Abstract
BackgroundTo date, specific therapeutic approaches to expedite recovery from apraxic deficits after left hemisphere (LH) stroke remain sparse. Thus, in this pilot study we evaluated the effect of anodal transcranial direct current stimulation (tDCS) in addition to a standardized motor training on apraxic imitation deficits.MethodsIn a rehabilitation hospital, we assessed apraxic, aphasic, and motor deficits in 30 LH stroke patients before and after a five-day standard programme of motor training combined with either anodal (10 min, 2 mA; n = 14) or sham (10 min, 0 mA, n = 16) tDCS applied in a double-blind fashion over left posterior parietal cortex (PPC). Where appropriate, data were analyzed with either t-test, Fisher’s exact test, or univariate/ repeated measures ANOVA.ResultsCompared to sham tDCS, five sessions of anodal tDCS expedited recovery from apraxic imitation deficits (p < 0.05): Already after 5 days, the anodal tDCS group showed levels of imitation performance that were achieved in the sham tDCS group after 3 months. However, the primary outcome of the study (i.e., anodal tDCS induced improvement of the total apraxia score) failed significance, and there was no significant tDCS effect on apraxia after 3 months. Anodal tDCS improved grip force (of the contra-lesional, i.e., right hand), but had no effect on aphasia.ConclusionsData from this pilot study show that repetitive, anodal tDCS over left PPC combined with a standardized motor training expedites recovery from imitation deficits in LH stroke patients with apraxia (relative to sham stimulation). Results suggest that in patients suffering from apraxic imitation deficits a randomized controlled trial (RCT) is warranted that investigates the effects of tDCS applied over PPC in addition to a standardized motor training.
Highlights
To date, specific therapeutic approaches to expedite recovery from apraxic deficits after left hemisphere (LH) stroke remain sparse
The pathophysiology of apraxic pantomime deficits is still a matter of debate [32], the pivotal role of the left PPC for gesture imitation is undisputed [12, 20]. Consistent with such a critical role, single sessions of anodal transcranial direct current stimulation (tDCS) over the left posterior parietal cortex (PPC) facilitated gesture processing in healthy subjects [43] and improved the performance of apraxic patients (n = 6) in imitation tasks involving the upper limb [3]
There were no significant differences between the anodal and the sham patient groups for any variable LH left hemisphere, tDCS transcranial direct current stimulation, PPC posterior parietal cortex, Mini-Mental State Examination (MMSE) Mini Mental State Examination, HADS Hospital Anxiety and Depression Scale, laterality quotient (LQ) Laterality quotient as assessed by the Edinburgh Handedness Inventory, MRC paresis scale Medical Research Council rating scale for assessing paresis, modified Rankin Scale (mRS) modified Rankin scale, Aphasia Check-List (ACL-K) Aphasia Check List-short version, KAS Cologne Apraxia Screening
Summary
Specific therapeutic approaches to expedite recovery from apraxic deficits after left hemisphere (LH) stroke remain sparse In this pilot study we evaluated the effect of anodal transcranial direct current stimulation (tDCS) in addition to a standardized motor training on apraxic imitation deficits. The pathophysiology of apraxic pantomime deficits is still a matter of debate [32], the pivotal role of the left PPC for (hand) gesture imitation is undisputed [12, 20] Consistent with such a critical role, single sessions of anodal tDCS over the left posterior parietal cortex (PPC) facilitated gesture processing in healthy subjects [43] and improved the performance of apraxic patients (n = 6) in imitation tasks involving the upper limb [3]
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