Size of a normal pituitary stalk
In adults, the normal pituitary stalk anteroposterior diameter is 3.35 ± 0.44 mm at the level of the optic chiasm, and tapers to 2.16 mm ± 0.39 mm at the level of the pituitary gland. In general, a stalk thickness ≥ 4 mm is considered abnormal.
The pituitary stalk, or infundibulum, lacks a blood–brain barrier and thus enhances intensely with gadolinium.
Slight deviation of the pituitary stalk is common and does not necessarily imply an underlying disease.