Introduction: Superior semicircular canal dehiscence syndrome (SSCDS) is caused by the absence of bone overlying the semicircular canal. While CT imaging is the most common method utilized to identify SSCDS, limitations in this technology may lead to the misidentification of thin tegmen tympani as true dehiscence. Furthermore, thinning of the tegmen tympani may also present with symptoms similar to those associated with SSCDS. In this study, data was collected in order to identify the frequency of misdiagnosis of thinning of the tegmen tympani as SSCDS.
Methods: A systematic review for relevant studies was conducted using PubMed and Google Scholar. Search terms included superior semicircular canal dehiscence, near dehiscence, thinning of the tegmen, and thin bone over superior semicircular canal. Inclusion criteria consisted of cases in which misdiagnosis of superior semicircular canal dehiscence occurred. Exclusion criteria were tegmental defects besides thinning of the bone and cases that lacked symptoms of SSCD.
Results: The study identified 245 cases characterized as probable SSCDS by CT imaging that fit our inclusion criteria. In 11% of the cases (27 cases), thinning of the tegmen overlying the superior semicircular canal was improperly identified as SSCDS.
Conclusions: Patients with thin bone overlying the superior semicircular canal can exhibit symptoms similar to those found in patients with true SSCDS. Our results suggest that while it is rare, thinning of the tegmen may be misdiagnosed as SSCDS. Therefore, it is important to know the condition of the bone pre-operatively in order to develop an accurate surgical plan. Thus, further studies testing the limitations of CT imaging on accurately differentiating between thin bone and SSCDS should be conducted.
Patient Care: It will bring increased awareness to the incidence of SSCDS misdiagnosis and improve the treatment of patients with thin tegmen by avoiding surgery in these patients.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of improved CT imaging in the diagnosis of SSCDS, 2) Discuss, in small groups, the potential for improvements in CT imaging, 3) Identify an effective treatment for SSCDS and thinning tegmen.