ReviewRehabilitation of neglect: An update
Highlights
► Spatial neglect occurs frequently after lesions to the right hemisphere. ► Despite significant advances in neglect therapy 1/3 of patients remains impaired. ► We review classic and novel treatment techniques, their efficacy and address gaps in treatment research.
Introduction
Neglect is a challenging and complex disorder. Typically, it is defined as the impaired or lost ability to respond to sensory stimuli (visual, auditory, tactile, olfactory) presented in the contralesional hemispace of a neurological patient (Kerkhoff, 2001). In addition to sensory neglect, motor neglect may occur and manifest itself as the reduced use or nonuse of the contralesional extremities during walking or bimanual activities.
But neglect is not just challenging to define and understand it also poses a challenge to our health system. The clinical, sociodemographic as well as epidemiological relevance of spatial neglect as a disease is substantial: every year about 3–5 million patients suffer from neglect after stroke (Corbetta, Kincade, Lewis, Snyder, & Sapir, 2005), and this incidence will continuously increase due to a rising incidence of cerebro-vascular diseases in our aging western societies and a shift to western life habits in the newly industrialized countries. Spontaneous recovery occurs but will not necessarily eliminate all signs of neglect. More importantly about a third of all patients manifest a chronic form of neglect and show clear signs of neglect even more than a year after their neurological incident (Karnath et al., 2011, Rengachary et al., 2011). Neglect interferes with rehabilitation attempts aimed at improving other symptoms of the patients (such as hemiparesis) and if left untreated will therefore lead to a poor rehabilitation outcome. It seems clear that the development of effective treatments for neglect should be a high priority. For the purpose of this special issue on unilateral neglect, we provide an overview over existing treatment options but also identify some of the gaps in current research on neglect-therapy. It is sobering to observe that while significant progress has been made, many of the gaps that were identified in previous reviews can still be found today. For this reason we will ask at the end of our review whether there are structural reasons that can explain the persistence with which important questions remain not only unanswered but effectively unexamined.
Section snippets
Early exploration
The first attempts to treat patients with unilateral neglect focused on the obvious problem that these patients seemed to explore only half of their visual world. The therapeutic answer to this problem was provided by Diller and Weinberg (1977) who used visual displays that contained multiple items and asked their patients to find specific items on these displays. It was hoped that through practice and guiding feedback from the therapist patients would learn to guide their eyes to the hitherto
Seeing straight
Karnath (2006) argued that the core-deficit in unilateral neglect is an orientation bias to the right. Even at rest right brain-damaged patients with neglect will show a 30° deviation of eye and head orientation to the right (Fruhmann-Berger & Karnath, 2005). On the basis of these and similar findings Karnath and Dieterich (2006) suggested that neglect results from damage to the multisensory cortex (localized in the right superior temporal cortex, insula and temporo-parietal junction) in which
Classics and newcomers
Recent reviews have typically focused on the sensory stimulation methods which we reviewed in Section 2. This is understandable and reflects the fact that sensory stimulation methods have recently attracted significantly more research than other treatment techniques. However, a review on neglect-therapy would be incomplete without mentioning some of the newer and some of the classic but now often neglected treatment options. Those options range from low-tech eye-patch techniques to high tech
Mix and match
During the last two decades a significant number of new options for the treatment of neglect patients have been introduced. The challenge today is thus to decide how to mix and match the treatment options that are available. Mixing and matching in this context means matching the treatment options to the patient, selecting those treatments which are superior to others and combining them in ways that will enhance the treatment outcome. Currently this process is based on instinct and also – we
Nonvisual neglect
Most treatment studies focus on visual neglect and pay little attention to other aspects of the neglect syndrome, namely auditory, somatosensory, haptic forms of neglect, body-neglect, motor neglect or representational neglect. This is most likely due to the easy availability and practical assessment of visual neglect by conventional screening tests (i.e. Bells test, Mesulaḿs test) and neglect test batteries (Wilson, Cockburn, & Halligan, 1987). In contrast tests for the assessment of auditory,
Conclusion
The last two decades have seen a dramatic increase in the number of techniques available for the treatment of unilateral neglect. Many of these techniques were developed from experimental interventions designed to influence the rightward orientation bias of neglect patients. These sensory stimulation techniques have some obvious advantages. They are easy to apply, their effects tend to generalize to a number of different neglect symptoms and they only require minimal patient-compliance – a huge
Acknowledgment
This work was partially supported by a grant from the Deutsche Forschungsgemeinschaft (IRTG 1457 “Adaptive Minds”) to Georg Kerkhoff.
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