Cholesterol granulomas are entirely benign fluid-filled cysts that occur within the bone of the base of the skull. They arise in bone that is usually air-filled and, therefore, characteristically this is in the temporal bone (the bone that surrounds your ear structures). The reason they arise is simply related to obstruction to the normal aeration of these air spaces. When air cannot freely move in or out of an air cell (such as when there is an ear infection), this creates a high pressure within that air pocket. This in turn in a very small number of cases leads to a small amount of bleeding and an inflammatory reaction being set up. It is this that produces the fluid that makes up the cyst, which is sometimes described as being “chocolate-like”.
If the cholesterol granuloma is very small, it will often be asymptomatic. If it is, therefore, found as an incidental finding, it is perfectly reasonable to not embark on any surgical treatment for it. In a few cases however, the cyst can gradually enlarge and creates a pressure effect on the structures running through the adjacent bone. In other words, it can interfere with hearing, as well as some other nerves that pass through the temporal bone such as nerves that control eye movement or facial sensation. Rare presentations of cholesterol granules, therefore, include double vision or changes in facial sensation (including trigeminal neuralgia).
Cholesterol granulomas are typically a condition that is dealt with by a Skull Base Multidisciplinary Team (MDT). This team holds fortnightly meetings at Salford Royal Hospital, with a team of experts with a huge combined experience of managing such problems. Your surgeon will convey the outcome and recommendations of this meeting to you.
The surgical treatment thereof is dealt with in the cholesterol granuloma treatment section.