiditis. 4.1 Otitis 4.1.1 Introduction The term "otitis" encompasses pathology of both the middle and outer ear. It is generally divided into two categoriesotitis media and otitis externa. Otitis media can present either as an acute infectious process of the middle ear (acute otitis media) or as a serous noninfectious process (otitis media with effusion). Otitis externa is an infectious inflammatory condition of the external auditory canal (EAC). Approaches to the diagnosis and treatment of acute otitis media have evolved over the last several decades as new immunizations, and more antibiotic choices have become available. 4.2 Definitions Otitis media with effusion (OME)-A collection of serous fluid in the middle ear space without signs of acute inflammation. OME is not an infectious process. Chronic otitis media with effusion (COME)-A collection of serous fluid in the middle ear space that persists for more than 3 months Acute otitis media (AOM)-An acute infection of the middle ear with signs and symptoms of acute inflammation. An effusion is also present. Recurrent AOM-Three or more episodes of AOM in a 6-month period or 4 or more episodes of AOM in a 12-month period Otorrhea-The presence of a discharge from the ear Chronic suppurative otitis media (CSOM)-The presence of a purulent middle ear effusion associated with otorrhea, secondary to chronic tympanic membrane perforation, for more than 6 weeks in the setting of antibiotic treatment Otitis externa (OE)-An infection of the external auditory canal 4.3 Basic Concepts 4.3.1 Otitis Externa. Fig. 4.1 Normal tympanic membrane.