Eagle Syndrome Information: Background- Including Anatomy, Classic or Vascular?, Length Vs Angulation:
Disclaimer: These answers to common questions were put together for new members to gain a head start in finding information about Eagle Syndrome; to give you confidence to discuss issues with your medical team and to encourage you to research issues further for yourselves. It was compiled by a volunteer Moderator, who does not claim to be a medical professional, merely an informed observer and patient! The sources used are personal experiences, LivingWithTheEagle members’ experiences, and research from professional publications (some of the articles can’t be read fully unless subscribed to). Many thanks to heidemt for her research and contribution, and for her example of being your own advocate and not giving up. Members are encouraged to seek medical opinion and these pages are not intended to replace that. Members are also encouraged to research more for themselves- there is more research available but with the limitation of time and neck pain, this was the best that I could do! Past discussions are useful sources of info as well; search whatever the subject is, and you’ll often find someone who’s been through it too!
What Is Eagle Syndrome?
It was first described by American otorhinolaryngologist Watt Eagle in 1937. Eagle Syndrome is a rare condition caused by an elongated or deviated styloid process, which interferes with nearby anatomical structures and causes pain in the oropharynx region and the face. It is now recognized that Eagle Syndrome can also be caused by a calcified stylohyoid ligament. (Ossification of the stylohyoid ligament was first defined by Pietro Marchetti in 1652.)
Eagle Syndrome can also be called
*Styloid-Carotid Artery Syndrome,
*Styloid Process Neuralgia,
*Calcified Ligamental Apparatus, and
*Stylohyoid Complex Syndrome
(SHCS was suggested by Candice C. Colby, MD; John M. Del Gaudio,MD in their paper ‘Stylohyoid Complex Syndrome- A New Diagnostic Classification’ on JAMA Network.
As well as elongated Styloid Processes and calcified Stylohyoid ligaments they also suggested that elongated hyoid bone processes could cause tension and reduced distensibility of the SHC, irritating the surrounding cervical structures with movement of the complex).
No wonder doctors (and us!) get confused!
Also member Emma suggested if approaching doctors for help you should mention ‘elongated temporal styloid process’ rather than ES, in her discussion:
Eagle also put forward 2 types of Eagle Syndrome- Classic Eagle Syndrome following tonsillectomy, and StyloCarotid ES, where pressure on the carotid arteries causes pain. (Also known as Vascular ES)
Eagle Syndrome is diagnosed when the elongated Styloids/ calcified ligaments cause pain; it is possible to have elongated Styloid processes or calcified ligaments and not have symptoms, therefore not Eagle Syndrome.
What is the styloid process?
The Styloid Process is a slender, pointed protrusion of the temporal bone. It arises from the 2nd brachial arch- Reichert’s cartilage- and serves as an anchor point for three muscles (stylopharyngeus, stylohyoid and stylomandibular), plus 2 ligaments (stylohyoid and stylomandibular), with the stylohyoid muscle and ligament inserting on the lesser cornu of the hyoid bone. (Mendelsohn, Berke, Chhetri).
These muscles help control the tongue, floor of the mouth, and larynx. The muscles are supplied with nerves (innervated) by the Glossopharyngeal Nerve, the Facial Nerve and the Hypoglossal Nerve. (Cranial nerves IX, VII and XII respectively).
The styloid process is situated in the maxillo-vertebro-pharyngeal recess (which contains carotid arteries, internal jugular vein, facial nerve, glossopharyngeal nerve, vagal nerve, and hypoglossal nerve).
The terms Stylohyoid Apparatus or Stylohyoid Complex are often used to describe the Styloid Process, Stylohyoid Ligament and the Hyoid Bone together.
What is the difference between Classic and Vascular ES?
As stated above, Eagle defined two types- Classic and Stylocarotid Syndrome (Vascular). He believed that the Classic Eagle Syndrome was seen after pharyngeal trauma or a tonsillectomy, with pharyngeal pain, centred around the tonsillar fossa region, and that a mass could be palpated here. Other symptoms were dysphagia (difficulty or discomfort with swallowing), foreign body sensation in the throat, tinnitus, and cervicofacial pain.
Stylocarotid Syndrome he identified as being caused by a deviated styloid process (or calcified stylohyoid ligaments) compressing either the External Carotid Artery or the Internal Carotid Artery, causing pain along the distribution of the artery, often giving headache and eye pain, and can be made worse by rotating the neck, or looking up or down.
Despite the majority of patients with symptoms having no history of tonsillectomy or pharyngeal trauma (Camarda et al, 1989), patients are still being categorized into those with a pain pattern following the carotid artery distribution and those with a classic palpable mass in the tonsillar fossa region into Classic and Vascular ES. (http://www.saudidentaljournal.com/article/S1013-9052(10)00094-5/fulltext)1.
And it’s not just the carotid arteries which can be compressed, but studies have shown the Jugular Veins can also be compressed by a posteriorly angled styloid process. (New Eagle Syndrome Variant- Complicating Management Of Intracranial Pressure After Traumatic Brain Injury by Callahan, Kang, Dudekula, Eusterman and Rabb). I have personal experience of this too!
JustBreathe also posted a useful recent research article about Jugular Venous Compression, there’s a link in this discussion:
In my opinion, it is possible to have both- for example an elongated styloid process causing the ‘foreign body’ sensation, and calcified ligaments pressing on blood vessels. See the Common Symptoms section for the different symptoms with Classic and Vascular ES.
How common is Eagle’s Syndrome?
The numbers in the population suffering from ES varies quite a bit, and it doesn’t help that doctors can’t agree on the ‘average’ length of a styloid process!(see section below)
According to a study by Petrović, Radak, Kostić, and Covicković-Sternić, (2008) “Styloid syndrome: a review of literature”, approximately 4% of the general population have an elongated styloid process, and of these about 4% give rise to the symptoms of Eagle syndrome.
But figures vary widely with different studies; for example Bilodi (2013) studied 300 unknown dry human skulls. Out of them, 61 skulls had elongated styloid process(es) with an incidence of 2.03%. The length of elongated styloid process ranged from 3.6 to 5.5cms. (Bilodi’s research also found that of the skulls 19.6% had a unilateral elongated SP, and 80.3% were bilateral elongated SP’s).
Murtagh RD, Caracciolo JT, Fernandez G (CT findings associated with Eagle Syndrome, 2001) found through CT’s the incidence of elongated styloid processes was 4%, with between 4 and 10% symptomatic.
Correll, Jensen et al examined 1771 panoramic x-rays and found 18.2% had mineralisation of the stylohyoid complex, and that 93% of these were bilateral. Research by Langlais, Miles and Van Dis stated only 1-5% of patients were symptomatic.
There seems to be an equal amount of women and men with elongated styloid processes, but more women are symptomatic. Gulnara SCAF(2003) reported on 166 panoramic radiographs of patients. He observed elongated styloid process in 12.6% of those, and it was similar in both genders.
Phennapa et al(2012) studied 176 Thai dry and 150 cadaveric skulls and found out of all styloid processes, 18.40% were elongated.
In the study: Study of Elongated Styloid Process in Dry Human Skulls and its Clinical Importance, (GJRA- GLOBAL JOURNAL FOR RESEARCH ANALYSIS) by Drs Chauhan, Rathod, Jain, Patel, Trivedi and Singel, the authors reported out of 110 skulls,16 (14.5%) skulls had elongated styloid process.
It’s worth noting too that because several of these studies were on skulls, the authors just looked at the styloid processes, and calcified ligaments were obviously not able to be taken into account, nor could they know if any of these people had been symptomatic, so possibly a higher percentage may have been found.
There can also be a higher incidence of ES in different ethnic groups, for example there is a higher incidence of elongated SP in the Turkish population. (Gocke et al, 2008, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633149/ )
In their study: ‘Eagle Syndrome masquerading as pain of dental origin’ (1997), Aral, Karaca and Gungor suggested that ES is infrequently reported but probably more common than is generally considered, and that the symptoms were often confused with facial neuralgias and/ or Temporomandibular Joint Disorders.
Given the time and struggle so many members take to get a diagnosis, I think I’d agree with them- how many people are out there suffering but never getting diagnosed?
What is the average length for Styloid Processes?
Eagle defined the length of a normal styloid process at 2.5-3.0 cm. The normal/ average length of the styloid process varies greatly, and doctors can’t agree on this, as can be seen from different research studies:
- Kaufman et al (1970) measured the SPs from 1.52-4.77 cms;
+less than 2.5 according to Correl etal (1979), Langlais et al (1986) and Montalbetti et al (1995);
+Lindeman (1985) from 2-3 cms;
+Keur et al (1986) considered above 30mm (3 cm) to be elongated;
+yet Mansour and Young (1986) considered styloid processes of 4 cms and over to be elongated!
(This information has been gathered from Wikipedia and the study 'Evaluation of the length and angulation of the styloid process in the patient with pre-diagnosis of Eagle Syndrome by Kosar, Atalar, Sabanclogullari, Tetiker, Erdil, Cimen and Otag, 2011).
+Başekim et al found the mean length of Styloid Process to be 2.83 cm (range: 1.58 –5.48 cm) and defined 4 cm and above as elongated.
+Mansour et al also defined 4 cm and above as elongated, and the incidence of ES occurrence was reported to be higher in this condition.
In one patient study, Kubikova and Varga reported a case with a Styloid Process length of 14 cm at both sides in a 28-year-old patient! (A case of extremely long styloid process without clinical symptoms and complications, 2009.)
Just to make this even more confusing, I have come across a research paper where the authors measured the length of the SP plus included any ossified stylo-hyoid ligament as well! (Evaluation of the length and angulation of the Styloid process in the patient with pre-diagnosis of Eagle Syndrome- Kosar et al, 2011, Via Medica)
However, some members have had symptoms with styloid processes 2-3cms. Research plus members’ experiences show that the angulation of the styloid process needs to be taken into account as well as the length- see next section.
Plus in the above report by Kosar et al, they state ‘There is no association between the severity of pain and the length of the styloid chain’ and reference this to Eagle Syndrome: Case 24- report and review of literature, by Kim, Hansen and Frizzi, 2008.
Angulation Of The Styloid Process:
There are several research papers which conclude that the angulation of the SP can have more of an effect than the length:
In the report ‘Evaluation of the length and angulation of the Styloid process in the patient with pre-diagnosis of Eagle Syndrome- Kosar et al, 2011, Via Medica’, the authors state ‘Abnormal angulation is responsible for the intensive symptoms rather than the length’ – and reference the reports by Atesci et al, (2010- Left Internal Carotid compression due to deviation of the SP- case report) and Yetiser et al (1997, Elongated SP: diagnostic problems related to symptomatology- Cranio).
‘As the Styloid process is located between the internal and external carotid arteries, deviation of the SP may cause pain as a result of the narrowing and irritation of the vessel.’ (Mendelsohn, Berke, Chhetri; Heterogeneity in the clinical presentation of Eagle’s syndrome, Otolaryngol Head Neck Surg, 2006)
And: ‘Abnormal angulation is responsible for the intensive symptoms rather than the length of the Styloid process.’ (Ateşçi, Karabacakoglu,. Gülmez, 2010- Left internal carotid compression due to deviation of elongated styloid process: case report; Yetiser, Gerek, Ozkaptan, 1997- Elongated styloid process: diagnostic problems related to symptomatology.)
In another study by Fusco, Asteraki, and Spetzler- (Eagle’s Syndrome Embryology, Anatomy, and Clinical management, 2012), the authors stated that ‘Symptoms present diversely according to the length and width of the styloid process, angle and direction of the curve, and degree of calcification of the stylohyoid ligament.’
In the book Temporomandibular Joint Dysfunction, by Anniker Isberg, the author suggests that:
+if the Styloid Process has a medial deviation, it can irritate the tonsillar fossa.
+If it deviates laterally it can impinge on the External Carotid Artery (close to the Maxillary and Superficial Temporal Arteries).
+If it deviates posteriorly it can impinge on the Internal Carotid Artery, the Internal Jugular Vein or any of the last four Cranial Nerves, narrowing the space between the SP and the transverse process of the Atlas Vertebra.
One Side or Bilateral?
Again, some doctors seem to be under the impression that you can only have symptoms one side, or that to have Bilateral ES is extremely, extremely rare, but we have seen on this site that many members have elongated styloid processes both sides, although often the symptoms one side are more severe.
Research papers showing the figures for this are:
In their study the authors found that 93% of people studied had bilateral elongation of the SP- Correl, Jensen, Taylor and Rhyne, 1979; Mineralization of the Stylohyoid-Stylomandibular complex.
In the study ‘Evaluation of the length and angulation of the Styloid process in the patient with pre-diagnosis of Eagle Syndrome- Kosar et al, 2011, Via Medica’, the authors found an incidence of 86% of patients with Bilateral elongation/ calcification.
In the article Eagle Syndrome by Dr Ian Bickle, Dr Gagandeep Singh et al, the authors state ‘It is often bilateral’.
Just a note – members with Bilateral elongated SP’s, but symptoms mainly one side have often found that following surgery on the worst side, the other side does become more symptomatic, so a second surgery is needed.
(see the section about surgery options for more info about having bilateral surgery).
Does The Styloid Process Keep Growing?
Research suggests it could be the case and also that calcification of the stylohyoid ligament also continues.
In a report ‘Biometry and Statistical Analysis Of The Styloid Process by DePaz, Reuda, Barbosa, Garcia and Pastor in 2012, the authors quote the following studies showing this:
+Monsour and Young (1986) found a steady increase up to age 30, then a slowing down, and then accelerates after 60 years;
+Carroll (1984) that calcification increased up to 30 years, showed a gradual rise from 30-70 years, after which there was complete calcification;
+and Sokler and Sander (2001) showed the longest styloid processes were in older age groups.
I also found reference to a study by Sokler in 1999 which showed 3.7% incidence of elongated styloid processes in people up to 20 years old, 37% in 20-40 year olds, and 59.3% in people over 40 years. But Bernfield (1982) believed that at 5-8 years ossification is complete.
Some members of this forum have found that their styloid process has regrown following surgery, and that they have had symptoms again. Earmom’s son has had his styloids re-grow, and has had to have further surgery. See her website: http://www.sherrijonas.com/store/c1/Featured_Products.html
See the discussion: Does Eagle Syndrome Regrow?
See ES Info: Treatment Available For ES- Surgery