Eagle syndrome or styloid process syndrome is a clinical condition of complex aetiology. A rare set of symptoms within the orofacial region is caused by an elongated styloid process or calcification of the stylohyoid ligament. It most commonly manifests as pain in the parapharyngeal, retromandibular and cervical regions that worsens when the patient swallows or turns his head [1], [2], [3], [4].

In 1937., an American otorhinolaryngologist at Duke University, Dr. Watt Weems Eagle was the first to notice changes in the styloid process associated with these symptoms, so the syndrome was named after him [1], [2], [3], [4].

He defined two forms of Eagle syndrome - "classic Eagle's syndrome" caused by the pressure on the nervus glossopharyngeus and other local structures, which usually appear after tonsillectomy and "stylocarotid syndrome", caused by the pressure on the carotid artery [5].

The average length of the styloid process is between 20 and 30 mm, while the length above 30 mm is considered extended. The incidence of the elongated styloid process in patients who have a similar set of symptoms is around 4–10% of the general population, but the true incidence of Eagle syndrome is 0.16%, with conflicting results in frequency with respect to gender [1], [6], [7], [8].

Odynophagia together with painful and limited head rotations are listed as the main symptoms of the Eagle syndrome. In addition, patients often have a history of symptoms such as cough, dysphagia, dysphonia, trismus and sinusitis[8]. Studies have also shown a link between Eagle syndrome and vertigo. A symptom of this type occurs due to internal carotid artery compression. These patients report dizziness appearing and disappearing suddenly due to changes in arterial flow. Besides this, it has also been confirmed that the cause of vertigo and tinnitus could occur after irritation of the sympathetic plexus [9], [10], [11].

Since, as a consequence of vascular compression, it can lead to isolated vertigo without other clinical manifestations [9].

Consequently, a large number of patients have vertigo of unknown aetiology [12]. It may be part of "isolated symptoms" of stylocarotid syndrome [9], which, in that case, should be confirmed or excluded.

The aim of this study was to investigate a possible influence of styloid process length on isolated vertigo of unknown aetiology as part of stylocarotid syndrome (Eagle syndrome). Also, the secondary aim of the study was to measure the lengths of styloid processes and their distances from the internal carotid artery in the control group of 800 subjects.