New information regarding the health of an elderly U.S. senator is raising questions about her continued service in Congress.

A representative for Sen. Dianne Feinstein confirmed that the senator's recent health-related absence from the Senate was more serious than previously thought on Thursday, responding to inquiry from The New York Times.

Feinstein returned to Washington after a two-month medical leave earlier this month to receive treatment for shingles.

Feinstein's representative disclosed that the 89-year-old Democrat experienced the shingles complication of encephalitis during her absence.

The rare condition can affect the mental state of those who suffer from it; causing memory problems, confusion, and difficulty walking, according to the Times.

Feinstein also experienced a shingles complication known as Ramsay Hunt syndrome.

The condition can cause facial, balance and vision impairments.

Feinstein's health and fitness for service in the Senate has been scrutinized since her return.

The 30-year veteran of the Senate has returned to the chamber in a wheelchair.

Dianne Feinstein, 89, has returned to the US Senate for the first time since she got shingles in February. pic.twitter.com/i1SRlTwepC

— Citizen Free Press (@CitizenFreePres) May 10, 2023

At times, she's been overheard speaking of continuing medical issues with her eyes, according to the Times.

Feinstein appeared unaware of her own absence from the Senate in one conversation.

“No, I’ve been here. I’ve been voting," the California Democrat said in response to a question about working from home upon her return, according to The Hill.

Feinstein's office rebuffed concerns over her health in a statement provided to the Times.

“I’m back in Washington, voting and attending committee meetings while I recover from complications related to a shingles diagnosis. I continue to work and get results for California.”

Figures from within Feinstein's own party have called for her resignation, questioning her ability to perform the vigorous duties of a United States senator while in need of continuing medical care.

Because Senator Feinstein was absent, the Senate overturned a Biden rule that would cut pollution from heavy duty trucks and causes harm to people’s lungs. We are putting decorum over democracy and our values. It’s time for Senator Feinstein to step down gracefully. https://t.co/qmNsJO671a

— Ro Khanna (@RoKhanna) April 27, 2023

Feinstein's cognitive acuity had already come into question before her February absence from the Senate.

She's the oldest member of Congress, and announced she wouldn't be running for re-election in 2024 earlier this year.

This article appeared originally on The Western Journal.