Parotidectomy-related facial nerve lesions: proposal for a modified Sunnybrook Facial Grading System / Lesões do nervo facial relacionadas à parotidectomia: proposta de um sistema Sunnybrook de graduação facial modificado

ABSTRACT Facial nerve injury, affecting mainly the marginal mandibular branch, is the most frequent neurologic complication from parotidectomy. Objective To test a modified Sunnybrook Facial Grading System as a new tool to assess the facial nerve function following parotidectomy, emphasizing the marginal mandibular branch. Methods We reviewed the medical records of 73 post-parotidectomy patients (40 female, 18-84 years old, mean age 53.2 years) with facial nerve sparing, referred to the Department of Physical Therapy. All patients had parotid neoplasms or advanced skin cancer, and were followed by the principal author between 2006 and 2014. Results The muscles innervated by the marginal mandibular branch were the most frequently affected (72.6%), particularly in patients undergoing neck dissection (p = 0.023). The voluntary movement scores obtained with the modified system were significantly lower compared with the original version (p < 0.001). The best and worst scores were observed in patients with benign parotid tumors and skin cancer, respectively. Patients requiring neck dissection (p = 0.031) and resection of other structures (p = 0.021) had the lowest scores, evidenced only with the modified version. Patients with malignant tumors had significantly worse ratings, regardless of the Sunnybrook system version. The post-physiotherapy analysis involved 50 patients. The worst facial rehabilitation outcomes were related to the marginal mandibular branch function. Conclusion The modified Sunnybrook Facial Grading System improved the marginal mandibular branch assessment, preserving the evaluation of other facial nerve branches.

RESUMO A lesão do nervo facial é a principal complicação neurológica relacionada às parotidectomias e, em geral, o ramo marginal mandibular é o mais frequentemente acometido. Objetivo Testar um Sistema Sunnybrook de Graduação Facial modificado (mS-FGS) como uma nova ferramenta para avaliar a função do nervo facial após a parotidectomia, enfatizando o ramo marginal mandibular. Métodos Estudo retrospectivo, baseado em prontuários de 73 casos (40 do sexo feminino, 18-84 anos, idade média = 53,2), submetidos à parotidectomia, com preservação do nervo facial. Todos os pacientes apresentavam neoplasias parotídeas ou câncer de pele avançado, e foram tratados pela autora principal entre 2006 e 2014. Resultados Neste estudo, os músculos inervados pelo ramo marginal mandibular foram os mais acometidos (72,6% dos casos), principalmente nos pacientes que realizaram esvaziamento cervical (p = 0,023). Os Escores de Movimento Voluntário obtidos pelo sistema modificado foram inferiores aos obtidos pelo original (p < 0,001). As melhores pontuações foram observadas em pacientes com tumores benignos parotídeos e os piores resultados, naqueles com câncer de pele. Pacientes que necessitaram de esvaziamento cervical e ressecção de outras estruturas, além da parótida, apresentaram escores menores (p = 0,031 e p = 0,021), evidenciados apenas pelo sistema modificado. Os tumores malignos geraram escores significativamente menores, independentemente do instrumento empregado. A análise pós fisioterapia envolveu 50 casos. Os piores resultados, após a intervenção fisioterapêutica, também foram observados nos músculos inervados pelo ramo marginal mandibular. Conclusão A avaliação da disfunção facial pós-parotidectomia, através do Sistema Sunnybrook com a modificação proposta permitiu uma apreciação mais detalhada do ramo marginal mandibular, sem prejuízo à avaliação dos demais ramos.

Alteraciones de las células de la microglía del sistema nervioso central provocadas por lesiones del nervio facial / Facial nerve injuries cause changes in central nervous system microglial cells

Resumen Introducción. El grupo de investigación del Laboratorio de Neurofisiología Comportamental de la Universidad Nacional de Colombia ha descrito modificaciones estructurales y electrofisiológicas en neuronas piramidales de la corteza motora producidas por la lesión del nervio facial contralateral en ratas. Sin embargo, poco se sabe sobre la posibilidad de que dichos cambios neuronales se acompañen también de modificaciones en las células gliales circundantes. Objetivo. Caracterizar el efecto de la lesión unilateral del nervio facial sobre la activación y proliferación de las células de la microglía en la corteza motora primaria contralateral en ratas. Materiales y métodos. Se hicieron pruebas de inmunohistoquímica para detectar las células de la microglía en el tejido cerebral de ratas sometidas a lesión del nervio facial, las cuales se sacrificaron en distintos momentos después de la intervención. Se infligieron dos tipos de lesiones: reversible (por compresión, lo cual permite la recuperación de la función) e irreversible (por corte, lo cual provoca parálisis permanente). Los tejidos cerebrales de los animales sin lesión (grupo de control absoluto) y de aquellos sometidos a falsa cirugía se compararon con los de los animales lesionados sacrificados 1, 2, 7, 21 y 35 días después de la lesión. Resultados. Las células de la microglía en la corteza motora de los animales lesionados irreversiblemente mostraron signos de proliferación y activación entre el tercero y séptimo días después de la lesión. La proliferación de las células de la microglía en animales con lesión reversible fue significativa solo a los tres días de infligida la lesión. Conclusiones. La lesión del nervio facial produce modificaciones en las células de la microglía de la corteza motora primaria. Estas modificaciones podrían estar involucradas en los cambios morfológicos y electrofisiológicos descritos en las neuronas piramidales de la corteza motora que comandan los movimientos faciales.

Abstract Introduction: Our research group has described both morphological and electrophysiological changes in motor cortex pyramidal neurons associated with contralateral facial nerve injury in rats. However, little is known about those neural changes, which occur together with changes in surrounding glial cells. Objective: To characterize the effect of the unilateral facial nerve injury on microglial proliferation and activation in the primary motor cortex. Materials and methods: We performed immunohistochemical experiments in order to detect microglial cells in brain tissue of rats with unilateral facial nerve lesion sacrificed at different times after the injury. We caused two types of lesions: reversible (by crushing, which allows functional recovery), and irreversible (by section, which produces permanent paralysis). We compared the brain tissues of control animals (without surgical intervention) and sham-operated animals with animals with lesions sacrificed at 1, 3, 7, 21 or 35 days after the injury. Results: In primary motor cortex, the microglial cells of irreversibly injured animals showed proliferation and activation between three and seven days post-lesion. The proliferation of microglial cells in reversibly injured animals was significant only three days after the lesion. Conclusions: Facial nerve injury causes changes in microglial cells in the primary motor cortex. These modifications could be involved in the generation of morphological and electrophysiological changes previously described in the pyramidal neurons of primary motor cortex that command facial movements.

Features of Facial Asymmetry Following Incomplete Recovery from Facial Paralysis

PURPOSE: The purpose of this study is to investigate peculiar patterns of facial asymmetry following incomplete recovery from facial paralysis that require optimal physical therapy for effective facial rehabilitation, and to decrease the incidence of avoidable facial sequelae. MATERIALS AND METHODS: This study involved 41 patients who had facial sequelae following the treatment of various facial nerve diseases from March 2000 to March 2007. All patients with a follow-up of at least 1 year after the onset of facial paralysis or hyperactive function of the facial nerve were evaluated with the global and regional House-Brackmann (HB) grading systems. The mean global HB scores and regional HB scores with standard deviations were calculated. Other factors were also analyzed. RESULTS: Four patterns of facial asymmetry can be observed in patients with incomplete facial recovery. The most frequently deteriorated facial movement is frontal wrinkling, followed by an open mouth, smile, or lip pucker in patients with sequelae following facial nerve injury. The most common type of synkinesis was unintended eye closure with an effort to smile. CONCLUSION: We described common configurations of facial asymmetry seen in incomplete recovery following facial nerve injury in an attempt to develop an optimal strategy for physical therapy for complete and effective facial recovery, and to decrease the incidence of avoidable sequelae.

Regeneração pós-traumática do nervo facial em coelhos / Posttraumatic facial nerve regeneration in rabbits

A paralisia facial periférica traumática constitui-se em afecção freqüente. OBJETIVO: estudo da regeneração pós-traumática do nervo facial em coelhos, por avaliação funcional histológica dos nervos traumatizados comparados aos normais contralaterais. METODOLOGIA: Vinte coelhos foram submetidos à compressão do tronco do nervo facial esquerdo e sacrificados após duas (grupo AL), quatro (BL) e seis (CL) semanas da lesão. A comparação entre os grupos foi feita pelas densidades total e parcial de axônios mielinizados. ESTUDO ESTATíSTICO: método de Tukey (p < 0,05). RESULTADOS: Houve recuperação funcional parcial após duas, e completa após cinco semanas. Na análise qualitativa, verificou-se em AL um padrão degenerativo, com maior processo inflamatório tecidual. Em BL, sinais de regeneração neural, praticamente completa em CL. Os nervos normais (N) apresentaram DT média de 15705,59 e DP média de 21800,75. O grupo BL revelou DT média de 10818,55 e DP média de 15340,56 e o CL, DT média de 13920,36 e DP média de 16589,15. BL obteve 68,88 por cento, e o grupo CL, 88,63 por cento da DT de N. N mostrou DP maior que os lesados; porém, esta não evidenciou diferença estatística entre BL e CL. A DT dos nervos revelou-se um método analítico mais fidedigno do que a DP estudada.

Posttraumatic facial paralysis is a frequent disease. This work studies posttraumatic regeneration of the facial nerve in rabbits. Functional and histological analysis compared injured and normal nerves on opposite sides. The left facial nerve trunk of twenty rabbits were subjectedto compression lesion, and sacrificed after two (subgroup AL), four (BL) and six (CL) weeks. Comparison between groups was made by analysing total and partial densities of myelinated axons. STATISTICAL ANALYSIS: Tukey Method (p<0.05). RESULTS:There was partial functional recovery after two weeks, and complete recovery after five weeks. Qualitative analysis demonstrated a degenerative pattern in the AL group, with an increased tissue inflammatory process. Evident regeneration signs were observed in the BL group, and almost complete regeneration was seen in the CL group. Normal nerves (N) had an average TD of 15705.59 and average PD of 21800.75. The BL group had an average TD of 10818.55 and an average PD of 15340.56. The CL group had an average TD of 13920.36 and an average PD of 16589.15. The BL group had an average TD of N equal to 68.88 percent, and the CL group had an average TD of N equal to 88,63 percent (statistically significant). N showed a significant higher PD than injured nerves. However, this was not statistically different between BL and CL subgroups. Nerve DT was a more reliable method than PD in this study.