Sinusitis. Coloured X-ray of the face of a patient with sinusitis, a bacterial infection of the sinuses (air-filled cavities in the skull). The mucous linings of the maxillary sinuses (centre right and centre left), which are behind the cheek bones, are inflamed and congested (grainy areas). The frontal sinuses (behind the forehead at top centre and top right and left) are not affected. Symptoms include pain and a thick nasal discharge, which may be accompanied by fever. Treatment is with decongestants and antibiotics.