HYPOTHALAMIC, PITUITARY, AND OTHER SELLAR MASSES
EVALUATION OF SELLAR MASSES
Clinical manifestations of sellar lesions vary, depending on the anatomic location of the mass and the direction of its extension (Table 5-1). The dorsal sellar diaphragm presents the least resistance to soft tissue expansion from the sella; consequently, pituitary adenomas frequently extend in a suprasellar direction. Bony invasion may occur as well.
TABLE 5-1Features of Sellar Mass Lesionsa ||Download (.pdf) TABLE 5-1 Features of Sellar Mass Lesionsa
|IMPACTED STRUCTURE ||CLINICAL IMPACT |
|Pituitary || |
Growth failure and adult hyposomatotropism
|Optic chiasm || |
Loss of red perception
Superior or bitemporal field defect
|Hypothalamus || |
Appetite and thirst disorders
|Cavernous sinus || |
Ophthalmoplegia with or without ptosis or diplopia
|Frontal lobe || |
|Brain || |
Headaches are common features of small intrasellar tumors, even with no demonstrable suprasellar extension. Because of the confined nature of the pituitary, small changes in intrasellar pressure stretch the dural plate; however, headache severity correlates poorly with adenoma size or extension.
Suprasellar extension can lead to visual loss by several mechanisms, the most common being compression of the optic chiasm, but rarely, direct invasion of the optic nerves or obstruction of cerebrospinal fluid (CSF) flow leading to secondary visual disturbances can occur. Pituitary stalk compression by a hormonally active or inactive intrasellar mass may compress the portal vessels, disrupting pituitary access to hypothalamic hormones and dopamine; this results in early hyperprolactinemia and later concurrent loss of other pituitary hormones. This “stalk section” phenomenon may also be caused by trauma, whiplash injury with posterior clinoid stalk compression, or skull base fractures. Lateral mass invasion may impinge on the cavernous sinus and compress its neural contents, leading to cranial nerve III, IV, and VI palsies as well as effects on the ophthalmic and maxillary branches of the fifth cranial nerve. Patients may present with diplopia, ptosis, ophthalmoplegia, and decreased facial sensation, depending on the extent of neural damage. Extension into the sphenoid sinus indicates that the pituitary mass has eroded through the sellar floor. Aggressive tumors rarely invade the palate roof and cause nasopharyngeal obstruction, infection, and CSF leakage. Temporal and frontal lobe involvement may rarely lead to uncinate seizures, personality disorders, and anosmia. Direct hypothalamic encroachment by an invasive pituitary mass may cause important metabolic sequelae, including precocious puberty or hypogonadism, diabetes insipidus, sleep disturbances, dysthermia, and appetite disorders.