Introduction

Cortical blindness refers to a total loss of vision caused by a bilateral lesion or dysfunction of the occipital lobe. It represents a subset of cerebral blindness, a more general term which indicates blindness from any damage to both visual pathways posterior to the lateral geniculate bodies. Cortical blindness results typically from direct insult to both the primary visual areas lying in the calcarine cortex. As the responsible lesion does not usually limit to the cortex, but also encompasses the posterior part of the optic radiations and variably the extrastriate visual areas, both de-afferentation and de-efferentation of the primary visual cortex may also contribute to the visual dysfunction that is observed at the acute and at the recovered stages as well. Ischemic strokes are the major cause of cortical blindness.

Description

Clinical symptoms

By definition, cortical blindness is defined by a bilateral and total loss of vision. Thus, affected subjects can no longer identify visual forms, colors, location, orientation or movement of objects, nor even differentiate light from dark. They are usually distressfully aware of their deficit. At the acute stage, however, degree of awareness is variable. Patients may not report spontaneously their problem or seem indifferent to it. A minority of patients may even deny any visual loss or attribute their faulty performance to external factors, such as unfitted eyeglasses or poor room illumination.

Introduction

Bálint's syndrome is a clinical entity which combines variously a set of complex spatial behavior disorders following bilateral damage to the occipital–parietal junction. The core syndrome is a triad, namely optic ataxia, gaze apraxia, and simultanagosia, to which visual–spatial perception deficits can be associated. Both diversity of terminology used in literature and bias in clinical descriptions, which often reflect a particular opinion of the authors on underlying mechanisms, add to the difficulty in describing and comprehending this rare and devastating syndrome. As the components are not elementary symptoms, and as they are not necessarily present in each case, indicating they do not rely upon a single brain mechanism, validity of the complex as a syndrome has been questioned (Rizzo and Vecera, 2002). Despite these flaws, Bálint's syndrome can be identified at the bedside examination and it allows robust anticipation of lesion localization.

Historically, Bálint provided in 1909 a thorough clinical and postmortem description of a patient who exhibited hitherto undescribed symptoms, he named Seelenlähmung des “Schauens,” optische Ataxie, raümliche Störung der Aufmerksamkeit, usually translated as psychic paralysis of gaze, optic ataxia, and spatial disorder of attention. He related these symptoms to a bilateral area of ischemic suffering in the posterior parietal and anterior occipital regions, including the angular gyrus and underlying white matter on both sides. In Bálint's view, psychic paralysis of gaze was a consequence of attention impairment and not of eye movement disorder per se; meanwhile optic ataxia was explained in terms of disconnection between visual and motor centers.

Democracy is widely accepted today, perhaps as never before, as the most suitable form of government. But what is democracy, and does it always produce good government? There is a tradition in popular thinking and in political science that associates democracy with the existence of competitive elections. This follows the tradition of Schumpeter (1950) and Downs (1957) in public choice. Competitive elections are undoubtedly a necessary condition for democracy. But they are not sufficient for true democracy or for democracy to function reasonably well. For example, the fathers of the American Constitution expressed their fear of factions and of mob sentiments. One problem with competitive elections is that they provide no protection for minorities. A second is that they may not express the long-term interests of the electorate itself, or their attitudes in sober second thought. Yet a third is the well-known Arrow problem of cyclical majorities – perhaps one of the central discoveries of modern public choice. A fourth is the recurring tension between the two principles of government by majority on the one hand and the rule of law on the other.

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