Odontogenic subdural empyema identified by masticatory muscle inflammation on magnetic resonance imaging: A case report.

Background: Subdural empyema secondary to dental infection is rare and often difficult to recognize early because initial symptoms may be nonspecific. Imaging findings that suggest an odontogenic source can support timely diagnosis and treatment. Case Description: A 70-year-old woman presented with right temporal pain, high fever, and impaired consciousness (Glasgow Coma Scale score of 11). Brain magnetic resonance imaging (MRI) showed a right frontotemporal subdural fluid collection, along with high T2 signal intensity in the masseter and lateral pterygoid muscles, suggesting an odontogenic source. A diagnosis of subdural empyema secondary to dental infection was made, and emergency surgical drainage was performed, followed by targeted antimicrobial therapy and extraction of the infected teeth. Consciousness improved after treatment, and follow-up showed no recurrence. Conclusion: Inflammation of the masticatory muscles on MRI can provide an important diagnostic clue for identifying the infection source to dental-origin subdural empyema in patients presenting with temporal pain and altered consciousness, and may facilitate prompt surgical and antimicrobial management. Such extracranial inflammatory changes have been described in previous reports; however, their role as a primary diagnostic clue has not been fully emphasized.