Interaction effect of tegmen tympani and superior semicircular canal statuses on the thickness of the roof of the glenoid fossa: a cross-sectional descriptive study.

PURPOSE: Homogeneous development of temporal bone structures is explained by their ontogenic origin; tegmen tympani (TT) and superior semicircular canal (SSC) are related with the glenoid fossa at the temporomandibular joint (TMJ). Therefore, our objective was to determine a possible relationship between TT status (dehiscence or integrity) and the roof of the glenoid fossa (RGF) thickness; SSC status has also been considered. METHODS: This cross-sectional descriptive study was conducted in two tertiary hospitals on 95 patients (109 ears) presenting hypoacusia, facial palsy, vertigo, tinnitus, and other single or combined symptoms, and submitted to a thin-section multidetector-row computed axial tomography (CT) scan. RESULTS: A significant interaction effect of TT × SSC statuses on RGF thickness was found (p = 0.049). A significant difference in RGF thickness was found only for SSC integrity status between TT integrity and TT dehiscence (p = 0.004). The TT dehiscence increased the risk for RGF dehiscence 12.047 times (p = 0.002). CONCLUSIONS: There is an interaction effect of the statuses of both TT and SSC on the thickness of the RGF, instead of an independent effect of the TT status. When RGF dehiscence is found, TT and SSC statuses should be assessed, to discard associated dehiscences.

Radiological patterns of the posterior semicircular canal.

OBJECTIVES: The identification and definition of the radiological patterns of the posterior semicircular canal (PSC), with a view to obtain readily applicable conclusions. DESIGN: The parietal morphology of the PSC has been studied by multi-slice helical computed tomography (Philips Brilliance 6). We have determined the distribution of the different types of bone cover of the PSC, taking some previously notified, standardised measurements of normality as reference. RESULTS: 318 patients have been analysed (604 petrous bone) by CT and we have distinguished five different radiological patterns: type or normal, thick, thin, pneumatised and dehiscent. The first three patterns, normal, thick and thin, have in common the existence of a compact bone interposed between PSC and posterior fossa, being in the normal pattern has a thickness of between 0.9 and 2.5 mm (327 cases, 54.13%), in the thick pattern is ≥2.6 mm (99 cases, 16.39%) and in the thin pattern is ≤1.2 mm (158 cases, 26.15%). The fourth pattern, pneumatised, is characterised by having retro labyrinthine cells between PSC and media fossa (19 cases, 3.14%). Finally, a dehiscent pattern was observed in 2 cases (0.3%). CONCLUSION: We describe five different radiological patterns: type or normal, thick, thin, pneumatised and dehiscent. The thin type (<0.5 mm or papyraceous type) and the dehiscent type would be subject to producing pathology, and in some cases the latter could be a consequence of the former.

Radiological patterns of the bony roof of the superior semicircular canal.

OBJECTIVES: To study the radiological patterns of the bony roof of the superior semicircular canal with a view for obtaining readily applicable conclusions. DESIGN: 84 patients (163 petrous bones) have been studied by Multi-slice Helical Computed tomography (Philips Brilliance 6). We have determined the distribution of the different types of bone cover of the superior semicircular canal, taking some previously notified, standardised measurements of normality as reference. RESULTS: During the analysis of the roof of the superior semicircular canal, we have distinguished five different types, depending on their thickness and tomodensitometric aspect. Normal pattern in 121 cases (74.2 %), with a thickness of between 0.6 and 1.7 mm, papyraceous pattern or fine thickness ≤0.5 mm that appears in 23 of our cases (14.1 %), thick pattern ≥1.8 mm that we have observed in 11 cases (6.7 %), and pneumatised pattern in 5 cases (3.1 %), which is characterised by having supralabyerinthine cells. Finally, a dehiscent pattern was observed in three cases (1.8 %). CONCLUSION: We describe five patterns of superior semicircular canal roofs: normal, thick, papyraceous, pneumatised and dehiscent. The papyraceous type and the dehiscent type would be subject to producing pathology, and in some cases the latter could be a consequence of the former.

Granular cell tumor: report of 8 intraoral cases.

Granular cell tumor (GCT) is an uncommon neoplasm of controversial origin that can appear in any corporal localization, including the orofacial region. Although aggressive and malignant variants of this neoplasm have been described, most of GCTs are benign. In spite of the amount of research, the etiology of this neoplasm remains unclear and its histogenesis and its possible muscular, connective or neural origin has been broadly debated. In this paper 8 oral cases are presented, corresponding to 5 women and 3 men, with a mean age of 36.1 years old and a mean time of evolution of the lesions of 8.3 months. The most common localization was the tongue (75%). In all the cases a resection with safety margins of the lesions was carried out under local anesthesia. The samples were fixed and processed for histopathological study. The main clinicopathologic and diagnostic features of this neoplasm are reviewed and discussed.

Association Between Tegmen Tympani Status and Superior Semicircular Canal Pattern.

OBJECTIVE: Detecting and quantifying the possible association between tegmen tympani (TT) status and superior semicircular canal (SSC) pattern. DESIGN: Observational study. SETTING: Study conducted in three tertiary Spanish hospitals. PATIENTS: Nonselected consecutive patients of all ages (607 temporal bones). INTERVENTIONS: Thin-section multidetector row computed axial tomography (CAT scan) of the temporal bones. MAIN OUTCOME MEASURE: Thickness of SSC bone coverture adjacent to the middle fossa, and TT status as a dichotomous variable: dehiscence (TTD) or integrity (TTI). RESULTS: The observed SSC patterns were dehiscence (3.79%), papyraceous or thin (11.20%), normal (76.77%), thick (4.94%), and pneumatized (3.29%). The observed TT statuses were TTD (10.87%) and TTI (89.13%). TTD was associated with SSCD and papyraceous patterns, and TTI percentages were higher in normal and thick patterns (χ2 = 11.102; p = 0.001). The TTD probability was estimated as a function of SSC pattern and age by a multivariate binary logistics regression model (χ2 = 45.939; p < 0.001). CONCLUSION: SSC pattern was significantly associated with TT status. Age influenced this association. The risk for TTD increased by 4.1% per each year of increasing age, did not differ significantly for normal and thick patterns, and increased 12 times and 20 times for papyraceous and SSCD patterns, respectively.

Effect of semicircular canal dehiscence on contralateral canal bone thickness.

OBJECTIVES: Our objective was to determine if the existence of dehiscence in the superior or posterior semicircular canal was associated with the thinning of the bone roof in the rest of the vertical canals (superior or posterior). METHODS: The thickness of the superior and posterior semicircular canals contralateral to a dehiscence was studied using computerized tomography and compared statistically. RESULTS: When a superior semicircular canal had a dehiscence, the contralateral canal showed a significant mean decrease in its thickness of 0.5mm (SD: 0.3 mm). This was not the case if the dehiscence was in the posterior semicircular canal, where the thickness of 2.1 mm remained unchanged (SD: 1.2 mm; P=.49). When a posterior semicircular canal showed dehiscence, no significant thinning was shown in the superior semicircular (1 mm; SD: 0.4) or in the posterior contralateral (1.3 mm; SD: 0.3) canals. CONCLUSION: The existence of a dehiscence in the superior semicircular canal is associated with bone thinning in the canal on the opposite side, but not with the posterior semicircular canal. In contrast, if the dehiscence is in the posterior semicircular canal, contralateral and superior canal thickness is not modified.

Congenital dehiscence in the posterior semicircular canal.

HYPOTHESIS: Posterior semicircular canal dehiscence (PSCD) may be of congenital origin. BACKGROUND: PSCD is characterized by the lack of bone coverage, which results in its lumen being exposed to the meninges of the posterior cranial fossa or to the gulf of the jugular vein. It has an incidence of 0.2%. Its presence has been associated with several well-defined entities, although a congenital origin has not been proven. METHODS: We have analyzed, from a macroscopic, microscopic, and radiologic (computed tomography) viewpoint, the right temporal bone of a 32-week-old human fetus that presented a defect in the bone coverage located in the rear. RESULTS: The macroscopic study showed a solution of continuity in the posterior semicircular canal, with elliptic morphology and smooth edges. This defect was 3.4 mm long with a width that varied between 0.67 mm in its apical portion and 1.42 in the basal portion. The radiologic study (computed tomography) showed the absence of bone coverage of the posterior semicircular canal, which was open to the intracranial space in the posterior fossa. Its histologic study showed good bone coverage of this canal at the expense of compact bone tissue. However, at the medial end, there is a lack of bone coverage, resulting in the lumen of the canal being open to the intracranial space. The bone edges of the defect did not present any osteoclast activity. CONCLUSION: The lack of bone coverage (dehiscence) of the posterior semicircular canal in a 32-week-old fetus suggests a congenital component of bony dehiscences of this canal. Even so, this single finding does not conclusively prove the congenital component, and the dehiscence is a finding that can be part of and not by itself a syndrome.

Influence of aging and menopause in the origin of the superior semicircular canal dehiscence.

OBJECTIVE: Determine if aging and menopause, known to be associated with bone resortion, also are associated with superior semicircular canal dehiscence. DESIGN: Observational study. SETTING: Study conducted in 3 tertiary Spanish hospitals. PATIENTS: Nonselected consecutive patients of all ages. INTERVENTIONS: Thin-section multi-detector row computed tomographic scan of the temporal bones. MAIN OUTCOME MEASURE: The minimum thickness of the bone covering the roof of the superior semicircular canal (SSC) measured in each temporal bone. The outcome was studied both as a continuous and as a dichotomous variable: thin (<0.6 mm) and normal (≥ 0.6 mm). RESULTS: Five hundred eighty-two ears of 312 patients were included in the study. Fifty-five percent of the sample were women. Patient's age ranged from 2 to 88 years. A 40-year age difference between ears was associated with a decreased thickness of bone covering the SSC of 0.10 mm, which is 10% of the average thickness of such bone. The thickness of the bone overlying the SSC of subjects younger than 45 years was an average of 1.14 mm (SD, 0.52 mm), whereas that of the subjects older than 45 years was equal to 1.02 mm (SD, 0.45 mm; p = 0.006). The percentage of ears with thin bone coverage of SSC was 7.1% in subjects younger than 45 years and 13.8% in those older than 45 years (p = 0.013). CONCLUSION: Our data support the hypothesis that there is a slight osteopenia of the roof of the superior semicircular canal associated with aging, and this effect seems to be more pronounced in menopausal women.

Peculiaridades anatómicas del canal semicircular superior y su posible implicancia clínica / Anatomical peculiarities of the superior semicircular canals and its possible clinical implication

El objetivo fue estudiar las peculiaridades en la morfología apical del canal semicircular superior, a nivel de la eminencia arcuata con la finalidad de obtener conclusiones aplicativas. Se estudiaron 48 cabezas de cadáveres humanos (96 huesos temporales), con la intención de identificar la presencia de adelgazamiento o dehiscencia del canal semicircular superior, así como la existencia de surcos vasculares de la eminencia acuata que, discurriendo sobre el techo del canal, pudieran afectar a su integridad anatómica. El estudio incluye un análisis histológico (Tricrómico de Martins) y radiológico (Tomografía Computarizada) de los hallazgos positivos (dehiscencias y adelgazamientos), así como estudio tomográfico de los canales con surcos vasculares visibles. En un caso (1,04 por ciento hemos observado cómo el canal presentaba un defecto óseo completo (dehiscencia), en tres (3,12 por ciento) el canal presentaba una pared muy delgada cuyo grosor no excedía de 0,2 mm. En 12 casos (12,5 por ciento) la eminencia arcuata estaba recorrida por surcos por el que discurrían vasos colaterales meníngeos, que determinaron una concavidad entre 0,1 y 0,2 mm, mientras que el grosor medio de dicha pared en estos casos fue de 1,2 mm. De las tres peculiaridades estudiadas, la falta de cobertura ósea es la que produce el síndrome de dehiscencia del canal semicircular superior. Los canales que presentaban una cubierta adelgazada pueden estar predispuestos a una rotura y por lo tanto causar patología en el canal. En cambio la presencia de surcos vasculares que recorren la superficie apical del canal, no parece tener consecuencias al disminuir minimamente su grosor...

The aim was to study the peculiarities in apical morphology of the superior semicircular canal are studied at level of the arcuate eminence to obtain application conclusions. We have studied 48 heads from human cadavers (96 temporal bones), with the intention of identifying the presence of thinning or dehiscence in the superior semicircular canal, as well as the existence of vascular sulci of the arcuate eminence, which, traveling along the roof of the canal, may affect its anatomical integrity. The study includes a histological (Martin's Trichome method) and a radiological analysis (Computerized Tomography) of the findings (dehiscences and thinnings), and as well as tomographic study of the canals with visible vascular sulci. In one case (1.04 percent we have observed how the canal presented a complete bone defect (dehiscence), in three (3.12 percent), presented a very thin wall, which did not exceed 0.2 mm thick. In 12 cases (12.5 percent) sulci covered the arcuate eminence through which meningeal collateral vessels ran, which determined a concavity of between 0.1 and 0.2 mm, whilst the average thickness of this wall in these cases was 1.2 mm. Of the peculiarities studied, the lack of bone coverage is what produces the dehiscence syndrome of the superior semicircular canal. The canals that had a reduced coverage may be predisposed to breakage and therefore cause pathology in them. On the other hand, the presence of vascular sulci that ran along the apical surface of the canal seems to have no consequences to decrease their thickness...