Chiasmal syndromes

This review of the more recent literature and testing strategies in patients with chiasmal syndromes focuses on the clinical evaluation and management of these patients. Visual loss is often the initial manifestation of disorders involving the optic chiasm. Hemianopic defects and preferential involvement of the temporal visual field are the earliest and most common visual deficits. Progression of the lesion may cause compression of adjacent structures, including the optic nerves and cavernous sinuses, and may result in more profound visual loss, ocular motor deficits, and hypopituitarism.

Although a number of modalities have been used to assess visual function in patients with chiasmal disorders, perimetry remains the most effective means of detecting and following the visual deficit.

Most chiasmal syndromes can be categorized as intrinsic (thickening of the chiasm itself) or extrinsic (compression of the chiasm from an adjacent structure). Magnetic resonance imaging is the best mode of neuroimaging for most chiasmal lesions and may also provide clues to the etiology of an isolated chiasmal syndrome.