Meningeal carcinomatosis and blindness.

The clinical syndrome of meningeal carcinomatosis includes headache, dementia, radiculopathy, and cranial nerve palsies. Blindness may be the first, or most prominent, symptom. When blindness occurs in adult life, meningeal carcinomatosis should be included in the differential diagnosis, even in the absence of other symptoms and in the absence of known malignancy. Although all pathophysiological mechanisms of the blindness in meningeal carcinomatosis have not yet been elucidated, optic nerve involvement by meningeal tumour-cuffing, by chronic papilloedema, and by direct tumour infiltration represent the likeliest causes. In the neuropathological analysis of such cases, the importance of analysing the intra-orbital portion of the optic nerves, in addition to the portions of the optic nerve and chiasm usually examined at routine necropsy, is emphasized. A case is described to illustrate this point, with the only pathological abnormality in the optic nerves being found within 6 mm of the retina.