The Belfast Trust is still searching for 300 patients who have been caught up in the controversy surrounding neurologist Dr Michael Watt.
Last week, Trust officials announced a recall of more than 2,500 patients treated by the consultant - the biggest recall of its kind in Northern Ireland.
It is holding special clinics over the coming weeks to see all of the patients concerned.
Some are thought to be as young as 14.
The Trust said that while 2,264 patients have booked appointments for their case review, hundreds more are still being sought through letters.
Dr Watt was suspended from duty by the Trust in June 2017 although he remains an employee.
Over 1,700 people have contacted a helpline set up in the wake of the controversy.
Concerned patients of Dr Watt have been booking appointments and will be seen by neurologists over the next 11 weeks.
Dr Watt also worked in the private sector and had patients at a clinic in Hillsborough and the Ulster Independent Clinic.
The senior consultant kept his own records for his private patients and the Ulster Independent Clinic is seeking advice to obtain the records in order to identify patients who need to be contacted.
A spokesman for the private clinic in south Belfast said that early investigations suggest there is likely to be a "significant number" of patients who have moved between the private sector and the NHS and who may already appear on the Trust's list. The spokesman added: "We are seeking to expedite this process as quickly as possible with the assistance of the Trust so we can then begin to communicate directly with those patients of Dr Watt who may be impacted by this issue.
"We confirmed our position that we are working as hard as possible to identify those patients of Dr Michael Watt under active review, exclusively in his private practice at the clinic.
"This is necessary to accurately identify any private patients who may need to be contacted for review. Following our recent discussions with the Belfast Health and Social Care Trust, we discussed with the Department the complex and time-consuming nature of this process, including the clear need to cross-reference this list with the active patient list being reviewed by the Trust.
"Having only received the recommendations and conclusions from the Royal College of Physicians report in the middle of last week, we can assure patients that we are moving as quickly as possible."