Chapter 10 Disorders of the Sella and Parasellar Region

Abstract

Publisher Summary This chapter discusses the disorders of the sella and parasellar region. Most of the patients seen with sella and parasellar pathology in a clinical neuroscience center have problems with their vision. Although visual symptoms are theoretically a less common presentation than those of hyperprolactinemia, the compression of the optic chiasm with its attendant symptom of bitemporal visual field loss by a macroadenoma remains a regular problem leading to a neurosurgical admission. Although 1 in 20 macroadenomas are associated with acromegaly and even Cushing's disease can present as a large tumor, the majority do not express a hormone excess, and the patient is often either partially or completely panhypopituitary. The classic visual presentation is of a bitemporal field loss, which is often not symmetrical. Early compression leads to upper temporal field desaturation for red, and the mass may compress one side of the chiasm earlier than the other. The position of the optic nerves and chiasm in relation to the sella is variable and about 12% of the population has a pre-fixed chiasm and a lesser proportion post-fixed. Pre-fixed chiasmata present with optic tract signs are typical of some rarer parasellar pathology, particularly craniopharyngiomas. Lesions that affect the intracranial optic nerves obviously affect one eye alone. These may be lesions of the optic nerve itself, its sheath, or adjacent structures, typically adenomas with a post-fixed chiasm or planum or anterior clinoid meningiomas. It is worth noting that for compressive lesions, it is the field that is damaged first, and acuity loss occurs as a later event.