Introduction

Delirium is a transient cause of mental dysfunction characterized by fluctuation in attention and alertness. It usually develops over a short period of time (hours to days) and may present with other cognitive symptoms such as memory, language, and visuospatial deficits, as well as disorientation or perceptual alterations¹. Delirium diagnosis is clinical and the most common diagnostic assessment instruments include DSM-5 and confusion assessment method-intensive care unit (CAM-ICU)².

There are several studies on delirium and its impact on prognosis in several diseases. Delirium occurs in up to 30% of patients in general wards, increases mortality risk in 60% of cases, and length of hospital stays³,⁴. It is currently considered one of the main public health problems, not only in elderly patients, but in intensive care units, terminal patients, and out-of-hospital settings, since it is one of the pathologies that are related with greatest intrahospital costs⁵,⁶.

Clinically, delirium is classified based on the pattern of behavior or psychomotor activity, subdividing into hypoactive, hyperactive, or mixed. The relevance of this classification lies in the prognosis, with the mortality rate being 33%, 34%, and 15%, respectively⁷,⁸. Delirium appears to be the consequence of the interaction between an underlying predisposing factor and an acute stressor. Proposed mechanisms for delirium pathogenesis include neurotransmitters dysfunction, inflammatory, and neurodegenerative mechanisms, as well as endothelial and direct neuronal injury³.

Little information exists on the frequency and associated factors of delirium in patients in neurological emergency departments; therefore, this study aims to determine the frequency and main risk factors associated with delirium in this group of patients.

Materials and methods

Results

Of 3661 patients treated, only 189 patients fulfilled inclusion criteria. The mean age of our population was 48 ± 19 years (Fig. 1), with male predominance (60.8%). Baseline clinical characteristics of our population are described in tables 1 and 2 which describe the main neurological diagnoses of admission.

Figure 1 Age ranges in patients with neurological pathology with and without delirium. 

Delirium occurred in 44 (23.2%) patients, with 36 (81%) diagnosed at admission, and 8 (18.1%) were during their hospital stay. The median severity of delirium (delirium index) at the time of diagnosis was 12 (IQR 10-16) points and the median duration was 5 (IQR 2-11) days (Fig. 2). The most prevalent subtype was hypoactive (72.8%), followed by hyperactive (18.1%) and mixed (9.1%). The median total hospital stay for patients with delirium was 7.5 (IQR 4-13) days. Delirium resolved in the emergency department in 29.5% of patients, persisted on discharge from the emergency department in 31 patients, of which 23 patients were admitted to hospitalization or ICU and were followed up during their stay. Fifty percentages of our patients were discharged without delirium. Clinical differences between patients with versus without delirium are described in table 2.

Figure 2 Duration of delirium in patients with neurological pathology. 

Regarding identification of preexisting factors for delirium, the following was statistically significant: Previous delirium OR 3.91 (95% CI 2.48-6.15, p = 0.003), stroke OR 2.29 (95% CI 1.34-3.98, p = 0.009), neurosurgery OR 2.17 (95% CI 1.23-3.83, p = 0.024), and a history of psychoactive drug use OR 2.55 (95% CI 1.39-4.69, p = 0.021).

Precipitating factors for delirium at admission or during hospital stay include polypharmacy OR 6.94 (95% CI 2.86-16.83, p ≤ 0.001), sepsis/septic shock OR 3.48 (95% CI 2.18-5.56, p ≤ 0.001), hydroelectrolytic imbalance OR 3.71 (95% CI 1.82-13.19 p ≤ 0.001), central nervous system infection OR 3.72 (95% CI 2.35-5.90, p ≤ 0.001), and uncontrolled epilepsy OR 3.21 (95% CI 1.96-5.24 p = 0.001). Among the findings in imaging studies, intraparenchymal left hemisphere OR 2.19 (95% CI 1.33-3.62, p = 0.004) and supratentorial lesions OR 2.31 (95% CI 1.33-4.02, p = 0.003) are risk factors for delirium (Tables 1 and 2).

The following variables were independent risk factors for delirium through the multivariate logistic regression model: uncontrolled crisis [OR 5.4 (95% CI 1.2-22.9), p = 0.023], supratentorial structural brain lesion [OR 6.1 (95% CI 1.7-21.2), p = 0.004], neuroinfection [OR 9.6 (95% CI 2.9-31.4), p ≤ 0.001], multiple drugs [OR 4.7 (95% CI 1.4-15.2), p = 0.009], and sepsis/septic shock [OR 3.4 (95% IC1.2- 9.9), p = 0.02] (Table 3).

Discussion

Delirium occurs in 30% of hospitalized patients, increases up to 56% in patients older than 65 years, and is related with greater mortality risk, up to 60%³,⁴. Neurological conditions such as stroke and prior cognitive impairment are risk factors for delirium in the general population⁴. In neurological hospitalization services, the population may differ from the general population as certain neurological or neurosurgical conditions are more frequent in young adult patients (for example: demyelinating diseases and primary tumors of the Central Nervous System). There is few information on the frequency of delirium in neurological hospitalization areas. A study from a hospital in Spain reported a delirium frequency of 16.5% in a neurological service⁴. A previous report performed in the neurological emergency department of our center in 2006 reported that 14.9% of the patients admitted to the emergency department presented delirium⁹. However, the demand for specialized medical care in neurological, neurosurgical, and neuropsychiatric conditions has increased in recent decades in our hospital, increasing to 23.3%.

The time in which the delirium is established from hospital admission is a prognostic factor. The earlier delirium diagnosis is established in the emergency area directly impacts the length of hospital stay up to 10-23 days if it is detected within the first 24 h¹⁰. Other authors state that delirium diagnosed in the emergency department is not transitory; in fact, it persists in up to 77%¹¹. In our population, found similar data as 70.4% of our population presented transient delirium lasting between 1 and 10 days, while in the remaining 29.54%, delirium persisted for more than 10 days (Fig. 2). Delirium may persist after hospital discharge, as partial remission and non-recovery have been reported in up to 20.2% and 31.7%, respectively, even to 4 months after hospital discharge¹². In elderly patients, persistence of delirium has been reported in up to 25.6% and 21% at 3 and 6 months after hospital discharge¹³.

Delirium is very common in intensive care hospitalization with incidence in intensive care, ranges from 45% to 56%, increasing to 93% in terminally ill patients¹⁴,¹⁵. In patients undergoing major surgery, delirium has been reported in 17-61%¹⁶. In our population, history of any neurosurgical procedure or stroke is risk factors for delirium. Other medical conditions that have been reported as risk factors for delirium, both in the general population and in the population with neurological disease, is history of previous delirium and cerebrovascular disease, which was observed in our study.

With the advent of new diseases such as COVID-19, which has been linked to long stays in the intensive care unit, delirium has occurred in 65-79%¹⁷; contrasting with outpatients with COVID-19 who arrive at the emergency department in whom delirium has presented as the main admission symptom in up to 28% of cases¹⁸. No patients with COVID-19 were included in our study since our center during the pandemic (2020 and 2021) was not a center for care of patients with suspected SARS-CoV-2 virus infection. Cerebrovascular disease is one of the most frequent diagnoses in the neurological population presenting with delirium.

Post-stroke delirium is a common complication in the acute phase, with incidences ranging from 11.8% to 66%. Qu J et al. reported a prevalence of 14.6% in patients with ischemic stroke, most diagnosed between the 1^st and 3^rd day of hospitalization (13.4%), and only in a small part (1.1%) delirium was established after 5-7 days of hospitalization¹⁹. Fleischmann et al. demonstrated that, in most cases, delirium was established immediately after the acute cerebral infarction (within the first 72 h)²⁰, like that reported in cases associated with acute systemic diseases²¹. Our study reported a prevalence of post-stroke delirium of 29.5%. In patients with cerebrovascular disease, the most relevant risk factor for the development of delirium is the presence of a left cortical infarction, followed by a history of previous infarction and infections¹⁹, which is consistent with our findings. In our multivariate model, we analyzed that supratentorial brain lesions are an independent risk factor for delirium (Table 3). Although some other studies oppose this argument and show that post-infarction delirium is more closely related to right lobe cerebral infarcts²²,²³. Delirium is a complication of cerebrovascular disease that must be addressed as soon as possible since these patients have a worse prognosis at 3 and 6 months compared to those who do not present it, and these patients also have a higher risk of developing delirium²⁴.

Other diagnoses of the neurological population that presents delirium are CNS infections and the lack of control of epileptic seizures. In our multivariate model, we demonstrate that both neuroinfections and uncontrolled epilepsy are independent risk factors for delirium in neurological patients, supporting previous reports⁹. Moreover, in our study, we reported that steroid treatment is a risk factor for delirium, which are used in support of the treatment of neuroinfection by Streptococcus pneumoniae or Mycobacterium tuberculosis, and in autoimmune diseases of the central nervous system. With respect to uncontrolled epilepsy as a risk for delirium in our population, we think that it is due to our population of patients with epilepsy, as most of them suffer from drug resistant epilepsy.

In the general population, infections such as electrolyte disturbances have been widely described as risk factors for delirium. In our study, which included only patients with neurological or neurosurgical conditions, only infections son independent risk factors for delirium³.

Conclusion

The frequency of delirium in the population treated in a neurological emergency department is 23.3%. Stroke and delirium history, as well as neurosurgical procedures are risk factors for delirium in the neurological population. CNS infections and uncontrolled epilepsy, as well as presenting structural changes in the imaging study in supratentorial areas, are independent risk factors for delirium.

We agree that the present study provides important information on this issue in the population of our country; however, we consider that subsequent studies must be done, involving more centers and for a longer duration of patient recruitment.