Temporary weakness of the forehead muscles after a browlift is not uncommon. There are several possible causes. The nerve that causes movement of the brow runs very close to a vein that frequently needs to be cauterized. This can cause some heat transfer to the nerve that may prevent it from working properly.
Also, the surgery itself can cause a direct injury to the nerve by stretching it. These types of injuries typically heal within 2-3 months and complete recovery of the movement is expected. Rarely, the nerve can be cut. This is extremely rare, but if it does occur, recovery could take 6 or more months and may not be complete, leaving that brow weaker than the other.
In the vast majority of cases, however, the brow movement returns completely, so be patient.
