Background: Some investigators have stated that monoparesis is almost never the result of a lacunar infarct or cerebral haemorrhage.
Objective: To describe the topography and aetiology in a consecutive population where first ever stroke was manifested by isolated monoparesis.
Methods: Patients with motor paresis of only one limb were included consecutively in the study. A neuroradiologist determined stroke location, while a neurologist reviewed the clinical records to assign stroke subtype. Both physicians worked blind to each other's findings.
Results: 51 of 2003 patients (2.5%) had isolated monoparesis, and of these 39 (76.5%) were ischaemic strokes and 12 (23.5%) were haemorrhagic. Cardioembolism was the cause of stroke in 15.7%, atherosclerosis in 9.8%, and small artery disease in 39.2%. Most of the haemorrhages were in the thalamic-capsular region (5/12). Most of the ischaemic lesions were in the deep territory of the middle cerebral artery, the corona radiate, or the centrum semiovale (20/39); 16 of 39 were in the cortical territories or the watershed region.
Conclusions: Isolated monoparesis is a rare symptom in stroke patients and is often caused by small artery disease or a small haemorrhage.