Yes, head injury can rarely lead to empty sella syndrome.

Yes, head injury can cause Empty sella syndrome, but only secondary type of empty sella syndrome, not primary.
To know, how head injury causes this we should know a little about anatomy and pathology associated with this syndrome.

Empty Sella Syndrome is a disorder in which pituitary gland shrinks or becomes flattened. Pituitary gland is located at the base of the brain. It is surrounded by a structure known as, Sella. When pituitary gland shrink or become flattened, this sella appears to be empty during radiological imaging. That is why its name is, empty sella.

There are two types of Empty sella syndrome.
Primary: It occurs due to obesity and high blood pressure. Some fluid enter inside sella and pushes pituitary gland to become flattened or shrink.

Secondary: This type occurs due to injury , surgery or radiations.

So, when somebody have head injury, there are chances of Empty sella Syndrome.