Absent/Thin Infundibular Stalk

Anne G. Osborn, MD, FACR

DIFFERENTIAL DIAGNOSIS

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Is small/absent stalk congenital or acquired?
Clinical information extremely helpful
- History of trauma or surgery?
- Hypothalamic/pituitary axis dysfunction?
- Short stature?

Helpful Clues for Less Common Diagnoses

Pituitary Stalk Transection, Post-Traumatic
- Usually occurs following motor vehicle accident
- Can occur with closed head injury
- May occur with or without accompanying basilar skull fracture
Pituitary Stalk Transection, Post-Surgical
- Children: Most common after craniopharyngioma resection
- Adults: Most common after macroadenoma resection
Pituitary Stalk Anomalies
- Most common = ectopic posterior pituitary
  - Posterior pituitary “bright spot” in hypothalamus
  - Stalk thin or absent
  - Shallow sella, small pituitary
- Less common = duplicated stalk
  - Two separate, thinned stalks present
  - Infundibular recess of 3rd ventricle widened, interposed between duplicated stalks
  - Tuber cinereum thickened, often fused with mammary bodies
Septo-Optic Dysplasia (SOD)
- Absent septum pellucidum
- Frontal horns “pointed” inferiorly
- “Squared” or “box-like” appearance of lateral ventricles on coronal imaging
- Small optic chiasm
Holoprosencephaly
- Many people consider lobar holoprosencephaly = SOD

Helpful Clues for Rare Diagnoses

Neurocysticercosis
- Racemose NCC cysts in suprasellar cistern surround, stretch/thin infundibular stalk
Meningitis
- Children with group B streptococcus
- Diencephalic infarction
- Secondary atrophy of optic chiasm, pituitary stalk