Related Subjects:
|Adrenal Physiology
|Cushing Syndrome
|Cushing Disease
⚠️ Nelson Syndrome: Occurs after bilateral adrenalectomy (TBA) for refractory Cushing’s disease.
Characterised by pituitary tumour enlargement, markedly ↑ ACTH levels, and skin/mucosal hyperpigmentation.
Incidence now rare due to advances in pituitary surgery, medical therapy, and radiotherapy.
📖 About
- First described by Don Nelson in 1958.
- Occurs in ~5–10% of patients after TBA (historically up to 25%).
- TBA is now rarely used - reserved for refractory Cushing’s disease.
- Pathogenesis: ACTH-secreting pituitary adenoma grows unchecked after adrenal removal (loss of cortisol negative feedback).
🧬 Aetiology
- Residual pituitary adenoma after surgery.
- Lack of prophylactic pituitary radiotherapy at the time of TBA.
- Rapid rise in ACTH, often within 1 year post-TBA.
🔎 Clinical Features
- Hyperpigmentation (skin, mucosa) - due to ACTH stimulating melanocortin receptors.
- Headache, visual disturbance (bitemporal hemianopia from optic chiasm compression).
- Pituitary failure: amenorrhoea, hypogonadism, hypothyroidism, adrenal insufficiency (if ACTH eventually fails).
🧪 Investigations
- ACTH: Typically very high (450–8000 ng/L).
- MRI: Enlarged pituitary tumour ± invasion of optic chiasm/cavernous sinus.
💊 Management
- Surgery: Transsphenoidal/endoscopic resection of pituitary tumour (first-line if feasible).
- Radiotherapy: Useful when surgery incomplete or not possible; prevents further growth.
- Medical therapy:
- Somatostatin analogues: may improve symptoms.
- Cabergoline (high dose): ↓ tumour growth and ACTH secretion in some patients.
- Ketoconazole: inhibits adrenal steroid synthesis (adjunct).
- Temozolomide: chemotherapy option for aggressive/resistant tumours.
- Hormone replacement: Pituitary hormone replacement often required (thyroxine, hydrocortisone, sex steroids).
📚 References
