Article

Functional Magnetic Resonance Imaging Study on Dysphagia after Unilateral Hemispheric Stroke: A Preliminary Study

Department of Neurology, West China Hospital of Sichuan University, Chengdu, Sichuan, PR China.
Journal of neurology, neurosurgery, and psychiatry (Impact Factor: 6.81). 07/2009; 80(12):1320-9. DOI: 10.1136/jnnp.2009.176214
Source: PubMed

ABSTRACT

Swallowing dysfunction is common and disabling after acute stroke; however, the mechanism of dysphagia or recovery of swallowing from dysphagia remains uncertain. The purpose of this study was to explore cerebral activation of swallowing in dysphagia using functional MRI (fMRI) to compare the functional anatomy of swallowing in unilateral hemispheric stroke patients and healthy adults.
In total, five left hemispheric stroke patients with dysphagia, five right hemispheric stroke patients with dysphagia and 10 healthy controls were examined with event related fMRI while laryngeal swallow related movements were recorded. Data were processed using the general linear model.
A multifocal cerebral representation of swallowing was identified predominantly in the left hemisphere, in a bilateral and asymmetrical manner. Cerebral activation during swallowing tasks was localised to the precentral, postcentral and anterior cingulate gyri, insula and thalamus in all groups. Activation of volitional swallowing in dysphagic unilateral hemispheric stroke patients might require reorganisation of the dominant hemispheric motor cortex, or a compensatory shift in activation to unaffected areas of the hemisphere.
The results indicate that unilateral stroke of either cerebral hemisphere can produce dysphagia. Effective recovery is associated with cerebral activation related to cortical swallowing representation in the compensating or recruited areas of the intact hemisphere. Functional MRI is a useful method for exploring the spatial localisation of changes in neuronal activity during tasks that may be related to recovery. Therefore, the subsequent information gleaned from changes in neural plasticity could be useful for assessing the prognosis of dysphagic stroke.

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    • "Hemispheric targets in swallowing innervation Although swallowing is a bilaterally innervated process, strong evidence by multiple researchers suggests that there is lateralization to a dominant hemisphere (Lowell et al., 2012; Li et al., 2009; Malandraki et al., 2009; Hamdy et al., 1998a, 1997; Hamdy et al., 1996; Robbins et al., 1993; Barer, 1989; Robbins and Levine, 1988; Gordon et al., 1987). A lesion in the dominant hemisphere is likely to result in oropharyngeal dysphagia leaving intact, but weaker, projections from the non-dominant side (Teismann et al., 2011; Li et al., 2009; Khedr et al., 2008; Hamdy et al., 1998b, 1997, 1996). Multiple studies have shown that re-organizing and increasing the strength of the contralesional hemispheric projections help to rehabilitate dysphagia (Park 2 J.M. Pisegna et al. / Clinical Neurophysiology xxx (2015) xxx–xxx Please cite this article in press as: Pisegna JM et al. "
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    ABSTRACT: Objective: The primary aim of this review is to evaluate the effects of non-invasive brain stimulation on post-stroke dysphagia. Methods: Thirteen databases were systematically searched through July 2014. Studies had to meet pre-specified inclusion and exclusion criteria. Each study’s methodological quality was examined. Effect sizes were calculated from extracted data and combined for an overall summary statistic. Results: Eight randomized controlled trials were included. These trials revealed a significant, moderate pooled effect size (0.55; 95% CI = 0.17, 0.93; p = 0.004). Studies stimulating the affected hemisphere had a combined effect size of 0.46 (95% CI = -0.18, 1.11; p = 0.16); studies stimulating the unaffected hemisphere had a combined effect size of 0.65 (95% CI = 0.14, 1.16; p = 0.01). At long-term follow up, three studies demonstrated a large but non-significant pooled effect size (0.81, p = 0.11). Conclusions: This review found evidence for the efficacy of non-invasive brain stimulation on post-stroke dysphagia. A significant effect size resulted when stimulating the unaffected rather than the affected hemisphere. This finding is in agreement with previous studies implicating the plasticity of cortical neurons in the unaffected hemisphere. Significance: Non-invasive brain stimulation appears to assist cortical reorganization in post-stroke dysphagia but emerging factors highlight the need for more data.
    Full-text · Article · May 2015 · Clinical Neurophysiology
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    • "Hemispheric targets in swallowing innervation Although swallowing is a bilaterally innervated process, strong evidence by multiple researchers suggests that there is lateralization to a dominant hemisphere (Lowell et al., 2012; Li et al., 2009; Malandraki et al., 2009; Hamdy et al., 1998a, 1997; Hamdy et al., 1996; Robbins et al., 1993; Barer, 1989; Robbins and Levine, 1988; Gordon et al., 1987). A lesion in the dominant hemisphere is likely to result in oropharyngeal dysphagia leaving intact, but weaker, projections from the non-dominant side (Teismann et al., 2011; Li et al., 2009; Khedr et al., 2008; Hamdy et al., 1998b, 1997, 1996). Multiple studies have shown that re-organizing and increasing the strength of the contralesional hemispheric projections help to rehabilitate dysphagia (Park 2 J.M. Pisegna et al. / Clinical Neurophysiology xxx (2015) xxx–xxx Please cite this article in press as: Pisegna JM et al. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: The primary purpose of this review is to evaluate the effects of non-invasive brain stimulation on post-stroke dysphagia. Method(s): Thirteen databases were systematically searched through July 2014. Studies had to meet pre-specified inclusion and exclusion criteria. Each study’s methodological quality was examined. Effect sizes were calculated from extracted data and combined for an overall summary statistic. Result(s): Eight randomized controlled trials were included. These trials revealed a significant, moderate pooled effect size (0.55; 95% CI=0.17, 0.93; p=0.004). Studies stimulating the affected hemisphere had a combined effect size of 0.33 (95% CI=-0.52, 1.18; p=0.44), while studies stimulating the unaffected had a much larger, significant pooled effect size (0.70; 95% CI=0.25, 1.15; p=0.002). At long-term follow up, three studies demonstrated a large but non- significant pooled effect size (0.81, p=0.07). Conclusions: This review found evidence for the efficacy of non-invasive brain stimulation on post-stroke dysphagia. A greater effect size resulted when stimulating the unaffected rather than the affected hemisphere. This finding is in agreement with previous studies implicating the plasticity of cortical neurons in the unaffected hemisphere. Non-invasive brain stimulation appears to assist cortical reorganization in post-stroke dysphagia but emerging factors highlight the need for more data.
    Full-text · Conference Paper · Mar 2015
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    • "However, the impact of stroke localization on cortical swallowing function has rarely been explored by functional imaging studies. The few existing works on cortical swallowing processing in stroke included only patients with unilateral supratentorial infarct and applied either TMS [19,20] or fMRI [21]. Those studies have been performed at different time points after stroke. "
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    ABSTRACT: Dysphagia is a major complication in hemispheric as well as brainstem stroke patients causing aspiration pneumonia and increased mortality. Little is known about the recovery from dysphagia after stroke. The aim of the present study was to determine the different patterns of cortical swallowing processing in patients with hemispheric and brainstem stroke with and without dysphagia in the early subacute phase. We measured brain activity by mean of whole-head MEG in 37 patients with different stroke localisation 8.2+/-4.8 days after stroke to study changes in cortical activation during self-paced swallowing. An age matched group of healthy subjects served as controls. Data were analyzed by means of synthetic aperture magnetometry and group analyses were performed using a permutation test. Our results demonstrate strong bilateral reduction of cortical swallowing activation in dysphagic patients with hemispheric stroke. In hemispheric stroke without dysphagia, bilateral activation was found. In the small group of patients with brainstem stroke we observed a reduction of cortical activation and a right hemispheric lateralization. Bulbar central pattern generators coordinate the pharyngeal swallowing phase. The observed right hemispheric lateralization in brainstem stroke can therefore be interpreted as acute cortical compensation of subcortically caused dysphagia. The reduction of activation in brainstem stroke patients and dysphagic patients with cortical stroke could be explained in terms of diaschisis.
    Full-text · Article · Mar 2011 · BMC Neurology
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