Makindo Medical Notes

Related Subjects: |Adrenal Physiology |Cushing Syndrome |Cushing Disease

Nelson Syndrome: In approximately 25% of patients, a pituitary tumor may continue to grow and secrete ACTH after the surgical removal of both adrenal glands (total bilateral adrenalectomy, TBA). The practice of TBA for Cushing's disease is now rarely performed due to advancements in other treatment options.

About

• Nelson Syndrome involves the enlargement of a pituitary tumor following TBA.
• Occurs in 5-10% of patients undergoing TBA.
• TBA is performed for refractory Cushing's disease when other treatments fail.
• The condition arises from an underlying ACTH-secreting pituitary adenoma.
• First described by Don Nelson in 1958.

Aetiology

• Residual tumor remaining after pituitary surgery.
• Lack of prophylactic neo-adjuvant pituitary radiotherapy at the time of TBA.
• Rapid rise in ACTH levels, particularly in the first year post-TBA.

Clinical Features

• Headache and visual disturbances due to tumor enlargement.
• Hyperpigmentation of the skin and mucous membranes caused by elevated ACTH levels.
• Bitemporal visual loss due to compression of the optic chiasm.
• Pituitary failure, presenting with symptoms such as amenorrhea in women.

Investigations

• ACTH Levels: Elevated levels ranging from 450 to 8000 ng/L.
• MRI: Shows an enlarged pituitary mass, which may invade surrounding structures like the optic chiasm and cavernous sinus.

Management

• Surgical Removal:
  • The ideal treatment is surgical removal of the pituitary adenoma.
  • Advanced surgical techniques, including transnasal (endoscopic) approaches, are often required for tumors involving the cavernous sinus.
• Radiation Therapy: Can effectively control tumor growth, especially when surgery is not feasible.
• Medications:
  • Somatostatin analogs may reduce symptoms in some cases.
  • Cabergoline at high doses may help control tumor growth and ACTH secretion.
  • Ketoconazole may be used to inhibit cortisol synthesis.
  • Temozolomide, a chemotherapeutic agent for glioblastoma, may improve symptoms, reduce ACTH levels, and cause tumor regression on MRI.
• Pituitary Hormone Replacement: Required to address deficiencies caused by pituitary dysfunction.

References

• Nelson's Syndrome: Review