Madonna's brother Christopher Ciccone knows he will reunite with his superstar sister, but he's terrified it won't happen until the funeral of their beloved grandmother Elsie Fortin.

Elsie, who is 99-years-old, helped raised Christopher and Madonna after their mother died when they were young.

But since Christopher wrote his best selling tell-all book, Life With My Sister Madonna, in 2008, the once inseparable siblings have not spoken to each other.

"The only contact I have had with my Madonna is via e-mail when I try to keep her up-dated about our family, but often she does not respond, and if she does it is through somebody else," Christopher told Breaking Celebrity News in an exclusive new interview.

"It could take my grandmother's passing for us to meet again, but one way or another I know it will happen."

He added: "I'm praying that my grandmother makes it to 100, but I know she is frail now... she is a remarkable person who raised my brothers and sisters and is very important to our family."