Quantitative assessment of facial muscle impairment in patients with hemispheric stroke

Abstract

Facial weakness is frequently observed in patients with hemispheric stroke. Most reports refer to qualitative assessment. The aim was to quantify the upper and lower facial muscle function in patients with hemispheric stroke. Three different facial expressions (forced smile, posed smile and maximum eyebrow lift) and facial rest position were mapped using a 3D video system. Twenty-seven patients with hemispheric stroke (PG) and 22 controls (CG) were recruited. Facial asymmetry was expressed as absolute side differences between four corresponding distances. In PG, a longer distance was found from inner canthus to oral commissure (dist1) on the impaired side in all investigated poses (PG non-affected-affected side: range of all poses 1·18 ± 4·45 to 1·80 ± 2·37 mm; CG right-left side: range -0·69 ± 1·55 to -0·43 ± 1·39 mm, Mann-Whitney tests: 0·0002 < P < 0·0423). In addition, the ratio of the impaired to the non-affected side was different in PG for dist1 in rest and eyebrow lift (Wilcoxon tests: 0·0011 < P < 0·0288). CG showed asymmetries in rest and forced smile (Wilcoxon tests: P = 0·0392 and P = 0·0424). Furthermore, dist1 in PG showed higher variances than in CG (F-tests: 0·0001 < P < 0·0445) except for the relative dist1 at rest (F-test: P = 0·0533). The distance between inner eyebrow corner and inner canthus showed no side difference in both groups during eyebrow lift (n.s.); nevertheless, two patients showed distinct asymmetries. The employed 3D video system proved sensitive in assessing facial muscle function. The results confirm and quantify that the lower facial muscles are more affected by hemispheric stroke than the upper ones and show that the measured distances were more variable in post-stroke patients than in control subjects.

Changes in oro-facial function and hand-grip strength during a 2-year observation period after stroke

“…In contrast to the control group their chewing efficiency was not correlated to the number of occlusal units. This supports the hypothesis that the reduced chewing efficiency in stroke patients might rather be dominated by neurophysiological impairment of the oro-facial structures [32,33] than the dental state [2].…”

“…Although bilateral innervation of the lower facial muscles was suggested, the most frequent abnormality found in patients with central facial paresis is the contralesional loss of motor evoked potentials [35] which was indirectly confirmed by the current study. However, central paresis of the lower facial muscles is often discrete [32].…”

Class II functional appliance treatment and dynamic three‐dimensional mimic muscle evaluation

“…Another 3D system available, the SmartEye Pro (SmartEye AB) is more versatile requiring less space, giving the possibility to create a portable system. Its use in dentistry still in its infancy, with only a small number of published studies using this system …”

“…Its use in dentistry still in its infancy, with only a small number of published studies using this system. [13][14][15] The general purpose of the present study was to analyse changes in facial expressions, using three-dimensional (3D) mimic muscle evaluation, in growing children with Class II malocclusion and increased overjet, undergoing functional appliance treatment.…”

Oral tactile sensitivity and masticatory performance are impaired in stroke patients

“…Although the motor deficiencies following stroke are well documented for the limb muscles, the cerebral lesion may also lead to a large range of oro-facial motor impairment. Whereas facial muscle palsy following stroke often presents with a clear laterality, the impairment of the chewing muscles is less asymmetrical (4,5), due to the presence of bilateral cortical projections to the motorical nuclei of the trigeminal nerve (6). Chewing movements are centrally generated by a central pattern generator located in the brain stem, with continuous integration of the afferent information from the oro-facial receptors (7,8).…”