American Journal of Gastroenterology ISSN 0002-9270 C  2006 by Am. Coll. of Gastroenterology doi: 10.1111/j.1572-0241.2006.00540.x Published by Blackwell Publishing CLINICAL REVIEW Pathophysiological Changes of the Gastrointestinal Tract in Ischemic Stroke Bernhard J. Schaller, M.D., Rudolf Graf, Ph.D., and Andreas H. Jacobs, M.D. Max-Planck-Institute for Neurological Research, Cologne, Germany OBJECTIVE: Dysphagia is common after stroke and represents a marker of poor prognosis. After ischemic stroke, dysphagia represents only one part of the clinical spectrum of changes in the gastrointestinal (GI) tract and includes GI hemorrhage, delayed GI emptying, and colorectal dysfunction. State-of-the-art imaging techniques have started to revolutionize to study the cortical and brainstem control of these GI symptoms. It has become increasingly obvious that GI alterations after stroke are complex and its recovery following stroke is even more so. METHODS: In this review, an electronic database research was performed in MEDLINE, EMBASE, and the COCHRAINE database using the terms stroke, dysphagia, GI motility, or cortical reorganization; an extensive manual searching was additionally conducted. RESULTS: Cerebral ischemia may lead to an interruption of the axis between central nervous system and GI system. This altered interrelation between the central nervous system and the GI system may cause, among other things, mainly dysphagia, GI dysmotility, and GI hemorrhage. The consecutive clinical symptoms can often be directly attributed to specific cerebral ischemic lesions involving the brain stem as well as certain cortical and subcortical structures. However, in some cases the pathophysiological mechanisms leading to GI symptoms are incompletely understood. Recent improvement of imaging techniques, especially in functional imaging, has lead to new insights of the central control of the GI tract, suggesting that its cortical and medullar organization is multifocal, and bilateral with handness-independent hemispheric dominance. CONCLUSIONS: Following stroke, patients may have swallowing impairment and other changes of the GI tract that could affect nutritional and hydration status and that lead to aspiration pneumonia. Impaired nutritional status is associated with reduced functional improvement, increased complication rates, and prolonged hospital stays. (Am J Gastroenterol 2006;101:1655–1665) INTRODUCTION After ischemic stroke, various secondary functional alter- ations can be expected in peripheral organs that are in close interrelation to the affected cerebral vascular territories (1– 3). This is especially the case in the different segments of the gastrointestinal (GI) system that is partly controlled by a complex hierarchy of neural substrates in the central and pe- ripheral nervous system. There is considerable clinical and experimental evidence that the incidence of certain GI al- terations, such as dysphagia and GI tract dysmotility, are strongly related to the topographical location of the cere- bral ischemic damage itself and does not represent a gen- eral state of severe illness (4–6). Main vascular territories involved seem to be those of the middle cerebral artery and the posterior inferior cerebellar artery (7, 8) and to a lesser extent the vertebral artery (9). Positron emission tomogra- phy (PET) and magnetic resonance imaging (MRI) studies in normal human subjects have also identified multiregional representation of the GI tract mainly within sensorimotor cor- tex (inferior precentral gyrus) and the brainstem. Dysphagia represents a common and distressing consequence of stroke in these vascular territories, occurring in up to 50% of pa- tients immediately after the event (9). Post-stroke dysphagia increases the risk of deaths (10) and worsens functional out- come after stroke, with lower recovery (11) and longer hospi- tal stay. However, despite similar dysphagia severity at onset, individual recovery pattern vary widely. The reason for this remains unclear; in particular, it does not appear to be directly related to stroke severity (12). In addition to swallowing, a number of other GI symptoms that are related to changes in the brain after stroke are not well understood. The severity and extent of neurological deficits in the GI system after ischemic stroke are likely to depend on the amount and location of brain tissue that suffers from an im- pairment of blood supply below the critical flow threshold (13). While not the sole determinant of damage (duration of reduced flow is also important), experimental work on 1655