[2 cases with unusual lid-jaw co-movements].

General review of the literature makes it apparent that there exist various combinations of associated movements between cranial nerves. Most of them involve four of nerves, the oculomotor, the abducens, the facial, and the motor potion of the trigeminal nerve. We report two patients in whom left upper eyelids produced peculior up and down movements in accompany with mastication. The one was a 9-year-old female who had shown left eye-lid retraction since 3 months; the other, a 4-year-old male, had produced the synkinesis one year since. Either children showed contraction of left palpebral levators associated with volitional mouth opening, deviation of the mandible toward the right, and sucking. Their pupils were normal and their upper eye-lids showed no ptosis on the affected side. The EEG showed high voltage rhythmic slow waves in parieto-occipital areas bilaterally. Head injuries or hereditary defects not being recorded in their histories, their synkinesis is assumed to be congenital in orgin. Abnormal neural connections have been presumed to be affected in the course of the development between the trigeminal and the oculomotor nuclei within the midbrain. In triggering the synkinesis, however, stretched muscle-spindles of the masseter muscle most play an important role. After all, synchronizing lid-jaw co-movements as observed in our two children represent an unusual pattern of the Marcus Gunn phenomenon.