Cerebrospinal Fluid Fistulas and Encephaloceles in the Setting of Superior Semicircular Canal Dehiscence

The cause of superior canal dehiscence (SCD) is likely a combination of congenitally thin bone and acquired changes from elevated cerebrospinal fluid (CSF) pressure or trauma. Dehiscence of the tegmen (the bone that separates the middle fossa from the mastoid and middle ear) is also a result of the same factors and is often present in patients with superior canal dehiscence. The combination of a dehiscent tegmen and elevated cerebrospinal fluid pressure may result in a spontaneous cerebrospinal fluid fistula or encephalocele. This chapter will discuss the association between superior canal dehiscence and spontaneous cerebrospinal fluid fistula and encephaloceles. Next, appropriate imaging and laboratory investigation will be discussed. Finally, the nuances of treating superior canal dehiscence in the setting of CSF fistulas and encephaloceles will be examined.