Pituitary stalk interruption syndrome

Other Names: Ectopic neurohypophysis; PSIS

Pituitary stalk interruption syndrome (PSIS) is a congenital abnormality of the pituitary gland characterized by the triad of a very thin or interrupted pituitary stalk, a misplaced (ectopic) or absent posterior pituitary and a small or absent anterior pituitary, with permanent growth hormone (GH) deficit.

Epidemiology

The prevalence of PSIS is unknown, however, some 1,000 cases have been reported either with or without the full triad.

Cause

The cause of this condition is unknown. Rare mutations in the HESX1, LHX4, OTX2, SOX3, and PROKR2 genes can be the cause in familial cases.

Signs and symptoms

Signs and symptoms in newborns include low blood sugar levels (hypoglycemia), jaundice, congenital abnormalities and small penis (micropenis) and/or testis that are not in the scrotal sac (cryptorchidism). Later in childhood, signs may include short stature, seizures, low arterial pressure (hypotension) and/or intellectual delay. Some people can also have vision problems (septooptic dysplasia) and Fanconi anemia.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 100% of people have these symptoms

• Ectopic posterior pituitary

80%-99% of people have these symptoms

• Failure to thrive(Faltering weight)
• Short stature(Decreased body height)

30%-79% of people have these symptoms

• Delayed puberty(Delayed pubertal development)
• Hypoglycemia(Low blood sugar)
• Hypoplasia of penis(Underdeveloped penis)
• Hypothyroidism(Underactive thyroid)

5%-29% of people have these symptoms

• Adrenal hypoplasia(Small adrenal glands)
• Cryptorchidism(Undescended testes)
• Death in infancy(Infantile death)
• Diabetes insipidus
• Global developmental delay
• Intellectual disability(Mental deficiency)
• Primary amenorrhea
• Seizure
• Septo-optic dysplasia

Diagnosis

The diagnosis is confirmed through MRI showing the characteristic findings.

Treatment

Treatment is based on replacement of deficient hormones, particularly GH, and should be started at birth to avoid hormone deficiencies and intellectual delay.

Prognosis

Prognosis is generally good in cases of prompt diagnosis and management. Delays may lead to seizures (due to hypoglycaemia), hypotension (due to cortisol deficiency), and/or intellectual disability (due to thyroid endocrine deficits). Due to the before-mentioned factors, mortality and morbidity is higher than that of the general population, particularly during the first 2 years of life.

NIH genetic and rare disease info

• NIH info on Pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome is a rare disease.

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