Yves Coderre, the director of operations at the emergency services company which sent the medics to Mont Tremblant in Montreal, told the Globe and Mail, a Canadian newspaper, on Wednesday that ski patrollers requested an ambulance after Richardson had fallen.
Coderre said the medical workers apparently responded but when they arrived they were told they were not needed.
Victims of head trauma often believe they are fine, a mistake
that can cost them their lives, said Coderre.
After developing a headache about an hour later, another ambulance was called to Richardson's hotel which took her to a hospital in Montreal. She was later transferred to New York where her family gathered.
Richardson had established an eclectic career in film, TV and theatre.
She first drew attention in 1986 at the age of 23 with an appearance opposite her mother, Vanessa Redgrave, in Chekhov’s The Seagull, receiving the London Drama Critic's Circle award as most promising newcomer.
In 1998, she received a Tony award for her leading role as Sally Bowles in the Broadway production of Cabaret.
The British actress made her first major film appearance as Mary Shelley in Ken Russell's 1986 film Gothic.
Richardson's performances thereon ranged from high-brow drama to lightweight comedy, starring in films such as Maid in Manhattan and Asylum.
The Wild Child, her latest film, premiered in August 2008.
Besides her lifetime of achievement, Richardson leaves behind her husband, Liam Neeson, an Irish actor, and their two sons.
Richardson also helped raise millions of dollars in the fight against Aids, a disease which killed her father Tony Richardson in 1991.