A hypoplastic frontal sinus is an underdeveloped sinus cavity located in the center of the forehead. Approximately 10 percent of all adults have hypoplastic frontal sinuses. The frontal sinuses develop as a person ages, reaching full size after 20 years.
Sinus cavities are hollow areas in the skull found in the center of the forehead, in the cheekbones, behind the nose and between the eyes. These cavities are connected by a series of passageways and are lined with a soft, pink tissue. There are a total of eight sinus cavities, though some people are born with an extra one. Most of the sinus cavities drain mucus through the nose.
Acute sinus infections can cause inflammation of the sinuses and increased mucus production. The inflammation blocks the nasal passages and keeps mucus from draining. This blockage leads to headaches and general discomfort in the area of the sinus cavities. Frequent sinus infections can turn into chronic sinusitis.
Allergies may affect the pink tissues lining the sinus cavities, causing itching, sneezing and inflammation. Allergy shots and avoiding the substances that cause the reaction can help alleviate these symptoms. A deviated septum can increase the potential for sinus blockages, leading to a greater number of infections.