What to know about post-shingles encephalitis

Senator Dianne Feinstein developed this rare and potentially debilitating complication after a shingles infection.

For Ms Feinstein, 89, the virus also caused a previously unheard-of case of encephalitis, a rare but potentially debilitating complication in which the brain swells. The disease is often caused by an infection or an immune response.

What are the symptoms of encephalitis?

Post-shingles encephalitis can cause headaches, fever, sensitivity to light, vomiting, confusion, stiff neck or even seizures.

It can also leave some patients with more lasting problems. These include memory or language disturbances, sleep disturbances, mood disturbances, difficulty walking, and other cognitive problems. Older patients tend to have the hardest time recovering.

There are milder and more severe cases. A French study last year of several dozen critically ill patients with the disease found that around a fifth of them were severely disabled a year after hospitalization and a third had died.

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A separate study in Denmark from 2020 found that around half of patients with post-zoster encephalitis admitted to hospital were at least moderately disabled three months after their discharge.

How common is the disease?

Dr. Adrien Mirouse, a doctor and immunologist based at Sorbonne University in Paris, who led the French study last year, estimated that less than 1% of shingles patients develop encephalitis.

< p class="css-at9mc1 evys1bk0 "> But precise rates, he said, were hard to pinpoint: less severe cases often go unreported, making it difficult to know the true number of patients with shingles or post-shingles encephalitis.

Brain swelling has historically been thought to primarily affect shingles patients with immune deficiencies. But recent studies have shown that many patients are simply older and struggling with a systematic weakening of their immune system. For this reason, the condition may be increasingly common as populations age, experts said.

What is the outlook for patients?

There is no It's not entirely clear why some shingles patients who develop encephalitis fare better or worse with the disease. Advanced age appears to put people at increased risk for more serious problems.

But published case studies have described even younger patients who show signs of recovery of their cognitive functions, only to deteriorate again.

"You may have symptoms that last after encephalitis," Dr. Mirouse said of the patients. "It's not sure that you can fully recover. It's true at 89, it's also true at 30 or 20."

Ms. Feinstein may have been at higher risk of developing encephalitis because his shingles had spread to his face and neck, which is known to put patients at risk for brain inflammation.

How the can shingles affect people's cognition?

Inflammation alone can damage brain cells.

But shingles may also contribute to cognitive decline in other ways, including by damaging blood vessels in the brain, said Dr. Sharon E. Curhan, a physician and epidemiologist at Brigham and Women's Hospital and Harvard Medical School who studies the link between shingles and changes...