Neglect after Isolated Thalamic Stroke: A Systematic Review of the Literature.

Introduction: Recent research has increasingly acknowledged the thalamus's role in the development of neuropsychological deficits, which were previously considered to be primarily related to cortical processes. Among these deficits, neglect is of particular importance in stroke survivors, as it is a predictor of poor functional outcome. This review aimed to clarify the relationship between stroke lateralization and location within the thalamus and the occurrence of neglect.

Methods: In the present study, we performed a systematic review according to the PRISMA guidelines. PubMed, Scopus, CINHAL, and Web of Science were searched for articles published from inception to June 30, 2024. All studies presenting cases of isolated vascular thalamic stroke (hemorrhagic, ischemic) and clinical neglect were included. Study quality was assessed using the Joanna Briggs Institute critical appraisal checklist for case reports, case series, and case-control studies. We divided the thalamus into four parts (anterior, lateral, medial, and posterior) based on the four classical vascular territories and performed a qualitative and a simple descriptive statistical analysis using absolute numbers and percentages of the data collected.

Results: A total of 23 articles involving 37 patients were included: 31 cases (84%) with right-sided thalamic stroke and 6 cases (16%) with left-sided thalamic stroke. In the hemorrhagic stroke group (21 cases), there was a clear predominance of localization in the posterior (10 cases; 47%) and entire thalamus (9 cases; 43%), with no cases in the anterior part of the thalamus and only one case (5%) each in the medial and lateral parts. In contrast, ischemic cases were predominantly located in the anterior and lateral parts (6 cases each; 37.5%) with only 3 cases (19%) in the medial part and 1 case (6%) in the posterior part.

Conclusion: Thalamic neglect appears to occur more frequently in right-sided thalamic strokes than in left-sided thalamic strokes. However, the exact neuroanatomical correlates differed between hemorrhagic and ischemic groups and the underlying mechanisms remain unclear due to the heterogeneity and paucity of data. Rather than drawing definitive conclusions, this work synthesizes existing literature and underscores the need for prospective studies with standardized assessments and advanced neuroimaging.