The County Court ruled that Dr Kyriacou was not capable of giving evidence or briefing his lawyer after independent neurological testing confirmed he suffered from cognitive impairment.
The Office of Public Prosecutions has told the alleged victims that a special hearing in the County Court can make only a qualified finding of guilt that does not amount to a conviction.
Dr Kyriacou is unlikely to be jailed if found responsible,but could be sent for supervision at Thomas Embling Hospital.
The former GP faces 34 charges,including three of rape,related to 15 women who allege he sexually assaulted them between 1978 and 2004 while they were medically examined.
But at least 51 women have provided statements to detectives at Box Hill sexual offences and child abuse investigation team,who are expected to lay dozens of additional charges.
Dr Kyriacou worked for decades as a GP at a Barkers Road clinic until 2017,when he voluntarily withdrew from the register of medical practitioners while under investigation by the Australian Health Practitioner Regulation Agency.