A leading consultant has warned plans to keep neurosurgery services in Swansea and Cardiff are a "disaster".
Two neurosurgery units will be kept running in south Wales
An expert report from Health Commission Wales recommended one site for brain surgery in south Wales based in Cardiff.
But Health Minister Edwina Hart has now announced she would keep the unit at Morriston Hospital in Swansea as well.
Consultant neurosurgeon Richard Hatfield said the move was detrimental to the needs of patients and staff.
Mr Hatfield, who works at University Hospital Wales Cardiff, said he thought it was "very bad news".
"We have two units which are non-viable in today's terms and to try and keep them both open will mean that it's almost certain that eventually, both will fail," he said.
Protesters have held marches opposed to the closure of Morriston
"The failure to organise neurosurgery on a proper footing now will mean that it will have no long-term future."
He said politicians were not prepared to face reality and consolidate services because it would be "a very unpopular decision".
"Mainstream neurosurgery has to be consolidated in bigger centres because you do not have the critical mass in a small centre to provide a safe, effective service."
He added that there was a "real risk" the decision could result in the loss of all neurosurgery from south Wales.
Neurosurgery treats disorders of the nervous system including diseases of the head, brain and spine.
Currently, adult neurosurgery is performed in both Cardiff and Swansea.
Swansea previously lost its child neurosurgery operations to Cardiff in November 2004.
The plans to centralise neurosurgery in Cardiff were announced in 2006 after a Health Commission Wales report.
Dr Gibbons delayed the decision when he was health minister
Since the overall move to Cardiff was proposed a year ago, a high profile campaign of opposition has been underway in Swansea and more than 100,000 people signed a petition opposing the change.
In October, five AMs from south west Wales constituencies wrote to the then health minister Brian Gibbons asking him to consider other factors before moving neurosurgery between the two cities.
In November, Dr Gibbons then decided to delay the controversial decision until after the assembly election.
Elin Ifan from the Wales Neurological Alliance, an umbrella group that represents patients, warned that south Wales did not have big enough a population to sustain two specialist centres for neurosurgery.