Nelson's syndrome is a disorder that occurs in about one in four patients who have had both adrenal glands removed to treat Cushing's disease. In patients with pre-existing adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, loss of adrenal feedback following bilateral adrenalectomy can trigger the rapid growth of the tumor, leading to visual symptoms (e.g. bitemporal hemianopsia) and hyperpigmentation.
Causes of Nelson’s Syndrome
Common causes include bilateral adrenalectomy for the treatment of Cushing’s disease, and hypopituitarism.
The onset of the disease can occur up to 24 years after a bilateral adrenalectomy has been performed, with an average of up to 15 years after.
A preventative measure that can be utilized is prophylactic radiotherapy when a bilateral adrenalectomy is being performed in order to prevent Nelson’s syndrome from manifesting.
Screening can also be done with the help of an MRI in order to visualize the pituitary for tumors.
If tumors are not present then an MRI should be performed at intervals.
Hyper-pigmentation and fasting ACTH levels within plasma above 154 pmol/l are predictive of Nelson’s syndrome after an adrenalectomy.
Risk factors include being younger in age and pregnancy.
Symptoms of Nelson’s Syndrome
Hyper-pigmentation of the skin
Abnormally high levels of beta-MSH and ACTH
Abnormal enlargements of the pituitary gland,
Interruption of menstrual cycles in women
Diagnosis of Nelson’s Syndrome
Common diagnostic techniques include:
Blood samples are assessed for the absence or presence of aldosterone and cortisol.
Physical examinations are also useful in patients in order to examine vision, skin pigmentation, how the body replaces steroids, and the cranial nerves.
Recent advancements in high-resolution MRIs allow for adenomas to be detected during the early stages of Nelson syndrome.
Physical examination including height, weight, vital signs, blood pressure, eye examination, thyroid examination, abdominal examination, neurological examination, skin examination and pubertal staging needs to be assessed.
Treatment of Nelson’s Syndrome
Common treatments for Nelson’s syndrome include radiation or surgical procedure.
Radiation allows for the limitation of the growth of the pituitary gland and the adenomas.
If the adenomas start to affect the surrounding structures of the brain, then a micro-surgical technique can be adapted in order to remove the adenomas in a transsphenoidal (bone at base of the skull) process.
Death may result with development of a locally aggressive pituitary tumor.
However, does not commonly occur with pituitary diseases.
In the rare case, ACTH-secreting tumors can become malignant.
Morbidity from the disease can occur due to pituitary tissue compression or replacement, and compression of structures that surround the pituitary fossa.
The tumor can also compress the optic apparatus, disturb cerebrospinal fluid flow, meningitis, and testicular enlargement in rare cases.