Prevalence rate and clinical symptom of extra‐articular diseases of the head and neck region mimicking temporomandibular disorders on 3T MRI

Few studies have reported on the prevalence rate of extra‐articular diseases and on the clinical symptom and temporomandibular joint (TMJ) magnetic resonance imaging (MRI) findings that are seen in these diseases and are not related to genuine temporomandibular joint disorders (TMDs). Therefore, we aimed to determine the prevalence rate and clinical symptom of extra‐articular diseases of the head and neck region that mimic genuine TMDs on 3‐tesla (3T) MRI.This study included 100 patients who were clinically diagnosed with TMDs and underwent TMJ MRI. We recorded lesions with abnormal signal intensities in the head and neck region using axial Dixon T2‐weighted imaging (T2WI). The clinical symptoms of the patients and pathology of extra‐articular diseases were determined based on medical records.Three patients (three males; mean age, 44.3 years) had lesions with abnormal high signal intensity in the head and neck region. All three patients presented with trismus as a clinical symptom. The locations of the lesions were as follows: the left medial and lateral pterygoid muscles, deep lobe of the right parotid gland, and body of the left mandible. Two patients had malignancies.Among the patients who visited the hospital, 3% had extra‐articular diseases and presented with genuine TMD symptom. Trismus may be a key clinical symptom indicating the presence of extra‐articular diseases and need for further clinical or imaging examinations.