Depressor labii inferioris resection: an effective treatment for marginal mandibular nerve paralysis.

In patients who show their lower teeth during smiling and facial animation, paralysis of the marginal mandibular nerve (MMN) causes a noticeable asymmetry of the lower lip due to the absence of depressor function. This paper presents a balancing technique for this lower lip asymmetry that involves resection of the depressor labii inferioris (DLI) on the nonparalysed side. The anatomy of the muscle, the operative technique, and the effectiveness of the procedure are outlined. A retrospective chart review was performed for 42 adult patients who were treated for MMN palsy with a DLI resection. Seven cases had only the MMN involved, and 35 cases had unilateral facial nerve paralysis. Thirty-six of these patients were available for a follow-up telephone survey. Of the 42 primary DLI resections performed, 36 cases had successful outcomes. Of the six patients who failed to achieve the expected results, five patients had repeat DLI resection and three of these achieved the desired result; the other two patients required a third resection. One patient continued to have DLI action with smiling and subsequently had a Botox injection into the DLI with good results. Of the 36 survey respondents, 21 patients felt their lower lip was asymmetrical at rest prior to DLI resection and 18 of these patients were improved by the procedure (P = 0.0001). Twenty-nine of the 36 patients reported that their lower lip was more symmetrical when they smiled following the DLI resection (P < 0.0001). The bilateral lack of movement in the lower lip when expressing emotions, such as anger and sorrow, was not as important to the patient as the lack of symmetry when expressing these emotions. Patients' speech either improved or showed no change, the amount patients bit their lower lip significantly improved (P = 007) whereas oral continence showed no significant changes (P = 0.147) following the DLI resection. DLI resection is a simple and effective procedure for the treatment of MMN palsy. The results are permanent and predictable. Lower lip symmetry is produced both at rest and with facial animation, without causing a functional deficit. The expected results of surgery can be trialed by local anaesthetic or botulinum toxin to block the activity of the DLI.

Planning, Encoding, and Overcoming Conflict in Partial Occlusion Drawing: A Neo-Piagetian Model and an Experimental Analysis

A theoretical model of partial occlusion drawing is presented, along with three experiments. The experiments used the materials similarity effect, i.e., the fact that it is easier to draw partial occlusion when the model objects are quite different from each other (Cox, 1985). Experiment 1, with 172 5- to 8-year-old subjects, manipulated materials (similar vs dissimilar objects) and viewing condition (unlimited visibility vs screened after 5 s), to study whether planning or scanning is involved in partial occlusion drawing. The results were consistent with the planning hypothesis, but not with the scanning hypothesis. Experiment 2, with 76 first-graders, explored group-encoding of similar objects. Encoding was assessed from verbal descriptions. Layouts were described differently (similar objects yielding group descriptions), and different descriptions were correlated with different drawing strategies. We suggest that group-encoding of similar objects creates a drawing problem (Experiment 2), and planning is required to solve it (Experiment 1). A neo-Piagetian model that accounts for drawing performance in terms of incompatible sets of activated schemes and of an activation balance between them is presented. Both experimental manipulations and differences among subjects in attentional resources are assumed to affect this balance. Three predictions were derived on the conjoint effects of object similarity and subject's M capacity and field dependence on drawing; Experiment 3, with 79 first-graders, successfully tested them.

Motion aftereffects with rotating ellipses.

The perceptual outcome and the motion-aftereffect duration generated by the rotation on the frontal plane of an ellipse with a bar depend on whether the bar is placed along the major or the minor axis. When the bar is placed along the minor axis, a stereokinetic transformation occurs, and the pattern looks like a tilting ring with a perpendicular bar moving rigidly with it. Placing the bar along the major axis prevents the stereokinetic transformation: subjects report deformations and relative motion of the bar with respect to the ellipse. We found that motion aftereffects last longer when the bar is placed along the minor rather than along the major axis. A series of experiments was carried out to investigate whether differences in aftereffect duration are related to the stereokinetic transformation. Results seem to suggest that they are not.