Styloid Process Elongation or Eagle's Syndrome: Is There Any Role for Ectopic Calcification?

The styloid process (SP) is a cylindrical, long cartilaginous bone located on the temporal bone. The normal SP length is approximately 20-30 mm. The styloid process elongation (SPE) can be assumed if either the SP or the adjacent stylohyoid ligament ossification shows an overall length in excess of 30 mm. Elongated SP is known as Eagle's syndrome when it causes clinical symptoms as neck and cervicofacial pain. It is supposed that this symptoms and signs are due to the compression of the SP on some neural and vascular structures. It may also cause stroke due to the compression of carotid arteries. This syndrome is diagnosed by both radiographical and physical examination. Instead of many hypotheses and studies, the exact etiology of elongated SP and the role of ectopic calcification are unknown. Ectopic calcification (EC) might have a role for the elongation of SP. Abnormal calcium (Ca), phosphorus (P) and vitamin D metabolism is very common in patients with end-stage renal disease (ESRD). Therefore, this calcification in nonosseous soft tissue due to abnormal serum Ca and P levels is commonly associated with this disorder. EC due to the abnormality in this metabolism which is related to the duration of dialysis is also very important for this calcification. Therefore, a study in patients with ESRD investigating the prevalence of SP and the correlation between dialysis period and the SP length may help us explaining the role of EC in the elongation of SP. Because, this disease might be a good model for the investigation of the EC in this elongation. However, further studies and large samples are also needed to clarify the etiology of this disorder.