Detection of cerebral embolic signals in patients with systemic lupus erythematosus

Background

Involvement of the CNS in systemic lupus erythematosus (SLE) is caused by several pathogenic mechanisms including cerebral embolism.

Aim

To measure the frequency of microembolic signals (MES) by using transcranial Doppler (TCD) ultrasound and to assess their association with cerebral infarction, neuropsychological dysfunction, and biochemical, sonographic and clinical variables in an unselected group of patients with SLE.

Methods

A 1‐h TCD recording from the middle cerebral artery was carried out in 55 patients with SLE having a mean age of 46 (SD 13) years. MRI of the brain, carotid artery ultrasonography with intima–media thickness and atherosclerotic plaque assessments were carried out in addition to a broad biochemical and clinical assessment. All patients underwent a neuropsychological assessment.

Results

Of the 55 patients, MES were detected in 5 (9%) and cerebral infarcts were found in 9 (18%). A significant association was found between MES and cerebral infarcts and considerably more neuropsychological deficits were found in MES‐positive patients compared with the negative group. MES were not associated with other clinical, sonographic and biochemical factors believed to be associated with cerebral embolism.

Conclusions

Cerebral embolism may be one of the important mechanisms responsible for the high prevalence of cerebrovascular events and the neuropsychological deficits observed in patients with SLE. Although the number of MES‐positive patients was small, the lack of a significant association between MES and other known risk factors for MES suggests a complex pathogenesis for the embolisation in these patients.CNS symptoms and signs are common in systemic lupus erythematosus (SLE) and as many as 50% of patients with SLE may have neuropsychiatric involvement.^1,2 Well‐known complications include psychosis, seizures, cerebrovascular accidents and cognitive dysfunction. Women with SLE, aged 18–44 years, are eight times as likely to be admitted to hospital because of stroke as controls.³ The pathogenesis of CNS involvement in SLE has not been clarified, and multiple factors may be associated, such as microvascular damage, small‐vessel vasculopathy, antibodies to nervous tissue and immunologically mediated thromboembolism. Postmortem examinations have shown microinfarcts and microhaemorrhages in cortical and subcortical regions. Several factors are associated with the increased risk of stroke in these patients. These include antiphospholipid antibodies, use of corticosteroids, cardiac involvement and other well‐known risk factors for cerebrovascular disease.^2,4,5Transcranial Doppler (TCD) examination, a non‐invasive technique, can detect cerebral embolisation in the major intracranial arteries.⁶ Microembolic signals (MES) have been detected during cardiac surgery and carotid endarterectomy.^7,8 Long‐term TCD monitoring of the intracranial arteries has shown abnormal signals, indicating clinically silent MES in patients with high‐grade carotid stenosis, with prosthetic heart valves or after recent cerebrovascular events.^9,10,11 Cerebral microemboli may cause cognitive dysfunction if they enter the cerebral circulation in considerably large numbers. This has been studied in detail in patients who have had coronary artery bypass surgery.¹² Some instances showing a positive association between cerebral microemboli detected by TCD and postoperative neuropsychological outcome after cardiac surgery have been reported.^7,10Three studies^13,14,15 that used TCD for embolic detection in patients with SLE have showed conflicting results. It is therefore of interest to carry out further studies on the possible importance of cerebral microembolisation in SLE.We measured the occurrence of MES in a group of patients with SLE and assessed the possible association with cerebral infarcts, neuropsychological function, risk factors for cerebrovascular disease, including carotid atherosclerosis, and biochemical variables associated with cerebrovascular disease.