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Background: Our understanding of brainstem swallowing centers is mainly based on experimental animals. In order to solve this problem also in humans, a clinical-anatomical study on dysphagic patients with different lesion patterns was performed., Patients and Methods: We studied 43 consecutively admitted dysphagic patients with unilateral paresis of the vagal nerve (PVN), Avellis' syndrome (AS), Wallenberg's syndrome (WS), posterior fossa tumour (PFT) or cerebellar hemorrhage (CH) with regard to clinical and anatomical aspects., Findings: There was a continuum with regard to functional outcome from neurogenic dysphagia (ND): Patients with PFT or CH had a significantly worse outcome than patients with WS; the outcome of WS patients was significantly worse than that of patients with PVN or AS. In AS only the Nucleus ambiguus (NA) and its surrounding reticular formation (RF) were affected. In all patients with WS, the infarctions of the dorsolateral medulla were situated in the rostral third of the medulla and affected the NA and the Nucleus tractus solitarii (NTS) with their surrounding RF. In patients with PFT and CH, the NTS and its surrounding RF were affected on both sides. The overlap area of WS and PFT lesions is situated in the NTS and the surrounding RF, especially in its Nucleus parvocellularis., Interpretation: Our results point to the fact, that in humans the dorsomedial central pattern generators (CPGs) for swallowing are situated in the rostral part of the dorsal medulla oblongata near the NTS/surrounding RF (especially Nucleus parvocellularis) and that the dorsomedial CPGs are superior to the ventrolateral CPGs (near the NA/surrounding RF) with regard to their swallowing-relevance. Furthermore, we hypothesize that due to the individual asymmetry of the swallowing-dominant forebrain hemisphere - the outcome from ND in WS depends on the side of the medullary infarction.

Background: No studies exist dealing with the outcome of dysphagic patients with posterior fossa (IV. ventricle) tumours (PFT) or cerebellar hemorrhage (CH), and the outcome of patients with Wallenberg's syndrome (WS) after functional swallowing therapy (FST) has so far not been studied in detail. Patients and methods. 208 patients with neurogenic dysphagia (ND) who were consecutively admitted for functional swallowing therapy (FST) over a 3 year period to our hospital were examined clinically, by use of a videofluoroscopic swallowing study (VFSS) and/or fibreoptic evaluation of swallowing (FEES). The most frequent etiology was stroke (48%), followed by CNS tumours (13%). In the present study we defined three groups. Group 1 comprised 8 patients with PFT or CH. Group 2 consisted of 27 patients with WS, which was the leading cause among patients with non-hemispheric stroke. Since in WS a vagal nerve paresis due to affection of the Nucleus ambiguus occurs, 8 patients with Avellis' syndrome or unilateral paresis of the vagal nerve served as controls and were defined as group 3. Findings. In the three groups, functional feeding status showed significant improvement after FST comprising methods of restitution, compensation and adaptation, each of which were applied in more than 80% of patients. Outcome was, however, significantly worse in group 1 as compared to group 2 and in group 2 as compared to group 3. Dysfunction of the upper esophageal sphincter and reflex triggering were significantly more severely disturbed in groups 1 and 2 as compared to group 3. Group 1 showed significantly more severe disturbances of the oral phase as compared to groups 2 and 3. After FST, more than 50% (5/8) of group 1 and 30% (8/27) of WS patients (group 2) were dependent on tube feeding, whereas all patients of group 3 were full-oral feeders. Interpretation. This is the first study dealing with the outcome of dysphagic patients with PFT or CH. Based on our results it can be assumed that in these patients pressure is exerted on both dorsomedial central pattern generators (DMCPGs) for swallowing in a posterior-anterior direction. Due to the importance of the DMCPGs for swallowing, bilateral (and often MRI-invisible) lesions seem to be very harmful. For a better understanding of the pathomechanism responsible for ND in patients with PFT or CH, modern imaging methods such as proton magnetic resonance spectroscopy should be used for studying metabolic changes in the dorsal medulla in the future. Since the outcome of patients with WS with regard to dependence of tube feeding was not associated with the site or size of the lesion, it may due to the individual asymmetry of the swallowing-dominant forebrain hemisphere - depend on the side of the medullary infarction.