Prevalence of Dysphagia in Acute Ischemic Stroke: Which Patients Are at Risk?

 Dysphagia is defined as swallowing dysfunction which leads to difficulty of passing food or water from mouth to hypopharynx or esophagus. Neurogenic dysphagia can be seen in lesions in one or both cerebral hemisphere or involvement of motor nucleus of swallowing muscles in brain stem or their motor axons (3,4). As mentioned in literature, swallowing dysfunction is one of the most common complications in acute stroke occurring in 13-94% of cases which can directly affect patients’ short term and long-term prognosis (2). It might complicate the course of acute stroke by developing malnutrition, dehydration, dependency on others, and silent aspiration pneumonia which all can lead to prolongation of hospital stay (5,6,7).On the other hand, dysphagia is considered as an independent predictor of mortality in acute stroke patients (2,8). Additionally, as discussed in many studies, location of brain infarction can predict the occurrence of dysphagia in stroke patients. For instance, infarctions in peri-insular cortex, right opercular cortex, left basal ganglia or thalamus are the most common sites leading to dysphagia following acute stroke. There are other factors associated with the occurrence of dysphagia in acute stroke including size of the infarction, right or left side of the lesion, age and gender of the patient and pre-existing comorbidities such as hypertension or diabetes (20, 22). Furthermore, it is suggested to initiate oral feeding as soon as possible in stroke patients. Therefore, it seems that early identification of dysphagia in acute stroke patient would lead to appropriate swallowing treatments and decrease the risk of pneumonia and related complications following acute stroke (9,10). So, in this study we aimed to estimate the prevalence of dysphagia after acute ischemic stroke in patients referring to Rasool-Akram hospital, Tehran, Iran and revealing whether there is a correlation between incidence of dysphagia and stroke characteristics including vascular territory and right or left side of the stroke, demographic variables or pre-existing underlying diseases.

In this historical cohort study, 177 patients with acute ischemic stroke who were admitted to Rasool-Akram hospital were evaluated. The study was performed for a-six-month period. Patients with incomplete medical records or who were suffering from dysphagia prior to their admission were excluded. Ultimately, 137 patients were included in our study and their medical records were carefully studied and data such as presence or absence of dysphagia following stroke within 48 hours of admission, demographic data including age and sex, history of previous stroke, smoking, diabetes, hypertension, side of the brain infarction (right or left) and vascular territory of acute stroke were all evaluated. Data were analyzed using SPSS version 22 and analytical significance was considered as p-value<0.05.

From 137 patients, 60.6% were male and 39.4% female with median age of 65.41± 13.51 years old, (the oldest patients was 95 years old and the youngest, 31 years old). Diabetes and hypertension were in 35.8% and 66.4% of patients, respectively. 34 patients (24.8%) were smoker and 40 patients (29.2%) had history of previous stroke. Dysphagia was seen in 43 patients so, the prevalence of dysphagia following acute ischemic stroke was estimated 31.4%. The localization of the infarction was divided into ten groups including complete middle cerebral artery (MCA), anterior cerebral artery (ACA), posterior cerebral artery (PCA), striatocapsular infarction, peri-insular infarction, and centromsemiovale infarction, infarction in territory of internal carotid ICA, cerebellum, brain stem and diffuse small vessel diseases. Statistically significant, dysphagia was more common in middle cerebral artery infarctions (p-value= 0.017, OR= 2.75 CI (2.05-3.55)).  Regarding the side of the infarction, 43.8% of patients had cerebral infarction on the left side, 36.5% on the right, 2.2% bilaterally and 17.5% of patients had diffuse small vessel diseases. Interestingly, there was a significant correlation between the left side infarctions and dysphagia (p-value= 0.034). Also, there was a significant correlation between age and occurrence of dysphagia, so that the older age was associated with the higher risk of dysphagia. No significant correlation was revealed between dysphagia and other variables including patient’s gender, diabetes, hypertension, smoking and previous stroke in this study.

In this study, 31.4% of patients had dysphagia after acute ischemic stroke which was nearly similar to other studies (12,13,14). However, in a meta-analysis study published in 2021, the prevalence of dysphagia following intracerebral hemorrhage (ICH) has been estimated up to 63.6% (23) and up to 55% in stroke patients (24). Association between dysphagia and different vascular territory infarction or lesions pattern had been evaluated in many studies with inconclusive results and approximately all vascular territories had been associated with dysphagia in various studies including anterior cerebral artery (ACA), middle cerebral artery (MCA), posterior cerebral artery (PCA), and vertebrobasilar arteries (16,21,22). However, in some studies no statistical significance was explored and it was revealed that probably this is the size of stroke that has an association with dysphagia rather than vascular territory of infarction (14). In this study, there was a statistically significant correlation between dysphagia and MCA territory infarctions. The side of the brain lesion is another item that has been discussed in studies and it is proposed that dysphagia is more common in left side strokes, the same result revealed in our study. Though there was no association between patients’ gender, smoking or underlying diseases such as hypertension, diabetes, and dysphagia in this study, in one study, diabetes, female gender and older age was associated with higher risk of dysphagia (20). Nevertheless, more studies are required to evaluate association of these factors and risk of dysphagia more precisely. Currently, 2018 best stroke practice guidelines for the early management of patients with acute ischemic stroke from the American Heart Association/American Stroke Association, support early detection for screening dysphagia and recommend adherence to dysphagia screening in acute stroke centers by healthcare professionals, however practice remains diverse. A recent systematic review assessed the benefits of early detection for dysphagia with bed sides screening by a non-swallowing expert in adult stroke. This survey revealed that evidence from both experimental and observational studies showed a considerable protective benefit of dysphagia screening following adult acute stroke which decreases post stroke complications including pneumonia, dependency on others foe feeding, and length of hospital stay, and mortality compared with similar patients with no or relatively less precise early detection (24). Since it is highly recommended to start oral feeding as soon as possible in stroke patients, it is worth to screen every stroke patient for dysphagia several times during first days of stroke to evaluate patient’s swallowing function and initiate appropriate feeding method accordingly.
It seems that despite excellent strategies that have been developed during recent decades in acute stroke management or secondary prevention, dysphagia has been overlooked in practice and it appears that there are still some uncertainties regarding dysphagia screening benefit in patients with stroke and adequate comprehensive data is still lacking, especially in Iran. However, as explored in this study, dysphagia was a common consequence of stroke so that about one third of Iranian patients with acute ischemic stroke suffer from dysphagia which can result in unwanted complications or even death. This survey and similar ones, highlight the importance of early evaluation of dysphagia in acute stroke which can be easily performed by primary health care professionals in stroke institutions.