Brow lift surgery can have a dramatic impact on facial aesthetics, but there is also the potential to have complications with this type of surgery. There are several different types of brow lift that can be used to address brow descent. One thing that they all have in common is the potential to damage the frontal branch of the facial nerve.
This nerve is responsible for elevating the eyebrow. During surgery, the nerve can be divided or damaged, and when this happens, eyebrow elevation is no longer possible. This may be a permanent problem. More commonly the nerve is stretched. When this occurs, the paralysis is transient and function usually returns with time.
You’re still early in the post-operative course, and there’s a good chance that this will improve with time. Be patient, your surgeon’s assessment is probably correct.