**8.1 Clinical presentation**

The most common presentation of NFPA is headache. It may be caused by intrasellar pressure increment and dural lining compression which are innervated by trigeminal nerve branches. Visual field defect is the second most common clinical presentation that may be seen in up to 61% of cases [64, 67]. Visual field defects are asymmetrical in 2/3 of the patients. They occur due to optic nerves and/or chiasm displacement and compression, which also may result in permanent deficit in longstanding compressions.

Tumor extension to cavernous sinus may result in ophthalmoplegia due to compression of CNIII, CNIV, and CNVI. CNIII is most commonly affected followed by CNVI and then CNIV.

Adenomas greater than >4 cm of diameter may obstruct foramen of Monro and cause obstructive hydrocephalus.

Pituitary apoplexy is another common presentation for these lesions. Pituitary apoplexy is most commonly seen in NFPA, accounting for 45–82% of pituitary apoplexy cases, and 7–9.5% of asymptomatic NFPA present initially with pituitary apoplexy [64].

Hypopituitarism is another common sequela of NFPA. 70–85% patients will have deficiency in at least one axis of pituitary cells secretion [68]. Hypopituitarism occurs in an expected sequence of hormonal loss which usually affect GH, then LF/ FSH, then TSH, and lastly ACTH. Diabetes insipidus is rare in non-surgically-NFPAtreated patients, and if it is found in a patient with pituitary lesion, other lesions should be considered (e.g. craniopharyngioma, aneurysms, metastasis).

Lastly, as stated previously, NFPA may be discovered incidentally on brain MRI that was done for other causes. In one large single-center prospective study, 49% of NFPA presented incidentally and 85% of them harbored macroadenomas. Interestingly, in the same cohort, they found that half of the patients in the asymptomatic group reported some mass effects symptoms like headache and/or visual symptoms and only 35% of the incidentally discovered group (in which brain imaging done for unrelated reasons) has no symptoms at all [69].
