Meeting chairman Dunedin Mayor Peter Chin said the issue was more than just a patch war, but a "fight for survival for all of us living here".
• Up to 10,000 in neurosurgery march
If the city lost neurosurgery, it could provide the precedent for other services being relocated.
He and his colleagues were delighted and overwhelmed by the response to the meeting, which had only been publicised since Tuesday.
At the end of the hour-long meeting, it was unanimously agreed, by acclamation, to send a message to Health Minister Tony Ryall, demanding he "retains the provision of safe, quality neurosurgical services based in Dunedin for the continuing wider benefit of the Otago and Southland region".
Among the messages read to the meeting was one from all four southern National MPs saying, in their view, on the information available, the needs of the people of Otago and Southland would be best served by the provision of a clinically robust and sustainable neurosurgery service based in Christchurch and Dunedin.
While MPs Michael Woodhouse, Eric Roy and Jacqui Dean have given clear support for a Dunedin service, it is the first time deputy prime minister and Clutha Southland MP Bill English has done so.
Earlier in the day, during parliamentary question time, Associate Health Minister Dr Jonathan Coleman, speaking for Mr Ryall, said he would take "a lot of convincing that there shouldn't be neurosurgery services in Dunedin".
In a message to the meeting, Mr Ryall encouraged people to await the advice of the independent panel, set up to advise the Director-general of Health.
Otago Daily Times editor Murray Kirkness said the 67-year-old service had literally meant the difference between life and death for many people.
"This is about my children, your mother, your cousin, your neighbours, your friends."
He noted the overwhelming response to the newspaper's campaign and the support of competing media, including More FM and The Southland Times.
Several speakers drew spontaneous applause, including Dunedin Hospital chief medical officer Richard Bunton when he said he agreed the service must be safe and sustainable, but this had been done in Dunedin for 67 years and "I don't see why that shouldn't continue".
It defied logic to change a service to 300,000 people in the South so that clinical safety was compromised, level of service reduced and the cost increased.
Otago Regional Council deputy chairman Stephen Woodhead also drew applause when he spoke of his family's experience when his youngest brother died, aged 8, of a brain tumour in the 1970s.
He referred to the cost for families if they had to go to Christchurch, describing the proposal as "just plain dumb".
Clutha Mayor Juno Hayes spoke of the extra 19 years his mother, who lived in Milton, had after undergoing treatment for an aneurism, an outcome which would not have been possible had she had to go to Christchurch.
He led the crowd in a chant - "Will they hear our views?", to which the crowd replied "Yes they will".
Southern District Health Board chairman Errol Millar outlined the background to the issue and said it had been a difficult exercise for him as "I get it from all sides".
He thanked people for the "outpouring of support", something he had not seen previously.
Southern board chief executive Brian Rousseau said the panel had to be given the opportunity to look at the matter carefully.
He had had preliminary discussions with chairwoman Anne Kolbe and, while he was not "overly confident", he was optimistic a sensible solution would prevail.
Clinicians from all South Island district health boards would have to work together to reach a solution, he said.
He was one of several speakers who referred to the impact of health services on the local economy and warned of the effect withdrawing neurosurgery services could have on the hospital and the university.
Labour MP David Parker, representing fellow Labour MPs, was one of the speakers who had a family member experience the Dunedin service.
He was applauded when he praised Mr Rousseau for his "very brave decision" to appoint two neurosurgeons, both expected to arrive next year.
He drew further applause when he said Dunedin was the education capital of New Zealand.
"We must fight for the strength of [Otago] university and medical school. I fear if anyone undermines them, it could be the tipping point for this city".
Green Party co-leader Metiria Turei, in a message read to the meeting, said the party supported the campaign.
• Others who addressed the meeting were Waitaki Mayor Alex Familton, Central Otago Mayor Dr Malcolm Macpherson, Gore deputy mayor Cliff Bolger, Invercargill city councillor Jacki Kruger, Southland district councillor Wallace Jack and Environment Southland chairman Stuart Collie.
