The Conservative PM’s comment about the Labour shadow chancellor caused anger among disability campaigners.
Cameron said: “He (Balls) just annoys me – I don’t really hate anyone in life.
“But I’m very bad, in the House of Commons, at not getting distracted, and the endless, ceaseless banter, it’s like having someone with Tourette’s permanently sitting opposite you. I’ve got to learn to tune it out.”
Tourette Syndrome is a genetic neurological condition that causes tics and involuntary sounds and movements.
Around 300,000 people in the UK have Tourette Syndrome.
Campaigner Nicky Clark, whose daughter has the disorder said his comment showed “an utter disregard for the condition and a lack of understanding from our prime minister.”
She said: “If we’re supposed to look to him as some kind of lead, is this the best we can expect and disabled people expect?”
Former deputy prime minister John Prescott said the remark was “another example of his poor judgement”.
The prime minister apologised, saying: “I was speaking off the cuff, and if I offended anyone of course I am very sorry about that. That wasn’t my intention at all.
“But I think probably it’s a lesson for me that in the Commons I have to try and tune out the noise that’s coming and just concentrate on trying to answer the question.”
Cameron’s oldest child, Ivan, died in 2009, aged six, after suffering from cerebral palsy and severe epilepsy.
Last year, Cameron said Balls was one of the most annoying people in modern politics.
