Whale Oil blogger Cameron Slater suffered a stroke in October last year, according to a post on his blog.
It left him "partially paralysed down his right side and totally paralysed in his right arm", and caused "severe impairment in higher order functioning and moderate speech impairment".
Mr Slater had not posted on the notorious right-wing blog he founded since October.
"Cam cannot concentrate, read or take phone calls for more than 10 or 15 minutes a day," the post by a staff member said.
"He cannot cope with loud noises, background noises or being interrupted and he certainly does not have the ability to form complex thought structures. The vision in Cam's right eye has also been affected."
The post blamed "stress", claiming Mr Slater was previously "fit and healthy with no predisposing stroke factors".
In a separate post, a Whale Oil staff member said Mr Slater's stroke was of the ischemic variety. According to WebMD, ischemic strokes happen either when a fatty deposit in an artery breaks off and travels to the brain, or poor blood flow caused by an irregular heartbeat results in a clot.
Mr Slater reportedly suffered a second, unspecified medical event a day after being discharged from hospital, allegedly brought on by stress caused by an unnamed reporter's attempt to access his medical records.
The blog post ends with a plea for financial help, as Mr Slater faces defamation proceedings resulting from Nicky Hager's 2014 book Dirty Politics.