Sinusitis - Introduction

Introduction

The skull contains a number of air-filled spaces called sinuses. They perform the following functions:

• Reduce the weight of the skull
• Provide insulation for the skull
• Provide resonance for the voice

Four pairs of sinuses, known as the paranasal air sinuses, connect to the nasal passages (the two airways running through the nose):

• Frontal sinuses (behind the forehead)
• Maxillary sinuses (behind the cheekbones)
• Ethmoid sinuses (between the eyes)
• Sphenoid sinuses (behind the eyes)

Sinusitis occurs in these four areas.

Sinusitis

Healthy sinuses are sterile and contain no bacteria. (The nasal passage, on the other hand, normally contains many bacteria.)

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The Disease Process. Sinusitis is an infection that occurs if obstruction or congestion leads to bacterial growth in the paranasal sinuses. Among the many causes of such obstruction or congestion are the common cold, allergies, certain medical conditions, abnormalities in the nasal passage, and change in atmosphere. In any of these cases, sinusitis can develop as follows:

• Mucus drainage and airflow are blocked.
• Secretions build up, encouraging the growth of certain bacteria.
• The resulting infection, swelling, and inflammation create further blockage, which may cause the sinuses to close up completely.

Forms of Sinusitis. Sinusitis is classified as acute, subacute, or chronic, or recurrent. The classification is based on how long symptoms last:

• Acute: Less than 4 weeks
• Subacute: 4 - 12 weeks
• Chronic: 12 weeks or longer
• Recurrent: 3 or more acute episodes in 1 year

Review Date: 05/10/2010
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).