This study showed two major things. Firstly, speech disturbance was frequently observed in stroke patients at the onset and therefore could be useful to identify the problem at the earliest stage. Secondarily, patients with speech disturbance had a higher mortality at 30 days after the stroke and speech disturbance could therefore be useful as one of the earliest tools to assess the severity of stroke. Paying more attention to speech disturbance should contribute to giving patients earlier access to hospitals and the appropriate immediate care of medical staff [18].
Speech disturbance was seen in about half of all stroke patients, which agrees with previous reports that it is one of the commonest symptoms of stroke. The study added information on the frequencies of the symptom in CI, CH, and SAH, respectively, and clarified differences in characteristics between patients with and without speech disturbances. Reports on the frequencies of speech disturbance in stroke vary widely. Jerntorp et al. reported that they observed a speech deficit in 26.1% of ischemic stroke patients and in 12.5% of hemorrhagic stroke patients [2]. Kothari et al. reported that they observed a speech abnormality in 11% at the onset of stroke [19]. Macdonell et al. reported dysarthria in 60% of cerebellar infarction patients [20].
The reasons why it is difficult to define the frequency of speech disturbance in stroke and to investigate its relation with mortality presumably include the followings. First, speech disturbance is a rather broad term, probably ranging from dysarthria to dysphasia, and may be difficult to assess in a detailed manner especially at emergency settings. Second, speech disturbance is a symptom that possibly fluctuates during emergency care.
In this study, patients with slurred and non fluent speech at the emergency room were regarded as patients with a speech disturbance. Since the speech disturbance researched here depended on information from patients and paramedics, it should be rather suitable to confirm its practical importance as a prompt identifier of stroke and as a prompt predictor of stroke outcome.
The present study showed that speech disturbance is more common in CI and in CH than in SAH. One possible explanation of this difference is that SAH is caused by the rupture of an aneurysm of the cerebral artery in the subarachnoid space outside of the brain cortex, and therefore should affect the brain in a rather indirect manner.
Odds ratios for speech disturbance, comparing those with and without various characteristics, past histories and paresis, are summarized in Table 3.
The most remarkable finding is the constant association of speech disturbance with early mortality in stroke as a whole, as well as in all three major subtypes of stroke. Although physicians empirically know that speech disturbance correlates with a poor outcome of stroke, there has been no quantitative data on the correlation with mortality.
Hazard ratios for death within 30 days after stroke onset in patients with a speech disturbance were much higher than those in patients without such speech disturbance. The statistical significance remained after adjustment for age, sex, systolic and diastolic blood pressures, arrhythmia and paresis. Therefore, speech disturbance at the onset of stroke can predict early stroke mortality, independent of age, sex, blood pressures, arrhythmia and paresis.
Outcomes and their predicting factors are great concern in stroke care. Various factors have been investigated and clarified the correlation to the outcome. The present study confirmed the validity of speech disturbance as a predicting factor, especially at emergency care.
Limitations
First, this study did not cover treatments such as thrombolysis for CI, which should affect the outcome. Treatments vary widely depending on various factors. It is virtually impossible to adjust them in the population-based study. However, thrombolysis has no indication for hemorrhagic stroke and surgery has rarely done for ischemic stroke. This study showed patients with speech disturbance had higher hazard ratios for death in both CI and CH.
Second, detailed language examinations are difficult at emergency care, and therefore speech disturbance was not linguistically classified in the study. Speech disturbance noticeable by ordinary people and confirmable by paramedics and physicians should have practical importance. The present study clarified the usefulness of such speech disturbance as a prompt indicator of stroke severity in a pragmatic manner.
Third, some patients were unable to be assessed as to the presence or absence of speech disturbance, for some reason including conscious disturbance. Consciousness disturbance, however, is well established as a predictor of a poor outcome of stroke. Prompt predictors of the mortality in stroke patients without consciousness disturbance are of importance.
Fourth, we analyzed all death up to 30 days after the stroke onset rather than death long after the event because we thought early mortality should reflect well deaths rather directly associated with stroke.
With all these limitations, however, the study is based on a large number of patients and a significant bias affecting the major conclusions is unlikely.