Optic ataxia
Optic ataxia is the inability to guide the hand toward an object using visual information where the inability cannot be explained by motor, somatosensory, visual field deficits or acuity deficits. Optic ataxia is seen in Bálints syndrome where it is characterized by an impaired visual control of the direction of arm-reaching to a visual target, accompanied by defective hand orientation and grip formation. It is considered a specific visuomotor disorder, independent of visual space misperception.Optic ataxia is also known as misreaching or dysmetria (English: difficult to measure), secondary to visual perceptual deficits. A patient with Bálints syndrome likely has defective hand movements under visual guidance, despite normal limb strength. The patient is unable to grab an object while looking at the object, due to a discoordination of eye and hand movement. It is especially true with their contralesional hand.Dysmetria refers to a lack of coordination of movement, typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is sometimes described as an inability to judge distance or scale. As Bálint states, optic ataxia impaired his patients daily activities, since, while cutting a slice of meat...which he held with a fork in his left hand, ...would search for it outside the plate with the knife in his right hand, or ...while lighting a cigarette he often lit the middle and not the end. Bálint pointed out the systematic nature of this disorder, which was evident in the patients behaviour when searching in space.
Bálints syndrome is an uncommon and incompletely understood triad of severe neuropsychological impairments: inability to perceive the visual field as a whole (simultanagnosia), difficulty in fixating the eyes (oculomotor apraxia), and inability to move the hand to a specific object by using vision (optic ataxia). It was named in 1909 for the Austro-Hungarian neurologist and psychiatrist Rezső Bálint who first identified it.Bálints syndrome occurs most often with an acute onset as a consequence of two or more strokes at more or less the same place in each hemisphere. Therefore, it occurs rarely. The most frequent cause of complete Bálints syndrome is said by some to be sudden and severe hypotension, resulting in bilateral borderzone infarction in the occipito-parietal region. More rarely, cases of progressive Bálints syndrome have been found in degenerative disorders such as Alzheimers disease or certain other traumatic brain injuries at the border of the parietal and the occipital lobes of the brain. Lack of awareness of this syndrome may lead to a misdiagnosis and resulting inappropriate or inadequate treatment. Therefore, clinicians should be familiar with Bálints syndrome and its various etiologies. Presentation
Bálints syndrome symptoms can be quite debilitating since they impact visuospatial skills, visual scanning and attentional mechanisms. Since it represents impairment of both visual and language functions, it is a significant disability that can affect the patients safety—even in ones own home environment, and can render the person incapable of maintaining employment.