IMAGING PROTOCOLS For Evaluating Orofacial Pain

In deciding whether to use imaging during the assessment of a patient with orofacial pain, the clinician must first obtain enough information from the history and clinical examination to determine the nature and probable cause of the problem and to decide whether imaging will provide any benefits in the diagnosis and management of the patient. In many cases, it may be necessary to rule out the teeth as a source of the pain. Select intraoral and/or panoramic radiography combined with the clinical examination can generally help in this situation.

If the patient’s symptoms are suggestive of temporomandibular disorder (TMD), a thorough clinical examination may provide enough information to establish a diagnosis and to select a management strategy without imaging, even though it has been shown that clinical examination alone will not detect all cases of internal derangement.

When there appears to be a bony component to the temporomandibular problem or if the patient is refractory to conservative treatment, it may be useful to obtain information on the condition of the osseous structures of the joints. A number of techniques can be used to confirm or rule out a variety of developmental, inflammatory, degenerative, traumatic, or neoplastic processes. Panoramic radiography provides a good overview of both joints as well as the rest of the maxillofacial complex. Although only gross structural abnormalities will be visualized with this type of radiography, this degree of detail may be adequate in many cases to determine the presence or absence of bony changes. If more detail is necessary to make the diagnosis or prognosis, conventional tomography should be performed, generally in oblique sagittal views, corrected for condylar angle, in both open- and closed-mouth positions.

Coronal or frontal tomography complements the lateral view by providing images at 90˚ to the first view. While some studies show that TMJ tomography provides additional information not anticipated clinically, others show mixed results as to the effect of the findings on the management of the patient.

If an internal derangement is suspected and if patient management depends on confirmation or rejection of this diagnosis, the position and function of the articular disk can be determined by either MRI or arthrography. In most institutions, MRI is the preferred examination because it is noninvasive and can provide information about the disk as well as other soft-tissue and bony structures.

There are other causes besides TMD for pain in the head region. Panoramic radiography may be helpful in the initial evaluation of the maxillary sinus if that structure is thought to be the origin of the facial pain. The floor of the sinus is well visualized, and discontinuity of the bony margins, thickening of the mucous membrane, partial or total opacification of the antrum, and the presence of mucous retention cysts can be noted on the resultant radiograph. A full imaging evaluation of the paranasal sinuses usually requires CT although a series of plain films may be made at some institutions.

 A, Periapical radiograph of a 29-year-old woman who presented with a throbbing toothache in the maxillary left. Endodontic treatment on the first molar had been completed 10 years earlier. The second premolar was extracted due to similar symptoms 1 year before. There is a thickening of the mucous membrane above the molars and a general cloudiness of the maxillary sinus. B, Panoramic radiograph taken the same day. The unilateral clouding of the sinus is more obvious. The patient was treated with antibiotics and antihistamines, with complete resolution of symptoms within 24 hours. The round radiopaque lesion in the mandible was not investigated at the initial appointment, and the patient did not return for further treatment.

If a central lesion is suspected of being the cause of the pain, an evaluation of the skull by CT or MRI is in order. The choice of the specific imaging examination depends on the presumptive diagnosis and should be determined in conjunction with the treating clinician and the radiologist.