The spot sign is more common in the absence of multiple prior microbleeds

Mural thickening and permeability changes in patients with amyloid angiopathy (CAA) and chronic hypertension are implicated in the pathophysiology of multiple, chronic subclinical microbleeds. The Spot sign, contrast extravasation on CT angiography, predicts hematoma expansion and is presumed to represent acute vessel damage. We hypothesize that the Spot sign is more common in patients without multiple prior chronic microbleeds.

A retrospective study was conducted of 59 patients presenting within 6 hours of primary intracranial hemorrhage onset undergoing CT angiography and MRI. CT angiography spot sign presence was documented blinded to MRI. Hematoma expansion was defined as >6 mL or 30% enlargement. The Boston criteria were applied to microbleed interpretation dichotomizing subjects into probable and negative CAA. Basal ganglia, thalamic, and brain stem microbleed location were interpreted as chronic hypertensive pattern. Univariate logistic regression and ordinal logistic regression analysis identified significant predictive factors between spot-positive and -negative patients or microbleed pattern.

The incidence of spot positivity was 42%, 22%, and 0% for CAA-negative, chronic hypertensive, and CAA-positive patients, respectively (P=0.01). CAA-negative patients had higher baseline National Institutes of Health Stroke Scale (P=0.039), larger follow-up hematoma volume (P=0.02), and poorer Rankin score (P=0.049) than chronic hypertensive or CAA-positive patients. After age adjustment, spot-positive (P=0.023), age-related white matter change (P=0.041), number of microbleeds (P<0.0001), and modified Rankin score (P=0.027) remained significantly different between groups.

Boston criteria-defined CAA-negative status demonstrates the highest risk of spot positivity compared with patients with probable CAA and chronic hypertension.