Clinical and radiological determinants of transient symptoms associated with infarction (TSI)

Background: The definition of transient ischemic attack was traditionally based on clinical features only. The wide use of magnetic resonance imaging (MRI) led to the definition of a new entity - transient symptoms associated with infarction (TSI). It is unclear why patients with similar radiological infarctions may have different clinical manifestation - ranging from complete symptoms resolution to major neurological sequelae. We sought to determine which factors differentiate acute diffuse weighted imaging (DWI) lesion presentation - stroke versus TSI.

Methods: 282 Participants, recruited for the Tel-Aviv Brain Acute Stroke Cohort study (TABASCO), were enrolled consecutively. Participants underwent extensive cognitive evaluation, wide laboratory tests and brain MRI scans evaluated for cerebral small vessel disease (SVD) biomarkers, according to the STRIVE protocol. Demographic and clinical characteristics were also examined.

Results: A total of 239 patients had stroke and 43 patients had TSI. TSI patients had smaller average lesion volume (0.77 cm³ versus 2.64 cm³, p = 0.002). Lesion location did not differentiate TSI and stroke. Stroke patients had elevated inflammatory markers, unrelated to lesion size (CRP 4.2 mg/L versus 1.7 mg/L, p = 0.011). TSI patients had better global cognitive score and MoCA score at admission and 24 months following the index event (p < 0.001). TSI patients also had better Berg balance score (p = 0.004). No significant association was found with MRI SVD markers.

Conclusions: Lesion size, but not location, differentiates TSI and stroke, especially at a cutoff value of 10 cm³. Elevated inflammatory response was linked to worse course independently of lesion volume. Cognitive and high function tests are associated to the clinical phenotype of ischemic lesion and may be a marker of brain reserve and compensatory abilities. SVD markers do not differ between TSI and stroke patients and probably do not fully capture the extent of brain vascular pathology and reserve.