Abstract
We performed a postoperative functional evaluation using electromyography of the lateral pterygoid muscle in a patient with temporomandibular joint disorders who underwent open TMJ surgery. The patient was a 44-year-old male with chief complaints of trismus and pain of the left temporomandibular joint.
Temporomandibular joint disorders (classification of JSTMJ: osteoarthritis), closed lock, and a stuck disc were noted on MRI. Exploratory pumping manipulation was performed, but was ineffective. Double contrast CT of the temporomandibular joint detected marked bilateral fibrous adhered lesions. Open TMJ surgery on removal of adhesions and pseudowalls assisted by arthroscopy was performed. We observed characteristic activities of the lateral pterygoid muscle (I-Lpt). Before surgery, muscular activity of I-Lpt was noted even when the mouth was closed, and no coordinated activity with the digastric muscle posterior belly of the mouth-opening muscles was noted.
After surgery, I-Lpt acted in coordination with the mouth-opening muscles, and reciprocal activity with the mouth-closing muscles was noted.
Regarding the jaw movement, limitation of right lateral movement was noted in the track of incisal point movement before surgery, but the range of protrusive and lateral movements increased after surgery. As for the movement of the heads of the mandible, the bilateral mandibular heads mainly showed hinge movement before surgery, but the range of movement of the left mandibular head increased in opening the mouth after surgery. This study revealed that pre-and post-operative functional evaluation using I-Lpt is useful.
