L acunar strokes are small subcortical strokes caused by occlusion of single penetrating arteries. Although thromboembolism is a common cause of large artery stroke, the lacunar hypothesis, 1 much debated, 2,3 proposes that key mechanisms in lacunar pathology are microatheroma and lipohyalinosis, and that thromboembolic lacunar stroke is uncommon. 4 Microatheroma are lipid-containing plaques, which are thought to accumulate in the parent main intracranial artery, such as the middle cerebral artery, and affect the origin of penetrating arteries, or develop in the proximal-penetrating arterioles themselves. Lipohyalinosis is a small-vessel pathology characterized by abnormal endothelial architecture and fibrosis, leading to thickening of the vessel wall and irregular luminal diameter. 5 Despite associations with inflammatory endothelial dysfunction and blood-brain barrier disruption, 3,6,7 the causes of these small-vessel changes are poorly understood.Around 25% of all ischemic strokes are lacunar, 8 and although they have an apparently good functional prognosis compared with cortical ischemic stroke, similar proportions of patients have poststroke cognitive impairment and long-term studies suggest that they identify cerebral small vessel disease (SVD), which puts patients at high risk of recurrent ischemic strokes 9 and of cognitive decline.
10,11However, there is incomplete understanding of the precise mechanisms that lead to the pathology described above, and current therapeutic strategies are limited. This occurs against a background of translational failure, where many interventions reported to improve outcome in animal models of ischemic stroke more generally are not effective in human clinical trial. 12 It may be that animal models do not model human disease with sufficient validity to guide drug development; or that they do have this external validity but their conduct and reporting make them a poor guide, in practice, to support clinical drug development and trial design. For several animal models of neurological disease, systematic review and meta-analysis Background and Purpose-A total of 25% of strokes are lacunar, and these are pathophysiologically different from large artery strokes. Despite emerging evidence of a substantial impact on physical disability and dementia, little attention has been paid to the development of specific treatments. The optimal use of the animal models of lacunar stroke used to test candidate interventions is not known. Methods-We conducted a systematic review and meta-analysis of studies testing candidate interventions in animal models of lacunar stroke. We used random-effects meta-analysis to assess the impact of study characteristics and trim and fill to seek evidence of publication bias. Results-The efficacy of 43 distinct interventions was described in 57 publications. The median number of quality checklist items scored was 3 of 8 (interquartile range, 2-4). Many models reflected mechanisms of limited relevance to lacunar stroke. Meta-analysis of results from 27 s...