Balint’s syndrome, first described by a Hungarian neurologist in 1909, consists of:
- Simultanagnosia (q.v.; dorsal type):
- A constriction of visual attention, such that the patient is aware of only one object at a time; visual acuity is preserved, and patients can recognize single objects placed directly in front of them; they are unable to read or distinguish overlapping figures.
- Spatial disorientation:
- Loss of spatial reference and memory, leaving the patient "lost in space."
- Disorders of oculomotor function:
- Specifically visually guided eye movements (fixation, pursuit, saccades); Balint’s "psychic paralysis of gaze", or "sticky fixation", refers to an inability to direct voluntary eye movements to visual targets, despite a full range of eye movements; this has also been characterized as a form of oculomotor apraxia. Accurate eye movements may be programmed by sound or touch. Loss of spontaneous blinking has also been reported.
- Optic ataxia:
- A failure to grasp or touch an object under visual guidance.
Not all elements may be present; there may also be coexisting visual field defects, hemispatial neglect, visual agnosia, or prosopagnosia. Balint’s syndrome results from bilateral lesions of the parieto-occipital junction causing a functional disconnection between higher order visual cortical regions and the frontal eye fields, with sparing of the primary visual cortex. Brain imaging, either structural (CT, MRI) or functional (SPECT, PET), may demonstrate this bilateral damage, which is usually of vascular origin, for example due to watershed or border zone ischemia, or top-of-the-basilar syndrome. Balint syndrome has also been reported as a migrainous phenomenon, following traumatic brain injury and in association with Alzheimer’s disease, tumor (butterfly glioma), radiation necrosis, progressive multifocal leukoencephalopathy, Marchiafava-Bignami disease with pathology affecting the corpus callosum, and X-linked adrenoleukodystrophy.
Husein M, Stein J. Rezso Balint and his most celebrated case. Archivesof Neurology 1988; 45: 89-93
Rafal R. Bálint’s syndrome: a disorder of visual cognition. In: D’Esposito M (ed.). Neurological foundations of cognitive neuroscience. Cambridge: MIT Press, 2003: 27-40