Introduction: Nelsons syndrome is a significant long-term complication of bilateral adrenalectomy for Cushings disease. However, evidence about possible factors that can predict its occurrence, is controversial and limited.
Objective: The objective of this analysis was to elucidate the role of various factors in prediction of Nelsons syndrome and the extent of their modifying effect.
Methods: All patients with Cushings disease subjected to bilateral adrenalectomy (n=45) at a tertiary centre were recruited. Baseline clinical features, metabolic comorbidities, cortisol dynamics and IPSS in some patients were documented by retrospective data retrieval and prospective surveillance. MRI of the pituitary or GaDOTANOC/CT thorax and abdomen was done, for non-visualised adenoma. Nelsons syndrome was defined as an expanding (>2 mm) or newly appearing sellar adenoma with or without ACTH values exceeding 500 pg/ml.
Results: Nelsons syndrome had an incidence of 40% (n=17) on follow-up of 7 years with a median of 3 years for its development. All these subjects had a high ACTH(median 1004 pg/ml) except 2(ACTH<500 pg/ml). 9 subjects had an expanding and 8 had a de-novo sellar mass. Not all subjects with adenoma at baseline showed tumour progression (n=12), 2 of whom had received gamma knife prophylactically. TSS, done in 53% and gamma knife in the rest, were both curative. An annual increment in ACTH of 113 pg/ml/year (adjusted OR 26.36), uncontrolled hypertension (adjusted OR 16.91) and ≥ 4 discriminatory features of protein catabolism(adjusted OR 14.51) were predictive of Nelsons syndrome as were a significantly higher 1st year increment in ACTH (116 pg/ml) and 1st year absolute ACTH(142 pg/ml) (sensitivity and specificity exceeding 85%). The baseline ACTH and adrenal weight in these patients was lower(P>0.05).
Conclusion: Nelsons syndrome can be predicted from the pre-operative presence of severe disease and post-operative higher rebound rise in ACTH.