Also patients with dementia need motor examination, but do we need more examination tools?

Publication
TitleAlso patients with dementia need motor examination, but do we need more examination tools?
Publication TypeJournal Article
Year of Publication2016
AuthorsPapeo, L., Tessari A., & Rumiati R.
JournalJournal of Neurology
Date Published2016-07-13
Type of ArticleE-letter
ISSN0022-3050
KeywordsE-letter, SDV.NEU.SC Life Sciences q-bio/Neurons and Cognition q-bio.NC/Cognitive Sciences
Abstract

In an editorial commentary accompanying a recent study on the prevalence of apraxia in dementia patients 1, Bak emphasizes two facts: 1) research in cognitive neuroscience is contributing to increase the awareness of a close relationship between cognitive and motor functions and, by extension, cognitive and motor disorders in clinical populations; 2) despite so, the examination of motor functions in patients with cognitive disorders is not part of the routine clinical evaluation. Apraxia is a disorder in executing voluntary motor programming, in the absence of deficits in primary motor or sensory processes, comprehension of task instructions, object recognition or frontal inertia. Bak identifies apraxia as the critical disorder to address in routine clinical evaluation of patients with cognitive symptoms, as "it is exactly at the intersection between both movement and cognition". In Bak's view, a major obstacle to the improvement of clinical practice in this direction, is the absolute lack of tests for apraxia, practical and fast to use as part of routine evaluation. The Edinburgh Motor Assessment, in preparation by Bak and colleagues, is thus introduced as the first tool to respond to this urge. We could not agree more with the importance of considering apraxia in the routine clinical evaluation of cognitive functions in neurological patients, including those with dementia. Apraxia is indeed a cognitive deficit, affecting the higher-order mechanisms that govern purposeful motor production. However, if poverty or absence of tools is the problem, then we might not have a problem. Researchers have long since recognized apraxia as a cognitive disorder (with consequences on motor production). Moreover, efforts have been made to offer handy, standardized tests of praxis functions (e.g., the test TULIA 2), based on models of apraxia, whose anatomo-functional correlates have been extensively studied in brain- damaged patients and in healthy individuals, with neuroimaging research. A problem with most previous tests, evaluating gesture recognition, identification and production in great detail, is the administration time, usually so long as to advise their use in a post-screening phase (i.e., after the patient received a diagnosis of apraxia). Addressing this problem, Tessari et al. 3 have developed STIMA (short test for ideomotor apraxia), a standardized test for an accurate but quick diagnosis of apraxia. The test, also usable for bedside screening, requires the patient to imitate 36 gestures that form eight subscales. The test and each individual subscale are accompanied by tables to correct raw-scores for age and education, and convert raw-scores into equivalent scores (useful for clinicians to estimate deficit severity) and percentiles (more often used for diagnosis in research). Different subscales test for different praxic impairments. In particular, STIMA emphasizes the distinctions between: 1) imitation errors indicative of cortical damage (e.g., sequence errors or unrecognizable gestures) versus subcortical damage (e.g., postural or timing errors); 2) producing distal (fingers/hand) versus proximal (arm) components of gesture; 3) producing known gestures, which recruits semantic structures in the left temporo-parietal cortex, versus producing novel gestures, which relies on a bilateral cortical network, to transform the visual input (the seen gesture) in a motor act. The evaluation of novel gestures is also crucial to detect praxis deficits in patients who can properly use objects and tools in their domestic context. Evaluation of praxis solely based on execution or reports of daily activities may leave those cases unnoticed. STIMA has been used and proven sensitive to apraxic deficits in patients with stroke 4, as well as neurodegenerative pathologies 5. Our short (and non-exhaustive) overview of available standardized tests of apraxia shows a scenario brighter than the total absence of suitable tools depicted by Bak, and does justice to the numerous research teams in cognitive neuropsychology and neuroscience, who have paid more attention than Bak fears, to the clinical scopes of their activity and the constraints of the clinical setting (i.e., time pressure). Since the Edinburgh Motor Assessment by Bak et al. comes after recent and less recent attempts to provide clinicians with a fast and accurate test of apraxia, one may ask: do we really need this new tool? Perhaps, the Edinburgh Motor Assessment introduces features that make it more suitable to dementia patients, than other tests; or it relates to a model of apraxia, not represented in the other tests. Presenting the Edinburgh Motor Assessment as the first step toward an apraxia test for clinical practice precludes the possibility to clarify those or other potentially important aspects of that test. Considering its relation to extant tools rather appears as a good method to provide clear indications about which tool one (e.g., a clinician) should select in which case. This may help reducing the noise in the exchange between researchers and clinical practitioners as well as within our research field. References 1. Ahmed S, Baker I, Thompson S et al. Utility of testing for apraxia and associated features in dementia. J Neurol Neurosurg Psychiatry 2016; doi:10.1136/jnnp-2015-312945 2. Vanbellingen T, Kersten B, Van Hemelrijk B et al. Comprehensive assessment of gesture production: a new test of upper limb apraxia (TULIA). Eur J Neurol 2010;17:59-66. 3. Tessari A, Toraldo A, Lunardelli A, et al. STIMA: a short screening test for ideo-motor apraxia, selective for action meaning and bodily district. Neurol Sci 2015;36: 977-984. 4. Mengotti P, Corradi-Dell'Acqua C, Negri GA, et al. Selective imitation impairments differentially interact with language processing. Brain 2013;136:2602-2618 5. Papeo L, Cecchetto C, Mazzon G et al. The processing of actions and action-words in amyotrophic lateral sclerosis patients. Cortex 2015; 64:136-147. Conflict of Interest: None declared

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