Eagle's syndrome: embryology, anatomy, and clinical management

Eagle's syndrome refers to a rare constellation of neuropathic and vascular occlusive symptoms caused by pathologic elongation or angulation of the styloid process and styloid chain. First described in 1652 by Italian surgeon Piertro Marchetti, the clinical syndrome was definitively outlined by Watt Eagle in the late 1940s and early 1950s.

This article reviews how underlying embryologic and anatomic pathology predicts clinical symptomatology, diagnosis, and ultimately treatment of the syndrome.

The length and direction of the styloid process and styloid chain are highly variable. This variability leads to a wide range of relationships between the chain and the neurovascular elements of the neck, including cranial nerves 5, 7, 9, and 10 and the internal carotid artery. In the classic type of Eagle's syndrome, compressive cranial neuropathy most commonly leads to the sensation of a foreign body in the throat, odynophagia, and dysphagia. In the carotid type, compression over the internal carotid artery can cause pain in the parietal region of the skull or in the superior periorbital region, among other symptoms.

Careful recording of the history of the present illness and review of systems is crucial to the diagnosis of Eagle's syndrome. After the clinical examination, the optimal imaging modality for styloid process pathology is spiral CT of the neck and skull base. Surgical interventions are considered only after noninvasive therapies have failed, the two most common being intraoral and external resection of the styloid process.