As non-functioning pituitary adenomas, also known as non-secretory adenomas do not produce any hormones, they tend to grow large before producing symptoms. Non-functioning pituitary adenomas represent approximately 30% of all pituitary tumours and they are usually macroadenomas (> 1 cm in diameter).
When they expand beyond the confines of sella, headache is commonly experienced because of the stretch on the sellar dura. Suprasellar expansion compresses optic nerve and/or chiasm causing varying degrees of visual disturbance and visual field defects (bitemporal hemianopia). Massive suprasellar growth may cause obstructive hydrocephalus and elevated intracranial pressure. Lateral growth into the cavernous sinus may cause double vision and facial pain or numbness.
Pressure on the normal pituitary gland results in hypopituitarism. The pituitary cells that are most susceptible to pressure are the gonadotrophs, which are responsible for the production of sex hormones such as luteinizing hormone (LH) follicle-stimulating hormone (FSH) and testosterone followed by the thyrotrophs that produce the thyroid stimulating hormone (TSH), the somatotrophs that produce the growth hormone (GH), and the corticotrophs that produce adrenocorticotropic hormone(ACTH). Hypopituitarism can be partial or may lead to a complete deficiency of all pituitary hormones (panhypopituitarism). Effects are loss of appetite, weight loss or weight gain, fatigue, irregular menstrual cycle, infertility, reduced sex drive, impotence or failure to get or maintain an erection, inadequate function of the ovaries or testes, frequent urination during night, joint pains, dizziness and low blood pressure.
Some patients with large pituitary tumours may have acute hemorrhage or infarction of the tumour (pituitary apoplexy) causing sudden onset of headache, visual loss, double vision, and/or pituitary failure, this condition is considered a surgical emergency requiring surgical decompression.
Hormonal evaluation is conducted to detect hypopituitarism. These blood tests evaluate baseline levels of different pituitary hormones such as TSH, ATCH, LH etc. Based on the results of the blood tests, additional hormonal studies may be required.
Radiological evaluation includes magnetic resonance imaging (MRI) of the pituitary with and without gadolinium (a contrast agent) for visualizing the pituitary tumour, determining its size, location, and appropriate treatment plan.
Observation is sometimes appropriate for smaller tumours that do not threaten vision or cause headaches or other symptoms. But the patient must be closely followed-up with periodic MRI scans and blood testing for hormonal levels. For symptomatic pituitary adenomas, observation, as well as medical treatment, do not have a significant role. Endoscopic transnasal pituitary surgery is the treatment of choice. It effectively relieves the mass effect caused by the tumour such as the visual manifestations caused by pressure on the optic nerve(s).
Hormonal function may gradually return to normal, and a complete cure is obtainable. Postoperatively, periodic MRIs and hormonal assessment should be carried out for the rest of the follow-up period.
