[Lockjaw caused by induction of anesthesia in a volunteer bone marrow donor]

A 43-year-old healthy female volunteer donor was scheduled for bone marrow harvesting. In the operating room her mouth opening was ascertained to be 5 cm. Anesthesia was induced with thiamylal 250 mg, fentanyl 0.1 mg and vecuronium 6 mg i.v. Her mouth opening was found reduced to 2 cm that was not improved by additional vecuronium 2 mg. A consulted oral surgeon diagnosed temporomandibular disorder. After she was awakened once with resumed mouth opening, anesthesia was reinduced with a bite block placed and with her jaw held open by the oral surgeon, which brought the same results. Laryngoscopy was performed with the jaw forcefully opened and with cricoid pressure applied and the trachea was intubated. The surgical procedure and anesthesia thereafter were uneventful. Postoperative MRI was coincident with the diagnosis of temporomandibular disorder. It was speculated that in the donor patient with preexisted type II temporomandibular disorder, muscle relaxation induced by anesthesia caused the mandibular head fall behind the articular disk and dislocated the disk forwardly ending up in closed lock of temporomandibular joint.