Moss was staying at the Ritz Carlton in Paris when she discovered she had lost all feeling in the limb.
A source said: “Kate was at the Ritz when she woke and had no feeling in her arm, which was terrifying. She saw the hotel’s doctor and when she came back, she got a second opinion.
“She has told her friends she has ulnar nerve entrapment, a common disorder that can result in a temporary paralysis.
“Her hand is not paralysed or injured in any permanent way.”
Moss is sufferning from a condition called ulnar nerve entrapment, say reports.
This comes just as the runway superstar, 38, is set to move into a new £7.25 million home in Highgate with her husband Jamie Hince, 43.
The pair have built a state of the art gym at the new home, along with a marble wetroom and sauna and a huge Turkish steam bath with Jacuzzi.
The source added: “Jamie will do most of the unpacking as Kate has been in a lot of pain. She was told the condition could take months to heal. She has told all her friends about her hospital drama.”
Kate has postponed a planned housewarming party until she has recovered fully.