Recognizing giant cell arteritis in dental practice

Pathology, applied anatomy and clinical features

GCA commonly affects the external carotid branches and the subclavian arteries. The inflammation of the arterial wall starts in the outermost layer, the tunica adventitia and works its way past the intermediate layer, tunica media, into the innermost tunica intima. The resultant swelling of the arterial wall reduces luminal size, makes the endothelium more prone to thrombosis and produces distal ischaemia.

The constitutional symptoms are a general feature of the inflammatory burden of the disease. More inflamed tissue often equates to more severe non-specific symptoms. In addition, specific arterial territory involvement can result in different symptoms (Table 1). The presence of dental and jaw pain may cause the individual to seek help from their dentist. In one UK series, 59/318 (19%) individuals with GCA had toothache at diagnosis.² In the same study, 143/318 (45%) individuals with GCA had difficulty in chewing.² The muscles of mastication, the pterygoids and the masseter, are all nourished by direct branches from the maxillary artery, as are the arteries to the teeth. Typically, the blood supply is enough to meet the resting needs of the muscles, but not when they are exercising. This causes the typical symptoms of jaw claudication.

Blindness occurs because of inflammation leading to narrowing, or occlusion, of the branches of the ophthalmic artery. The ophthalmic artery is a branch of the internal carotid artery, which enjoys rich anastomoses with the branches of the maxillary artery. Ophthalmic manifestations include diplopia (double-vision), anterior ischaemic optic neuropathy (optic nerve head infarct), and central retinal artery occlusion. This can cause severe and irreversible blindness that can affect one or both eyes, with 20–62% of patients eventually suffering from bilateral vision loss.⁶ Vision loss is most commonly caused by arteritic anterior ischaemic optic neuropathy, with oedema and pallor of the optic nerve head in the acute phase. Of patients with permanent vision loss, 8–28% report premonitory transient monocular vision loss lasting seconds that is most commonly caused by ocular ischaemia.⁶ This is termed ‘amaurosis fugax’, in which ‘amaurosis’ refers to blindness and ‘fugax’ means fleeting. Compared to embolic causes of amaurosis, GCA-induced amaurosis may present insidiously with much more frequent and shorter episodes.⁶ Diplopia is less common with GCA, tends to be transient, and may relate to ischaemia of cranial nerves or extra-ocular muscles, or even a brainstem stroke.^6,7 Involvement of the vertebral artery (a branch of the subclavian artery) can lead to posterior cerebral strokes, which can become life-threatening. The involvement of the subclavian artery and its branches is usually silent, but may be associated with symmetrical shoulder stiffness and pain.

Diagnosis

Diagnosis depends on pattern recognition, followed by appropriate investigations. An older person with symptoms, including new persistent headache, tenderness on brushing the hair, difficulty on eating ‘chewy’ foods such as meat or toast, a symmetrical difficulty in raising arms, having ‘flu-like’ symptoms including loss of appetite, low-grade fever, night sweats and weight loss, should raise suspicion of GCA. The superficial temporal arteries may be inflamed and tender. However, no single symptom or sign is pathognomonic for GCA, and it is important for a differential diagnosis to be considered because GCA commonly appears to present with symptoms that may be confused with local oral or dental issues. When GCA presents with dental symptoms, the commoner features include: jaw claudication resulting in jaw pain or discomfort while chewing that gradually worsens, or myofascial pain and odontogenic pain that may not resolve following extraction.^8,9,10

Differential diagnoses for jaw claudication include TMD, which affects 5–12% of the population with peak incidence in 20–40 year-olds.¹¹ TMD usually produces acute pain, particularly after a prolonged period of jaw opening or chewing, around the muscles of mastication with tenderness to palpation of the temporalis or masseter.¹¹ Other oral manifestations of GCA that have been identified in a review (from predominantly case reports) include trismus (a reduction in the opening of the mouth), submandibular mass and hypoaesthesia of the chin (numbness).⁹ Tongue and lip necrosis have been reported as rare manifestations of GCA. Case reports demonstrate severe tongue ulceration and necrosis that often present with multiple ischaemic sequelae of GCA.^12,13 This can cause significant morbidity, including dysarthria and dysphagia, which can be minimized with prompt initiation of steroid therapy. Indications of a developing ischaemic tongue include claudication, macroglossia, glossitis, cyanosis or blanching and dysgeusia.^12,13

On suspicion of GCA, an immediate review with the relevant secondary care team must be sought, with blood tests for markers of inflammation, including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Only 1–3% of individuals will have normal markers for inflammation at diagnosis.¹⁴

There is no gold standard test for the diagnosis of GCA. However, ultrasonography of the cranial and extra-cranial arteries is now taking over from biopsy as the first test of choice for making a diagnosis.¹⁵ Fast-track ultrasonographic examination in the first 7 days after commencing high-dose glucocorticoid therapy is more reliable than clinical judgement for making a diagnosis, saves vision and is cost-effective.^16,17,18 The presence of a concentric, hypoechoic thickening around a large artery is virtually diagnostic of GCA in the appropriate clinical context.¹⁹ In a proportion of individuals with GCA, the ultrasonography may be normal and a second diagnostic test may be required. This may either be a biopsy of the superficial temporal artery, or a positron emission tomograph (PET).¹⁵ Occasionally, PET scans may be helpful when there is diagnostic uncertainty or extra-cranial involvement of GCA that is not easily accessible through ultrasonography.²⁰ If a temporal artery biopsy is carried out, histological examination may demonstrate the characteristic finding of giant cells in the granulomatous inflammation at the intima-media junction. Histology may alternatively show a panarteritis with a predominantly lymphocytic infiltrate.²¹

Management

Suspected GCA is a medical emergency. Urgent diagnosis and treatment should minimize the risk of visual loss or stroke. International guidelines recommend that individuals with suspected GCA should be assessed within 3 working days.^1,22 Patients who have already lost some vision should be treated as an emergency. Evaluation may be with any specialty that has an expertise in GCA. One approach is that individuals with visual symptoms are seen by the ophthalmology team and those without are assessed by the rheumatology team. Most dental practices have established referral pathways with their local maxillofacial surgery department, but not with the ophthalmology or rheumatology departments. Dental practitioners in the community are not expected to commence high-dose glucocorticoid treatment, or arrange investigations. However, the act of an assertive referral by a dentist, along a GCA pathway (see Figure 1) may reap long-lasting rewards for their patient.

Individuals with suspected GCA should be commenced on high-dose glucocorticoid (eg prednisolone) treatment without delay by the appropriate secondary care team. The only prerequisite to starting glucocorticoid treatment is to collect blood for the checking of C-reactive protein, it is not necessary to wait for the results. This may not be possible in a dental practice and therefore, it is imperative to establish urgent referral pathways to avoid delays. Further investigations may also be necessary to look for alternative causes, as recommended by specialist society recommendations.^1,22

Once diagnosis of GCA is established, glucocorticoid therapy should be started. The dose should be tailored according to gender, body size, and if possible, disease extent.²³ This may not always be possible and in most individuals, practically, a dose of oral prednisolone between 40 mg and 60 mg daily suffices to induce remission. The usual duration of prednisolone therapy is about 2 years, although in approximately 10% of individuals, 6 months of prednisolone is enough to cause sustained drug-free remission.^23,24 For individuals in whom there is relapse, there is evidence that the addition of additional immunosuppression in the form of methotrexate or tocilizumab reduces the risk of future relapse, reduces the cumulative exposure to glucocorticoids and can affect long-term drug-free remission.^24,25

Medicolegal considerations

Case reports demonstrate significant morbidity associated with a delayed diagnosis of GCA in patients presenting initially to the dentist with orofacial pain. In one case, the patient presented to the GDP with ongoing orofacial pain and developed blindness in both eyes 3 weeks following undiagnosed GCA.²⁶ In another case, the patient underwent dental extraction, without resolution of facial pain, until GCA was diagnosed 2 weeks later.⁸

It is reasonable for patients to expect their dentist to be able to recognize signs and symptoms that would warrant further assessment for suspected GCA. The General Dental Council (GDC) Standards for the Dental Team highlights in standard 1.4 that professionals ‘must take a holistic and preventative approach to patient care’ and, ‘a holistic approach means you must take account of patients' overall health, their psychological and social needs, their long-term oral health needs and their desired outcomes’.²⁷ Furthermore, while it is not in a dentist's remit to commence treatment for GCA in the community, it is expected that a timely and clear referral is made to the relevant clinicians in accordance with the GDC recommendations for referral.²⁷ Depending on the circumstance, this might mean an urgent referral to the patient's general medical practitioner, to the hospital rheumatology or ophthalmology, or to accident and emergency.

Conclusions

GCA is a rare inflammatory condition, although all GDPs should expect to see a few cases in their career. Classic presentation is of an older person with non-specific headache, loss of appetite, weight loss, and feeling unwell. Symptoms, such as toothache and difficulty in chewing, may cause individuals with GCA to first present to the dentist. Early recognition may help to prevent catastrophic complications, such as loss of vision, tongue necrosis and stroke. The hospital specialist should treat GCA promptly with glucocorticoid therapy, usually in the form of prednisolone. GCA is a chronic condition that requires long-term immunosuppression and multidisciplinary input. Early diagnosis (and treatment) should prevent blindness or other serious sequelae. Therefore, GDPs should be aware of the condition, and should refer any case of suspected GCA urgently to a hospital specialist.