Actor Julian Hee, 39, suffered a skull fracture after he was allegedly assaulted by a motorist following a spat at the Old Airport Road Hawker Centre on Wednesday.
Mr Hee, who is under observation at Mount Elizabeth Hospital Orchard, said he intends to press charges against the man.
He said over the phone: "If the injury worsens, I may have facial palsy and paralysis, like a stroke... I'm also on anti-epilepsy medication because of a blood clot in my brain."
He claimed that the blows caused him to black out for about 45 minutes and he woke up with a bruised face. The police were called in.
He said: "The only thing I remembered doing is grabbing onto his shirt and trying to push him away. That's when he rained his fists on me, on my neck, my head, I think, because I have a lot of bruises on my face. My teeth are chipped.
"I'm also bothered by the fact he went for lunch after assaulting me, according to an eyewitness, while I was on the ground."
Mr Hee recounted the incident on Facebook yesterday. He wrote that a man had opened his car door, which knocked Mr Hee's car so hard that the "whole car shook". He got out of his car and confronted the man and things turned ugly.
"I went down and said, 'Come on, be careful when you open your door'. He beckoned me to go over to the side to check if there were any dents on my car. I saw a dent on the car door and pointed it out to him. The man said the position of the dent shows that it could not have been caused by his car door. He started to call me names and got very aggressive."
The actor said he is now unsure whether the dent was caused by the other man. He said: "The car is a small issue, but the violence that he used is unforgivable."
Police investigations are ongoing.