Martin MacFarlane, in a presentation delivered in Christchurch to interested clinicians and the expert panel considering the future of neurosurgery services, gave some information on the services since 1979.
The slides he displayed were released to the Otago Daily Times.
It requested them after being advised that the speech, given on September 3, the day before the earthquake, would be closed to the public.
The last of his 24 slides, entitled "Neurosurgery for the South Island - the Future", referred to one service, one site at Christchurch.
Mr MacFarlane also lists the one-site model as providing services to international standards for the people of the South Island, having funding advantages for both high-technology equipment and employing staff.
It would attract appropriately-trained staff, allow for subspecialisation and succession planning.
One slide outlining New Zealand neurosurgeon numbers lists Christchurch as having four, plus one in private practice, and there being none in Dunedin, where it says sole locums are used.
The Southern board recently advised it would have two locums by the end of last month.
The board has also signed up two permanent neurosurgeons expected to start next year.
In a section from a 1998 discussion document on services in the South Island, Mr MacFarlane quoted two former Dunedin neurosurgeons saying in 1996 and 1997 at Dunedin Hospital there were between six and 10 cases annually requiring urgent neurosurgical intervention.
Of these, fewer than half were from the Dunedin area, with surgical stabilisation already performed in some cases in Invercargill by general surgeons prior to transfer to Dunedin.
In his brief review of the 10 reports on neurosurgery services, he included reference to then Minister of Health George Gair saying in 1979 when the decision to start the Christchurch unit was made that the Dunedin unit would function week-to-week with neurosurgeons not replaced when they retired.
Mr Macfarlane was the Christchurch foundation neurosurgeon, appointed in 1981.
The unit is now the second largest neurosurgical unit in New Zealand.
He also highlighted a section in a Ministry of Health 1995 report which said that fewer than three neurosurgeons in a unit "may reduce quality outcomes".
Centres that met the quality criteria but had fewer than three neurosurgeons might be at serious risk of compromised quality if there were changes of key staff, particularly neurosurgeons.
The planning report, presented last June by the chairman of the South Island neurosurgical services working party Prof Spencer Beasley, says a single service with three neurosurgeons in Dunedin and Christchurch would mean neither unit would be viable in the longer term.
It suggests that recruitment could prove difficult because of insufficient work. In a covering email releasing Mr MacFarlane's Power Point presentation, Canterbury District Health Board chief executive David Meates said 58 neurosurgical operations were carried out by the Canterbury clinicians on Southern patients last year, something which had been a regular service for some years.
Among the neurosurgery treatment provided in Canterbury is that for child cancer patients.
Mr Meates said an outreach service was of critical importance to all populations in the South Island including South Canterbury, West Coast and Nelson Marlborough.
About two-thirds of Nelson-Marlborough neurosurgery patients go to Canterbury, with acute cases mostly going to Wellington, where air travel time is shorter.
In Timaru, outpatient clinics were offered from Dunedin.
Under the one-site proposal all surgery would be carried out in Christchurch, with outpatient clinics offered at Dunedin, Invercargill and Nelson.
Mr MacFarlane, in comments in the Beasley report, does not support elective surgery at Dunedin because of the complex nature of much of the work and the need for "close peri-operative consultant supervision".
In an email comment included in the report, one of the Canterbury neurosurgeons, Ronale Boet, says he is not in favour of multiple outreach clinics and would not be keen to "travel all over the South Island to do these clinics".
He thought the service should be centralised in Christchurch.
Mr Boet practises in both the private and public setting and one of his specialties is coiling (a procedure for sealing aneurysms), something not available in Dunedin.