Shingles may raise risk of stroke

8^th October, 2009 -- Adults with shingles are at increased risk of suffering a stroke, especially if they have shingles that affects the eyes, a study shows.

The study is not the first to show an elevated stroke risk associated with shingles, but it is the first to quantify the risk, researchers say.

Compared to adults without shingles, those with the painful skin rash were about 30% more likely to suffer a stroke within a year of the attack. Patients who had shingles in and around an eye had four times the risk of stroke in the year following the episode.

"If a person is already at risk of stroke, they should be aware that their risk may be higher if they have had shingles," says researcher Dr Jiunn-Horng Kang.

Also known as herpes zoster, shingles is caused by the varicella-zoster virus (VZV), the same virus that causes chickenpox.

Anyone who has had chickenpox in childhood can develop shingles at some point in their lives.

In many people, the virus remains dormant in nerves, but in some, especially older people and those with compromised immune systems, it can reactivate as shingles.

The reawakened virus initially causes numbness, itching, severe pain and even fever, headaches, and chills, followed by the blistering rash characteristic of shingles. The skin rash usually occurs within three to five days after symptoms begin.

Shingles can result in persistent pain lasting for months and even years after the rash has gone away.

The newly published study included nearly 8,000 adults treated for shingles between 1997 and 2001 and about 23,000 people matched for age and sex who had no history of shingles or stroke before 2001.

During the year following the shingles episode, 133 shingles patients (1.7%) and 306 people in the comparison group (1.3%) had strokes.

The shingles patients had a 31% increased risk of strokes of any kind and a nearly three times increased risk of haemorrhagic strokes.

Haemorrhagic strokes, caused by bleeding in the brain, are much less common than ischaemic strokes, which are caused by blocked arteries. Only about 10% to 15% of strokes involve brain bleeds.

Patients with shingles involving the skin around the eye and the eye itself were 4.28 times more likely to have a stroke than were people without shingles.

The study was published online today and will appear in the November issue of the American Heart Association journal Stroke.

Stress and inflammation may play a role

Varicella zoster virus-related blood vessel damage has been linked to stroke after shingles attacks, but this did not fully explain the high stroke risk seen in the study, say the researchers.

They added that the stress associated with shingles and the intense pain that can occur with outbreaks and following them could play a role, as could the inflammation that occurs with shingles outbreaks.

Commenting on the study online, experts at NHS Choices say that there may indeed be a link between shingles in adults and stroke but “more robust research” is needed to confirm the link. It points to shortcomings in the research around other factors which could have influenced the results, such as other underlying medical conditions.

Early, aggressive treatment with antiviral drugs can lessen the length and severity of shingles attacks.

Dr Kang says it remains to be seen if aggressive antiviral treatment can also lower stroke risk.

"This is a question we need to study," he says.