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Letters and Responses |
The patients in the study were all currently in the residual phase: at least 6 weeks after onset of facial paresis. Although we did not report the level of synkinesis in the platysma and depressor anguli oris muscles in the patient population, patients were in the residual phase.
Although we agree that surface electromyography would add to the study of facial movement in puckering and blowing, we would like to point out that the presence of a facial electrode close enough to the muscle of interest to record electrical activity would likely affect the movement. One advantage of using the automated method of measurement is that it does not require any markings on the face, an advantage that would be negated by the use of electrodes.
We would like to comment on the hypothesized effects of coactivation of other muscles in the movements studied. Halili states, "In the blowing movement, the platysma muscle is normally activated; in the puckering movement, it is not." We are skeptical that this is the case. We have no evidence of this from studies of movement in healthy individuals. In fact, greater activation of the platysma muscle in blowing would pull the lip corners laterally, causing less inward movement. In a recent study of healthy individuals,2 we found the opposite to be the case: blowing produced greater centrally directed movement.
Lastly, we are confused by Halili's suggestion that the type of movement involved in puckering and blowing actions differs in that puckering involves active movement of the orbicularis oris muscle, whereas blowing involves a holding contraction. First, Halili's classification of the type of movement in blowing—"the orbicularis oris is held in more of an isotonic contraction"—is confusing because the definition of an isotonic contraction is a contraction in which tension increases and the muscle changes length (eg, movement). The change in length can either be shortening, as in a concentric contraction in which the tension produced exceeds the resistance, or lengthening, as in an eccentric contraction in which the resistance exceeds the tension produced. The movements that we requested patients to demonstrate and the movements that we recorded from start to full excursion of the action were the usual acts of performing puckering and blowing, in which the orbicularis oris muscle shortens and the lips protrude.3,4 Given that blowing involves movement of the lips associated with a shortening contraction of the orbicularis oris muscle, we do not find Halili's second explanation reasonable in understanding the results reported or an acceptable challenge to our interpretation. The statement that, when treating patients with synkinesis, "...synkinesis is more easily integrated...when the primary mover...is in isotonic contraction rather than actually moving" is inaccurate as written and is not congruent with our clinical and research experience with patients with facial movement disorders.5
KL Schmidt, PhD, is Assistant Professor, Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania.
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