Sen. Dianne Feinstein suffered additional health complications from her months-long battle with shingles that kept her away from Capitol Hill, raising fresh questions about her ability to continue serving in Congress.

The New York Times reported Thursday that Feinstein, 89, suffered impaired vision and balance as a result of the illness, as well as facial paralysis known as Ramsay Hunt syndrome. The shingles also reportedly brought on a rare case of encephalitis, which causes the brain to swell and can affect language skills, sleep and mood.