Giant cell arteritis (GCA) is a nasty inflammatory disorder that affects the large arteries. Because it characteristically involves the temporal artery, this form of vasculitis is also referred to as temporal arteritis. It usually affects people over the age of 50 years and manifests with sudden onset headache, scalp pain, and a thick, tender temporal artery. GCA is often accompanied by polymyalgia rheumatica (PMR) , a painful condition of the joints and muscles. The active systemic inflammation in GCA is often detected by the erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) tests. These distinguishing features constitute most of the diagnostic criteria for GCA.
Most people with GCA however do not have all the ‘classical’ features of the disease. A high index of suspicion is therefore required to sniff out the duplicitous miscreant. It is particularly imperative to make the diagnosis as early as possible to prevent the dreaded complications of GCA, sudden blindness and stroke. The treatment of GCA, implemented according to established treatment guidelines, involves several months of oral steroids, drugs which cause immune suppression and a host of other side effects. It is therefore essential that the diagnosis of GCA is made correctly to avoid putting the patient on a long, risky, and unnecessary treatment.
What then is the value of the temporal artery biopsy in the diagnosis of GCA? This is the question posed by Bowling et al in their incisive paper titled Temporal artery biopsy in the diagnosis of giant cell arteritis: does the end justify the means?They reviewed 129 temporal artery biopsies and found that the clinical diagnosis of GCA was confirmed in only 13% of cases. Furthermore, the outcome of the biopsy rarely ever influenced the treatment; 87% of those with a normal biopsy result still continued their treatment. The miffed authors therefore rhetorically, and indignantly, asked: “can we justify invasive surgery to all patients on histological grounds when the results may not alter management?”
This is an entirely reasonable question especially because there are other more accurate and less invasive ways of establishing the diagnosis of GCA. These include:
But the answer to the authors’ rhetorical question is anyones guess. It is a sad tradition of medicine that studies such as these take ages to change practice. Indeed I predict the the temporal artery biopsy will sidestep this minor hurdle and simply continue its long and agonising reign. Despair!