Ireland and Ulster centre Luke Marshall suffered another concussion during Friday's win over the Dragons, his fourth within a year.
The 23-year-old started for Ireland in their opening Six Nations win over Scotland, but has since lost his place to veteran Gordon D'Arcy.
Playing in Ulster's 38-8 victory at Ravenhill, Marshall sustained his fourth concussion in less than 12 months, raising alarm over his future participation in the sport.
A talented inside centre who appears to be Ireland's long-term option in the position, the Ulster medical team will manager Marshall through the return to play protocols this week.
However with so many concussions sustained within such a small period of time, Marshall may have to make a serious decision regarding his future at some stage this season.
Marshall missed Ireland's tour to North America last year after having suffered three concussions in three consecutive games, during the final two matches of last year's Six Nations and in the Heineken Cup semi-final loss to Saracens.