Rafael Crovetto

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.

Influencia de la existencia de una dehiscencia en un canal semicircular en el espesor óseo de los canales contralaterales

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.

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 (&khgr;2 = 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 (&khgr;2 = 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.

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.

Peculiaridades en el desarrollo del canal semicircular superior

OBJECTIVE Our objective was to study the ontogeny of the superior semicircular canal in order to describe its peculiarities. METHODS We analyzed 76 series of human embryos aged between 32 days (6mm) and newborns. The samples were cut serially and stained using Martins trichrome technique. RESULTS In semicircular canal development there were a number of peculiarities, such as: a defined chronological sequence of osteogenesis with a variable rate of ossification; the fact that each nucleus of ossification was involved in the formation of one of its covers (the upper in the superficial and the lower in the deep); the appearance of transitory dehiscence; and canal closure by means of bone with laminar pattern, with a minimum thickness of 0.1mm. CONCLUSION The peculiarities in canal development could explain the origin of pathological dehiscence in the canal, whether congenital or acquired.

Granulocytic Sarcoma Presenting as Atypical Mastoiditis with Facial Paralysis: Description of a Case

We describe a case of temporal granulocytic sarcoma in a 26-year-old patient after apparent molecular remission of an acute myeloid leukaemia. He complained of otodynia with hearing loss and facial paralysis on the right side. He was treated with chemotherapy and self-transplant haematopoietic stem cells. He was cured clinically, molecular remission of the haematological processes was achieved, and he remained asymptomatic for three years. Facial paralysis and hearing loss associated with temporal GS should be treated with chemotherapy. Aggressive surgery may complicate the clinical course of the disease and it should be avoided.

Explicación ontogénica para la asociación entre dehiscencia del tegmen tympani y dehiscencia del canal semicircular superior

OBJECTIVES To analyze the ontogeny of the superior semicircular canal and tegmen tympani and determine if there are common embryological factors explaining both associated dehiscence. METHODS We analyzed 77 human embryological series aged between 6 weeks and newborn. Preparations were serially cut and stained with Massons trichrome technique. RESULTS The tegmental prolongation of tegmen tympani and superior semicircular canal originate from the same structure, the otic capsule, and have the same type of endochondral ossification; while the extension of the squamous prolongation of tegmen tympani runs from the temporal squama and ossification is directly of intramembranous type. The nuclei of ossification of the superior and external semicircular canals and accessory of tegmen collaborate in the ossification of the tegmental extension and by growth extend to the tegmental prolongation. This fact plus the fact that both structures share a common layer of external periosteum could explain the coexistence of lack of bone coverage in tegmen and superior semicircular canal. CONCLUSION The development of the semicircular canal and tegmen tympani could explain the causes of the association of both dehiscences.

Influence of Sex and Age on Posterior Semicircular Canal Thickness

Objective: The aim of this study is to determine whether sex and age influence posterior semicircular canal (PSC) thickness. Methods: This observational study was conducted in 3 tertiary hospitals. The minimal distance between the PSC and the posterior cranial fossa (PSC thickness) was estimated by thin-section multidetector row computed axial tomography (CAT) scan of the temporal bones. Nonselected consecutive patients of all ages (607 temporal bones) were considered. Results: A significant effect was only detected for sex (F = 5.418, p = 0.020); PSC thickness showed a higher mean value in women (mean difference ± SE: 0.224 ± 0.096 mm). A significant and negative r value was detected for males aged >45 years (-0.173, p = 0.026); in that group of patients, PSC thickness decreased as age increased (0.018 ± 0.008 mm/year). For females aged ≤45 years, a significant and positive r value was found (0.198, p = 0.022); in that group, PSC thickness increased as age increased (0.020 ± 0.008 mm/year). Conclusions: PSC thickness did not significantly evolve with age in young males (≤45 years) but it decreased from age 45 years onwards. On the other hand, PCS thickness increased with age in women until the age of 45 years and it did not significantly change in older females.