United Kingdom, May 25 -- Christie Brinkley has sent her ex-husband Billy Joel well-wishes amid his battle with a brain disorder.

The 71-year-old model - who has daughter Alexa Ray Joel, 39, with the 'Uptown Girl' hitmaker - hopes her former spouse has a "full and speedy recovery" and is able to return to the stage, after he was diagnosed with Normal Pressure Hydrocephalus, which has caused problems with his hearing, vision and balance.

In a touching post, Christie penned on Instagram alongside a video of the family at a recent concert: "Dear Billy ,The whole Brinkley gang is sending you lots of love and good wishes for a full and speedy recovery . I was looking for some cute photos of you and Alexa to send you, when I came across this ...