The chewing gum test that could prevent blindness and save lives

GCA is caused by inflammation of the lining of arteries in the head, most commonly in the temples, which restricts arterial blood flow. Symptoms can include headaches, scalp tenderness, jaw pain and vision problems. GCA is most commonly observed among people aged 50 and older.

The condition can be hard to diagnose because early symptoms are often subtle and found in a range of other diseases. For example, claudication of the jaw muscles (cramping pain caused by inadequate arterial blood flow) is a specific indicator of GCA, but there is no current clinical test to differentiate it from other causes of jaw pain. GCA patients with jaw claudication have a higher risk of permanent visual loss, but this symptom isn’t commonly reported because many people favour soft food as they age.

Save Sight Institute researchers have developed a straightforward ‘chewing gum’ test designed to unmask this important jaw symptom. By chewing gum at a rate of one chew per second the test can reproduce a patient’s telltale pain, prompting further investigation with a blood test and an arterial biopsy to confirm diagnosis.

In a letter published in this month’s New England Journal of Medicine, researchers presented two cases where the chewing gum test allowed clinicians to better characterise jaw pain, confirm a diagnosis and successfully treat both patients.

“GCA is one of the most common causes of blindness in older people,” says Dr Peter McCluskey, Director of the Save Sight Institute and a professor of clinical ophthalmology at the University of Sydney. “Not only can it send you blind, but it can kill you. It also can affect vision extremely quickly. If one eye is already involved, around one third of people go blind in the other eye within a day, another third within a week and the remaining third within a month. It’s a very serious condition which requires rapid and correct diagnosis.”

The research team is doing further research to validate the chewing gum test, and will incorporate dentistry, rheumatology and nuclear medicine specialist researchers.

Fast facts: factors can raise the risk of developing giant cell arteritis

• Age: Giant cell arteritis affects adults only, and rarely those under 50. Most people with this condition first experience warning signs between the ages of 70 and 80
• Sex: Women are about twice as likely to develop the condition than men
• Race and geographic region: Giant cell arteritis is most common among white-skinned people from northern Europe
• Polymyalgia rheumatic: Having polymyalgia rheumatica puts you at increased risk of developing giant cell arteritis
• Family history: The condition sometimes runs in families.