Jaime Whyte

Anatomo-radiological study of the Superior Semicircular Canal Dehiscence Radiological considerations of Superior and Posterior Semicircular Canals.

INTRODUCTION The main purpose of this study is to determine the radiological incidence of Superior (SSCD) and Posterior Semicircular Canal Dehiscence (PSCD) and to compare radiologic SSCD to the incidence of this condition on cadaver specimen. We have also analysed the relation between the ossification state of the semicircular canals and the degree of mastoid pneumatization and integrity of Tegmen Tympani. MATERIAL AND METHODS Temporal bones have been investigated by means of CT scan on patients and direct observation on cadaver specimen, respectively. RESULTS 604 ears and 160 cadaver temporal bones have been investigated by means of CT scan and direct observation, respectively. 3.6% and 0.3% of the studied ears had SSCD and PSCD, respectively, on CT scan. Only 0.6% of the cadaver specimen ears did have anatomical SSCD. Degree of pneumatization of the mastoid bone is related to the mean thickness of bone overlying the Superior and Posterior Semicircular Canal. Radiological absence of Tegmen Tympani is more frequent in ears that also have radiologic SSCD. CONCLUSION CT scanning gives higher incidence figures of SSCD than anatomical studies, 3.6% vs. 0.6%. We also found a 0.6% incidence of radiological PSCD in the studied ears. There is a direct relation between the degree of ossification of Superior and Posterior Semicircular Canal and certain temporal bone anatomic features: temporal bone pneumatization and absence/presence of Tegmen Tympani or Antri.

Functional Structure of Human Auditory Ossicles

In a series of 52 auditory ossicles, their structure and functional significance were studied, with special reference to the patterns of force transmission. The significance of the different degrees of cavitation in the ossicles as well as their eventual pathological significance are also discussed.

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.

Malformations of the epididymis, incomplete regression of the mesonephric tubules and hyperplasia of Leydig cells in canine persistence of Müllerian duct syndrome.

Persistence of the Müllerian duct syndrome (PMDS) is a rare form of pseudohermaphroditism characterized by the presence of uterus and oviducts in otherwise normally differentiated SRY-positive 78 XY canine males. Undescended testicles are also common. We report a case of a male PMDS dog with a uterus and bilateral cryptorchidism. The dog had an incomplete regression of the mesonephric tubules. As a consequence of this an abnormally enlarged head of the epididymis was observed. In addition, an extreme reduction in size of both the body and the tail was found. Microscopic examination of both testicles revealed bilateral hyperplasia of Leydig cells. The progesterone blood level was measured by ELISA and was found to be abnormally high (3.18 ng/ml) compared to that of normal male dogs (lower than 1 ng/ml). Three months after surgical removal of the internal genitalia, the serum progesterone, testosterone and oestradiol levels were normal for a castrated male dog.

Absence of COCH gene mutations in patients with superior semicircular canal dehiscence

Absence of COCH Gene Mutations in Patients With Superior Semicircular Canal Dehiscence Miguel A. Crovetto, JaimeWhyte, Esther Sarasola, Jose A. Rodriguez, and Mar ia J. Garc ia-Barcina* Department of Otolaryngology, Basurto University Hospital (OSAKIDETZA/Servicio Vasco de Salud), University of the Basque Country (UPV/EHU), Bilbao, Spain Department of Human Anatomy and Histology, Faculty of Medicine, University of Zaragoza, Zaragoza, Spain Department of Genetics, Basurto University Hospital (OSAKIDETZA/Servicio Vasco de Salud), Bilbao, Spain Department of Genetics, Physical Anthropology and Animal Physiology. University of the Basque Country (UPV/EHU), Bilbao, Spain

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.

Tympanic Ossicles and Pharyngeal Arches

We have performed a study on 11 human embryos regarding the development of the tympanic ossicles and their relationship with the first pharyngeal arch. After performing measurements to date the embryos and foetuses chronologically, we performed a meticulous dissection of the temporal bones. Subsequently, they were fixed in 10% formol, decalcified with 2% nitric acid, embedded in Paraplast, sectioned in 7‐mm sequences and stained with Martin’s trichrome technique. In the 21‐ and 24‐mm cranium‐raquis (CR) length human embryos, we have observed the head of the malleus and the body of the incus close to Meckel’s cartilage, in addition to the handle of the malleus, the long limb of the incus and the stapes. Between them there was a mesenchymal band inside the primordium of the tympanic cavity. In the 27‐mm CR embryo, the various components of the malleus and incus were fusing, and in the 30‐mm CR embryo the union was complete. From our observations, we can conclude that the malleus and the incus are derived from the first and second pharyngeal arches.

Canine stage 1 periodontal disease: a latent pathology.

To evaluate the potential health issues associated with periodontal disease (PD) in dogs, 1004 teeth from 25 dogs were examined. The dogs were randomly selected, aged 2-14 years, and had at least 95% of their teeth at the first PD stage. Significant positive correlations between plaque grade (PG) and gum inflammation, gingival regression, periodontal pocket, age and serum alanine aminotransferase (ALT) activity were identified. In contrast, PG was negatively correlated to total platelet count. Altogether, these findings suggest that prevention and therapy at the first PD stages can have an important impact on the general health condition of dogs.