You're not getting any response because there probably 1/2 dozen different styles of MV cables, and you're not providing sufficient info.
Most MV cables I've worked with DO have a shield that is a full ground/neutral (in some cases), but I have worked with just a shield. That shield is grounded, but is not of sufficient size to be considered a ground in the true sense.
The shield in that case is there only to displace lateral stress on the cable, and if it is not grounded, your cable will NOT last long. You normally do not pull a ground in these conduits, but some designs absolutely require it. Where are you? do you have many thunderstorm days? Wide open area like an airport? Ground wire is indicated IF the shield is not at least 50%.
That's probably all I can help (confuse?) with the info provided.