Buccofacial apraxia and the expression of emotion.

Apraxia is a disorder in executing “learned”1 or “skilled” movement (excluding explicitly symbolic movements2) not accounted for by weakness, incoordination, sensory loss, incomprehension or inattention to commands.3, 4 In a classic case, the patient carried out commands such as, “show me how you would use a hammer” with his right arm without hesitation.1 However, when asked to perform the same actions with his left arm, the patient would either do nothing or make an obviously incorrect response. When given real objects, the patient showed no deficits with either arm. The fact that the right arm performed the actions normally rules out the possibility of incomprehension, inattention, or uncooperativeness; while the successful performance of the left arm with real objects rules out the possibility of weakness or incoordination. This particular pattern of deficits is now called ideomotor apraxia. When patients have damage centered in the premotor area of the left frontal lobe, they may exhibit limb apraxia (LA) but may also show apraxia of the face, so-called buccofacial apraxia (BFA). These patients cannot pretend or imitate facial movements such as blowing out a match or sucking through a straw, but they usually perform normally when presented with a real match or straw. BFA, while fairly common, has been less studied than limb apraxia and has seldom been related to facial emotion expression. Care must be taken to separate BFA from automato-voluntary dissociation (AVD) affecting the face. In AVD, corticospinal innervation of the face is im-