Effect of meaning on apraxic finger imitation deficits.

Apraxia typically results from left-hemispheric (LH), but also from right-hemispheric (RH) stroke, and often impairs gesture imitation. Especially in LH stroke, it is important to differentiate apraxia-induced gesture imitation deficits from those due to co-morbid aphasia and associated semantic deficits, possibly influencing the imitation of meaningful (MF) gestures. To explore this issue, we first investigated if the 10 supposedly meaningless (ML) gestures of a widely used finger imitation test really carry no meaning, or if the test also contains MF gestures, by asking healthy subjects (n=45) to classify these gestures as MF or ML. Most healthy subjects (98%) classified three of the 10 gestures as clearly MF. Only two gestures were considered predominantly ML. We next assessed how imitation in stroke patients (255 LH, 113 RH stroke) is influenced by gesture meaning and how aphasia influences imitation of LH stroke patients (n=208). All patients and especially patients with imitation deficits (17% of LH, 27% of RH stroke patients) imitated MF gestures significantly better than ML gestures. Importantly, meaningfulness-scores of all 10 gestures significantly predicted imitation scores of patients with imitation deficits. Furthermore, especially in LH stroke patients with imitation deficits, the severity of aphasia significantly influenced the imitation of MF, but not ML gestures. Our findings in a large patient cohort support current cognitive models of imitation and strongly suggest that ML gestures are particularly sensitive to detect imitation deficits while minimising confounding effects of aphasia which affect the imitation of MF gestures in LH stroke patients.

Diagnosis and treatment of upper limb apraxia.

Upper limb apraxia, a disorder of higher motor cognition, is a common consequence of left-hemispheric stroke. Contrary to common assumption, apraxic deficits not only manifest themselves during clinical testing but also have delirious effects on the patients' everyday life and rehabilitation. Thus, a reliable diagnosis and efficient treatment of upper limb apraxia is important to improve the patients' prognosis after stroke. Nevertheless, to date, upper limb apraxia is still an underdiagnosed and ill-treated entity. Based on a systematic literature search, this review summarizes the current tools of diagnosis and treatment strategies for upper limb apraxia. It furthermore provides clinicians with graded recommendations. In particular, a short screening test for apraxia, and a more comprehensive diagnostic apraxia test for clinical use are recommended. Although currently only a few randomized controlled studies investigate the efficacy of different apraxia treatments, the gesture training suggested by Smania and colleagues can be recommended for the therapy of apraxia, the effects of which were shown to extend to activities of daily living and to persist for at least 2 months after completion of the training. This review aims at directing the reader's attention to the ecological relevance of apraxia. Moreover, it provides clinicians with appropriate tools for the reliable diagnosis and effective treatment of apraxia. Nevertheless, this review also highlights the need for further research into how to improve diagnosis of apraxia based on neuropsychological models and to develop new therapeutic strategies.

[How to diagnose and treat limb apraxia]. / Diagnostik und Therapie der Gliedmabenapraxie.

Apraxia is a disorder of higher motor cognition. Deficits in imitating abstract and symbolic gestures as well as deficits in appropriate tool use are common apraxic symptoms which, importantly, cannot be explained by primary sensorimotor deficits alone. In spite of the relevance of apraxia for neurorehabilitation and the individual stroke patient's prognosis, apraxia is to date still too rarely diagnosed and treated. In this review the currently published assessments for the diagnosis of apraxia are evaluated. Based on this, an apraxia screening instrument as well as a diagnostic test for clinical use are recommended. In addition, different published approaches to the therapy for apraxia are described. Although current evidence is scarce, the gesture training suggested by Smania and co-workers can be recommended as a therapy for apraxia, because its effects were shown to extend to activities of daily living and to persist for at least two months after completion of the training. This review aims at directing the clinician's attention to the importance of apraxia. Moreover, it provides the interested reader with instruments for a reliable diagnosis and effective treatment of apraxia. These are also important prerequisites for further research into the neurobiological mechanisms underlying apraxia and the development of new therapy strategies leading to an evidence-based effective treatment of apraxia.