Nelson's syndrome -- 46 years later: clinical experience with 37 patients.

OBJECTIVE: Pituitary tumours occurring after bilateral adrenalectomy for Cushing's disease (Nelson's syndrome) are frequently aggressive, so an early diagnosis and careful management are of prime importance. For a new insight into this entity it is necessary to analyse the factors predisposing to its development and the course of the disease, as well as the methods of diagnosis and modalities of treatment. PATIENTS AND METHODS: Thirty-seven patients with Nelson's syndrome were observed, 32 women and 5 men, aged 16 to 61 years at the time of pituitary tumour detection (at present, 27 to 82 years old). The diagnostic methods included clinical observation, imaging examinations (X-ray studies, CT, MRI), hormonal evaluation (especially ACTH and cortisol levels during replacement therapy) and ophthalmologic investigations. Neurosurgery was the main method of treatment.
RESULTS: The clinical analysis indicated that young age at the time of adrenalectomy, pregnancy, insufficient replacement therapy and fulminant course of Cushing's disease were the main factors predisposing to Nelson's syndrome. MRI appeared to be the most valuable imaging method, as this detected Nelson's tumours in the microadenoma stage in 7 patients. Plasma ACTH levels varied between 32.6 pmol/l in an early phase to 2 000 pmol/l in the full-blown syndrome. Absolute temporal scotomas found in ophthalmologic examinations were an early abnormality. The best results after therapy were obtained in patients treated by neurosurgery using a transsphenoidal approach in an early stage.
CONCLUSIONS: MRI, ophthalmologic examination and plasma ACTH determination were the most valuable investigations for early diagnosis of Nelson's syndrome. Early neurosurgery offered the best outcome in our group of patients.