HEMIFACIAL spasm is a condition in which the patient has paroxysms of twitchings in muscles innervated by the seventh nerve. The condition is not under voluntary control and defies mimicry. It imitates the effect of faradization of the facial nerve and characteristically involves one half of the face. Cases of bilateral spasms1 have been reported. In the latter a different mechanism is apparently operative, and most of the cases reported have been associated with paralysis agitans. Cases have also been reported in which first one side was involved, with a remission, only to be followed by involvement of the other side. The condition has also been called facial hemispasm; but when one half of the face is involved the term hemifacial spasm is more correct.
Hemifacial spasm is not a tic. According to A. Gordon,2 a tic is a sudden and abrupt contraction of one or several of
GORDON DM. HEMIFACIAL SPASMReport of Two Cases. Arch Ophthalmol. 1947;37(3):282-293. doi:10.1001/archopht.1947.00890220292004