Apraxia is a cognitive disorder, which prevents a person from performing a learned movement (West et al., 2008). Apraxia is caused by interference in the planning and execution of a motor activity. There is a dysfunction in the left fronto-parietotemporal hemisphere of the brain, which is located beside the speech area (Hödl, Bonelli, Kapfhammer, 2006).
Apraxia is a feature of corticobasal degeneration (CBD), which is characterized by various types of apraxia affecting limb function, especially ideomotor apraxia and limb-kinetic apraxia. Buccofacial and oculomotor apraxia can also be present (Zadikoff & Lang, 2005). The corticobasal syndrome or CBS, i.e., parkinsonism and prominent apraxia, may be caused by conditions like progressive supranuclear palsy, Alzheimer’s disease, dementia with Lewy bodies, and frontotemporal dementias (Zadikoff & Lang, 2005).
Ideomotor apraxia is apraxia without tool use and includes imitation of hand and finger positions, performing gestures on-demand, and pantomime of object use. Ideational apraxia is apraxia with tool use, like cutting with a knife or using a pencil (Hödl, Bonelli, Kapfhammer, 2006). Apraxia is also used to describe a variety of syndromes, which are, however, not considered to be true apraxias. This includes dressing apraxia, constructional apraxia, gait apraxia, gaze apraxia, apraxia of eyelid opening, etc (Zadikoff & Lang, 2005).
Contralateral neglect occurs as a consequence of right hemisphere strokes. Contralateral neglect involves attentional and cognitive deficits, along with contralateral spatial and personal awareness distortions (Reep et al., 2004). In contralateral neglect, the visual acuity, somatic sensation, and motor ability are intact but there is an inability to perceive and attend to objects, or even the body, as a part of space (Purves et al., 2001.)
When a patient with contralateral neglect is presented stimuli to the side of the body (or visual space) opposite the lesion, they do not report, respond, or even orient to the stimuli. In addition, they have difficulty in performing complex motor tasks on the neglected side like reaching for objects, dressing, drawing, writing, and orienting to sounds (Purves et al., 2001.)
Contralateral neglect syndrome is specifically associated with damage to the right parietal cortex because there is little or no compensatory capacity in the left hemisphere, while left parietal lesions tend to be compensated by the intact right hemisphere (Purves et al., 2001.)
Prosopagnosia or face blindness is selective agnosia for faces. The affected person is unable to recognize faces. This disorder is seen after trauma involving the right occipital temporal region or could be congenital, without any detectable lesions (Kennerknecht, Pluempe, Welling, 2008)
While the inability to recognize faces is apparent, prosopagnosia is frequently associated with three other clinical findings. This includes a visual field defect (left or bilateral upper quadrantanopia or left homonymous hemianopia), achromatopsia or hemiachromatopsia, which is an impairment of color perception, and topographagnosia, which is getting lost in familiar surroundings (Nardelli et al., 1982)
References
Hödl, AK, Bonelli, RM, Kapfhammer, HP, 2006. Limb apraxia. Med Klin. 101(1):24-8.
Kennerknecht, I, Pluempe, N, Welling, B, 2008. Congenital prosopagnosia–a common hereditary cognitive dysfunction in humans. Front Biosci. 13:3150-8.
Nardelli, E, Buonanno, F, Coccia, G, Fiaschi, A, Terzian, H, Rizzuto, N, 1982. Prosopagnosia. Report of four cases. Eur Neurol. 21(5):289-97.
Purves, D, Augustine, GJ, Fitzpatrick, D, Katz, LC, Lamantia, A, McNamara, JO, Williams, S, 2001. Neuroscience, 2nd Ed. Sinauer Associates, Inc.
Reep, RL, Corwin, JV, Cheatwood, JL, Van Vleet, TM, Heilman, KM, Watson, RT, 2004. A rodent model for investigating the neurobiology of contralateral neglect. Cogn Behav Neurol. 17(4):191-4.
West, C, Bowen, A, Hesketh, A, Vail, A (2008). Interventions for motor apraxia following stroke. Cochrane Database Syst Rev.
Zadikoff C, Lang, AE, 2005. Apraxia in movement disorders. Brain. 128:1480-97.