An overview of Eagle’s syndrome

Abstract

Eagle’s syndrome is a condition that typically does not present to pain clinics. It consists of an elongated styloid process greater than 25 mm and/or stylohyoid ligament calcification causing an unusual array of symptoms, relating to anatomical involvement. Multiple specialities may be involved with the diagnosis of this rare condition. Three-dimensional reconstructive computed tomographic (CT) scan remains the gold standard for diagnosis. Depending on the presenting symptoms, care should be directed to an appropriate specialist. Pain surrounding Eagle’s syndrome does not typically resolve using simple pharmacological methods. Eagle’s syndrome should remain a diagnosis to be considered when faced with non-resolving head/facial pain.

Introduction

Eagle’s syndrome, first described by Watt Weems Eagle in 1937, ¹ is a rare condition affecting around 4–8 per 10,000 people. ² It is more common in females than males (2:1 ratio) and in ages greater than 50 years. ³ It is characterised by elongation of the styloid processes and/or stylohyoid ligament calcification, classically unilateral or less commonly bilaterally. ⁴ Some patients with elongated styloid processes may never present with clinical symptoms; the abnormality may be an incidental finding on computed tomographic (CT) scan, at post-mortem, or at operation such as carotid endarterectomy. It typically presents to ear, nose and throat (ENT) specialists due to the nature and location of presenting symptoms. Symptoms are often associated with the anatomy surrounding the elongated styloid processes. Differential diagnoses include temporomandibular disorders, tumours, ear pathologies, skeletal neck pain, trigeminal and glossopharyngeal neuralgia.

We will discuss the presentation and treatment involved in Eagle’s syndrome. In this report, we present two cases of head and facial pain presenting to pain clinic without prior diagnosis. We also crucially report the patient’s experience of living with this condition and success with surgical treatment.

Case 1

A 42-year-old female was referred to pain clinic by her general practitioner (GP) complaining of a 6-year history of parietal/facial pain, with hyperacusis, and some intra-oral symptoms. There was no history of trauma or infection; she had had regular dental check-ups with no pathology found.

Pain was described as background constant pressure sensation, which was one of the most troublesome symptoms, with episodes of increased pain lasting for around 3 days; her hearing problems appeared to be worse at these times. There was also report of burning pain in the left gum, cheek, and tongue. These pains were worse when stressed.

Pain was improved by alcohol and she took a daily combination of co-codamol 8/500 and ibuprofen 400 mg with rather variable and uncertain effect.

Multiple treatments had been tried:

• Gabapentin 300 mg three times daily – ‘suicidal’ side effects

• Pregabalin 300 mg twice daily – no benefit

• Propranolol 10 mg three times daily – no benefit and side effects

• Amitriptyline 10 mg at night – no benefit, excess drowsiness

• Naproxen 500 mg twice daily – no benefit

• Indometacin 25 mg three times daily – excellent analgesic effect, side effect of dyspepsia

• Multiple antibiotics – no benefit

• Topiramate 25 mg twice daily – with short-term benefit

• Carbamazepine 200 mg three times daily – no benefit

Previous history was of cerebellar astrocytoma requiring resection through midline posterior fossa craniectomy with reservoir formation; indigestion and stomach bleed. She had some family and work stresses and admitted to being rather short-tempered. She had seen multiple specialists including ENT, maxillofacial, another pain clinic and neurology. Multiple diagnoses had been offered including stroke, temporal arteritis, cluster migraines, deviated septum and sinus problems (functional endoscopic sinus surgery (FESS) procedure had been performed), and trigeminal neuralgia, with treatments as listed without lasting benefit.

On examination, there was full range of movement of the neck, with just some minor pulling in the posterior neck muscles on the left; she reported very slightly reduced sensation in the left trigeminal 2nd and 3rd divisions but nothing dramatic. Temporomandibular joint examination appeared normal, and there was no lymphadenopathy; there was some irritability/tenderness over the reservoir in her skull and one or two other points around burr holes. The most marked finding was that she was exquisitely tender just below the left mastoid and behind the angle of the mandible.

It was felt that common causes of pain had been excluded by other specialists, and an alternative cause considered. A 3D CT scan was requested to look for Eagle’s syndrome, which was the prime differential diagnosis. Differential diagnoses included myofascial pain, cervical facet joint pain, mastoiditis and salivary gland dysfunction, the latter two differentials having been ruled out by referring ENT surgeon. A number of initial treatment options were discussed, including transcutaneous electrical nerve stimulator (TENS), lidocaine patch, lidocaine 10% metered dose intra-oral spray, and capsaicin. Most of these were considered unlikely to be of significant benefit. It was agreed to retry indometacin with proton-pump inhibitor (PPI) cover (due to dyspepsia symptoms previously), recognising the risks.

At follow-up 4 weeks post investigations, the 3D CT scan (Figures 1 and 2) was noted to show bilateral significantly elongated styloid processes at 43 mm and 50 mm associated with pseudoarthroses, the normal maximum being around 25 mm. Indometacin had not been of significant benefit. Given the failure of multiple previous medicines, options of ultrasound guided injection for diagnostic purposes, and operative resection were discussed. It was agreed that injection in this area would be potentially risky without lasting benefit, and therefore referral to a maxillofacial specialist was made.

Figure 1.

Patient 1 3D CT scan.

Figure 2.

Patient 1 3D CT scan.

The maxillofacial surgeon agreed with the diagnosis, and both styloid processes were resected in two procedures, left side followed by right, around 6 months apart because of the significant risk associated with major surgery in the neck. The operation on the right side was particularly difficult due to the rather curved nature of the process; both operations were by an extra-oral approach (surgical preference and experience). There were no complications from the procedure. She was followed up by the maxillofacial surgeon with input and communication from the pain physician, at three appointments over 6 months. She has been discharged with excellent recovery from her pain and hearing symptoms.

Patient one experience

“I had suffered 6 years of disabling pain until this condition was correctly diagnosed and treated. It started with face and scalp pain, swelling, and intolerance of loud noises. After no response to antibiotics, I was referred to a neurologist who diagnosed chronic headache with migrainous features, treated unsuccessfully with propranolol, indometacin, amitriptyline and topiramate. An ENT specialist diagnosed temporal arteritis, and a maxillofacial specialist thought that it was neuropathic pain, prescribing carbamazepine and requesting a second neurologist’s opinion. A request for a CT scan was rejected. After 4 years, another ENT specialist diagnosed hyperacusis and provided a noise generator hearing aid, then performed septoplasty and FESS operations, prescribed betamethasone drops and pregabalin. A second maxillofacial opinion also diagnosed neuropathic pain, prescribed gabapentin and indometacin. Two GP referrals to an NHS pain clinic were rejected.

At first consultation, A.S. formed a differential diagnosis to include Eagle’s syndrome and requested a 3D CT scan, which diagnosed the condition. After discussion of options, I was referred to another maxillofacial surgeon who performed operations on each side of my neck. This was major surgery but went without complication.

My symptoms have dramatically improved, and I am taking no medications. The neck scar on the left side is just a little thick in places, and I have some mild sporadic discomfort on the right. The pain and hearing disturbances have resolved and I feel much better. For several years until a correct diagnosis, I was left with an addiction to co-codamol (I am off them now), weak teeth, loss of the best years with my children, lack of career, loss of confidence, and stomach issues. I had been given multiple medications, and undergone surgery, without benefit.”

Case 2

A 29-year-old female, 5 weeks pregnant, was referred to pain clinic by an ENT surgeon with a 2-year history of bilateral retro-mandibular pain worse on the right. There were also some symptoms of altered hearing. She had not presented to other specialities prior to this.

There were no other medical problems, and the ENT surgeon had excluded pathology of the ear, nose and throat. She had already had a CT scan requested by the referring ENT surgeon, and the request was modified in advance to be a 3D scan.

At assessment, she was found to have exquisite tenderness behind the angle of the mandible on the right, more than the left. There were no other significant findings.

The CT scan (Figure 3) was available at this consult. It showed a 42 mm long styloid process on the right side, but also an extensively calcified left stylohyoid ligament.

Figure 3.

Patient 2 3D CT scan.

A diagnosis of Eagle’s syndrome was made, and referral to the maxillofacial surgeon, as above. Due to pregnancy, it was recommended that she accepted her symptoms rather than take more medications, and the surgeon informed so that an operation could be planned after delivery.

At the time of writing, the patient has just delivered her baby, and is awaiting planned surgery. This surgery is anticipated to be via an extra-oral approach with follow-up from maxillofacial surgeon in communication with pain physician over 6 months depending on the patients’ recovery, as per patient one’s management.

Discussion

The aetiology of Eagle’s syndrome is poorly understood. Approximately 4% of the population have elongated styloid processes, although only 4% of these cases will present clinically with Eagle’s syndrome. ⁵ Incidentally elongated styloid processes are also found at post-mortem. A normal styloid process measures up to 25 mm; clinically, styloid processes are described as elongated at lengths above 30 mm. ⁶ Elongation and calcification of the stylohyoid ligament can co-exist.

The stylopharyngeus, stylohyoid and styloglossus muscles attach to the base, middle part and tip of the styloid process, respectively. The spinal accessory and vagus nerves run medial to the styloid process. The facial nerve runs anteromedially, before piercing the substance of the parotid gland. Hence, symptoms may be intra-oral, facial, and in the neck. Examples of symptoms include cerebrovascular insufficiency, dysphagia, sensation of a foreign body or facial/neck pain. The length of the process does not typically relate to the severity of the pain. ⁵ The elongated process in Eagle’s syndrome can cause interaction with the internal carotid artery. Tears in the vessel and compression can cause cerebrovascular accidents. ⁷ Horner’s syndrome has also been documented in some cases. ⁸ Rarely, compression of the internal jugular vein can cause increased intracranial pressure.

The cause of onset of pain in patients previously free of symptoms is unknown, but several mechanisms have been proposed that include vascular/neurological impingement, rheumatic styloiditis caused by pharyngeal infections, trauma, tonsillectomy and involutional changes associated with aging (e.g. degenerative cervical discopathy, which may shorten the cervical spine and alter the direction of the styloid process). ⁹

Examination can often lead to identification by palpation of the calcified or elongated styloid processes, reproducing symptoms, which is then formally diagnosed with CT scan. Three-dimensional reconstruction of the CT images is considered to be the gold standard for diagnosing Eagle’s syndrome. It allows for effective demonstration of surrounding anatomical involvement, especially when planning ongoing care and treatment. A classification proposed by Langalis et al. ¹⁰ in 1986 for Eagle’s syndrome consists of three subcategories depending on radiographic appearance. In contrast, O’Carroll and Jackson classify ossifications of the styloid process into four main types depending on its location (Table 1). ¹¹

Table 1.

Eagle’s syndrome classifications.

Langalis classification – radiological appearance
Type I	Uninterrupted, elongated styloid process
Type II	Styloid process apparently being joined to the stylohyoid ligament by a single pseudoarticulation. This gives the appearance of an articulated elongated styloid process.
Type III	Interrupted segments of mineralized ligament, creating the appearance of multiple pseudoarticulations within the ligament
O’Carroll and Jackson classification – location of ossification of Styloid process
Type I	Higher than the mandibular foramen (bilateral)
Type II	On the same level as mandibular foramen (bilateral)
Type III	Lower than mandibular foramen (bilateral)
Type IV	Unilateral or having different lengths on either side

Treatment of Eagle’s syndrome depends on the nature of the symptoms, functional limitation and biopsychosocial impact; in these cases, of chronic pain. In both of our cases outlined above, the patients had had long periods of time before a diagnosis was made, and is commonly a matter of years. This can have a significant impact on a patient’s well-being living with unexplained symptoms, as is clear from the first patient’s self-report. This may have relevance in agreeing a treatment plan. Conservative management, pharmacological management, and surgery are all viable options for patients suffering with Eagle’s syndrome. Medications suggested include steroids, anti-inflammatories, local anaesthetics, and carbamazepine. Injection of local anaesthetic ± steroid under ultrasound guidance can be considered, targeting the tonsillar branches of the glossopharyngeal nerve. Stellate ganglion block has also been considered in some cases where patients do not wish for surgical intervention. ² There is a significant increased risk with these procedures, including arterial injection and damage to closely related structures. Other more unusual treatments ¹² include traditional Chinese medicines, and manipulation with manual fracture, although this is reported as rarely of benefit, and has significant associated risks.

Surgical resection is the only definite treatment; ¹³ this may be by an intra-oral or extra-oral approach, depending upon the surgical assessment and experience. The extra-oral approach gives a wider view to assess local structures, and greater access to the stylohyoid ligament if involved, as in these cases. ¹⁴ Given the location, there are significant risks associated with surgery, and a 20% chance of subsequent problems from scar formation; the extra-oral approach also reduces the chance of deep cervical infection. ¹⁵ Surgical outcomes vary; however, patients undergoing styloidectomy may achieve a success rate of up to 80%. ³

Conclusion

Eagle’s syndrome is uncommon, and a difficult condition to diagnose, with involvement from multiple specialists. In the cases presented, diagnosis was made in pain clinic after several years of difficulty with chronic pain. Due to the wide range of patients seen, the ability to diagnose conditions in pain clinic is important to plan effective treatment. It is clear that a number of specialists need to have awareness of this syndrome (pain, ENT, vascular) to allow for effective diagnosis and management due to the wide range of symptom presentation. Good relations with other specialists should ensure optimal outcome for patients. There are no clearly defined diagnostic criteria for classification of Eagle’s syndrome in current use. 3D CT scan is highly beneficial to understanding the anatomical relationship of structures especially when undergoing surgical resection.