Recruited to lead Dunedin neurosurgery after a huge public outcry when the service was nearly lost, Prof De Ridder brought world-leading research, as well as ensuring neurosurgery was provided in Dunedin Hospital.
He arrived in early 2013.
His research includes inserting electrodes into the brain to treat alcohol addiction, and brain stimulation techniques to cure tinnitus.
Uncertainty has surrounded high-level specialties in Dunedin since Health Minister Jonathan Coleman replaced board members in June with commissioner Kathy Grant.
Mrs Grant and her deputies are charged with creating a long-term plan for health services, but no-one has spelled out what this could look like.
It is understood neurosurgery is unlikely to be cut because the furore is still fresh in the minds of politicians and senior officials.
Up to 10,000 people marched in Dunedin to save the service on August 6, 2010, and then the public raised $3 million to fund the Chair in Neurosurgery.
However, lack of information has led to speculation about the future of some services.
Prof De Ridder told the Otago Daily Times this week he planned to stay put regardless of the future of clinical neurosurgery in Dunedin, as his research will keep him in the city.
The lack of certainty was not good for the unit and the other two neurosurgeons.
''If they can [provide certainty], that would settle down the restlessness which is now present in the unit.
''You don't want this uncertainty to last too long.
''If somebody doesn't tolerate the uncertainty and leaves, it's difficult to replace them.
''People can tolerate a yes or a no answer better, because you can make some decisions for the future organisation of your life and your family,'' he said.
Other neurosurgeons were asking the Dunedin surgeons about the unit's future.
''If the clinic decides to stop, then of course all of us have to look for a Plan B, what to do if all of a sudden we would be out of a clinical job.''
If necessary, he would travel to another centre for clinical work, while remaining based in Dunedin.
New Zealand needed to figure out how to provide neurosurgery for the long term and in how many centres, he said.
Deputy commissioner Richard Thomson, who took a leading role in the neurosurgery campaign, said Prof De Ridder was a ''world-class'' appointment.
''He clearly gives kudos. He is a world-class neurosurgeon and he's clearly really important to the university and to the neurosurgery programme.
''We don't want to leave him or indeed anybody else in suspense, but equally we don't want to create a problem that isn't actually there in the first place.''
He suggested neurosurgery's special structure as a South Island service with Christchurch and Dunedin surgeons working together might help protect its future.
It is the kind of set-up that might be put in place in other clinical services, although Mr Thomson said that was not necessarily the case.
However, ''If you were looking to apply a regional service to more than one site, then it's important that this model be given every chance to succeed.
''If it were to fall over for whatever reason, it would make it more difficult to implement other such models [on a South Island basis].''
He acknowledged frustration over the lack of information, but the commissioner team had not worked through the issues yet.
''We get it that uncertainty is not what we want, but it would be much worse to come out and make stupid statements that you have to retract.
''I can't say with absolute certainty anything about anything at the moment.
''The problem is that when you say that, it's interpreted potentially as meaning that it might [change] when, in fact, it's saying I can't say anything with any certainty about anything.''
Neurosurgery timeline
2010: The South retains service after protest and public meetings.
2012: $3 million raised to endow top academic neurosurgery position.
2012: Dirk De Ridder appointed to Chair in Neurosurgery.
2013: Prof De Ridder arrives to lead Dunedin clinical and research neurosurgery.
2015: Commissioner regime creates uncertainty around high-level specialties.
