Stroke is one of the most frequent causes of death and disability worldwide and has significant clinical and socioeconomic impact [15]. The World Health Organization (WHO) refers to stroke as the incoming epidemic of the twenty-first century [16, 17]. The outcome of stroke depends on several factors: the stroke itself, initial treatment, early rehabilitation, the early detection, and prevention of complications [5].
Delirium is a multifactorial neuropsychiatric disorder with definite predisposing and precipitating factor [18] and is one of the most common complications that older patients develop affecting up to 30% of all older medical hospitalized patients [19].
This study included 74 acute stroke patients, 54.1% of our patients were males and 45.9% were females. This was in agreement with other studies that reported males were more vulnerable to stroke than females [20,21,22].
Regarding the medical history of stroke patients, in this study, hypertension and diabetes mellitus were the most important risk factors of acute stroke with the highest population-attributable risk at 71.6% and 40.5%, respectively; this was in agreement with many studies [23,24,25].
As regards the incidence of delirium in acute stroke patients, our study showed that the incidence of delirium among stroke patients was about 20.3%. The prevalence of post stroke delirium is widely discrepant in the various studies, ranging between 10% [5] and 48% [26]. This wide range of prevalence of delirium across studies could be due to the use of different criteria and assessment instruments for delirium, different inclusion and exclusion criteria, and different age groups included, sample size, and where and how the patients with stroke were treated [5].
Regarding age, we found that patients who developed delirium were older with mean age of 68.6 ± 9.6. This was in agreement with other studies [5, 26,27,28,29,30,31]. However, Oldenbeuving and colleagues [32] and Melkas and colleagues [32] found that age was not an independent risk factor for delirium. Several factors may precipitate delirium in higher age, most probably due to physiological loss of cholinergic reserve with aging.
As regards sex and incidence of delirium, no significant difference was found between male and female stroke patients. This is in agreement with previous studies [5, 29,30,31,32,33].
We found that there was no significant relationship between incidence of delirium and certain risk factor of stroke (hypertension, diabetes mellitus, previous stroke, TIA, and cardiac diseases). This was in agreement with previous studies [26, 30]. However, this was in disagreement with other studies that found delirium was significantly less prevalent in hypertensive patients [18] and smokers [28] and higher among stroke patients with cardiac disease [5].
Regarding the conscious level GCS at admission, we found highly significant relationship between the development of delirium and lower GCS at admission. Similar findings were obtained by other studies [29, 30].
Regarding NIHSS, delirious patients had higher NIHSS at admission. A highly significant relationship was found between the development of delirium and presence of severe neurological impairment at admission (NIHSS > 15). This was in agreement with results carried out by [32, 34]. Lower GCS and higher NIHSS at admission have been used as predictors of stroke severity. Severe strokes are more likely to be associated with medical complications, which by themselves could precipitate delirium [31].
Regarding incidence of delirium and type of stroke, we found that delirium is more prevalent in patients with cerebral hemorrhage compared to patients with ischemic stroke. This was in line with previous studies [26, 29, 30, 34].
Concerning the incidence of delirium and stroke subtypes according to TOAST criteria, we found that patients with cardio-embolic stroke type were more likely to develop delirium. While Oldenbeuving et al. [32] found that delirium was more frequent in patients with large-vessel stroke, other studies did not find an association between stroke etiologies defined according to TOAST criteria and incidence of delirium [35].
In the current study, the Oxfordshire classification criteria of cerebral infarction were used, and we found that delirium was more likely to occur in patients with a TACI. This was in agreement with several studies [30, 31, 33]. While Nicolai and Lazzarino [36] found that incidence of delirium was higher in patients with lesions of posterior cerebral artery territory, moreover, other studies [5, 28] found no significant association between lesion type or location and the development of delirium. Regarding our results showing that delirium is more prevalent in patients with TACI lesions and of cardio-embolic etiology, this is may be because such lesions are often larger, and hence, the findings may have been a reflection of stroke severity rather than the effect of its etiology [3].
Regarding the location of stroke lesion and development of delirium, our study disclosed that delirium was more frequent after hemispherical strokes. This was inconsistent with the results of Caeiro et al. [29] who found no significant difference between right and left hemispherical lesions. In our study, we found a significant association between the development of delirium and right hemispherical lesions. This was in agreement with the results carried out by other studies [32, 37,38,39]. However, other studies [36, 40] reported that delirium was more frequent with left-sided lesions. The right hemisphere has a critical role in spatial, bodily perception and orientation [41, 42] and plays a major role in perceiving emotion [42]. Disturbance of both spatial and emotional orientation might increase the likelihood of misinterpretation of the environment, leading to a higher risk of delirium [32].
Regarding the outcome of delirious patients, we found that those who experienced delirium had unfavorable outcomes in the form of increased hospital stay and higher mortality mainly in hospital mortality. In addition, we also found functional outcomes measured with BI to be worse after delirium. Similar findings were consistently reported by many previous studies [26, 27, 29,30,31,32]. The latter found that 1-month mortality was not significantly different between patients with and without delirium, although long-term (6 months and 12 months post stroke) mortality was higher in patients with delirium. Henon and colleagues [28] reported that there is no significant difference in inpatient mortality between delirious and non-delirious patients. The heterogeneity in inpatient mortality could be explained by the different timeframes of delirium onset and differences in management of stroke patients [43].