Nonfunctional pituitary adenomas comprise an estimated ≈ 30% of pituitary tumors. NFAs typically occur in patients in the fifth to sixth decades of life and have a slight male predominance. The clinical spectrum of NFAs varies from being asymptomatic and detected incidentally (< 10% of adenomas), to presenting with large tumors with mass effects. Delayed diagnosis is common because NFAs lack a characteristic clinical syndrome of hormone overproduction; therefore, these tumors are often macroadenomas at the time of diagnosis (80%), and patients are often symptomatic from tumor-compressive effects on nearby neurologic or vascular structures. Common symptoms may include:
• Headaches: Via stretched dural membranes containing pain receptors, increased intrasellar pressure, and/or activation of trigeminal pain pathways in the cavernous sinuses.
• Vision defects: Large tumors initially compress the inferior aspect of the optic chiasm and the superior nasal retinal fibers, resulting in superior temporal visual field defects. With further compression of the central portion of chiasm, inferior vision loss and classic bitemporal hemianopsia occur. Depending on the pattern of tumor compression, the vision defects may be asymmetric, unilateral, bilateral, or central.
• Pituitary hormone deficiencies: From interruption of pituitary-specific releasing hormone delivery through the pituitary stalk, anterior pituitary gland compression, and/or hyperprolactinemia (from stalk effect). Gonadotropins (LH, FSH) and GH are the most common deficiencies, occurring in > 50% of patients. Thyroid and adrenal hormone deficiencies are less common, occurring in < 30% of patients.
• Ophthalmoplegia/Diplopia: From cranial nerve (CN) III (oculomotor), IV (trochlear), VI (abducens), or V (trigeminal) compression. Palsy of CN III is most common (presents as ptosis and “down and out” eye position), followed by CN VI palsy (presents as convergent strabismus) and then CN IV palsy (presents as vertical diplopia).
• Pituitary apoplexy: A clinical syndrome of headache, visual deficits, ophthalmoplegia, and/or altered mental status caused by the sudden hemorrhage or infarction of the pituitary gland. It complicates an estimated 10 to 15% of pituitary adenomas, and importantly is associated with a high incidence of central adrenal insufficiency (75%) and central hypothyroidism (50%).
• Cerebrospinal fluid leak/Rhinorrhea: From inferior tumor extension through the sphenoid bone and into the sphenoid sinus.
• Rare presentations: Very rarely, patients may present with (1) stroke from internal carotid artery occlusion, (2) seizures from temporal lobe tumor involvement, and (3) giant tumors rarely obstruct the foramen of Monro, leading to intracranial hypertension and hydrocephalus.