ABSTRACT
Abstract Introduction: The exact etiology of Bell's palsy still remains obscure. The only authenticated finding is inflammation and edema of the facial nerve leading to entrapment inside the facial canal. Objective: To identify if there is any relationship between the grade of Bell's palsy and diameter of the facial canal, and also to study any possible anatomic predisposition of facial canal for Bell's palsy including parts which have not been studied before. Methods: Medical records and temporal computed tomography scans of 34 patients with Bell's palsy were utilized in this retrospective clinical study. Diameters of both facial canals (affected and unaffected) of each patient were measured at labyrinthine segment, geniculate ganglion, tympanic segment, second genu, mastoid segment and stylomastoid foramen. The House-Brackmann (HB) scale of each patient at presentation and 3 months after the treatment was evaluated from their medical records. The paired samples t-test and Wilcoxon signed-rank test were used for comparison of width between the affected side and unaffected side. The Wilcoxon signed-rank test was also used for evaluation of relationship between the diameter of facial canal and the grade of the Bell's palsy. Significant differences were established at a level of p = 0.05 (IBM SPSS Statistics for Windows, Version 21.0.; Armonk, NY, IBM Corp). Results: Thirty-four patients - 16 females, 18 males; mean age ± Standard Deviation, 40.3 ± 21.3 - with Bell's palsy were included in the study. According to the HB facial nerve grading system; 8 patients were grade V, 6 were grade IV, 11 were grade III, 8 were grade II and 1 patient was grade I. The mean width at the labyrinthine segment of the facial canal in the affected temporal bone was significantly smaller than the equivalent in the unaffected temporal bone (p = 0.00). There was no significant difference between the affected and unaffected temporal bones at the geniculate ganglion (p = 0.87), tympanic segment (p = 0.66), second genu (p = 0.62), mastoid segment (p = 0.67) and stylomastoid foramen (p = 0.16). We did not find any relationship between the HB grade and the facial canal diameter at the level of labyrinthine segment (p = 0.41), tympanic segment (p = 0.12), mastoid segment (p = 0.14), geniculate ganglion (p = 0.13) and stylomastoid foramen (p = 0.44), while we found significant relationship at the level of second genu (p = 0.02). Conclusion: We found the diameter of labyrinthine segment of facial canal as an anatomic risk factor for Bell's palsy. We also found significant relationship between the HB grade and FC diameter at the level of second genu. Future studies (MRI-CT combined or 3D modeling) are needed to promote this possible relevance especially at second genu. Thus, in the future it may be possible to selectively decompress particular segments in high grade BP patients.
Resumo Introdução: A etiologia exata da paralisia de Bell ainda permanece obscura. Os únicos achados confirmados são a inflamação e o edema do nervo facial (NF) que levam ao aprisionamento no canal facial. Objetivo: Identificar se há alguma relação entre o grau de paralisia de Bell e o diâmetro do canal facial e também estudar qualquer possível predisposição anatômica do canal facial para a paralisia de Bell incluindo as partes que ainda não foram estudadas. Método: Os prontuários médicos e exames de tomografia computadorizada de 34 pacientes com paralisia de Bell foram avaliados neste estudo clínico retrospectivo. Os diâmetros de ambos os canais faciais (acometidos e não acometidos) de cada paciente foram medidos no segmento labiríntico, gânglio geniculado, segmento timpânico, segundo joelho, segmento mastoideo e forame estilomastoideo. As escalas de House-Brackmann (HB) de cada paciente na apresentação inicial e três meses após o tratamento foram avaliadas a partir de seus prontuários. O teste t de amostras pareadas e o teste dos postos sinalizados de Wilcoxon foram usados para comparação de largura entre o lado acometido e o lado não acometido. O teste de postos sinalizados de Wilcoxon também foi usado para avaliação da relação entre o diâmetro do canal facial e o grau de paralisia de Bell. Diferenças significativas foram estabelecidas em um nível de p = 0,05 (IBM SPSS Statistics for Windows, versão 21.0; Armonk, NY, IBM Corp). Resultados: Foram incluídos 34 pacientes - 16 mulheres, 18 homens; idade média ± desvio padrão (DP), 40,3 ± 21,3 com paralisia de Bell. De acordo com o sistema de classificação do nervo facial de HB, oito pacientes eram de grau V, seis de grau IV, 11 de grau III, oito de grau II e um de grau I. A largura média no segmento labiríntico do canal facial no osso temporal acometido foi significativamente menor do que o equivalente no osso temporal não acometido (p = 0,00). Não houve diferença significativa entre os ossos temporais acometidos e não acometidos no gânglio geniculado (p = 0,87), segmento timpânico (p = 0,66), segundo joelho (p = 0,62), segmento mastoide (p = 0,67) e forame estilomastoideo (p = 0,16). Não houve relação entre o grau de HB e o diâmetro do canal facial no nível do segmento labiríntico (p = 0,41), segmento timpânico (p = 0,12), segmento mastoideo (p = 0,14), gânglio geniculado (p = 0,13) e forame estilomastoideo (p = 0,44), mas houve uma relação significativa no nível do segundo joelho (p = 0,02). Conclusão: O diâmetro do segmento labiríntico do canal facial foi um fator de risco anatômico para a paralisia de Bell. Também houve relação significativa entre o grau de HB e o diâmetro do CF no nível do segundo joelho. Estudos futuros (RM-TC combinadas ou modelagem 3D) são necessários para promover essa possível relevância especialmente no segundo joelho. Assim, no futuro, pode ser possível descomprimir segmentos específicos em pacientes com alto grau de PB.
Subject(s)
Humans , Male , Female , Adult , Temporal Bone/diagnostic imaging , Bell Palsy/etiology , Bell Palsy/diagnostic imaging , Facial Nerve/diagnostic imaging , Temporal Bone/pathology , Severity of Illness Index , Tomography, X-Ray Computed , Retrospective Studies , Statistics, Nonparametric , Facial Nerve/pathologyABSTRACT
BACKGROUND AND OBJECTIVES: High Resolution Computed Tomography(HRCT) of the temporal bone is the most accurate diagnostic tool and is popularly used in the chronic otitis media with cholesteatoma. However, the bony dehiscence of tympanic segment of the facial canal may be difficult to evaluate by the conventional HRCT of the temporal bone. This study was undertaken to develop a modified technique of axial CT scan for evaluation of bony dehiscence of tympanic segment of the facial canal. MATERIALS AND METHODS: A prospective study was performed in 33 patients with chronic otitis media with cholesteatoma. These patients had also underwent canal down mastoidectomy from August of 1996 through July of 1997. A correlation study of the CT and surgical findings at 40 degree and 30 degree axial scans was carried out. RESULTS: The sensitivity and specificity of this method for dehiscence of tympanic segment of the facial canal were 88.9% and 95.6%, respectively and the diagnostic predictability was 93.9%. However, the sensitivity, specificity, and diagnostic predictability of the 30 degree axial scan were 77.8%, 83.3%, and 81.8%, respectively. CONCLUSION: We think that the modified technique of axial CT scan of temporal bone is an effective method for detecting the dehiscence of tympanic segment of facial canal.
Subject(s)
Humans , Cholesteatoma , Facial Nerve , Otitis Media , Prospective Studies , Sensitivity and Specificity , Statistics as Topic , Temporal Bone , Tomography, X-Ray ComputedABSTRACT
The anatomical relations of the jugular fossa with the vertical portion of the facial canal, the posterior cranial fossa and the tympanic ring were surveyed in 100 adults, skulls(57 males, 43 females); the dimensions of the jugular fossa were measured. The depth of the jugular fossais 7.73?0.33(2.0-1.52mm) at left, 9.47 ? 0.34mm(2.8-19.0mm) at right. The thickness of the bony plate separating the jugular fossa from the vertical partion of the facial canal is 2.77 ?0.17(1.5-2.8mm) at left, 2.33?0.17mm(1.0-2.9mm) at right. The top of the jugular fossa above the tympnic ring level is accounted for 35% at left, 62.24% at right. In these surveys, some anatomical variances were observed. These data can give the reference to the clinicians in the operations of the facial nerve and the jugular bulb.
ABSTRACT
The development of the human facial canal and the facial nerve of 229 temporal sides from 11 weeks fetuses to infancies were studied by histological method. The results showed that the facial canal was formed by the membranous ossification and by cartilaginous ossification. The lateral wall, inferior wall of the horizontal segment and the eminous segment, the superior wall of the labyrinthine segment of the facial canal were formed by the membranous ossification. The sequence of the membranous ossification had some regularities. The rest of the facial canal was ossified in the cartilaginous bone. The development of the facial nerve grew in advanced embrylogical age. The length and width diameters of the facial nerve in the facial canal were almost the largest in size before birth. The size of the facial nerve to that of the facial canal is kept in a more or less constant proportion. It was found that the facial norve was largest at the distal portion of the labyrinthine segment of the facial canal and smallest at the stylomastoid foramen.We put forward the conclusion that the disturbances of the membranous ossification in any portion of the facial canal and the anomalies of the pneumatization of the mastoid process were the main causes for the deficiency of the facial canal.