Ultrasound-guided inferior alveolar nerve block for trismus during dental treatment: a case report

BACKGROUND: Temporomandibular disorder (TMD) is a broad term that encompasses pain and/or dysfunction of the masticatory musculature and TM joints (TMJs). When TMD becomes a chronic condition, the symptoms are extremely difficult to manage and require multiple interventions. CASE PRESENTATION: A woman in her 50s developed TMD after a traffic accident 30 years ago. The patient presented with severe trismus due to TMJ pain and a maximum mouth opening of 20 mm. Ultrasound-guided inferior alveolar nerve block (IANB) was performed with ropivacaine. After IANB, the pain during mouth opening subsided and the maximum mouth opening improved to 40 mm. Dental treatment could be performed without difficulty and the patient could keep her mouth open throughout the treatment. CONCLUSIONS: Treatments for chronic TMD are limited and it is necessary to identify the precise etiology before choosing a treatment option. In this patient, ultrasound-guided IANB proved to be effective in relieving TMD-related trismus.