Superior Semicircular Canal Dehiscence:Variation Of Bone Thickness In Relation To Age And Gender Among Chinese Descents

Superior semicircular canal dehiscence syndrome is a condition that is characterized by symptoms of oscillopsia and pressure-/sound-induced vertigo,autophony,tinnitus,hearing loss,and hyperacusis.This syndrome was first introduced over two decades ago and is said to be because of a default in bone covering the superior semicircular canal resulting in a third window between the middle cranial fossa and the superior semicircular canal(SSC).Some researchers have suggested that the cause for this condition could be congenital where a very thin born at birth does not fully develop as the child grows resulting in a persisting thin bone that covers the superior semicircular canal and thus lead to superior semicircular canal dehiscence in adulthood.Trauma such as closed head injury has also been linked to the causes where it may disrupt the bone and thus expose the labyrinth to fluctuations of intracranial pressure and cause symptoms of superior semicircular canal dehiscence.Superior semicircular canal dehiscence is mainly diagnosed using temporal bone computed tomography(CT)imaging.Initial studies suggested using High Resolution CT scan(HRCT),however recent studies have showed that cone beam computed tomography(CBCT)is far more superior to HRCT in the diagnosis of inner ear abnormalities(including superior semicircular canal dehiscence).Other investigations that can be done to diagnose the syndrome are Vestibular Evoked Myogenic Potential(VEMP),Pure Tone Audiometry(PTA),Electrocochleography(ECoG),and Magnetic Resonance imaging(MRI).The treatment of superior semicircular canal is mainly surgical and there are two types of surgeries that are currently in use that is canal plugging,canal resurfacing and capping,and round window reinforcement.The approach for these surgeries differ and one can choose either to do Transmastoid approach(TMA),transcanal approach(TCA),and middle fossa approach(MFA).Hormones and advanced age have been linked with the decrease in thickness of the bone covering the superior semicircular canal especially in menopausal women.Studies done in the Western world showed that as the age increased the size of the bone decreased.There are no similar studies done in the Eastern world.Taking this into consideration we decided to conduct a study to determine the variation of superior semicircular canal bone thickness among the Chinese descents.Objective:To determine if the thickness of the bone that covers the Superior Semicircular Canal is the same or changes with advancing age and if there is a difference in the thickness between females and males at different age groups among the Chinese descents.Study Design:This was a Retrospective Observational Study.Methods:We included 311 temporal bone Cone Beam Computed Tomography scans of patients who attended Otology clinic at Second Hospital of Shandong University from January,2017-April,2018.The age range was between 3-90 years.A chart was made that consisted of demographic data and the results of the size of the bone together with the measured ear.The images were taken from the saved data and reconstructed in the line of Poschl and the thinnest area of the bone covering the Superior Semicircular Canal was taken.Statistical analysis was done using Excel of Microsoft Office and analyzed using SAS,and p value of<0.05 was considered statistically significant.Results:The overall median was 0.71 with a mean difference of-0.0210(95%CI;-0.13260.0906)with the females having a median of 0.72 while the male had a median of 0.71.There was no significant difference between the female and male bone thickness(p value 0.7113).Grouping our data in terms of age the mean difference was 0.0801(p value 0.1557)showing no significant difference between the young and old.Categorizing each gender group with respect to age difference still showed no significant difference in females for those less than 45 years and those 45 years and above(p value 0.6672)and the same was found in males(p value 0.1336).Conclusion:There was no significant change in bone thickness with advancing age.The males and females also showed similar results with no significant difference between them.CBCT clearly showed the superior semicircular canal as well as anatomical structures of the inner ear.This method might be a gold standard in the diagnosis of superior semicircular canal radiographically.