The Dissociation of Voluntary and Emotional Movements of the Face with Special Reference to Emotional Paresis as a Physical Sign.

OCCASIONALLY reports liave appeared in the literatuire of cases in which there was paresis of the lower part of one side of the face for emotional movements without any correspondinig disturbance of facial movements when carrying out definite tests at command such as showinig the teeth or whistling. This type of facial paresis has been referred to briefly as emotional paralysis of the face or mimic facial paralysis. In addition it has been a, common observation tllat a smile which is free and equal oIn the two sides of the face is possible with the facial paralysis associated with hemiplegia. It was thought that the persistence of emotioinal movements on the two sides of the face was due to bilateral innervation of the face for emotional movements, but the persistence and evein the exaggeration of emotional movements of the face in cases of double hemiplegia made it evident that only the presence of a separate path for emotional movements would explaini this dissociatioin of facial movements. Subsequently, a certain amount of evidence, both clinical and experimental, accumulated in support of a separate path for emotional movements of the face and rather less in support of the actual extent and position of that path. In view of the possible value of emotional paresis of one side of the face in the localisation of lesions of the central nervous system it is necessary to examine the practical difficulties connected with the identification of emotional paresis of the face as a physical sign and to consider, in the light of the information so obtained and the work already done on the presence and position of a separate path for emotional movements of the face, the conditions responsible for the dissociation of voluntary and emotional movements of the face. Approximately 5,000 cases have been examined and the condition of the voluntary and emotional movements of the face noted in each. The findings so obtained have been correlated with the rest of the physical examination in those in which dissociation of the voluntary and emotional movements of the face was found, and with operation and post-mortem findings when they