[Disorders of the coordination of masticatory muscles in lesions of the brain stem].

Observations of 10 patients were reported. In addition to other neurologic deficits, coordination of the trigeminus, a motor nerve, may also be disturbed with brain lesions. Disturbance of bilateral synergism can be demonstrated with the EMG. The muscles closing the jaw on the affected side are paradoxically innervated when the jaw is opened, i.e., they function like antagonists to the muscles responsible for jaw closure on the opposite side. This condition may produce trismus. Similar central disturbances in bilateral coordination of the ocular muscles have also been established. Bilateral synergism of the trigeminus is also controlled via a center in the brain stem.