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Some psychiatric conditions produce symptoms that can mimic an acute neurological disease, including stroke.1–3 In several studies, such symptoms seemed to be more common on the left side of the body.1–3 The predominant processing of emotional information by the right hemisphere offers a hypothetical explanation for this finding.
We reviewed the discharge summaries of patients who were admitted to a stroke unit during the period May 1996 to December 2003 with a diagnosis of acute stroke and who had a discharge diagnosis of somatoform disorder and/or anxiety disorder according to the DSM-IV, revised4 criteria, and no recent stroke, according to the World Health Organisation definition.5
Two investigators (CS and LC) reviewed the discharge summaries independently and collected the following datain a standardised form: (a) age; (b) sex; (c) discharge psychiatric diagnosis (somatoform disorders: somatisation disorder and conversion disorder; anxiety disorders: generalised anxiety disorder and panic disorder); (d) type (motor paresis and/or involuntary movements, sensory, visual, other) and side (right, left, bilateral) of the symptoms; (e) vascular risk factors; (f) neuroimaging data; and (g) length of stay. Disagreements were solved by consensus.
From 2279 consecutively admitted patients to our stroke unit, we included 35 (1.5%) discharge summaries for review. Of these, 25 patients had received a diagnosis of somatoform disorder (14 with somatisation disorder and 11 with conversion disorder), and 7 patients had a diagnosis of anxiety disorder (4 with generalised anxiety disorder and 3 with panic disorder). Three patients had other psychiatric diagnoses. Symptoms were presented on the left side of the body in 11 patients, on the right side of the body in 14, and 10 presented bilateral symptoms (table 1). There were 21 patients (60%) with vascular risk factors, of whom 11 (31.4%) had more than one risk factor. Median hospitalisation stay was 3 days.
There were no statistical differences in demographic variables, discharge psychiatric diagnosis, type of the symptoms, vascular risk factors, neuroimaging data, or length of stay between patients with left sided symptoms and those with right sided symptoms concerning (table 1). Patients with somatoform disorders had motor symptoms more frequently than did patients with anxiety disorders (χ2 = 6.84; p = 0.02).
In this study, 1.5% of the patients admitted to a stroke unit presented symptoms unexplained by stroke or other neurological disease and fulfilling the criteria for psychiatric diagnosis. Contrary to most of published studies, our results did not show a preponderance of left sided symptoms. In a meta-analysis of all studies describing patients with medically unexplained symptoms, Stone et al concluded that is not certain that the functional symptoms are more common on the left side than on the right side of the body. They found a preponderance of the left symptoms only in the studies in which the investigators were aware of the laterality hypothesis before performing the study.1 As in that meta-analysis, we did not find a preponderance of left sided symptoms.
The younger median age and the female preponderance of patients with psychiatric conditions mimicking a stroke reflects the demographic characteristics of somatoform and anxiety disorders. One interesting finding was the high frequency of vascular risk factors, which increases diagnostic uncertainty and could explain the admission to the stroke unit. A major limitation of our study is the lack of use diffusion magnetic resonance imaging to exclude definitively the unlikely possibility of a concomitant ischaemic lesion.
We conclude that left sided laterality of symptoms cannot be used as a tool to establish a psychiatric diagnosis in patients with acute lateralised neurological symptoms.
Competing interests: none declared