Dianne Feinstein, a Democratic senator from California, returned to the Capitol after spending more than two months recovering from shingles. The disease, often characterized by a painful rash, is triggered by the same virus that causes chickenpox, which stays in people’s bodies for life and, years later, can reactivate.
For Ms Feinstein, 89, the virus has also caused a previously unreported case of encephalitis, a rare but potentially debilitating complication in which the brain swells. The condition 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 serious cases. A French study last year examining several dozen critically ill patients with the disease, about one-fifth of them were severely disabled a year after hospitalization and one-third had died.
A separate study in Denmark from 2020 found that about half of patients with post-zoster encephalitis admitted to hospitals were at least moderately disabled three months after discharge.
How common is the condition?
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 patients with shingles develop encephalitis.
But precise rates, he said, were hard to pin down: 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 always 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?
It’s not entirely clear why some shingles patients who develop encephalitis fare better or worse with the disease. Advanced age seems to put people at increased risk for more serious problems.
But published case studies have described even younger patients who show signs of cognitive recovery, only to deteriorate again.
“You may have symptoms that last after the 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 her shingles had spread to her face and neck, which is known to put patients at risk of brain inflammation.
If not, how can shingles affect people’s cognition?
Inflammation alone can damage brain cells.
But shingles can 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 in cognition.
According to a study led by Dr. Curhan published last year.
Mrs. Feinstein had received a shingles vaccine, which in most people offers strong protection against the virus and the complications that may follow. Federal health officials recommend the vaccine for people 50 and over and young adults with weakened immune systems.